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”