Postive Input Ventilation or extractor fans

donmaico

Hello I have a small let Victorian end of terrace house which has experienced damp and condensation problems especially in the downstairs cloakroom where there is a considerable amount of black mould present .I am concerned that the tenant should not suffer any health issues resulting from it ( eg asthma) so am wondering what the best option would be .I thought maybe an extractor fan in the kitchen and one in the toilet might solve the problem but my electrician didn't think it would necessarily do so.The I thought about one of those PIVs which seems to attract quite a bit of approval .More expensive for sure but if it's better option then I will go for it .
I am not entirely sure how they work, though .From watching a Youtube video it would appear that they draw in fresh clean air from the outside to replace the toxic air within , but the video also seems to suggest that toxic air gets pushed towards the windows and not up into the roof space and towards the soffit boards. Is that correct ?
My electrician also does not think a whole house ventilation system is necessary .Could you please advise me ? Thanks

Senseicads

We had a really bad black mould problem in our home, all around the windows upstairs, in the bathroom.  It wasn't good.  We had windows with trickle vents installed on the basis that a lot of the advice was to aerate the upstairs by opening windows.  The windows needed replacing anwyay to be fair, but it didn't solve the problem.  We installed a PIV, no more mould. we cleaned up the mould after the windows were replaced and painted over with antifungal paint.  that didn't work.  did the same after the PIV...never come back! Genuinely it was a great fix for us!

neilmcl

PIV are pretty good things but I'm not sure how much they'll help in an enclosed, downstairs cloakroam where condensation is almost inevitable in an older property with cold solid walls. Do you have any heating in the room?

Petriix

In my opinion (from a physics point of view) local extraction is better than PIV. The air in certain parts of the house will be likely to contain more moisture. The trick is to avoid allowing that moisture to circulate round the whole house and extract from specific areas to avoid unnecessarily losing heat from the drier areas.

Condensation occurs where moist air meets cold surfaces. Better insulation and more heating will help keep surfaces warmer, but removing the moist air is important. PIV simply introduces more (cold) dry air into the whole house, which can be reasonably effective but is rather crude; forcing air out of any gaps rather than specifically the moist air in the wetter parts of the house.

Either way, ventilation allows heat to escape which is costly (economically and ecologically) to replace; so targeted extraction with heat recovery is ideal. That's the philosophy of the whole house ventilation systems but you can also get individual heat exchanging extractors for bathrooms and kitchens.

tacpot12

PIV can be combined with trickle vents on the windows so that warm damp air is forced out of the vents before condensation has time to form on cold walls and windows. 

I've found that humidistat controlled extractor fans in the 'wet' rooms in rented properties have been very successful in keeping rooms clear of mould. I use E925 humidistats from MS Electronics - see here E925 Standard Humidistat | MS Electronics | Bathroom Humidity Control and ordinary extractor fans (silent ones if they are near bedrooms). 

If your electrician says there is a problem wiring a separate humidistat in a manner that is compliant with Building Regs, let me know and I'll post a wiring diagram. 

donmaico

neilmcl said:

PIV are pretty good things but I'm not sure how much they'll help in an enclosed, downstairs cloakroam where condensation is almost inevitable in an older property with cold solid walls. Do you have any heating in the room?

no its very small and we would only be able to fit a radiant heater , in fact i got a quote to fit one but thought that would not remove the problem of condensation 

neilmcl

donmaico said:

neilmcl said:

PIV are pretty good things but I'm not sure how much they'll help in an enclosed, downstairs cloakroam where condensation is almost inevitable in an older property with cold solid walls. Do you have any heating in the room?

no its very small and we would only be able to fit a radiant heater , in fact i got a quote to fit one but thought that would not remove the problem of condensation 

Just to be clear is it a cloakroom as in WC or an actual cloakroom for coats/shoes etc?

rob7475

I've fitted a PIV unit in our house which has cured our condensation problems. The one I have is a nuaire drimaster which was easy to install myself. You do ideally need extractors in the kitchen and bathroom too though. You also need to make sure the PIV unit is sited centrally in the house and doors are left open a bit to allow air flow.

donmaico

neilmcl said:

donmaico said:

neilmcl said:

PIV are pretty good things but I'm not sure how much they'll help in an enclosed, downstairs cloakroam where condensation is almost inevitable in an older property with cold solid walls. Do you have any heating in the room?

no its very small and we would only be able to fit a radiant heater , in fact i got a quote to fit one but thought that would not remove the problem of condensation 

Just to be clear is it a cloakroom as in WC or an actual cloakroom for coats/shoes etc?

It's a WC

donmaico

rob7475 said:

I've fitted a PIV unit in our house which has cured our condensation problems. The one I have is a nuaire drimaster which was easy to install myself. You do ideally need extractors in the kitchen and bathroom too though. You also need to make sure the PIV unit is sited centrally in the house and doors are left open a bit to allow air flow.

Yes I did wonder that as the extractor fans would provide an exit point for the damp

neilmcl

donmaico said:

neilmcl said:

donmaico said:

neilmcl said:

PIV are pretty good things but I'm not sure how much they'll help in an enclosed, downstairs cloakroam where condensation is almost inevitable in an older property with cold solid walls. Do you have any heating in the room?

no its very small and we would only be able to fit a radiant heater , in fact i got a quote to fit one but thought that would not remove the problem of condensation 

Just to be clear is it a cloakroom as in WC or an actual cloakroom for coats/shoes etc?

It's a WC

Can you install a small towel rad and extractor fan?