Table 6.8.1F, ASHRAE 90.1 lists the minimum boiler efficiencies for
modelling the budget case. Two types of efficiencies are listed Et -
thermal efficiency and Ec - combustion efficiency. How do these two
efficiency rating types translate into DOE2.1e boiler efficiency.
For example a boiler listed in Table 6.8.1F with an Et = 75%, would
that be HW-BOILER-HIR = 1.333?
What about a boiler listed as 80% Ec?

I am somewhat confused about the two efficiency ratings.

Chris Jones, P.Eng.