UPDATE:  As of late 2016, Nuaire have released a new updated range of DriMasters – called DriMaster Ecos.  These are blue, not green.  See right, and also see HERE

TheSAM_1818[1] main purpose of this site is to give you my views and experience of a Nuaire Drimaster heat PIV anti condensation system installed into my “new” home – a 1930’s detached old house.  We had condensation issues – see HERE for details, but in summary:

  • Bedroom windows were “wet” every morning, needed wiping/drying daily (even with windows slightly open)
  • Mould growing in corners & ceiling edges, clearly painted over by old owners
  • Water “running down” walls in bathroom after a shower etc

So clearly, we loved the house and needed to deal with it.   See HERE for details of other tips we applied, but then we installed this PIV system.

Anyhow, we all know mould/damp is a pain, and we thought we’d be proactive about it, and thus try and avoid any future problems (like mould behind wardrobes etc) – especially as we’ve just started decorating the new house.

A couple of “internet friends” on a forum mentioned http://www.envirovent.com/ and that they had a PIV system installed from them, and had astounding results.  Environvent seem to be a consultancy/installer and not really suitable for DIYers – and hence the cost is fairly high.  But, the first-hand results I heard were positive.  So I started looking for alternative PIV systems…

What is a PIV system?

Well, its a “Positive Input Ventilation” system which basically is a system which increases air pressure inside a house which forces older/wetter air out of the house and thus prevents condensation.  Thats the theory, and to be fair I’m not entirely convinced it isn’t a snake-oil product!  The forum threads http://markbrinkley.blogspot.co.uk/2005/09/shit-misses-fan.html and http://www.diynot.com/forums/viewtopic.php?t=110195&start=0 give both sides of the story – many people saying the systems are superb, and a few saying they are not.  Interestingly, the miracle stories seem to be from owners, and the negative comments seem to be from the theorists.

I came across Nuaire Drimaster products http://www.nuaire.co.uk/our-products/search?m=1104&pt=1685 and as these can be bought as DIY installations at reasonable cost, I thought it was worth a punt…

So I ordered it, and was surprised when it came as to how big it was and how “professional” it felt.  A cheap ebay import it isn’t – it feels like a commercial grade product, which (as Nuaire do commercial products) isn’t a surprise, and hence the confidence of a 5yr manufacture guarantee.


The above picture shows the unit the grey bit at the front is the heater (with controller electronics on the left) – and the PIV is the green bit (electronics in there) – the white ears are the filters.  Ducting and vent included, the switches are mine.

Nuaire Drimaster Heat

I opted for a Nuaire Drimaster Heat (http://www.nuaire.co.uk/products/catalogue/residential/positive-input-ventilation-piv/drimaster-heat/ ) .  This is a loft-based PIV system with a single loft based unit with an outlet on the landing.  This system (apparently) does:

  • Programmable speed for small or up to 5 bed houses.
  • Clever automatic heat recovery to use “solar gain” if the sun is warming the loft space
  • Auto summer shut-down
  • Air heater if loft air is cold

The air heater is a 500w heater which makes the air warmer if the air in the loft is cold.  This is for “our” comfort rather than any anti condensation functionality as it just prevents cold draughts.

Another benefit is that as the air is sucked out of the loft, it will actually force air movement and refresh in the loft space which of course will help with loft ventilation.

Nuaire have been established for 20 or so years; sell internationally, and also sell commercial grade products.  This inspires confidence in the product and company as I doubt they’d be around so long if it were snakeoil…  The product feels well made, and if nothing else, it is well engineered!  It comes with a 5 year warrantee.

Possible issues

As the air is pulled from the loft, when it is very cold, then very cold air will be blown into the house.  This is minimised with the heater, but of course it is still sending in cold air.  Our stairs/hall are coldish anyway so not overly concerned, and I’m guessing this is better than open windows in each room anyway.  In my experience, when the heater is on the loft can be cooler – so personally I’d not want one without the heater.  Remember though the heater takes the chill off the air (on thermostat) only – it isn’t a fan heater – and it won’t blow out hot air!  (My laser thermometer does show the air coming out is roughly the expected temp)


The kit comes withSam_1929[1] everything you need, bar some suitable cables, but I’ve opted to wire it slightly differently.  I’ll use 2 double-pole fused isolators, one for the entire unit, and one just for the air heater.  This will mean it complies with regs having an isolator, but also I can enable/disable the heater if I desire without affecting system functionality. (if I find a spur-timer cheap enough, then I’ll install one for the heater to prevent the heater running overnight).

The rest of the install looks a doddle….!

  1. Cut a 225mm hole in the loft ceiling suitable for the output vent.
  2. Mount the brackets on suitable joists
  3. Fix unit to brackets
  4. Connect and seal ducting tube
  5. Cable up as necessary

Sam_1931[1]I connected it to a fused spur off the lighting circuit as this was more accessible in the loft and isn’t as naughty as it sounds as, for example, shower extractor fans and shaver points are run off the lighting circuit.  The Drimaster Heat is fused at 3A but pulls a maximum of just over 500W, and as the lighting circuit is 6A and all our lights are low power, there is plenty of capacity.

Once installed, we set it to speed 4 (of 6) which is the right speed for our size house, and this seems to pull a constant 16W to run the fan which equates to 4p per day (excluding heater).   Pending success or otherwise, I may reduce speed to 3.  (4 = 40 litres of air per minute)

All that can be seen in the landing is a fairly discreet and flat vent, and the isolating switches.  Once the ceiling and landing is finished and decorated it will blend in fairly well.

In the loft, the grey bit (between the green bit and the flexi pipe) is the heater, and clearly I’ve ensured there isn’t any insulation touching or close the heater enclosure, even though its not that high powered or likely to be a problem.

Overall, a nice simple install, and now see if it works…..



Does it work?

The system works, and you can feel a nice amount of air movement.  The fan is very quiet and completely non intrusive.  We installed it as per the instructions and do not have a noticeable draught.

