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Posted by rbeck on September 02, 2007 at 21:36:35:
In Reply to: Radiator Size More Important Than J-Manual posted by DS on August 12, 2007 at 19:20:03:
I totally agree. Let's expand on this a little. Don't add anything for piping. If there is no insulation on the mains or a portion of the main, insulate it. The homeowner may complain but it only makes sense.
It takes 970 btu's to convert 212* water to 212* steam. That is 5 times the amount of energy it takes to raise water from 32* to 212*. When main are not insulated the steam will collapse back into water (condensate) and must be converted back to steam. Un-insulated mains (2" iron) will steam about 212 btu's per ft of pipe.
Also keep in mind that the amount or connected load to a hot water boiler has no bearing on boiler sizing what so ever, only boiler piping. I was at job where the boiler was 120k and the connected load was 271k. House was completely remodeled and insulated. Old radiation re-installed. Had problem heating and used a lot of fuel. Re-piped and fuel bill went down 64%. Same boiler used.