Calculating efficiency of older boilers

Jesse_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.

jp_2

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 boiler

Jim Davis_7

don't forget you have to multiply gpm times 60 minutes for the BTUH.

johnny4

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 off-cycle losses, and so forth. Of course, this requires a combustion efficiency test to begin with.

Unknown

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?

Noel