Still getting condensation three weeks after PIV installed

Matt_OX4

We had our PIV installed yesterday morning, and the relative humidity in the house according to the cheap Amazon humidistat we have has dropped from the 60s to the 50s. Heating is currently set to a set back of 16.5c, then a short burst to 18c in the morning, then 17.5c the majority of the day, before going back to 18c from 5:30pm to 9:30pm - however, I need to reassess where the thermostat lives as the landing/GF hall, which are all effectively one space, is now (as expected) a bit colder due to the PIV. I am running the heating a degree colder than last year due to the energy cost crisis, which has naturally resulted in more condensation as the colder air can't hold as much of the moisture we creating.

While I am loathe to immediately say the PIV has cured things, the condensation this morning on all the upstairs windows was massively reduced from yesterday morning, and I'd expect that on a typical UK winter day with an overnight temperature in the low single digits there would be none. We are running the unit on setting 3 for our 3 bed semi-detached 1950s era house in Buckinghamshire, with the two small windows furthest from the PIV on the setting where the window is slightly cracked open (we don't have trickle vents)

Doubleshotdamo

Matt_OX4 said:

We had our PIV installed yesterday morning, and the relative humidity in the house according to the cheap Amazon humidistat we have has dropped from the 60s to the 50s. Heating is currently set to a set back of 16.5c, then a short burst to 18c in the morning, then 17.5c the majority of the day, before going back to 18c from 5:30pm to 9:30pm - however, I need to reassess where the thermostat lives as the landing/GF hall, which are all effectively one space, is now (as expected) a bit colder due to the PIV. I am running the heating a degree colder than last year due to the energy cost crisis, which has naturally resulted in more condensation as the colder air can't hold as much of the moisture we creating.

While I am loathe to immediately say the PIV has cured things, the condensation this morning on all the upstairs windows was massively reduced from yesterday morning, and I'd expect that on a typical UK winter day with an overnight temperature in the low single digits there would be none. We are running the unit on setting 3 for our 3 bed semi-detached 1950s era house in Buckinghamshire, with the two small windows furthest from the PIV on the setting where the window is slightly cracked open (we don't have trickle vents)

Thanks for your reply. I wish I could say the same, but there's no improvement after 3 weeks. 

Effician

Matt_OX4 said:
 the condensation this morning on all the upstairs windows was massively reduced from yesterday morning,

Same here , it just wasn't as cold last night & we've no ventilation just circulation.

Ventilation is managed by opening the lounge window once a day for 10 mins whilst also opening the loft window.in our 1870's terraced  We've tried dehumidifiers but with little effect on condensation while at the same time making the air uncomfortably dry.

As the OP's experience with PIV is less than encouraging it's clear that reducing condensation is not as easy as a one solution for all.

ComicGeek

Doubleshotdamo said:

ComicGeek said:

Both heat and ventilation are needed to combat condensation. You need to bring in sufficient cold dry air and then heat it, so that it can pick up water vapour - you then need to get rid of that warm moist air, replace with dry air and repeat. If it's just condensation on windows, which can be wiped down in the morning, why bother spending lots of money trying to change that? 

Condensation on bedroom windows with heating off and people sleeping = normal.
Condensation on other room windows = not normal, and would normally mean ventilation/heating issues.

We keep our bedrooms cool to help with sleeping, and don't have the heating on overnight - normally drop from 17 degrees in the evening to 14 degrees in the morning, with night time temperatures of -5 around here at the moment. Condensation on the windows is guaranteed at the moment with sub-zero outside temps, but quick wipe down in the morning in the bedrooms and all good. Our house is now at 19.5 degrees downstairs (bedrooms at 17 degrees), bedrooms, bathroom and ensuite windows open a crack, and all condensation is cleared.

If you overventilate the house (ie bringing in too much cold air), then this will in turn reduce the surface temperatures of the house and potentially result in increased surface condensation. How is the incoming air (which has now picked up the moisture from your breathing overnight) getting out of the house? You might need to open a window a crack to provide the end part of that ventilation cycle. It's about finding that compromise for your house, in terms of ventilation rate and heating.

PIV systems are good for dealing with damp issues in landings, internal walls etc, but I don't see them as being the correct answer for condensation on windows. 

Our living space was nice and warm yesterday evening. I checked the windows (curtains were drawn) and there was condensation about a third of the way up, that was early evening. We went to bed around 11.30pm, so a good 8 hours on no activity downstairs, yet the windows were covered with condensation. All upstairs rooms are now cold with the increased speed of the fan. 
I've now turned it off. 

Is your heating on for a while before you draw the curtains? Curtains can be very effective at keeping heat in rooms, but also could mean that the inside face of the windows never gets warm enough. Although should equally be preventing warm moist air from reaching the cold windows to condense, so that might just mask the real issue. 

Do you have extracts in the kitchen and bathrooms, and use them when cooking/showering? The PIV system doesn't do the same job as these, you need them as well.

You either have high levels of moisture from cooking/showering that you're not removing effectively, or the windows aren't great and the inside face is getting too cold - or both! The PIV system won't deal with either of these.