After a few hours

Placebo effect or not, the upstairs landing definitely felt fresher, so if nothing else, the system moves more air around!  The landing does feel a bit cooler, but not colder….   We’ve closed half of the upstairs windows and will see how things look in the morning…

First day

Well, the upstairs landing is definitely cooler and fresher.  I guess a thermometer would show it being colder, but it doesn’t feel cold.  Weird, but guess its the humidity change.  Overnight we closed 1/2 the bedroom windows, and in the morning the windows were still a bit condensated 🙁  So no magic solution after the first night.

5 days later

After being out for a couple of days, we came back and the hall/landing was still fresh.  Maybe we need to turn the speed down a bit!  But, we have closed all windows upstairs (and we don’t have trickle vents).  As such, the bedrooms are definitely much warmer.  The first night back we slept with the windows fully closed which would normally mean wet windows, but on the first night back (day 5) the windows had a light mist only on the bottom 1/4 of the window.  And by light mist, I mean as if you just simply breathed on the glass.   It was however a warm night in the bedroom 🙂

The next day it was 0’C outside, and with windows closed would normally result in very wet/condensated windows.  However, in the morning the windows were 99% clear of any misting or condensation. maybe 1cm high light mist at the bottom.

Bizzarely I’m still not convinced lol!  But the last 2 days have been mightily impressive.  Just need to monitor to ensure it is working as it still feels too good to be true.

The cooler landing isn’t an issue as the bedrooms are definitely warmer, and we’ve opted not to use the built-in air heater just to see how it goes.  (update:  over the winter months we now do have the heater on for OUR benefit to stop the landing getting cool)

So, 5 days in, looking good….

Update 30 October 2013

Well there has been a lot of interest on this page, and a fair few people asking how it has gone and if it works, so thought I’d do an update.

Its interesting as, as you know, I’m a sceptic 🙂  We have at last decorated the landing so the system is now much more discreet.  Its been on 24×7 and the heater (which I’ve got on a separate switch) was only on during the very cold winter.

Its hard to say for 100% certainty if it works as no two nights are the same humidity or internal/external temperature, so the scientist in me hasn’t yet proved it.  A mild October doesn’t help comparison.  BUT – since installation we have NOT had to wipe any windows down at all.  Last night (Wet and 5′ outside), we have 2-3cm of LIGHT misting at the bottom of the window.  (prior to installation it was thick misting all over that would run off and the sort you could wet a towel on – but we’ve had nothing like that).

The mould we did have (fresh and small black dots) has gone or gone grey and easily wipes off.

We have checked, and there is NO mould behind any furniture or wardrobes etc.

BUT – we’ve also learned about condensation and made other changes which all help:-

  • We fitted a powerful shower extractor fan (vented externally), and leave the bathroom window open for a few mins after a shower, and close the bathroom door.  We also have the temp a bit lower.
  • We’ve had the house re-roofed (not related!) and this meant a new breathable felt membrane and also meant we could add insulation to otherwise impossible to get at areas in the corners of the rooms.
  • We leave windows on “night” settings in rooms we have the heating on low (e.g. guest room)
  • We use the cooker extractor fan (vented externally) when cooking
  • We have had a log-burner installed (which when used sucks moist air from living area and uses it thus removing moisture)
  • We have installed vents in other chimneys that were bricked up
  • We leave the bedroom door slightly ajar most of the time (though we close when guests stay and its still okay)

So the Nuaire Drimaster is only part of the changes we’ve made – and hence hard to say 100% if it does the job by itself.  Oh – and we altered the default program so it goes into “heat recovery mode” when loft is 18′ or more which is lower than normal, and set the heater to only come on <14′ over winter, which suits our install.

SO – the bottom line is – I can’t 100% prove it, but from a week after installing, we have not had to wipe down any windows or had any condensation issues……..

Would I buy and install again – yes.

Update March 2014

After Darren took the time to post in the comments section, completely unsolicited, I thought I would also give an update.

After decorating we found evidence that mould had been covered up and bodged by previous owners.  However, after decorating and with this system still running, we have had NO mould appear, walls dry, and windows only “very minor” condensation on a cold night – and that is with windows locked closed (so minor, windows not wiped or opened).

Over winter the loft air is cool so the heater takes the chill off but (of course) uses power to run – 500W, so max 12kwh a day, £1.50 max?  Of course it isn’t on full all the time (automatic), but maybe £20-30 a month over cold winter months.  Still cheaper than fixing mould!  And of course the heater is for OUR benefit, not to help with condensation.  The reverse, when the sun comes out the loft gets hot and we’ve tuned the Nuaire to go into “high speed” mode when loft is >18′ – so when sun on roof we get “free” heat blown out.  Also as air is “better” the heating is probably lower than it used to be for the same comfort.

We’ve decorated the landing now so the unit can hardly be seen and its just forgotten about and it quietly gets on with the job.  Still happy with it, and it still works….

From Darren (see comments):  “Just wanted to say thanks to Ryan for this blog, it helped persuade me to purchase a drymaster heat which has been running since early December. My house suffered really bad with surface condensation on windows, walls, behind furniture, mold etc. Thought I had rising damp at one point but after research and reading this blog heard about PIV. All I can say is that this system has totally cured our problem. Since installing I have not ONCE had to wipe down windows at all. This is amazing as our windows were normally saturated every morning in the winter months. I cleaned all the mold off the ceilings and walls after a week of installing the unit and to my amazement it has not come back whatsoever. The house feels fresher as all the stale air is constantly pushed out of the house so it is just a nicer environment. I will mention that you will notice the landing will be a bit colder due to the fresh air being pumped into the house, I could turn on the heater but have not felt the need so far. For people asking about settings it depends on your house, installation and severity of problem, I have a 4 bed house and suffered terribly, I initially had it on setting 4 but have recently turned it down to 3 and it is still working fine. I have also been able to turn down the heating thermostat as its so much quicker to heat the house due to much lower moisture.

I got a sparky to fit it and it was real simple for him. I purchased a heavy duty chain and hook from screw fix for £10 and hung mine from the rafters, it really works well and means no vibration. I would recommend anyone buying one to do the same. I also like Ryan run the heater off a different switch in my airing cupboard, that way if I need the heater on its simple to do without climbing into the loft.

