External condensation on double glazed windows

[TheLarches]

We had new double glazing fitted this summer, ever since it's been subject to frequent external condensation, four days in the last six; it's averaging at one day out of every two and sometimes starting late afternoon, early evening and lasting until mid morning. Both upstairs and downstairs windows are affected, the facing direction is east however all four windows on two bays and two windows on the southern wall are also affected. Clear or cloudy days / nights don't seem make any difference neither does having open or closed windows.

No other property on the road (including those with k-glass) or within the surrounding area has the same problem.

I think it is more than just the common dew point problems and would be grateful for any other suggestions the installers are at a loss.

 

[masona]

Do you mean the condensation is on the glass outside and not on the inside room?

 

[TheLarches]

Yes, it's on the outside of the house, inside panes are clear.

 

[masona]

There's nothing you can do about it because the pilkington k glass reflects the heat back into the room which is doing its job correctly therefore a colder surface on the outside. Not every properties with pilkington k glass have this problem because of the difference location of the property with trees, brushes, building & your internal room temperature maybe higher than others and also they may have a better wind flow keeping the condensation off the glass etc. It's just bad luck

 

[squowse]

condensation occurs on cold shiny surfaces first so a warmer room temp inside would lead to a warmer outer pane temp = less problem.
either way, the fact that youy have a cold exterior pane is a sign that your units are leaking very little heat to the outside.
a lot of new units now will be soft-coat low E which is better than K-glass.

only thing you could look at is increasing wind flow around the outide panes if they are sheltered somehow, or moving/deflecting sources of moisture such as a condensing boiler or kitchen/bathroom extractor.

 

[TheLarches]

Thanks.
I think the windows are low E rather than K-glass.

The really strange thing is that even with all the windows open on a warm, breezy night the glass is still steaming up, on the inside of the open ones too.
The rest of the house (walls, single glazed windows, doors etc) is completely unaffected.
There are no moisture sources on the side of the house affected and we live in a very windy position so lack of air movement is not really a problem (more important that windows are well caught and can't be slammed open!).

Since this started and we've been inspecting the windows regularly we've discovered that two are leaking, there's very find dust getting in somehow.

 

[JohnD]

you are sure the mist isn't forming inside the units, then?

 

[TheLarches]

We're sure it's on the outside. You can run a finger across the moisture and leave a trail, it's definitely on the outside. Although I'm sure it won't long before the leaky units are misting up in the 'sandwich'.

 

[mointainwalker]

It's extremely likely that the very fine "dust" you are seein is comin out of the frame.

There is a very fine powder which is filled into the aluminium seperator - between panes -.

 

[TheLarches]

Thanks, but it's not the Alu dust, this is fine paper dust up to 1.5mm long and small grey gritty wood ash dust from the wood stove. It's on both panes of glass in the cavity and seems attached by static; however it does move around the cavity. The dust was not present when the windows were fitted and is now highly visible and increasing daily.

 

[kfoggy]

We had new double glazing fitted this summer, ever since it's been subject to frequent external condensation, four days in the last six; it's averaging at one day out of every two and sometimes starting late afternoon, early evening and lasting until mid morning. Both upstairs and downstairs windows are affected, the facing direction is east however all four windows on two bays and two windows on the southern wall are also affected. Clear or cloudy days / nights don't seem make any difference neither does having open or closed windows.

No other property on the road (including those with k-glass) or within the surrounding area has the same problem.

I think it is more than just the common dew point problems and would be grateful for any other suggestions the installers are at a loss.

 

[newquayguy]

Look between the two panes is there little brown balls in side it sounds like these particular units may have dessicant inside them, or they may not have any inside the ali bar ,dessicant prevents condensation on both panes get you fitters to get replacement units, as they should be a garentee of ten years .