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Posted by HeatPro on December 02, 2007 at 19:38:12:
In Reply to: Re: Convector and recessed radiator EDR calc posted by steve on December 02, 2007 at 19:26:41:
: What type of person do I hire to do such a conversion? Can a GC do it or am I better of with some sort of consultant helping the process along?
++ An experienced major plumbing/heating contractor should be able to handle it.
: : ++ What's 'normal'? You'd change when the old steam boiler died. Then it would be worth it over the next decades.
: ++++That sounds like at best a 10+ year payback versus just a new steam boiler.
--Yup, the choice is to leave it as is and pay for double the fuel forever, or invest in saving fuel now. 10-year payback is nothing compared to 4 owners paying for a white elephant over 100 years.
: : : How can you run the water at the same temperature as the steam?
: : ++ Set the high limit to 225F. Steam or water inside a radiator at 215F provides the same heat output.
: ++++Won't the water be steam above 212F or not because of the system pressure or does it get superheated?
-- Water boils at 250 F when under 15 psig. It would only need get to that for 2 weeks out of the year with a water system. Heat loss depends on the cold temperatures, not all year in warmer weather. Steam ALWAYS has to reach 215F ALL heating season.
Can PEX take such hot water?
++ Yes, with proper support.
: : ++ When the new boiler is a water boiler it will be smaller right away as you'd size for the actual heat loss instead of total steam radiation plus 50%.
: ++++ Is the heat loss always less than the steam system size?
++ Yes, when there is enough steam radiation to heat the house to begin with.
What about rooms that haven't needed heat with the steam system such as an enclosed porch mudroom? I am concerned these may not get warm enough with hot water.
++ Reminds me of the old saw: The back porch radiator always worked before you repaired the system. (It's obvious the pipes were disconnected ages ago.)
C'mon now. Stop leg-pulling. Either the porch had a steam radiator to heat it or not. You are asking if a system can heat a house after you put a new addition on it. Of course not, you'd have to plan for whatever addition in advance.
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