There are always a lot of questions being asked, so I’ve tried to get them all summarised here for you.  Click on the question to see an answer.

Am I (aka site author) an expert?

No.  Not in the slightest.  So suggest you ignore most of on this site, or at least just use it as pointers for your other research.  I am just an owner and user of the system sharing my personal experiences.  If you want expert advice please look elsewhere for an expert.

What is the difference between a Nuaire Drimaster Heat and one without Heat?

In term of PIV functionality, nothing.  Both do the same job.  In fact, as far as I am aware both PIV aspects are identical. The “heater” version has a heater attached to the outlet which heats up the air that is pushed into the house.

The heater is for YOUR benefit only to stop the air being cold.  Its not a fan-heater, it just takes the chill off the air.  The heater has a thermostat on and you can set the temperature you want the air at.

Without it, the landing could be very cold in the winter as the air is pushed in from the cold loft.  If you are on a budget, this will be fine, albeit leaving you a colder landing.  Personally, I’m happy to pay the extra electricity to stop the landing getting too cold.

So, personal choice.

How have I wired it up?

I have the Drimaster Heat version, and the heater is wired separately to the PIV system.  You can cable them up together, I’ve opted to wire them separately.

I have a fused spur (with correct fusing/cabling/connectors) to power the PIV system and the heater off the lighting circuit (3A fuse).  The heater though is off a fused spur from this.  As such, one switch powers on/off the PIV and heater.  However, the second switch can power enable/disable the heater as required.

As such, the PIV is on 24x7x365, but the heater I only turn on over the winter (and even then its on its own thermostat so “on” just means “on when thermostat tells it”).

Do you need to be certified/qualified to install a Drimaster

As far as I am aware, yes.  If you are not competent or qualified and need to ask, then you should seek professional advice

Why do I only mention Nuaire Drimaster models?

Because that’s what I have, that’s what I know.  Others may be available but I can’t comment.

How much does it cost to run?

I believe the PIV system takes about 2W 16W constant – depending on the speed settings.  This is tiny and costs a few pence per day.  So you won’t notice this.

The heater aspect is the “optional” bit that costs more to run.  Bearing in mind its on a thermostat, the amount of power it uses depends on how cold it is.  So, assume its -10’c outside and the heater is on constantly, then this would be 500W, so 24hrs is 12kw – and a kw is about 12p – so a maximum of £1.44 per day, £43 per month.

I’d GUESS for me October +£5, November +£15, expect Dec/Jan/Feb +£25-£30, Mar +£15….., Apr +£5….

However, this is worst case and I’ve never seen that cost, though for no mould I’d be prepared to pay it!


  • with the sun on the roof during the day, this will heat the air up during the day etc and you will gain from this.
  • The air in the house is less moist, and hence it can be cooler whilst feeling warmer, so you will save some as you can have the normal heating thermostat lower
  • The PIV system runs “heat recovery” so if the loft is a lot warmer, it will speed up and blow the warmer air in the house

So with all this, I’d say over summer, the cost is negligible.  Over winter for me, maybe £100-150.

What else needs to be considered?

What about heat recovery?

These systems do not use heat exchange recovery.  They just pull air from the loft.  When the loft air is warmer, it can speed up and take the free heat into the house.  This is very noticeable, but sadly not often enough for free heat lol!

In my research, full heat recovery is not cost effective in UK climates.

Isn’t it just a fan?

Yes and no.  Its mainly a very clever, quiet, and efficient fan and an electronic controller.  The heater is of course a heater and thermostat with clever electronics.  It may appear expensive for what it is – but when you see it and feel it – it feels good value for money.

Do these systems dehumidify?

No – they are PIV – they do not provide dehumidification facilities.  The humidity is lowered, but due to moist air being pushed out rather than “drying” existing air

How do I fix or paint over mould damage?

We had one corner in our guestroom which was badly mouldy and had been treated with various chemicals, and we could not emulsion over it.  It was a right mess.  On the right, you will see us mention Zinnser BIN.  It should be made by Ronseal, but isn’t, as it does what it says on the tin.

We used it to paint over this bit of wall, and it does just that – it covers over everything. Rust, stains, mould…..  Amazing!  Even better, after 45 mins, you can emulsion over it.  Honest!  And once that’s dried you’d never know.  A couple of coats of emulsion and the wall looks perfect.  Considering emulsion would not dry or stick too the wall, and stains would come through anyway, this has been a godsend.  Expensive yes, but – WOW.  Works well and hassle free.

