How much propane does my furnace use

[Jeff Bittner]

How many hours will 30gal of propane last when using my furnace? I know there are many variables but I've read 1gal every 3hrs when running continuously but what is continuously? The furnace kicked on every 12 minutes or so set at 64 degrees with an outside temp of 28. International 25 FBT.

[TitusNW]

Jeff,


I can get you some good info but I'm out of town until next Wednesday. The furnace burner runs independently from the furnace fan and I was curious about the same information for our 25'. I installed a 12v hour meter into the circuit that activates the burner of the furnace. We recently spent a week at the Oregon coast and I can tell you the number of hours the burner ran during that week.


Steve

[Acheron2010]

When we had that deep freeze in Texas 2 winters ago, I burned through a tank each day, with thermo set at 68. I imagine with wind chill it was in the low 20's. 2019 FC 26.

[Wazbro]

Actually your Airstream came with only 7 gallon/30 pound propane cylinders not 30 gallon which is about 130lbs. Unless you have a separate tank by your trailer.

When my parents use to visit friends in Bloomsburg, PA with daytime highs about 20F and single digit lows they got about 2.5 days out of a 40lb cylinder with a 31' Airstream.

[Jeff Bittner]

You're correct. I misspoke. 7gal would give me roughly 21hrs?

[foobar]

Originally Posted by Jeff Bittner

You're correct. I misspoke. 7gal would give me roughly 21hrs?

Last November, we camped at Palo Duro Canyon state park here in Northwest Texas.

6 days, 5 nights of camping. Low temperatures were 12-15F for 3 of the nights and around 25F during for 2 of the nights.

We ran the furnace 24 hours a day for the 3 coldest days, with the thermostat set at 65F, but turned it off in the daytime for about 8 hours on the warmer 2 days as the sun warmed up the trailer enough by itself. We also ran the oven every day and cooked with a Campchef Ranger II stovetop outside for several meals.

Over the entire camping trip, we ended up burning a total of 5 gallons of propane (about 2/3rds of the 7 gallons of propane in a 30lb tank).

The tough part of this estimating process is that the 'duty cycle' or the percentage of time the furnace runs can vary quite a bit. As I noted above, on cloudy days with a lot of wind the duty cycle will be much higher and on sunny, still days the furnace runtime will be much lower on average.

[GetawA-S]

Jeff,
Have you checked the specs in your owners manual?
As mentioned above, the most easily measured variable is the duty cycle . How long does it run every twelve minutes? Multiply by 5 to get the hourly usage.
Most furnaces are rated for 35000 BTU/hr output. Divide by the efficiency if you know it (divide by 100 first to convert from %) to get the input BTU/hr.
Each pound of propane is worth about 20,000 BTU. This is equivalent to a bit over 80,000 BTU/gallon.
When we leave a domicile empty we set the thermostat to 50 F, which reduces the heating load by as much as 50%, depending on the outside temperature and wind conditions.
Stay warm!

[FredWilma]

We are currently in Santa Fe NM. Overnight temps in the low 20s, days in the low 30s. We’re in a 22’ caravel. I happen to have been measuring usage as I’m paranoid of running out of propane. In the last 24 hours we’ve used 40% of a 5 gallon tank. So around 2 gallons. We’re running the furnace constantly at 72F daytime and 65F at night.

In addition we’ve taken two normal showers and boiled water 3 times for coffee.

So in these conditions the two 5 gallon (20lb) tanks last about 5 days.

I hope this helps.

[jeffb831]

Originally Posted by Jeff Bittner

How many hours will 30gal of propane last when using my furnace? I know there are many variables but I've read 1gal every 3hrs when running continuously but what is continuously? The furnace kicked on every 12 minutes or so set at 64 degrees with an outside temp of 28. International 25 FBT.

You don't have 30gal tanks but instead 30# tanks, which hold a little over 7 gal of propane.

Based your reading (1 gallon every 3 hours) and Acheron2010's experience (1 tank for 24 hours) they seem to agree for an estimate.

[Wazbro]

Originally Posted by Jeff Bittner

You're correct. I misspoke. 7gal would give me roughly 21hrs?

Sounds about right, that is with the heater running with a flame burning.

It would need to be well below 0f to need to be running close to constantly. At 15f in a 1973 31' Airstream the furnace only ran about 1/3 of the time to keep inside about 62f. The temp you want inside and amount of wind will make a difference to.

[TitusNW]

For our 4 day trip to the Oregon Coast our furnace burner was active for 11.2 hours.

The weather was highs of 48, lows of 32.

Propane burner clocked 11.2 hours on the hour meter

So the propane calculation is:

11.2 hours active burner
x 30,000 furnace btu/hr
/91,500 propane btu/gal
___________
3.67 gallons of propane was consumed over the 4 day trip

Steve

[kbmwrs]

Originally Posted by Acheron2010

When we had that deep freeze in Texas 2 winters ago, I burned through a tank each day, with thermo set at 68. I imagine with wind chill it was in the low 20's. 2019 FC 26.

Please do not consider wind chill. This is a metric ONLY for the human skin. Metal/air only relate to actual temperatures not wind chill.

[ASFC25_2019]

Originally Posted by TitusNW

For our 4 day trip to the Oregon Coast our furnace burner was active for 11.2 hours.

The weather was highs of 48, lows of 32.

Propane burner clocked 11.2 hours on the hour meter

So the propane calculation is:

11.2 hours active burner
x 30,000 furnace btu/hr
/91,500 propane btu/gal
___________
3.67 gallons of propane was consumed over the 4 day trip

Steve

We are about to head to the Oregon coast and were curious how much propane we would use. We have installed the Mopeka propane tank monitor, which might help ease my mind a little more! Planning on leaving the thermostat at 50-55. From this chats seem like we will be ok.