# Positive Input Ventilation



## P4ULT (Apr 6, 2007)

Anyone got any experience of these. We get loads of condensation and we try and keep the place as well ventilated as we ca. They claim to purify the air and stop the condensation. Look really good but would like some input on these or an alternative from actual users. Can also get ones with a heater in. We have looked at the Nuairs Dri Master


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## Deniance (Jun 28, 2008)

Thing is with piv, it works perfectly , condensation will disappear overnight, but it blows your warm air you’ve paid to heat outside through all the gaps in your house, I’m currently gathering materials to fit MVHR at my house, these also work very well but more install work, plus a lot more air sealing!


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## Andpopse (Mar 19, 2009)

Hi, I bought a Nuaire Drimaster back in the 80s, I had a house in Cornwall which had mould and condensation. It literally stopped within a few days.
I started selling them as an agent and later worked for Nuaire ( 20 years). 
So I do know about PIV. The Drimaster works by drawing air from the loft into the house at about 0.5 air change per hour. The slight drawback is colder air in the upper hallway, only noticeable in the very cold months. But what people don’t realise is that your RH is reduced and thus your internal air contains less moisture and is therefore easier to heat !
Yes air is also filtered and as your home is now under positive pressure, draughts are reduced. Running cost is negligible.
So in a nutshell it does work ! Yes MVHR works even more efficiently but cost and install is much more.
I hope this helps.


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## P4ULT (Apr 6, 2007)

Cheers Gents

Have looked at other options but the PIV seems so simple. My only concern is my loft isn’t that big so will need to be sure on measurements. 

@andypopse what do you mean by RH? Good to have some serious knowhow on them, how long would you expect the unit to last. Would you suggest the option with the heater in over the one withou? Being from Bristol as well I’ll take your word for it �� the 2 question marks are supposed to be a smiley face but keeps changing for some reason.


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## Andpopse (Mar 19, 2009)

R H (Relative Humidity) = the amount of moisture in the air expressed as a percentage.
Just make sure you have air gaps so that air can be drawn into the loft (can you see some light ?) Then place your Drimaster diffuser over the stairwell. Also ensure loft door well sealed to prevent recirculation. You actually get free solar gain from your loft and capture any heat loss from the living area and both of these things add temperature to the incoming air. Drimaster speeds up above a set temp to take advantage on a sunny spring / autumn day. The diffuser also sends the incoming air sideways to mix with the warm air at ceiling level.
I’ve still got one and have had them in my houses since the 80s.
Btw other company’s do make them now the patent is out of date.
Cheers


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## Andpopse (Mar 19, 2009)

My current unit has been running 20 years ! It’s a slow running fan that’s not stressed.


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## GSI-MAN (Sep 12, 2017)

Yes I believe we have one in our ex council house 
Been here about 20 years now 
Think it was put in about 16-17 years ago
I turned it off once only to find out the next day the windows had condensation over them 
Our next door neighbour does not have one fitted and suffers a lot from mould and condensation.


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## fatdazza (Dec 29, 2010)

How much noise do these units generate?


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## McC (Apr 9, 2017)

I put a nuiare version in our last house, seriously gets rid of the condensation in a day or less. 
We had electric storage heaters for our heating so it was pretty much impossible to keep a constant heat so yes temperature in the main hall where our unit was installed was an issue as the model we got was either on or off, so we just had it constantly going at the lowest speed.
Minimal noise unless you turned the speed right up which you never need to do unless your having a sauna.
We are contemplating about putting one into our current house.


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