I really can not say enough good about this system and for anyone wondering if it really works, it really does. Would I buy one again, 100%

Update October 2014

So, its 30 October 2014 and I’ve just turned the “heater” part back on as its getting cooler.  The heater has been on for just over a week and using an extra couple of units a day, but nothing too much and even then cheaper than dealing with mould.  But the system has been on all summer and still, house is mould free and even checking behind units its fine.  So still really happy with it.

I thought I’d better upload a pic of the final install as the picture above makes my house look like a building site!  It was, but once decorated the unit is very discreet.  The lighting is poor and the photo makes it look more obtrusive than it is its the early morning shadows- in fact its barely noticeable and visitors seldom see it, and as its quiet they don’t hear it.



TOP TIP (painting over old mould)

When redecorating we had one corner that use to be very mouldy, and previous owners clearly bodged it which meant that I could not paint over it – standard emulsion would just not dry.  No idea what on earth they did!

So, another top-tip from me is to buy some Zinsser BIN (B-I-N).  This is a special paint which is expensive, but it does what it says on the tin.  Basically, you roller-paint it over any problem areas (like mould, old water damage, rust marks, rusty nails embedded in wall, old chemicals/gloss paint etc) – and go for a cuppa. After 45 mins its dry and you can emulsion over it as normal (!).  Yeah – really!  It is a must-have for every old house.  I’d recommend a cheap foam roller set from Poundland as the roller will need binning after use.

Where I’ve used this, the emulsion paint has been perfect, and no marks have come through.

Final Update, November 2018

What can I say that hasn’t been said before!  5 years on, and still the device seamlessly prevents our condensation and mould issues.  Why wait!


Please note these comments were made by genuine posters on my blog here, and were copied from there to here to retain their valuable contributions.

86 thoughts on “Nuaire Drimaster”

  1. Hi. Just wondering after 6 months what your impression is of the Drimaster now? We are thinking of installing one in our solid stone walled house that suffers with inevitable damp issues. Any feedback would be welcome. Thanks.

  2. just wanted to share my experience fitting a Nuaire Flatmaster with everyone, this could happen when fitting a Nuaire Drimaster too!

    I had been quoted £980.00 + VAT from Envirovent and £780.00 + VAT from a Nuaire fitting company. Both prices sounded reasonable but I did a bit of research and found I could buy a Flatmaster on Google with a heater for £320.00 + VAT so I went ahead and purchased it.

    The unit arrived the next day, I was then shocked by the complexity of fitting it, which needed to be sighted in a central location and an input vent cut through the wall and various ducting installed.

    This was too much for me, so I called Nuaire and they recommended an installation service but he wanted £600!

    The solution was obvious call in a local contractor; I looked on Google and found a PCA approved company who was a damp and condensation specialist.

    They sent around Miguel (with an invoice of £400.00 + VAT) he sat on the floor and opened the box and read the instructions then proceeded to cut a hole through my wall to install the inlet. The mess was so bad, dust everywhere! He said it was the only way. He then spent time installing the ducting and finally wired in the unit to the main ring. I asked him if he was qualified and said we are Part P approved.

    He blew all the MCBs and I could smell burning at that point I showed Miguel the door with his unpaid invoice.

    I contacted Nuaire again who gave me condensationcontrol-uk.com phone number who I called, they fixed the wiring and sorted the fan.

    They told me installers should be BPEC this is an industry regulation relating to ventilation products.

    The summary of the story is always use a proper company or it will lead to problems like I had and even invalidating your insurance by having an unsafe unit fitted.

  3. Hello to everyone interested in this post, we are west Yorkshire based specialist remedial company(www.xxxxxxxxxxxxxxxxxxxxxxxx.com) who supply and install the Nuaire Drimaster Heat and other Nuaire Products, i can only praise this unit as this works with great performance where condensation has become problematic, we have been installing this unit over the last 4 years and have never had one complaint or criticism.If you are in two minds if to install this in your property i can only advise to go ahead and you will not be disappointed, please use a reputable installer that fully understands the product and also understands the property and severity of the condensation problem so the unit can be set up to deliver its best performance,if you live in the Yorkshire or surrounding areas and require further advice or a quotation for installation please do not hesitate to contact us further.

    Steve Pearce

    1. NOTE FROM DYD: Thanks for your comments Steve – but as you didn’t have the courtesy to ask first I have deleted reference to your company as this is not for free advertising for any old company who spams my blog. I’ve left your comments though as they may be useful to readers

      1. Like your idea about wiring the heater separate. Was this easy to do as the wiring diagram for the unit looks pre-wired.

        1. Hi
          It was trivial – the heater is pretty much entirely separate – it can be added separately and is fully independent from the main unit – the thermostat and control is in the heater, not the drimaster.
          So I had

          power----->switch 1---> Drimaster
                             \--> Switch 2 --> Heater

          So switch 1 isolates both, switch 2 just heater.

          Hope this helps

      2. Sorry to all for making reference to my company name no hurt or malice intended, sorry Ryan and mell



  4. Hi Ryan

    i just installed the unit today the way i wired the unit is on two separate fuse spurs one for the main unit and one for the heater. Son one fuse spur switches the main unit on/off and the other one switches the heater on/off. Can you please confirm this is OK??

    1. I am not qualified to give you advice – this page just shows how I did it. I did it differently – my heater fused spur is off the main fused spur. Thus the main switch turns and isolates everything; and the second switch isolates just the heater. Current draw etc taken into account. This is my way – not giving advice nor saying which is better. I am not qualified to advise.

      1. Thanks i spoke to Nuaire today and they confirmed it can be wired both ways. One more thing Ryan how can i check if my heater is working? there is a red light in the control box which flashes when i switch the heater on. does the red light means the heater is on??


        1. I don’t actually know – I always had the cover on when linked up to the mains! 🙂 Its easy to check if you watch a “power meter” as it’ll drop about 450W when its on!

