AFUE vs. Thermal efficiency for steam boilers

Kamar

Hi,
What is the difference for AFUE vs. TE for a steam boiler? I believe that TE is combustion efficiency less jacket losses, but doesn't take into account cycling losses. I've read conflicting accounts of whether AFUE takes into account cycling losses, and that it doesn't take into account jacket losses. What DOES AFUE take into account? Would a steam boiler's AFUE be higher or lower than its TE? Thanks for any help you can give!

SWEI

ASHRAE Standard 103 determines the method. https://en.wikipedia.org/wiki/Annual_fuel_utilization_efficiency has some general info.

Jamie Hall

and the whole thing is a can of worms. About the only thing one can say for sure is "your mileage may vary".

SWEI

I'd probably change that to "Your mileage will vary." AFUE and EF are both quite broken when it comes to modulating appliances.