Positive input Ventilation units – What is your experience?

Reply to the comment left by Ashley at 30/11/2024 - 14:07
If you forbid the drying make sure they know that any remedial costs will be levied on them. Good luck!

Reply to the comment left by Laura Delow at 01/12/2024 - 05:59
Hi Laura, In my view the PIV systems are good in all properties where air tightness is a problem and tenant induced humidity will always be an issue. Providing you have some roof space that itself is well ventilated to draw in fresh air.
I installed a Nuiare system in a 1980's built semi. Never had a problem since. In my previous comment I meant to add that the unit is hard wired to the lighting circuit, so the tenant is unlikely to turn it off without taking out the fuse.
The unit has been in a while now so probably due new filters, but the filters are only catching airborne dust rather than mold spores growing internally from the house.
I bought the same unit for my own home in Australia, I live in a humid environment and just having the air changed regularly without running expensive AC or heating all the time is a benefit.

As for pre-war/post war homes, I can't see how forcing ventilation will harm the structure, if anything it will help dry or keep dry timbers, also force out Radon (Maybe) if in areas affected, (Like Northampton, Cornwall etc)
Timbers and in some cases brick, will really only be affected if they don't get airflow, like when many people blocked subfloor vents in Victorian style buildings.

Reply to the comment left by Darren Bell at 01/12/2024 - 20:19
Thanks Darren - I rest easier

Hi,
I wonder if someone on here can help?
This is about my own home - I am a landlord however and the answer may help other period property landlords.
The property is a solid wall, listed property with leaded light single glazing that I’m not allowed to change.
In the areas with high humidity, we have issues with the windows running with condensation in the mornings. This tends to be bathroom, kitchen and occupied bedrooms although the other rooms do accumulate some. And thus unless we keep very on top of it by wiping down every window in the house every morning and then giving the house a half hour blow through, we end up getting mould. Only a bit and I’m careful to keep on top of it - but the condensation bothers me in terms of cleaning it up and also damage to the paintwork and windows. I’m aware that this problem is of our own creation - my other half likes the property to be warm and we don’t necessarily have an hour a day every morning to wipe down the windows and sit in a freezing house with the windows open while the wind whips through it.
The house is not being used as it was designed 150 years ago - however we have become soft in our old age and like to be able to sit around in the relatively warm.
I looked at secondary glazing and am considering it - however it is ugly (the house is very pretty, inside and out), expensive (£8-14k quoted for 14 windows) and from what I have seen from other properties the condensation doesn’t necessarily stop - either the condensation moves from the outside windows to the secondary glazing as the outside windows are quite drafty, or gets into the gap between the two where it is difficult to get out.
We have good quality extractors with over double the recommended air changes in the room for both kitchen and bathroom and the bathroom one runs almost all the time.
We open the window when we shower (hardly ever bath) and the heating in the bathroom is on for most of the day to dry it out, in conjunction with the extractor.
The major issue is our bedroom which overnight transforms to a windowsill overflowing condensation mess.
My other half will not sleep with the window open which is what I always did before she moved in. I’m happy with it being arctic - she is not…..
I was wondering if a mechanical ventilation with heat recovery (MVHR) would work well in a property such as this by pumping out the humid air and bringing in fresh not humid air from outside and heating it via the heat recovery system?
It would presumably not result in much heat loss like blowing the house through with open windows and doors, not take any time as it would work continuously, and resolve the humidity that is causing the problems. I am lucky enough to be able to install it myself and have worked out a pathway for all the ducting through upstairs cupboards and roof voids that would be fine in terms of the listing - and I’m fine with installing a couple of roof vents for incoming and extraction - hidden in a valley that no one will see.
I’m hoping I haven’t missed something - can anyone confirm or deny please?
Options are:
This
Change house
Change other half
Something else I haven’t thought of!
Happy to consider a combination of things such as secondary glazing and MVHR if sealing off the drafts further and then introducing heated ventilation would work better.
Thanks!

Reply to the comment left by Fred Flintstone at 21/12/2024 - 08:45
I run a dehumidifier in my bedroom during the day (too noisy at night) which keeps the room dry and free from mould. Consumes about 300 watts, which takes the chill off the room, as I have no other form of heating.
As to your options, you have to carefully consider whether you prefer your partner or your house! 😇

I do the same. I like a cold bedroom with no heating and I run a Meaco 20 litre dehumidifier with a huge tank and hepa filter. In my house I only need it for an hour or two each day in winter