The problem is the temperature of the surfaces of heating system (convector/radiator). From about 45 °C above the heated air can tear off from the heated surface and will stream around the room. It will give the warmth indirectly to the rooms envelopes and so they are cooler than the air.
The air has humidity and so the humidity must condensate in cooler parts, mostly where the heated air stream will not come to so good, will say all corners in the room, behind furniture etc. Mold and dry rot can follow.
So I am planning (as architect and civil engineer) since more than 10 years only IR radiation heating systems for old and new buildings by most simple (and cheap) ways. IR radiation can not heat the air, it will only heat the solid materials and then indirectly the air molecules by contact. So the air is cooler (saves money and energy, because the heated air streams outside) and never will be any condensate, mold and insane room atmosphere!
We don't calculate the heating needs with the normal U-values but with better values (Ueff-value) which count in the solar radiation and energy storing of solid walls. Quite a revolution in german eyes and argued very much from collegues. That better calculation is saving money also, because we need not so much heating system and energy by using the solar favours. Look on the pic, thats all we do in technical sense,besides the normal heating system and some improvemnets of systems regulation:
The tubes with warm water are installed open, follow very near the floor all exterior walls, and are heating by radiation permanently (without letting cooling off the walls during night). This saves a lot of energy, in my house 5 liter oil per m²/year. And we don't pollute our best food we have - the air to breath - with dust and dirt and spores - because with a mostly IR radiation based heating there are nearly no air streams in the room which take off this **** from floor level and sents it to the lungs.
When it is very cold outside (< 4 °C), the small radiator plate will work additional. The system we name "Huellflaechentemperierung', what means giving constant but low heating temperature to the rooms envelope.
Just now I don't have an english infotext translated, you can find it in
german,
danish and
russian language. Lots of pics! I recommend to translate the more simple danish or the 'enriched' german text by online translator like Google offers.
Best regards and pardon my poor school english
Konrad
