Condensation on the frame of new aluminium windows – slight reprise

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Wow, didn’t that thread go on…


Anyway, people are going to disagree, but I found a few cures for this problem, the first is the most radical:

1 Stop breathing:

Yes, if you stop breathing the relative humidity will drop, and it will be harder for the condensation to form (because it would need to be cooler).

2 Turn up the heating:

Discovered this one by accident! If you turn up the heating the relative humidity will drop. The automatic assumption is that this might make the problem worse, because it is probable that real humidity (ie the actual water vapour in the air) will increase. However, even if that happens, the extra heat will increase the temperature of the window frames, thus it is less likely that you will get condensation.

The real issue here is that all you are really doing is exacerbating the problem and transferring even more heat (ie money) from the inside of your property to the outside.

Typically we'd have the temperature around 20 degrees. Somehow, accidentally, the temperature got up to 24 degrees inside, and that encouraged the condensation to disappear. No other changes. However, that’s too warm for us, and now I also understand why most of my neighbours don't have the same condensation problems - they’re just overheating their homes.

3 UPVC secondary internal cladding:

I stuck UVPC extrusions to the internal surfaces of the aluminium frames. This almost worked. The reason it did not 100% solve the problem is that I used the thinest extrusions I could find, and they were only about 1mm. For all but the coldest days this solved the problem. On the coldest days we got a little condensation on the window glass, and on the internal UPVC.

So, as this was an experiment in one room, I am rolling it out to the other rooms, but with thicker UPVC extrusions, which I am hopeful will solve the problem completely.

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Now, I expect that some people will start arguing about there being a problem with water vapour coming from some source within the property. I believe that is not the case, in fact it is most likely that relative humidity in the property is probably on the low side of normal (ie it always seems very dry). However, the problem is that the window frames are significantly cooler that the room temperature (ie the room temp is 20 and the frames are in the range 10-12) - I don't think you need to be Einstein to work out that condensation is going to occur on the window frames well within the normal range of humidity.
 
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If only there was some way of taking excessively humid air out of a building.

A ventilator, perhaps. Or an extractor fan. Or a trickle vent.

Somebody should invent one.
 
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Perhaps read the original thread?

We seem to be having the same debate again, with people that don’t understand the differences between condensation caused by excessive humidity and condensation caused by cold surfaces (or, in this case, widow frames that readily conduct heat, from the inside to the outside).

Pretend, just for a couple of micro seconds, that humidity in a room is within the normal bounds - but you are still getting condensation.

How would you solve the problem?

Your answer would probably be to get “A ventilator, perhaps. Or an extractor fan. Or a trickle vent.”

All you are doing in those cases is increasing your heating costs.

My answer is to insulate the cold surface… one of us will be wrong though.

The answer cannot be to reduce humidity at the window frame, because to do that would be to reduce overall humidity in a room far below normal levels.
 
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A ventilator, perhaps. Or an extractor fan. Or a trickle vent.


And for the OP, all things that , since June 15th this year are part of Building Regulations on windows, whether new build or replacement ( there are some exceptons but they are very few! )


BUt as OP states , yes insulating the cold surface will stop condensation .......on that surface ... where is that now condensating though ( as I can guarantee it will be somewhere )
 
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BUt as OP states , yes insulating the cold surface will stop condensation .......on that surface ... where is that now condensating though ( as I can guarantee it will be somewhere )
If the humidity in a room is "normal", and you are getting condensation, then that is an insulation issue, not a ventilation issue. As far as my experiment has gone there is no transfer of the condensation to another location. As noted above, the only transfer I am seeing is to the glass, which is a small fraction of what was on the frames, and is (probably) resolvable with thicker UPVC sections.
 
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If it cant condense on the glass because its too warm then any other surface as warm as that glass is also safe from condensation so where does the humidity go, I guess it just sits in the house till its ventilated out, just because its not condensating doesn't mean its not there
 
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Erm by you own answer the water vapour transfer is happening to the next coldest location
.. the glass... insulate that ( with a modern day sealed unit for an a rated window ) and it WILL end up elsewhere.

Water vapour doesn't just vanish ...unless ventilated to the open atmosphere.
BUT I do agree that your experiment is stopping it from condensating on the Aluminium. All aluminium box gutters in conservatories are insulated for this very reason
 
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in winter, what does your RH meter read?
The combined temperature and humidity gizmo reads ~50% at 20-22 degrees in the middle of the room (sometimes it is lower). At the windows this increases dramatically when it is cold outside, as the temperature there can be 6-8 degrees lower. On the frames themselves I would imagine the temperature can be 2-4 degrees cooler again (never found a way to accurately measure it).
 
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Water vapour doesn't just vanish ...unless ventilated to the open atmosphere.
BUT I do agree that your experiment is stopping it from condensating on the Aluminium. All aluminium box gutters in conservatories are insulated for this very reason
Of course it doesn’t vanish – but if there is no cold surface for it to condense on, then it is not a problem. Humidity in the air (water vapour) is "normal", you end up with problems if it is not there.

In a "normal" room, with no humidity problems, you’ll get condensation on a glass filled with chilled water/ice cubes. Ventilating the room won’t solve the problem, unless you cool the room down to the level where the humidity is more or less zero.

That’s the problem at hand here. The windows are so poorly insulated that condensation occurs on the frames where humidity in the room is well within the bounds of "normal".

The least humid areas of the planet? The poles.
 
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Of course it doesn’t vanish – but if there is no cold surface for it to condense on, then it is not a problem. Humidity in the air (water vapour) is "normal", you end up with problems if it is not there.

In a "normal" room, with no humidity problems, you’ll get condensation on a glass filled with chilled water/ice cubes. Ventilating the room won’t solve the problem, unless you cool the room down to the level where the humidity is more or less zero.

That’s the problem at hand here. The windows are so poorly insulated that condensation occurs on the frames where humidity in the room is well within the bounds of "normal".

The least humid areas of the planet? The poles.

one way to solve it is a tube heater positioned on the windowsill and switched on at night when curtains are closed.
 
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Of course it doesn’t vanish – but if there is no cold surface for it to condense on, then it is not a problem. Humidity in the air (water vapour) is "normal", you end up with problems if it is not there.

In a "normal" room, with no humidity problems, you’ll get condensation on a glass filled with chilled water/ice cubes. Ventilating the room won’t solve the problem, unless you cool the room down to the level where the humidity is more or less zero.

That’s the problem at hand here. The windows are so poorly insulated that condensation occurs on the frames where humidity in the room is well within the bounds of "normal".

The least humid areas of the planet? The poles.
Ventilating the room removes the moisture laden air while drawing in outside air which is less moisture laden.
 
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one way to solve it is a tube heater positioned on the windowsill and switched on at night when curtains are closed.
Yes, heating up the window frames removes the condensation. Just blowing a fan over the windows, with no heat, alleviates the issue a little (I would guess that this is actually just drawing in warm air from the room, and sending cold air out into the room).

But, I think insulation is a more sustainable solution.
 

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