Matt_OX4

Effician said:

Matt_OX4 said:
 the condensation this morning on all the upstairs windows was massively reduced from yesterday morning,

Same here , it just wasn't as cold last night & we've no ventilation just circulation.

Ventilation is managed by opening the lounge window once a day for 10 mins whilst also opening the loft window.in our 1870's terraced  We've tried dehumidifiers but with little effect on condensation while at the same time making the air uncomfortably dry.

As the OP's experience with PIV is less than encouraging it's clear that reducing condensation is not as easy as a one solution for all.

I would agree, the whole thing is a delicate balance of ventilation, internal temperature and getting the air moving, and there's no one size fits all solution. I did a lot of research over several years and finally decided that a PIV might be the solution for us after doing everything else we could do to get moisture levels down (bathroom in-line fan with run-on, dehumidifier with closed door to utility while clothes are drying, windows on latch etc), and for around £425 installed (I got a good discount on the unit), I thought it was worth a punt, but I realise not everyone is fortunate enough to be in this situation.

Doubleshotdamo

ComicGeek said:

Doubleshotdamo said:

ComicGeek said:

Both heat and ventilation are needed to combat condensation. You need to bring in sufficient cold dry air and then heat it, so that it can pick up water vapour - you then need to get rid of that warm moist air, replace with dry air and repeat. If it's just condensation on windows, which can be wiped down in the morning, why bother spending lots of money trying to change that? 

Condensation on bedroom windows with heating off and people sleeping = normal.
Condensation on other room windows = not normal, and would normally mean ventilation/heating issues.

We keep our bedrooms cool to help with sleeping, and don't have the heating on overnight - normally drop from 17 degrees in the evening to 14 degrees in the morning, with night time temperatures of -5 around here at the moment. Condensation on the windows is guaranteed at the moment with sub-zero outside temps, but quick wipe down in the morning in the bedrooms and all good. Our house is now at 19.5 degrees downstairs (bedrooms at 17 degrees), bedrooms, bathroom and ensuite windows open a crack, and all condensation is cleared.

If you overventilate the house (ie bringing in too much cold air), then this will in turn reduce the surface temperatures of the house and potentially result in increased surface condensation. How is the incoming air (which has now picked up the moisture from your breathing overnight) getting out of the house? You might need to open a window a crack to provide the end part of that ventilation cycle. It's about finding that compromise for your house, in terms of ventilation rate and heating.

PIV systems are good for dealing with damp issues in landings, internal walls etc, but I don't see them as being the correct answer for condensation on windows. 

Our living space was nice and warm yesterday evening. I checked the windows (curtains were drawn) and there was condensation about a third of the way up, that was early evening. We went to bed around 11.30pm, so a good 8 hours on no activity downstairs, yet the windows were covered with condensation. All upstairs rooms are now cold with the increased speed of the fan. 
I've now turned it off. 

Is your heating on for a while before you draw the curtains? Curtains can be very effective at keeping heat in rooms, but also could mean that the inside face of the windows never gets warm enough. Although should equally be preventing warm moist air from reaching the cold windows to condense, so that might just mask the real issue. 

Do you have extracts in the kitchen and bathrooms, and use them when cooking/showering? The PIV system doesn't do the same job as these, you need them as well.

You either have high levels of moisture from cooking/showering that you're not removing effectively, or the windows aren't great and the inside face is getting too cold - or both! The PIV system won't deal with either of these.

Hi, yes, the heating was on yesterday before the curtains were closed. And we have extraction in kitchen and bathroom. Both doors are closed when in use and remain so. Kitchen outside door often open to help with ventilation. 

Doubleshotdamo

I just had a look online regarding cold internal surface of the windows, and, apparently, this is a good sign of the windows working correctly. 

sevenhills

Warmer air holds more moisture. I get condensation and I don't have the heating on overnight. I have very little mould though. I have vents in my bedroom walls. Condensation on windows is normal, when it's warmer inside, surely.

Condensation on walls and black mould is different.

ComicGeek

Doubleshotdamo said:

I just had a look online regarding cold internal surface of the windows, and, apparently, this is a good sign of the windows working correctly. 

Not really. You want the outside surface to be cold and the internal surface to be warm - that then shows there is limited heat transfer from inside to outside.

Heat transfer through glass is much higher than insulated walls, so the internal surface of windows is always going to be lower, even with the best triple glazed windows. The better the window, the closer to the rest of the internal surfaces, the better the comfort levels and the lower the risk of condensation.

Fogging on the outside of the windows on a clear night shows the windows are working correctly.

bristolleedsfan

Matt_OX4 said:

Effician said:

Matt_OX4 said:
 the condensation this morning on all the upstairs windows was massively reduced from yesterday morning,

Same here , it just wasn't as cold last night & we've no ventilation just circulation.

Ventilation is managed by opening the lounge window once a day for 10 mins whilst also opening the loft window.in our 1870's terraced  We've tried dehumidifiers but with little effect on condensation while at the same time making the air uncomfortably dry.

As the OP's experience with PIV is less than encouraging it's clear that reducing condensation is not as easy as a one solution for all.

, and for around £425 installed (I got a good discount on the unit), I thought it was worth a punt, but I realise not everyone is fortunate enough to be in this situation.

What make is PIV, is it heated version, who installed it ?