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Original poster

Nuaire/other positive input ventilation systems - any experiences good or bad?

36 replies

SnotMikeUpPuffedHe · 14/01/2022 16:24

Does anyone have experience of these? I've seen it mentioned on a couple of other threads which tend to be when people recommend them as a solution to damp/black mould but would be interested to know more.

We've recently had some new windows fitted and noticing more moisture and a little black mould around them and I wonder if something like this would be the answer.

We also have a few cold corners in the house which have always been a little prone to slight mould and it would be good to sort that if we can.

As well as whether these systems are effective or not I wonder whether they make the house colder? And also I'd be interested in how you found someone to install or whether you did it yourself.

It's a four bed semi detached house.

Thanks!

OP posts:
starpatch · 14/01/2022 19:19

Bumping for you as I am interested in this too.

FurierTransform · 14/01/2022 20:23

I've not used one but they seem a pretty terrible solution on paper. A fan in a box, blowing freezing loft air into your hallway... I don't get it.

A proper fresh air heat recovery system seems a million times better.

Original poster
SnotMikeUpPuffedHe · 15/01/2022 11:51

At the moment the best I can do is open windows all the time so cold is an issue whatever.

Anyway, bumping again!

OP posts:
ClaudiusTheGod · 15/01/2022 13:04

not used one but they seem a pretty terrible solution on paper. A fan in a box, blowing freezing loft air into your hallway... I don't get it

Works really well in my house. You only feel a very slight draught as you walk down the stairs and most of the time I don’t notice it. It has made a huge difference. Together with very powerful bathroom extractor and kitchen extractor fans, it’s solved the problem of persistently mouldy walls in this house. I also use a dehumidifier if I’m drying washing. IMO it was £3k well spent (for all of the above).

ClaudiusTheGod · 15/01/2022 13:05

I got a firm to do the whole thing, supply and installation, but if you are useful yourself then you could do it.

gg96cgp · 15/01/2022 13:23

We have it installed in our house and includes an extraction booster for our kitchen to save having a separate extractor fan. I only notice it's on when we use the kitchen booster. No mould anywhere.

Theteapotsbrokenspout · 15/01/2022 14:12

I was considering having one put in but our damp surveyor was very scathing of them:

'Positive input ventilation' is a waste of time and money. Independent tests show it doesn't work and some schools of thought are of the opinion it can make things worse. The versions sold in this country have also been banned in some other parts of the world as they can pump toxins and lung irritants into the house from the loft.

We are working on other methods to reduce damp and mould in our property.

FusciasBright21 · 15/01/2022 14:19

We've had one installed for a year in our 1900s terrace. Seems to have solved our damp issue, which was apparently down to lack of ventilation. It did cause issues when our neighbours were smoking weed in their loft conversion Envy they moved out and no problems since. Ours contains a heating element so it's not bringing cold air in.

I think ours cost £800 with installation (north east)

Original poster
SnotMikeUpPuffedHe · 16/01/2022 12:45

Thanks all; it looks like people who do have them like them.

Interesting if the same units are banned elsewhere though.

And quite a range in price mentioned on the thread! Although @ClaudiusTheGod was that £3k paying for other things as well - you mentioned extractors, dehumidifiers etc?

OP posts:
Daftasabroom · 16/01/2022 15:06

We have mechanical ventilation with heat recovery by brookvent it's awesome.

AlannaOfTrebond · 16/01/2022 15:16

I have two in rental properties, one victorian terrace and one 1930's terrace.

They have made a huge difference to the levels of condensation in the houses especially in cold areas like corners and bay windows.

As a pp have said you can feel a cool draught directly under the unit, but nothing too noticeable or buy one with a heating element.

Surely whether a unit pumps lung irritants or toxins from the loft into the house depends on whether they are already present in the loft?

PigletJohn · 16/01/2022 15:30

do you mean the problem you observe, is traces of condensation after fitting new windows?

were the old windows draughty?

are the new windows not draughty?

do the new windows have trickle vents?

please show us some pics of the windowframe joint with the wall, inside and outside. Does the damp follow rainy spells?

ClaudiusTheGod · 16/01/2022 16:36

@SnotMikeUpPuffedHe yes all in

nodogz · 16/01/2022 16:38

Had one that worked really well to solve a damp problem in Victorian house which has original windows and fireplaces blocked off. Some corner grew black mould as there wasn't enough air circulating. Wasn't practical for good airflow.

The house needed ventilation and it was the best (least hassle) of sorting it. House immediately became 1-2 degrees warmer and we could dry washing indoors, no condensation on windows and no mould anywhere.

ruthieness · 16/01/2022 16:47

we had one put in a flat with all sealed windows no trickle vents - bringing in fresh air from outside
included in the unit was with a heater that took the chill off the air

It totally solved a serious damp mould problem -
puddles of water on windowsills

it was a life changer!!
One of the top 10 days of my life!