  5. Really grateful for all of your info Ryan/Mel. I’ve just been quoted £800 to have one of these installed in a three-bed standard terraced house!!! Thanks to you, I’m going to buy a unit myself and have my (fully qualified) electrician install it for me.
    Thanks again from (Fellow Motorhomer) James

  6. I’ve installed a drimaster heat. Could you tell me what settings it should be on please. The upstairs landing is really cold, a lot lot colder than it was before I installed it. I live in a 3 bedroom semi detached house. Thankyou

  7. My son installed a nuaire drimaster heat for me. Could u tell me what settings it should be on plz. It is very cold on my landing. I live in a 3 bedroom semi detached house. Thankyou

    1. I would try setting 3. If any sides of the diffuser are very close to a wall (less than about half a meter) I would also block that side of the diffuser off with the provided sponge blockers, it will then divert the air out of the other sides and should reduce the cold air running down the walls which may be why you are feeling the cold. Just a thought.

  8. Just wanted to say thanks to Ryan for this blog, it helped persuade me to purchase a drymaster heat which has been running since early December. My house suffered really bad with surface condensation on windows, walls, behind furniture, mold etc. Thought I had rising damp at one point but after research and reading this blog heard about PIV. All I can say is that this system has totally cured our problem. Since installing I have not ONCE had to wipe down windows at all. This is amazing as our windows were normally saturated every morning in the winter months. I cleaned all the mold off the ceilings and walls after a week of installing the unit and to my amazement it has not come back whatsoever. The house feels fresher as all the stale air is constantly pushed out of the house so it is just a nicer environment. I will mention that you will notice the landing will be a bit colder due to the fresh air being pumped into the house, I could turn on the heater but have not felt the need so far. For people asking about settings it depends on your house, installation and severity of problem, I have a 4 bed house and suffered terribly, I initially had it on setting 4 but have recently turned it down to 3 and it is still working fine. I have also been able to turn down the heating thermostat as its so much quicker to heat the house due to much lower moisture.

    I got a sparky to fit it and it was real simple for him. I purchased a heavy duty chain and hook from screw fix for £10 and hung mine from the rafters, it really works well and means no vibration. I would recommend anyone buying one to do the same. I also like Ryan run the heater off a different switch in my airing cupboard, that way if I need the heater on its simple to do without climbing into the loft.

    I really can not say enough good about this system and for anyone wondering if it really works, it really does. Would I buy one again, 100%

    1. Hi Darren. Thanks for your comment – really good to hear. We still have a zero issue (even with windows closed) – but as it is a bit of a snake-oil product, I am pleased to hear firsthand that it is helping someone and isn’t just luck. We also tuned our heat recovery settings, so whilst the heater is on when its cold, when the sun is out the heater clicks off and the fan speeds up sucking the heat out of the loft space – and that does help.
      Thanks again for making an effort to post here.

  9. been charged £850 to supply and fit
    what u think?
    how much electric does it consume a year? in pounds?
    i have a big mould and black condensation problem

    1. I’m only another customer, so can’t say as every install is different and may take a while to do depending on access etc. Seems a bit steep though as its <£400 for item and other parts, so £450 labour... Depends how long it takes. Took me probably 3-4 hours? As for how much cost to run, again depends on your settings. My costs are listed in main post.

    1. Thank you for your post – pleased to hear other successes as otherwise “readers” may think I’m just doing an info-mercial!

  10. i had a Drimaster installed about two years ago in my very old stone cottage. We had dreadful mould problems as the walls are three feet thick and very cold. The Drimaster has completely cured the mould and I haven’t had to bleach the walls since installing it. My only query is whether, now that I’ve had central heating installed, we are paying to heat the outside air, since presumably the warm indoor air is being drawn out and cold, dry air being drawn back in. Any comments would be welcome. Thanks.

    1. The system pulls in air from loft/outside and blows it in. Yes, in winter its cool/cold, that’s why I bought the drimaster heat. The warm air inside only escapes via normal holes, its not blown out. If you want to minimise that you need a fully blown heat recovery system. But the Drimaster Heat should be fine, but of course cost to heat the cold air in winter, but cheaper than fixing mould!

  11. Ive the Drimaster Heat but cant work out the heater settings can someone give me some advice on this please. My landing is certainly drier but a lot cooler.I only seem to manage to turn the fan up or down and cant get my head around the settings.
    I fitted the unit about 6 months ago.

    1. There are 2x different settings. One on the behaviour of the unit (see section 12) – for loft heat recovery. Think I went for option 2 or 4 – can’t remember. Read the manual as getting to this program mode is awkward. Also, you can adjust the dial on the board of the heater to the set temperature on the heater. Make sure the heater is working and “on” too – as if “on” the air should be as warm as you want it. (though balance between heat & cost….)

  12. I bought my Drimaster-heat on Amazon for £307, cut the hole, installed the vent, then the unit in the loft as per the instructions, the only difficult bit was getting the flexible tube on to the unit but all in all one afternoon, wired it, tried it, works perfectly (have to have it checked by a qualified sparky now). So, not too difficult to install, there is also a very good video on Youtube which helped me.

  13. After extensive research, due to being cynical that it would work I purchased this unit. We have a 90yr old bungalow with solid walls and suffered with mould in the three bedrooms. Humidity levels were 74 – 77% every morning, Envirovent suggested readings should be 45 – 55% along with their quote of £2000 which is why we went for Nuaire.It has now been installed for a week, I helped the electrician install it so his charge was £100 and took us 5hrs.
    24 hrs after install (on setting 4 which is probably too high for the size of property) the readings had dropped 10% , after five days they have dropped to 53%. The walls affected by mould now have a “powdery” feel to them as they are drying out. Their is a 2cm band of condensation on one of the bedroom windows and that’s it. We’re staggered by the results and has by far exceeded expectations so thanks to this blog and all the comments for advice. We never believed that we would cure it for £400 – as I look out now all the neighbours have their windows open except for us.

