efo141 wrote:can you get transfer efficiency from these numbers?
Yes & no, kind of, approximately. If you know the rated BTU and know how many pounds per hour it uses, that kind of gives you overall efficiency. But, toss that out the window, as mentioned, hand feds run about 70%, stokers higher, boilers higher than hot air. The carpet boilers seems to be a bit less than the *huge fan* boilers like the AA & AHS. In any appliance the coal, the draft, seemingly even the phase of the moon can make things run differently. For sure my AA likes to run. It burns more efficiently when it's dead of winter than in the warmer days of Fall.