SylvanFox · 17/01/2022 17:45

So we just had a quote for a Daikin VAM system that captures the heat of the outgoing air and uses it to warm the incoming air.

The price of the unit and the ducting seem reasonable enough but the installation cost seems bonkers. I'm really not sure if the installers are having a laugh. Can i ask what others have paid for duct installation?

The installers we spoke to want nearly £5k to run the duct in a straight line down through two floors and not even make good afterwards. The total cost including VAT is £8k. Can that possibly be right?? (if it makes a difference, we live on the edge of South East London...)

DuesToTheDirt · 17/01/2022 17:50

We have one (Envirovent) and it's great. We do still get condensation on the windows, but it's made a big difference to the damp feel we used to get upstairs.

Sorry, don't remember what it cost.

Lfie1 · 10/11/2023 23:36

Bit late to the game for this post but for anyone else looking at a PIV. Omg, best thing I ever done for my house. Bought house in May 2021, first winter windows streaming and running about with a window vac every morning. Bought the system Nov 2022 and only got round to fitting start of Nov 2023 and I can't believe I waited so long. Windows are completely condensation free, fluffy black dust my house was plagued with is gone. The 'cold draught' some people are worried about needs to be looked for, like you need to stand at a specific spot and be very sentive to a gentle breeze. If you have condensation please save yourself 15 minutes of window vac in the morning and install one. I got the Nuair Drymaster, fitted in an hour with drywall saw and a bit of patience getting the ducting on. I had hygrometers in ever room in my house and all have dropped by at leat 15%

Seamy1 · 14/12/2023 10:24

Hi. Im late also to this thread. I just had a positive ventilation system installed in my house yesterday. My issue had been poor ventilation in my basement so we were hoping that this would be the solution. Both me and my wife woke this morning with chesty coughs. Something definitely not right. Also, I have been checking all the vents where the air should supposedly be leaving the house and it seems like air is coming in instead of out. There is a current of air entering through the two diffusers coming from the machine. Really worried now as we dont want to spend another night if our health is being affected. I have been on to the installers this morning and their first defence is that it always works well in other houses. I won't name the brand of machine until I know what they are going to do for us, if anything😥. I suppose the system must work in many houses. But there is something seriously wrong here.

GasPanic · 14/12/2023 11:27

Don't really see the difference between these and an open window with a fan blowing air into your house.

If I had a damp/mould problem I would try dehumidification first, which would probably be a fraction of the price.

Seamy1 · 14/12/2023 11:33

Already starting to regret not just putting a dehumidifier in the basement. The installer now saying that we may have just caught a cold and that it has nothing to do with the PIV. Looks like we could be in for a long battle here that we could really do without. They say that they will reduce the inflow of air but will that just decrease any effect that the system should have on the air? Not a happy customer here!!!!!

GasPanic · 14/12/2023 11:41

As far as I am aware cold air is supposed to be driven from outside the house through the vents and then exit through other gaps in the house, so it sounds like it is working as expected. I am not an expert on them though. It's just an extraction fan operating in reverse with a much higher price tag AFAIK.

Seamy1 · 14/12/2023 12:43

The idea we were sold was that the machine would pump outside air into the house through two diffusers creating positive air pressure which would then escape through the small vents they made in the windows and walls. However, we checked this morning and the air is actually coming in to the house from outside through these small vents. This would indicate to me that there is not enough pressure inside the house, or that the machine is unable to produce sufficient pressure to then send air back outside through the small vents in each room. I can't see how they can solve this. On the one hand, the air circulation seems to be causing us respiratory issues. But reducing the circulation will only reduce further any pressure inside the house thus rendering the whole thing redundant.

Reallybadidea · 14/12/2023 18:19

We were considering a piv system but managed to cure our condensation issues with a dehumidifier and leaving the heating on low overnight when the temperature drops very low. Can't even say I've noticed an increase in our energy usage.

Lfie1 · 15/12/2023 00:04

I would challenge the installers and make sure they have fitted it properly and the ducting is air tight, have you got adequate ventilation and free flowing air in the loft etc. I had terrible condensation and measuring humidity in the 70s, sometimes high 80s when first waking in the morning. I've had my PIV in for around 8 weeks, condensation COMPLETELY cleared in the first day and humidity reduced to 40s within the first 12 hours. My house is so much more comfortable, heating up faster and holding the heat longer. I cannot believe the difference it has made, we fitted ourselves, ducting was difficult to make sure it was airtight, had to adjust a few times and I have 2 sufficient roof vents. I tried a dehumidifier, would have needed more than one throughout the house and I can't bear them using up floor space.