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Calculating efficiency of older boilers
Jesse_3
Member Posts: 3
I am trying to find some information on calculating the efficiency of older style gas hot water boilers. I was wondering if there are a set of equations or some software that would be helpful. Thanks.
0
Comments

easy on paper
clock the gas meter.
measure delta T water temp. in/out of boiler
measure flow rate of water.in/out of boiler
delt T x 8.33 x gallons flow = btu's boiler output
meter clocking will give you btu's into the boiler0 
don't forget you have to multiply gpm times 60 minutes for the BTUH.0 
estimating efficiency
If you don't have access to temp in and temp out, or flow rate in & flow rate out, one way to *estimate* efficiency of an old boiler is to take a combustion efficiency test result and multiply by 0.85. So if a technician performs a combustion efficiency test and says the boiler has a combustion efficiency of 84%, then the overall efficiency (similar to AFUE) is about 71% (85% x 0.85). This would account for offcycle losses, and so forth. Of course, this requires a combustion efficiency test to begin with.0 
Okay.....
How do you factor in whether it has a vent damper; or electronic ignition?
How do you account for a boiler with a circulator post purge cycle? With 3" of insulation vs. 1" of insulation?
Where did this formula come from?
Noel0
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