    1. Hi Paul
      Thank you for taking the time to reply, I never checked humidity levels to good to her the difference that makes. After 2 years, we are still surprised it works lol – but even today, -2’c outside, windows closed, we just have a 2cm band of condensation which clears quickly. One day this year we had a light dusting of mist over the window (maybe we generated too much moisture overnight lol) – but still never wiped the window.
      Hope this page helped in your research. Best wishes

  14. We have a 4500 sq ft 3 story house with 26 windows which would have approx 1 inch of condensation on a cold frosty night. We fitted 3 drimasters units 6 weeks ago, 2 of them on the top floor set at 4 and 1 on the 2 nd floor set at 3. The house was originally 2 houses put into 1 big house. I bought a humidity meter and the readings on it can be as high as 83percent, should this not be lower. We would still get condensation approx. 1 inch on very cold nights. The air in the house is fresher and cooler. The 2 drimasters fitted in the top storey use the same roof space which is about 30 ft long and 12 ft wide. Should these drimasters not work better at these settings and why is the humidity still so high. Does it depend on the outside weather conditions, if it is a wet day the humidity inside is higher, is damp air being pulled into the house or does it depend on temperature of the house? Please if someone can help me, should we still get condensation with the drimasters running at the settings stated and the approx. size of the house. If you have any thoughts on these I would really appreciate your comments. Thank you

    1. Hi Linda. Please see the “about us” page, as I am most definitely not an expert on this topic, I’m just some bloke on the internet who has one!
      I would say, 1″ of condensation isn’t bad – we still get maybe 1″ at the bottom of the bedroom windows on some nights. Previously, prior to install, we used to get the entire window “wet” – not just condensation but water running down, so getting to 1″ for us was a success.
      83% humidity does sound high though, and remember the PIV does not dehumidify and should only be part of the solution. So I would say you need to look at HOW the moisture is getting there in the first place and address that. See http://www.drimaster-piv-condensation-system.co.uk/condensation-removal-control-solution/ – as if you are drying clothes over the radiators, and do not extract from the bathroom, then you need to address this first.
      If your loft is damp/leaking or has high humidity, then yes that will be pulled into the house. No one else has mentioned this…. Maybe monitor the loft humidity? We had the house reroofed with a breathable membrane (post PIV install due to roof leaking, not related).
      Sorry I can’t help more

  15. I live ina 1979 bungalow that had condensation issues with musty smells effecting our clothes, youngest developed asthma. I met an MSP in Scotland who said that there were issues with insulating houses to such a gegree and neglecting ventilation. He told me abot these funny machines that you can fit in the loft. I didn’t think much about it until my neighbour had a PIV installed and thay said it transformed their home. They got charged £1000 for supply and fit.
    I looked arounda nd decided to go fora Nuaire Drimaster Heat, i had read reviews and they seemed positive but i was still sceptical.
    I paid £300 and fitted it myself which took a few hours but was very simple, wired into the ceiling ring with the appropriate fused switch. I also wired the heater seperately with its own switch so i could have control.

    Wow! i can’t belive it, in amatter of days the Drimaster has transformed my home into a fresh smelling airy environment with absolutely no condestaion issues on the windows even in minus temperatures outside. i am totally over the moon with this and would recommend this unit without hesitation if you have any concerns about damp and humid environment in your home. I have mine on setting 3 and all is good considering knocking it to 2 next week to see if still as effcetive. i ahve the heater set to come on at 10c as recommended by Nuiare. I cannot hear the fan at all in the house and i have mine screwed to the joists above the hall on its supplied rubber mounts, i can’t unless i really concentrate feel any draft or flow either in the hall but can see that its working as a bit of fluff at the coving is moving.
    I so wish i had installed one years ago.

    1. Coley – many thanks for taking the time to post that. I have my heater a little warmer (14′ I think). Interesting the price difference between DIY and supplied/fitted by a “condensation company”.
      lol @ seeing fluff on the coving moving – same here 🙂
      Thanks again

    2. Two fans mounted in the same place can cancel each other out. Its the same if you use two extractor fans in a kitchen at the same time. The drag from the two fans can create a negative pull as they pull against each other. One fan running at higher speed would be much better. I am not a scientist at all but in my years in the building trade I have seen this happen. The first time was a kitchen that had a fan in the window and a ducted cooker hood over the hob. The lady naturally though to put both the fans on at the same time and get double benefit but no, the kitchen was full of condensation. I told her only to use one fan at any time an no condensation. I suppose you could say that was a scientific experiment.

  16. Hi,

    I am thinking of getting a Flatmaster for our 2 bedroom flat. Only place I can install it is in our boiler room. Do you think it’s ok to have the inlet next to the boiler’s exhaust outlet? There is a hole already on the wall that I can put the inlet of the Flat master through.

    Any comments are much appreciated.

    Thank you.

    1. I’m not an expert and don’t pretend to be, so you really should contact Nuaire and ask them for their rules & regulations My personal feeling is not a hope in hell! The flue is there to get rid of toxic gas. Even having a window close is prohibited. Having a suction inlet pulling those fumes in is likely to put you on the Darwin award list.
      Maybe outlet and run ducting to somewhere safer – but please speak to the manufacturers and experts. Gas combustion fumes can easily and quietly kill – so don’t risk it

  17. Can you help I have installed a drimaster about 12 years ago and it has stopped going the transformer box with the green light seems to be flashing and all the red lights are flashing as well nothing seems to be going has the motor gone and do I need to replace the unit

    1. I have just had the same issue, however I have only had mine a matter of months. Did you ever find out what was wrong?

  18. Hi, we have condensation on our bedroom windows. We sleep with the door closed. Would we have to have the vent in our bedroom or would a landing vent still be effective.
    Many thanks,

    1. The way these things work, is *slight* extra pressure and that causes air movement. A single unit, vented on landing, is good enough for 4 bed house. On most doors, closed or not, there are big gaps where air naturally flows. So no, you do not need an outlet in the bedroom – just a single outlet on landing.