Do I need to add any vents?

No – the PIV systems rely on natural air leakage via doors, windows and other holes in your house.  These holes must exist otherwise there would be no air for you to breath and you’d eventually die!  If you have a super insulated house (as in tested against air leakage) then a PIV isn’t for you!  We would recommend if there is a vent in the bedrooms then maybe use it before buying PIV.  Also, we chose to vent our chimneys for other reasons too as they were blocked.  But no, no extra holes needed in most houses.

Technical documentation

Here are the links to technical documentation:-

Nuaire Drimaster Heat Manual

Nuaire Drimaster Heat Product Brochure

13 thoughts on “FAQs”

  1. I have just had a drimster fitted in one of the bed rooms it’s it meet to make it cold in the room I have the heating on most of the time and it is still cold in the room my email address is cummings_linsey@talktalk

    1. Do you know how they work? They pull air from the loft and use it to have positive input pressure in the house. If the loft is cold, it will blow in cold air. that’s what they do. did you buy the heat version or the non heat version? The heat version counteracts this (at extra cost and usage cost, but IMO well worth it for zero condensation and mould).
      Also if its running too fast it may need tuning and turning down.
      I’d not want to install one in the bedroom for the reasons you say.
      If you have the non-heat version, then nothing you can do, you bought the wrong thing.
      If you have the heat version, maybe turn it down a speed and turn the heater up a bit.
      But ideally, install in a landing area – not bedroom

      1. We had the heat version fitted some months ago.. it is a touch cooler in the hall where it is fitted, but this doesn’t bother us as we now have no mould in our bedroom (bungalow), no damp carpet in the corner, and not a drop of condensation on windows in the mornings since fitting.. would highly reccomend these fans. You need to keep windows and outer doors closed in winter, inner doors ajar or a bottom vent for it to be able to work properly. We have it set mid way and the heater on auto and 3 setting.. works brillianly for us. The heater automatically cuts off as loft space warms up. You need a good dry ventilated loft space, or you can have an outer wall one fitted if not so

        1. Hi Tracey. Sorry, only just noticed this in the comment spam pool – but clearly isn’t. Thanks for taking time to give your feedback and glad its working for you too!

  2. All lofts constructed pre and slightly after (while stocks lasted) 1980 are asbestos riddled (comes from soffits and other fire retardant materials used being rubbed as houses vibrate and move, grinding these up, even concrete roof tiles) not to mention fiberglass, so my question is, what certificate is there making the filters on these units safe? And how are they changed safely once blocked with said asbestos particulates? And finally how often must they be changed? No one seems to have information on this, is it the elephant in the room? Is it not believed to be an issue? (it is)? Is love to buy one but need more info, can you help?

    1. If you have asbestos or potential of, or you think you have, then get an expert in and do not DIY. Obvious really. Personally if there was any risk of asbestos I’d have that sorted before considering PIV – and I would not consider PIV in the situation you describe regardless of spec! Mice can make holes. So, if you think you have asbestos – get an expert surveyour in.

    1. Maybe, I guess. But the air input goes through the big ears which are the filters so not very easily. That’s why the heater is post filters/fan.
      You can buy just the heater but it is a lot more than buying the unit with the heater built in. A DIY solution would be a challenge. Good luck!

  3. My system just stopped working and says 0 on the display should I be worried, or because of the heat does it cut off ??

    1. Hi. Don’t know, mine does not have that type of display.
      Did it restart overnight?
      Depending on how its configured, if the loft space is warm (with the sun on it) then it detects its not needed and shuts down. I think its something like 24′? I’ve configured mine to a different setting so it doesn’t shut off till 30′ or something.
      That is the only reason I know why it’d stop by itself

  4. Ive installed several of these units but only 2 with the 4 way switch .ive bonded the switch and works ok but when they switch the landing light on the boost comes automatically .ive tapped off the lighting supply like i normally do ive told my client to reboot the system . Not heard any come back yet

  5. We have a Drimaster eco with heater. The ceiling fixture has a red light which is flashing on and off. Is this normal? I haven’t noticed it before . It was fitted @6 months ago. Thanks

    1. Hi
      No idea I’m afraid – your unit is newer than mine. A look at the installation manual does not help me guess either! Suggest you contact the installers or Nuaire directly. May be you have a remote sensor linked, and that link is broken for some reason – but I’d only be guessing. Good luck

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