Boiler Efficiency Testing

jp_2

measure air flow through firebox.

measure air temp in & out

measure water temp in & out

measure water flow

calculate btu's to raise air temp

calculate btu's output to water

air BTU + water flow BTU = total BTU's

water flow BTU's divided by total BTU's = efficiency

Brian_18

Can someone steer me to where I can find the testing protocol that is used to determine boiler efficiency? The reason is I, have recently commissioned my own solid fuel boiler, which the manufacturer claims 85% efficiency, I have my doubts. I'd like to figure out a way to conduct my own rudimentary testing just to gauge if the boiler is in the ballpark or not.

Jim Davis_3

I have no idea how you can calculate the input BTU's of coal or wood?? 85% is not usually possible unless you condense on most fuels, wood & coal not sure. Equipment is only as efficient as the person that sets it up correctly, not any factory rating. The percentage will be the max.

Brian_18

Seems Simple Enough

JP;
Your method seems elegantly simple. Correct me if I'm wrong, but this method of calculation is testing the thermal transfer efficiency only, and disregarding combustion efficiency (?) Which brings up a question of exactly what does 85% efficiency mean when a manufacturer states this? All of the parameters are easy to measure, except for measuring the air flow through the firebox. Any suggestions on measuring this? Some sort of anemometer, or pitot tube method perhaps(?) This is a coal boiler, which has a combustion blower so in this regard the air flow while the combustion blower is running will be pretty much constant. Thanks for your input.

hot_rod

some of the boys over at www.hearth.com

in the boiler room have been playing with efficiency number calcs on wood burners.

I know independant labs have tested the OWF at around 40- 45% i suspect the gasification boilers around 70%.

Weigh the fuel and install a BTU meter on the boiler output

hot rod

jp_2

combustion eff

similar to what hot rod said, could track outside temp, heat loss for house and the amount of wood you use for 2 weeks?

lots depends, moisture and quality of wood, how far the stove will damper down, how often it dampers down...then you have the question of how well the house transfers the boiler heat.

eff of heat transfer is a good measure I think.

Brian_18

Nice to see you around

here again, Hot Rod. Although, I was anticipating a reply in Italian !!! (sorry, couldn't resist). Seriously, you've shared lots of valuable info, from which I personally (as a DIY'er) have benifited. I thank you and the other Wallies for sharing your knowledge. Lifelong Learning is where it's at!