I have 20-25 year old aluminium double glazing (and external doors)in a
1960's semi, the glass does not appear to be turning blue, however every winter I wake up to find the windows dripping with water, and the wall paper around the windows(first 2-3 inches) growing black mold. Is this stuff safe ? (even though the windows are wiped every morning). The old brush seals have been replaced with a modern seal, to stop all the noise and wind coming in between the windows
Apart from the additional security offered by new upvc windows , child opening restriction & built in air flow. Will changing from my current windows to new UPVC ones help . I have noticed how cold the (frames and) glass feels in the morning, could this mean the gas between the glass as gone and they are not working properly
Aluminium DG comes in 2 forms, those without a thermal break and those with a thermal break.
A thermal break insulates the inside frame from the outside frame, so preventing the inside frame becoming as cold as the outside frame. When the inside metal frame temperature drops below the dew point of the air inside the room, condensation will form across its surface. A thermal break prevents the inside frame temperature dropping with outside temperatures.
There is AFAIK no way to retrofit a thermal break. Replacing "functioning" double glazing is expensive and will have a very long payback period (50-100yrs) in terms of energy saved over single glazing. It is possible to use a dehumidifier to reduce moisture level in the house, you have black mould which tends to indicate lack of ventilation, lack of heating or combination of the two. Dehumidifiers come in two forms - dessicant & compressor, the best compressor model is a Mitsubishi but they are expensive, the dessicant models also provide some heating and can be more powerful at low (cold) temperatures, costing about 60-50% less than the Mitsubishi model (Prem-I-Air do a good model, about =A3119 on Ebay). The disadvantage of a dehumidifier is noise (quiet is not silent re night time), some running costs (10hrs @ 0.032p for 150 days =3D =A348 in electricity), and requirement to empty them unless plumbed into a nearby drain - plus perhaps most of all they can not dehumidify through closed doors (!).
If the condensation can be contained - paper towels placed on window cills the night before to prevent it getting near carpets and particularly curtains - then there is no real problem. If the moisture levels in the house are high, such as drying washing on radiators or not using a kitchen/bathroom/shower extractor, then you need to deal with that via extraction or dehumidification. Dehumidifiers remove moisture and provide heat, extractor fans remove moisture and remove heat.
Do you avoid drying clothes on radiators? Do you have a cooker-hood extractor (not set to recirculate) in the kitchen, and an extractor in the bathroom/shower?
If the answer is no, then you are putting quite a lot of water vapour in the house. Water vapour will condense on the coldest part of the house - that is to say any surface which is below the Dew Point of the air. The coldest part of the house will be aluminium window frames without a thermal break (because it is a thermally conductive piece of metal from the outside to the inside. They were notorious for "running in water" much like Crittal steel window frames. Thermal break aluminium & steel units do have a thermal break (like commercial property windows).
The cheapest solution is to 1) use or fit extractors as necessary 2) absolutely no drying clothing on radiators 3) use a dehumidifier (will take a few days to "catchup". The best dehumidifier I have owned is the Prem-I-Air PRDHZ80U dessicant, it is well built, well thought out, decent water tray design, lightweight & relatively quiet on the "quiet" setting - as well as being extremely powerful (on a par with the Mitsubishi compressor unit which is =A3350). I have owned Mitsubishi, X-Dry, DryItOut Ruby, cheap b&q stuff (fan seizes as the bearings wear out in a few years). There are many reviews on the internet for it, I think it first appeared before last xmas but I held of buying to see how it "panned out". There are other dehumidifiers out there such as Ebac etc, but always read the lowest scoring reviews. Amazon & Argos are good for reading reviews, examine the worst reviews because they tell you the real shortcomings often by people more perceptive (or bluntly intelligent!).
Also, opening a window with the sun on it for 20mins in a morning can strip condensation off a window very effectively - use the towels for the other windows.
A lot cheaper than the ?=A33-8k? it costs for new double glazing unless you plan on selling in the near future, in which case might be less hassle to let the new buyer pay (they may not care). That kind of money can buy a new boiler or a reasonable 3yr old car, so "if it ain't broke" I would tend to go with a ventilate + heat + dehumidifier solution. I do understand how bad it can be, a neighbour had stuff without a thermal break on the 1970s folding french doors - the carpet actually rotted for about a foot, it was a splash splash splash paddling pool.
New windows simply don't pay back their cost. Fit them if you actually need to, otherwise its not worth it.
The short answer is you have a probelm other than the windows. Condensation on DG means a high RH, that can be due to any of:
- significant water ingress somewhere
- plenty of cooking steam, showering and drying clothes indoors
- little or no ventilation
The traditional solution is ventilation, but a dehumidifier provides better control and doesn't cost as much since you're not throwing heat outside. In summer a dh can be switched off and passive ventilation used, often by fitting the windows with locks that lock it in the 1/4" open position. There are other ways to provide a switchable trickle vent of course.
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