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: 410

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

Photos

Loading…
  • Add Photos
  • View All

Latest Activity

Profile IconBob Eldredge and Thomas Joseph joined Home Energy Pros
2 hours ago
Colin Genge updated an event
Thumbnail

Measuring HVAC Performance webinar at Online

February 23, 2016 from 11am to 12pm
If you install, service or test HVAC systems you will want be there for this special webinar.…See More
3 hours ago
Colin Genge updated an event
Thumbnail

Testing for IECC Code Compliance for duct and house leakage webinar at Online

February 16, 2016 from 11am to 12pm
The International Energy Conservation Code (IECC) is in use or adopted in 47 states, the District…See More
3 hours ago
Jan Green posted a status
"I'm honored to be selected to speak at the 2016 RESNET Conference right here in sunny Scottsdale 2/29-3/2/16 with SRP & others!"
4 hours ago
Joe Konopacki posted an event

Duct & Envelope Tightness (DET) Verifier at Temperature Equipment Corporation

February 26, 2016 from 8:30am to 4:30pm
The Duct & Envelope Tightness Certification (DET) was designed by the Midwest Home Performance…See More
5 hours ago
Diane Jackson liked Don Hynek's discussion Superinsulation retrofit is Complete!
6 hours ago
Alice La Pierre liked Dave Robinson's discussion Can We PLEASE Stop Calling Them “Ductless”
7 hours ago
Alice La Pierre liked Linda Wigington's discussion Congrats Ceniceros Household! 26th Project to Officially Meet 1000 Home Challenge
7 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service