Radiators for Condensing Boilers
My current small house (modern, well-insulated) has a Viessmann boiler and standard rads. Unfortunately the installers had little clue about the niceties of this system, so it’s not operating as well as it could. Little can be practically done at this point but I may be moving in a year or two and although heat pumps are “the way to go”, I may opt for the same type of system as the backup power requirements are lower. In a power outage, my modest whole-house battery backup can run basics + the boiler for 4-6 hours. Not so with a heat pump drawing 1,500+ watts.
I have learned quite a bit recently about these boilers, including the performance improvement “slope” as the return temp. is reduced below 130ºF. There will be a practical limit to this, but I figure about 145º out and 115ºF return might be realistic. In looking at baseboard specs, there are various “high output” units such as Slant Fin Multipak 90 + H1 elements, which put out as much heat @150º in as standard units do at 170º, which is a good start in “losing” more heat. I notice that the same elements installed in a taller cabinet (Series 350), produces even more heat, presumably because the taller cabinet creates more convective air flow. I have also been reading about “convective radiators” (like these from Stelrad: https://www.stelrad.com/radiators/designer-radiators/white-radiators/flat/ )which are tall and thin, with single, dual or even triple elements, but these seem to be only available in the UK (?) It appears these combine both tall vertical fins (good convection) and a flat panel. With the numerous “thermally-challenged” homes in the UK, they need all the BTUs they can get.
There will be other design considerations aside from this, of course, but it seems “losing” as much heat before the water returns to the boiler is an important first step. Any comments or recommendations on this would be appreciated.
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