      However, if you have an air-tight door then well, that isn’t going to work 🙂

      Also remember I am a single happy customer/user and not an “expert” contact supplier with any questions – but hope the above is useful

  19. Hi Ryan and Mel. Thanks for the detail on the drimaster. I’ve just moved into a 1930’s bungalow which has a condensation problem. Having researched the Nuaire products, I think that this would definitely solve the problem for us. I have one question which I hope you can help with. Our house has an upstairs extension, so very little loft space remains (and certainly not enough for the drimaster). We have a large cupboard in one of the eaves, which I thought could be used, but it would mean that the kit would have to be installed with the output vent and diffuser being aligned horizontally to the machine rather than vertically as is shown in all the photographs I’ve seen. Do you think that this would be ok? I’ve looked at the flatmaster as an alternative but would prefer to avoid the trouble of putting a hole through an external wall. Thanks for your help.
    Best, Frank

    1. Remember I am an owner/user – not an expert.
      But if I read you right, you want the outlet vent horizontally? Personally, I see no issue with that as long as the air comes out it should work. Depends where it is and ensure the room has airflow. Make sure the cupboard has a large volume of air that would otherwise be isolated from the house (e.g. drawing air through eves from outside).
      So in other words, if it is the equivalent of in a loft, vented externally, I don’t see why a horizontal outlet would differ from a vertical one.
      Good luck

      1. Thanks. Your point about having air coming in through the eaves is exactly what I was thinking. Will check this out. Thanks again.

  20. Hi Ryan/Mel, Just a quick question…and many thanks for all your hard work in putting all this info together. If the unit is basically sited in the upstairs loft, is the flow of air just as effectiuve downstairs as upstairs? My problems are mainly downstairs but also a bit upstairs. Many thanks! Pete

    1. hi
      in theory yes they cover the whole house.
      bt condensation is caused by moisture in air so bedrooms usually suffer. so why do you get in downstairs? where is the moisture coming from? cooking, washing, drying clothes, leaky pipe, damp etc…? if so sort that – piv is not a miracle fix all you need o address the cause if you can – then piv will help
      see my site dedicated to this rather than my travel blog lol see http://www.drimaster-piv-condensation-system.co.uk/
      more info and hints there on addressing getting rid of moisture
      remember I AM NO EXPERT

  21. Hi there. After reading this blog I have also decided to install a nuaire Drimaster, but as my property is rented out I’ve decided to save myself £150 and have the standard drimaster (unheated version). We live in cornwall which doesnt suffer so much from the cold as it does rain and dampness. I too have a 100+ year old cottage with no cavity and mold appears EVERY winter behind sofa’s and in corners of the bedrooms (outside walls) The installer who is fitting it next week said it should be fine as long as they have central heating on you will not feel draft from the fan? Has anyone else opted for the standard unheated version and have any comments on how it make the house feel? As last thing I want is phone calls from tennants saying house is colder!!!

    1. I would opt for the heated version, it does not have to be used but as it can not be retrofitted it will save you hassle if you find it too cold.

  22. Hi l live in a rented house and have a drimaster heat installed by the landlord when it first went in it was freezing only when heating was on full was it bearable, he then had the setting changed lowered fan setting and lowered the heating setting to come on it is now winter and its like having a window open constantly, the hallway struggles to get upto 18oc and when my heatings off falls to 15oc and bellow so cold. Electric its costing £1.50 a day add that to heating costs its so expensive yes its sorted the condensation, but its costing me a fortune in heating and electric and making the house cold its like chucking money down a drain trying to keep the house warm!

    1. hi
      thanks for your comment. I think the fan speed may be too high still. ours is cool but not freezing and don’t think it has effected the heating costs at all. Though yes with the heater on it costs to run. its 500w so can be 12kwh per day so depends what you pay. Our heater isn’t on 24×7 and is set it, I think, 14’….
      From our elec usage it only runs the heater constantly in the cold months. If your fan is too fast….
      Though even at 1.50/day over winter, its cheaper than fixing mould everywhere… A price we are happy to pay
      See link at top of page as I have a better list of info to reduce moisture/condensation. If those addressed maybe your landlord could turn speed down a notch?
      Ours feels nothing like an open window. And an open window didn’t work either! In fact our bedroom windows stay closed now whereas before we had to have them open and still got condensation. Our bedroom deffo warmer now!
      Good luck!

  23. Hi !

    I am a landlady , it’s a 4 bed semi detached house , we bought it about 6 months ago , it was a total rack and we done full refurbished , and rented the house , this was the first proper winter for a tenant , condensation appeared on one of the bedroom , and tenant moaning about the mould , she also said she is out most of the time and when she is back , heating they put it on for a full speed , which obviously cause more condensation , we have fitted extractor fan in kitchen – which I doubt that it’s being used , and have a small mould growth in pantry. And in one of the big bedroom there is a lot of condensation on window My question is , do you think this product will help me to sort out this issue and most importantly as tenants don’t like to pay big electricity bill to pay – and she switched that off than condensation problem would be still there ? Or can we adjust the settings that she can’t manipulate it ,( I assume that it will go in loft and the ceiling in landings are quite high anyways) thanks ,

    1. Yes it will help! We have installed an enviro vent system in one of our rentals. Tenants were drying clothes and not using the fan as it was always switched off. This unit has dried out the bungalow completely. Been installed for 2 years. I will be fitting the nuaire unit above in our holiday home shortly, same idea but lots cheaper than envirovent system.
      If and when you have it fitted don’t tell the tenants how to turn it off though!

  24. Hi
    I have just had a nuaire drimaster Heat fitted this week. The heater has been connected seperately to the fan so I can switch it on or off when I like. My question is is there anyway you can tell the heater bit is working when I switch it on, I cannot feel any heat.

  25. We live in a detached 3 bed house near the coast and get a lot of condensation and black mould. I am considering the nuaire system but have 2 questions…..
    1, Should I get the heater? Some comments make me think it will be very expensive to run as we live in a cold area (wild Northern Ireland coast!) though it is seldom cold enough for snow to settle.
    2, My landing is very small, basically just as wide as the stairs (800mm) with all three bedroom doors leading direct off the top step, so just a small 800mm sq space. Will the vent work there as the installation says leave at least 400mm around the vent for setting 3.

    Help! and thanks!

  26. Hello, I’m interested in the PIV but am wondering how it might work for me. I have a Dormer Bungalow with two bedrooms upstairs at the same height as the loft. Would these bedrooms benefit from PIV as the unit would be at the floor level of the first floor pushing air downwards. I am not really able to install it any higher as there is nothing between the ceilings and roof.

