Russdl Posted November 23, 2021 Share Posted November 23, 2021 On the last two mornings where its been pretty cold outside I've found a small amount of condensation on the insides of some of our triple glazed windows, I promised the good lady this would never happen!! The house is built to passive standard, has good airtightness and MVHR. Should I be getting condensation on the insides of the windows, and if not, what is going wrong? Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 I've not experienced condensation on the inside in 4.5 years. What temp do you run your house at? and do you know the relative humidity in the rooms showing condensation? Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 2 minutes ago, IanR said: I've not experienced condensation on the inside in 4.5 years. I thought I was going to hear that ? The house is currently around 20° and the humidity is around 63% (a degree/percent or two different in different rooms) Link to comment Share on other sites More sharing options...
joe90 Posted November 23, 2021 Share Posted November 23, 2021 I got condensation these last two mornings (frosty weather) but I only have double glazing in wooden windows, I run the upstairs cooler than downstairs, I did ramp up the MVHR a bit last night but it made no difference. Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @joe90 I've ramped up the MVHR as well, but maybe not for long enough. It wasn't part of my master plan to have condensation on the inside and aside from ramping up the MVHR I'm out of ideas. Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 (edited) 14 minutes ago, Russdl said: The house is currently around 20° and the humidity is around 63% (a degree/percent or two different in different rooms) If those are the conditions when condensation appears, it would need the inside pane to have dropped to 12.7°C to condensate. I can't find the reference now, but I'm sure I have something that shows the inner pane of 3G only dropping a couple of degrees when 0° outside. Hence the improved "comfort" over 2G. Is the condensation at the edges, where a cold bridge through the frame may be having an effect? Edited November 23, 2021 by IanR Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @IanR Thanks for those figures, interesting. I'll see if my IR thermometer can give me an answer on the pane temperature. On the windows/sliders with condensation it's all along the bottom where the pane meets the frame. Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 Is it an Aluminium frame? Obviously thermally broken, but the thermal breaks can be quite thin, I wonder if there's a small cold bridge. Link to comment Share on other sites More sharing options...
ProDave Posted November 23, 2021 Share Posted November 23, 2021 We have 1 pane that gets some condensation. All the ones supplied fitted by Rationel have no condensation issues, but this one pane the glass unit was supplied by the local window company, and I am building up evidence to "reject" it. When it is very cold outside (sub zero) it gets condensation near the bottom, there is also under certain circumstances evidence of marks on the inside of one of the pains. My trouble is I have not been able to convincingly photograph the issues. So i am hoping when the weather gets properly cold the condensation at least should show a lot more often, often enough to get their sales rep to visit and witness it. Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @IanR they're timber frame, ally clad, Internorm windows. In theory the thermal breaks should be up there with the best. Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 Also, there are three different types (standard windows, frameless and sliders) all of which have had condensation on them. Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 4 minutes ago, Russdl said: @IanR they're timber frame, ally clad, Internorm windows. In theory the thermal breaks should be up there with the best. How odd, I have the same windows, with the extra foam between cladding and timber frame. Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 6 minutes ago, IanR said: with the extra foam between cladding and timber frame. Sorry, I don't understand that bit? Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 4 minutes ago, Russdl said: Sorry, I don't understand that bit? I've got the 310's with the foam under the cladding, which is what I thought you meant by "thermal breaks" Looks like most of their Aluclad options now have something similar. It wasn't on all their ranges when I purchased. Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @IanR Ah! With you now. Yes, ours are the same. I was on about the thermal breaks that the spacers between the panes provide, poor terminology on my part. Link to comment Share on other sites More sharing options...
Ian Posted November 23, 2021 Share Posted November 23, 2021 We’re coming up for 5 years with our 3G windows. The only condensation we get is on the outside. They are bog-standard Rehau upvc frames but fitted with 44mm glazing units 1 Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 6 minutes ago, Ian said: We’re coming up for 5 years with our 3G windows. The only condensation we get is on the outside. Clearly I have a problem Link to comment Share on other sites More sharing options...
Roundtuit Posted November 23, 2021 Share Posted November 23, 2021 2 hours ago, Russdl said: humidity is around 63% (a degree/percent or two different in different rooms) Is that a bit high? We only have one humidity sensor (its in a weather station, so can't really vouch for accuracy), but it's usually <50% in the kitchen. We're approaching our 4th winter and not seen any condensation yet. Link to comment Share on other sites More sharing options...
Makeitstop Posted November 23, 2021 Share Posted November 23, 2021 Have to admit, I'm unsure of what the general rh is in passive houses with controlled ventilation, but to my mind, 60%+ rh sounds fairly high. I only refer to my knowledge of good humidity control of the timbers I use for my work, which cover a range of some of the most valuable timber on the planet. If I see the environment getting to 60%, then I know it isnt good for it. I'd expect a range of 35%-50% in a centrally heated home. Perhaps that's the issue, but as I said, I'm not up to speed on such a property. Link to comment Share on other sites More sharing options...
ragg987 Posted November 23, 2021 Share Posted November 23, 2021 When we moved into our newly finished house, humidity was around 60% and by the end of 1 year it had dropped to the 40s. I put this down to drying out of the build. Could this account for your observations? Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @Roundtuit & @Makeitstop I’m inclined to agree, the humidity is higher than I expected it to be (based on nothing other than a SWAG) and it is seldom below 60% and normally closer to 70%. I’ve no idea what I should expect it to be and I’d be interested to hear what the humidity is in other Buildhubber’s houses for comparison, especially if they’re down here in the southwest. Link to comment Share on other sites More sharing options...
tonyshouse Posted November 23, 2021 Share Posted November 23, 2021 Are you sure that the condensation is on the inside, I get it on the outside at this time of the year, How do you ventilate the house? Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @ragg987 I would have thought ours would have dried out by now, but maybe not? It’s been many months since the last ‘wet’ trade was in. Link to comment Share on other sites More sharing options...
IanR Posted November 23, 2021 Share Posted November 23, 2021 RH inside will tend to drop when it's cold outside. Mine is in the 40% - 50% range at the moment. I'd normally be at around 60% in the summer. 1 Link to comment Share on other sites More sharing options...
Russdl Posted November 23, 2021 Author Share Posted November 23, 2021 @tonyshouse we have the pleasure of condensation on the outside of the windows at times as we expected but we also, very definitely, have condensation on the inside. Not a huge amount but enough to pee me off. Ventilation through the summer months, and until quite recently, was MVHR and windows/doors open. Now it’s just MVHR. Link to comment Share on other sites More sharing options...
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