installing new hw boiler in place of oversized boiler

mitch moore

heat loss is 152,000btu.Exsisiting boiler is 264,000btu in with a net rating of 184,000.Do I replace by heat loss plus pick up factor(how much is the pick up factor?-uninsulated 1 1/2"pipe in unconditioned basement aprox 200')or size by EDR.If sizing by EDR,where can I obtain btu values per sq' of radiation @ given temps?

Paul Mitchell

boiler size

Hot water boiler really should be sized by the actual heat loss. You can count the radiators, Ht, # of sections, # of tubes to tell if there is too much radiation. This will help only for water temp of system. If you have too many radiators you might be able to heat the house at a lower water temp. Most likely if you size by the radiators you will probably oversize again. If you don't want to get Dan's book "Every Darn Radiator" then you can go to Burnham web site they have a pretty good chart.

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

[Deleted User]

what kind of radiation do you have?

cast iron radiators, convectors, fin tube, ???
if its fin tube go with the heat loss....if they are radiators you may want to work the existing edr out to see how things compare..there may be radiators to remove..or put reset controls on the boiler..with radiators there is still alot of metal to heat..

mitch moore

cast iron

radiators are cast iron 3 tube aprox. 30" high. So replace with a net = to the the heat loss? What about the 1 1/2" pick up for the pipe in the basement? How can I determine if I put a small boiler in that I will stay above mfg. recommended 130*? Should I run a constant 140* boiler temp and cycle the circ off the stat? Customer wants to stay away from constant boiler temp does he have a choice? WIll the cold starts cause premature boiler failure? He lives alone and wants to install a setback and turn stat to 50* daily for 10 hours while at work. Seems like a lot of cold starts.

mitch moore

by pass

will I need a by pass? If so should I set up a boiler bypass. I was told to stay away from gate valve at all costs do you agree?