    1. Hi Bill, I’m interested to see if you went ahead with an installation, I have exactly the same issue, thanks

  27. Interesting and helpful read. Going to be installing a pic soon. JG having read the installationinstructions on a couple of different units , they say to seal all possible leaks in ceiling. Has I have downright in all rooms do they need to be sealed some how.


    1. I’d not overly worry about downlighters to be honest. You jut don’t want gaping holes. We have downlighters in the bedroom, bit (non closing) extractor vent in bathroom – and it works a treat

  28. I have a problem in a large downstairs flat roofed bedroom/En suite extension at back of house mainly with a foisty smell on clothes in wardrobe and dank smell on towels in the En suite so would a drimaster unit in the loft(which is quite a way from problem site) be of any help? There is no condensation mould or anything like that but feel there is an airflow problem in this large low extension. Would be grateful for any advise.

    1. Hi Jan
      I am no expert, but what you describe sounds like high humidity. Id say buy a handful of the cheap humidity meters and place them in various locations, good places and bad places, and compare. If you have high humidity in the smelly areas and low elsewhere, then could be moist air. A drimaster woukd help move the damp air. However, see top of this page t o my PIV specialist site, and it gives more advixe. eg hints to get damp air away – eg MUCH BETTER fan to get air out of the ensute (shower?). So Id GUESS at checking humidity, then finding sources of nmoisture and removing thenm, and drimaster only if improved extraction and ventilation does not help

  29. I have my loft converted..ie have had floorboards and carpeted. However the loft space is not loving dpace (i use for storage). Its a 1900 property i think …solid cold walls. A company i have contacted thinks they can still install this in the following way..
    1) to have it fitted as normall but i will have to take a bit of carpet off and remove a bot of floorboard
    2) it must then be ducted to an existing vent on the loft roof to fetch the external air

    my landing space is already very freezing …will the heater element bring in watm air? i cant have it any colder!

    we have wet windows and also very cold external ealls which attract wet mold

    1. I am no expert, but their plan sounds logical but you would lose out on solar heat gain when the “loft” usually gets warmer than the outside when the sun is shining on it.
      The heater will help – you can turn the thermometer down so it cuts in earlier. Do remember its not blowing out like a fan heater, its just a gentle air movement. But if you don’t want it any colder, the heater model will be better.
      Please see my other site (link at top of page) that talks about these, as PIV is one part of the solution – if you can prevent moist air (damp, shower/kitchen extraction, not drying clothes inside netc) that halps, and PIV is just the final icing.

  30. Fitted the drimaster without the heater in my bungalow works well but got a cold draft running through the hall into the lounge. Just wondered if I can fit a heat unit to it.

    1. Hi, yes you can. The drimaster heat is actually a drimaster and heater combined – but they are separate (ish). Problem is the heater is over £150 so a lot more than buying a drimaster heat to start off with 🙁

  31. Excellent site. Have had the Drimaster with heat fitted recently (can already see a major difference).

    I have noticed that some of our lights start to flicker. If I turn the heater part off and then on again the flickering stops. Turning it back on does not immediately start the flickering it can be anything up to a week.

    Before I get an electrician I was wondering if you had similar problems or could think of what could be causing it?



    1. no idea really. The heater takes 500w when on, but clicks on and off as and when needed, so unless its very cold its not always on.
      Are your lights LED? It may be your lighting circuit is at/near limits and the extra power being pulled is lowering the voltage somewhat and the LEDs can’t cope?
      Normal bulbs may flicker when the heater cuts in and out – again depending on your load.
      I have no such issues – but lights do flicker briefly when my oven goes on and off!.
      Don’t understand why, after turning heater off/on it behaves for a week though…..

      So nope- no ideas from me!

      1. It is a odd one. I should’ve said that not all lights need to be on, in fact can see the flickering when only 1 bulb is on (LED). I’ve reset it this morning and again all ok. If it does it again I’ll turn the heater off and see what happens and then get an electrcian in to check…

        1. Some LED bulbs can be more sensitive – but doesn’t explain it in full. It may be for some reason its “noisy” on the wire?
          Maybe get the PIV wired off a fused spur off the ringmain rather than lighting.
          We have mixtures of LED bulbs here, and not seen the issues you describe.

  32. Love the site and extremely informative. 🙂 It helped us to decide to install the Eco Heat. Can I ask if over time you have modified the fan speed setting to the most optimal one for the house, and are you still running it at speed 4 as you initially set it up with?
    Many thanks!

    1. Hi. Hope it works as well for you as it does for us. We still can’t believe it works lol. I *think* we backed ours down to 3 – but I really can’t remember as once its installed we don’t touch it (except the heater isolator on/off for winter). But I think 3…..

      1. Well the result has been fantastic for us since install! We were normally hitting 70 to 80% RH upstairs with regular condensation buildup, with similar levels in the conservatory with mould spots appearing on the roof underside. The de-humidifiers helped to dry the house out and bring the levels down but there would still be build-ups of humidity which would take them some time to clear. Since the Drimaster has been charging the house with the loft air continuously, the humidity levels have slowly come down day by day and have now reached an average point of around 55% RH although it did fall to a before unseen level of 48 this week. I’m keeping an eye on the levels and if it falls more then I’ll back off the fan speed to 3 to see if that will keep it stable. Anyway, a great success and the device seems to do what it claims!

  33. Hi I wonder if you can help me I’ve just fitted my drimaster heat vent and it seems like the heater element is not working as there is no heat whatsoever coming from the fan is there any way of re-booting and or checking to see if the heater element is not faulty

    1. Hi Nick, is this original Drimaster Heat or Heat Eco? Best way to check if it’s working is to record ambient temperature of loft and then use temperature probe to measure air coming out of diffuser… think it is supposed to warm it by around 9 or 10 degrees ?

