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!

Views: 492

Reply to This

Replies to This Discussion

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

http://www.joppaglass.com/burner/lowp_chrt.html

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.

Ernst,

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. 

Bud

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.

For the oil burning furnaces, you should check the pump pressure. Older furnaces run at 100psi, and newer ones run at 140psi. When the pressure is higher, you need to cross reference the nozzle size to get proper Btu ratings. Plenty of reference materials are located on the Beckett website.

For propane figure about 20-25k per burner rated input. Varies some form unit to unit but 22k is typical.

Thanks Bob, we'll go woithout. It should be close enough without having to factor in pressures and temps, etc and  complicate the process too much.

I'll apologies in advance for drifting here a bit, but your "close enough" comment threw me back to my beginning in this business (05) when I questioned every number we use.  The idea of pinning down the performance of a home to the last tiny detail is laughable when we consider just how many of our inputs are "close enough" numbers.  From insulation values, HDD, window performance, and air leakage (to name a few), we guess and we guess and then carry our calculations out to two decimal places (or the computer does).  I think my tape measure is the only real source of accurate information :).

I enjoyed the comment

Bud

RSS

Forum Discussions

Origin of guarded blower door testing

Started by Kim Tanner in General Forum. Last reply by Eric Kjelshus 6 hours ago. 9 Replies

Electro Magnetic Fields (EMF)

Started by Barry L NewDelman in General Forum. Last reply by Daniel Cullen Aug 10. 5 Replies

When is it too windy to use blower door?

Started by Brandon Walton in General Forum. Last reply by Iain Walker Aug 10. 17 Replies

Latest Activity

Eric Kjelshus replied to Kim Tanner's discussion Origin of guarded blower door testing
"That same house that meet highest sealing rate in early 1980 we went back and super sealed it and…"
6 hours ago
Jill Cliburn posted an event
Thumbnail

National Solar Conference and NZE Decathlon at University of Colorado

October 9, 2017 at 6pm to October 12, 2017 at 7pm
6 hours ago
tedkidd replied to Kim Tanner's discussion Origin of guarded blower door testing
"Brendan, Eric, great stuff!"
7 hours ago
tedkidd liked Kim Tanner's discussion Origin of guarded blower door testing
7 hours ago

Photos

Loading…
  • Add Photos
  • View All

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service