PIV system questions

ChasingtheWelshdream

Our dehumidifier used 2.5kw in a days useage last week  (full blast to help laundry admittedly) so not exactly cheap for long term. Our bathroom and kitchen have extractors. In fact the bathroom is the one room to rarely have condensation and never mould. Unlike the bedrooms which have no ventilation other than the windows, with no trickle vents.

FreeBear

A low power PIV system pumping air in to the bedrooms via small vents may well help in the bedrooms. You don't need a huge amount of air being blasted in.

chris_n

FreeBear said:

rob7475 said: MHVR is a better solution but for many it's not a suitable retrofit option.

I have looked at installing a MHRV system here (3 bed semi). The cost is the key thing putting me off at the moment. In the meantime, I may well install a PIV system to pump a small amount of air into the landing/stairwell.

Why not just a through the wall MHRV then at least you get 80% of the heat back?

Ben1989

I haven't read all the comments but a PIV will work on a three story house providing you get one with different power settings. You'll just have to pump more into the house but it will work downstairs. We run ours 24/7 and shut the doors ajar at night and the air still gets in just fine, unnoticeably.

markin

ChasingtheWelshdream said:

Our dehumidifier used 2.5kw in a days useage last week  (full blast to help laundry admittedly) so not exactly cheap for long term. Our bathroom and kitchen have extractors. In fact the bathroom is the one room to rarely have condensation and never mould. Unlike the bedrooms which have no ventilation other than the windows, with no trickle vents.

Not really a fair test when it has to work very hard for 3-6hrs, A smart one should basically be off 95% of the time, On a low setting say 30w the fan would use around 0.7khw so i would guess 1kwh a day in normal use.


Some PIV models have 400w heaters, So on cold days it could be 9.6KWH ?

rob7475

markin said:

ChasingtheWelshdream said:

Our dehumidifier used 2.5kw in a days useage last week  (full blast to help laundry admittedly) so not exactly cheap for long term. Our bathroom and kitchen have extractors. In fact the bathroom is the one room to rarely have condensation and never mould. Unlike the bedrooms which have no ventilation other than the windows, with no trickle vents.

Not really a fair test when it has to work very hard for 3-6hrs, A smart one should basically be off 95% of the time, On a low setting say 30w the fan would use around 0.7khw so i would guess 1kwh a day in normal use.


Some PIV models have 400w heaters, So on cold days it could be 9.6KWH ?

I'd never recommend buying a PIV unit with a heater. Our nuaire drimaster was bought with a heater and it barely changed the temperature of the air flow so I never have it turned on.

Racky_Roo

1616six said:

I’m keeping an eye on this thread as we are due to complete on a house in December which has a PIV system but I know nothing about them, just read it in the advert!

I have one in my now 2 year old new build. certainly doesn't cost anything to run, think it's quoted as £7 a year and doesn't make the house colder but really does help with clearing the bathrooms of steam and stale air. I think they work best when fitted when the house is built rather than added later.

What I would say is that in the bedroom which it's mounted above, you can really hear it at night running so I now have mine on a timer so it turns off at 10pm and back on at 8am