  34. I read through pretty much every comment on this blog and other sites. I am very satisfied with installing my Drimaster Eco Heat with Hall Controls and RF Link. I had condensation problems after spending quite a bit of time upgrading, insulating and all round refurbing an old 1930’s house. I was having readings in the high 70s for humidity on a regular basis especially during winter. This was leading to mould behind cupboards, corners of windows and bed headboards and streaming misted up windows every morning. One company came in and drilled a few ventilation holes in my walls and added more heavy duty always on bathroom vents etc. This, on a good day, reduced humidity to high 60’s. Installing a PIV was my last resort. It worked. Now I have blocked the vent holes, turned off the all day fans and have a regular 50’s humidity rating. I have not needed to turn on the heating element on my PIV and now leave it on a number 2 setting. We have noticed no cold air and its silent unless you turn the boost on (which we have not needed to do) the windows are now devoid of mist and zero mould. Also I have not noticed any uptick in heating or electric bills. It cost me around £300 for an electrician to install an electric point in the loft and the unit itself. It sits in the ceiling on our landing above the stairs surrounded by 4 bedrooms and one radiator on the landing. Brilliant. Couldn’t recommend this product more. Buy it.

    1. Thanks for the feedback. Sometimes I think readers may think its still snake oil fake site – so appreciate your time to reply. Ours still working fine and saving us all that grief 🙂 Glad it works for you too.

  35. Stupid question but can I get a 225mm hole saw with cowl to cut the ceiling hole as my ceiling has artex and i don’t want to risk a saw!

  36. My Dri-Eco-Heat (hc) system has now been in for about one month – and whilst I can feel the cooler, fresher air coming from the diffuser (situated at the top of the stairwell ) – I have been closely monitoring the RH levels – expecting them to fall !
    However – RH levels are still 70% and above and so I am wondering whether the diffuser setting of `2` is high enough ?
    NB: I also have the temp. setting at mid-way
    There has been very little or no window condensation as yet in the bedrooms, which is great! – but the RH levels are bothering me.
    Should I increase the fan speed – setting ? – or the temp setting ? (or both?)

    1. Hi.
      I never monitored RH. But see rest of this blog for a list of other ideas to reduce moisture. The PIV is brilliant and sorts us out, but it has limits – so make sure you aren’t putting moisture in the air by other means. I guess if no condensation (and there used to be) – then that’s good and shows it can work in your house, but try and reduce humidity. If there is no cause you can see as to why its 70%+ then consider leaks, leaking food, blocked extractors etc.

  37. Hi,
    I’m Just about to purchase my nuaire non heated PIV, But I have 1 Question I just can’t seem to find answer to. I have had a new log burner installed which has helped with a lot with condensation, but mainly In the lounge, the bedrooms still suffer a little from (DG) window condensation and a little mould behind the furniture on the ‘Cold wall’. Would the log burner flue that goes through the loft interfere with the operation of the nuair? i.e. Turn it off due to higher temperature in the loft (summer mode). It is of course a twin wall flue?
    Thanks in advance
    Cornish 3 bed Bungalow

    1. Hi, I can only speak for ours (drimaster heat), but the summer heat recover and turn off is a programmable option. Option 1 = turn off at 23′. Option 2 = turn off at 30′ (we use this). option 3 = disable temperature sensing function (so would work even if loft very hot – may be good to reclaim extra heat from your flue! Option 4 = turn off at 27′ .

      So should be okay

  38. Hi. Thanks for a great blog – it’s been so useful in my quest for a solution to our condensation problems. I’m consequently about to buy a Nuaire Drimaster unit, but I’m torn as to which model to go for. We have relatively recently bought a 3 storey Edwardian stone house, with 6 bedrooms. It tends to be quite hard to heat and quite damp, and is consequently causing me asthma problems. We’ve had new radiators and boiler fitted, fixed a leaky pipe and leaky extension roof, and we’re now more careful to use extractor fans when cooking and showering. We do dry clothes indoors during the winter, but we use the laundry setting on the dehumidifier by the airer. However, we still have considerable problems with condensation and mould.
    Firstly I wanted to know if anyone had any experience of using a Drimaster in a 3 storey house? I see that they do a (considerably more expensive!) 3 storey version, but the only difference seems to be that the material used for the vent is fire resistant. Is that to meet fire regulations for if you’re renting out the property, or do they apply anyway? We have mains smoke alarms on all floors, so I’m not too worried about fire resistance. My main concern is whether the unit will work across all the floors? Will it just need to be on one of the highest settings to work properly?
    I also don’t know whether to go for the heated version or not. The hallways are already quite chilly, so I don’t know how much difference it will make and presumably heating via the gas central heating will be more cost effective than heating it via the unit itself?

    1. Hi
      Fire regs are important as a big hole in the roof will allow flames through – so no one can/should advise not to go for the fire rated one. I don’t think it affects how it works. you would need it on “full speed” and in winter that is still cold air. the heater (500w) is costly to run when its cold but it will blow cold air in otherwise. Over winter we say £25/30 a month (for maybe 3-4 months) but in my view, that’s worth it for mould/damp free house. Our heating is crap so the rad in the hall doesn’t do much. Better to get heat and not use it than regret it.
      Also, you have done right by getting rid of moisture by other means. Check the extractors are working and the vent pipework is in tact (one of ours was split!) and make sure cooker is extracting not recycling.
      Also we now use a stand-alone spin-dryer which gets loads of water out of clothes before drying in the house – water that would otherwise get into the air.
      Good luck! Still glad we have ours, and still no issues since install….

  39. I have just installed the nuaire eco heat in my bungalow hall. The heat is so negligible it wasn’t worth paying out for. On heat no 2 its just cold air.Whats the point of having a heat control with very little warmth. On complaining they told me this was normal. My advice to anyone don’t pay the extra for the heated version.

    1. You misunderstand the heating part. The heater is max 500w and yes, it is not enough to heat up anything at all. Its not designed to.
      The unit pulls air from the loft space, and in the winter the loft can be very cold. So the unit without heater pulls in very cold air from the loft making the room the unit is fitted in colder and/or cool draft. The heater on these units is just to take the chill off the air being blown into the house so it does not make the room cold. It is not meant to heat the room, its meant to stop the room getting colder over winter.
      For sure, its not a huge about but without it our stairs/landing are “chilled” – and with it on its okay over winter.

Leave a Reply to Mat Koocak Cancel reply

Your email address will not be published. Required fields are marked *