Does anyone have an inexpensive method to "clock" a combustion furnace to estimate BTU output similar to Natural gas, but for propane, kerosene, or oil? I work in the Weatherization Assistance Program and often the nameplates are missing from existing furnaces. Without BTU output it is tough to do an accurate computer model of the home. Thanks!
For natural gas, run only the furnace for a given time, mark the dial difference on the meter and multiply the gas used by the heat multiplier for your gas supplier. This will give you a ball park estimate.
For propane, you can look at the burner orfice size. there are charts that give the btu rating for the orfice size. then multiply by the numbers of burners. will give approx output. LP orfices are usually slightly smaller btu than Nat. ones.
Follow the link
Thanks for all the comments plus the link. I think based on them I have enough information forfollks in the field to get close enough to the correct size furnaces for modeling the houses thanks all.
You mentioned oil, but the replies seem to all be for gas, unless I didn't read correctly. For oil you can look for the nozzle size. Sometimes it is notes on the service tag or in the manual, if still around. In some cases you might be able to call the service company as they may have that noted for their HDD fuel calculations or service work.
Thanks, I did find that out. In weatherization we deal with some really old furnaces, so sometimes getting a ballpark furnace size is the best we can do but the nozzle sizes for oil seem to be pretty specific.