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-   -   How much propane does the furnace use? (https://www.airforums.com/forums/f42/how-much-propane-does-the-furnace-use-216073.html)

switters 10-26-2020 03:23 PM

How much propane does the furnace use?
 
I'm in a situation where temps are below freezing, I haven't winterized the trailer, and won't be able to do so until Wednesday. The trailer is in our driveway and I have the furnace on 24/7 set to 70 degrees. One of my propane tanks is about 80% full, with ~5.5 lbs of propane, and the other is about 20% full, with ~1.5 lbs. I'm pretty new to Airstreaming (have taken 2 trips) so don't yet have a good sense of how much propane the furnace uses. Will this be enough to get me through until Wednesday about mid-day, when I will winterize?

Silvr_Bullet 10-26-2020 03:36 PM

Do you have a propane barbecue ? If you have 20 lb tanks fill it and replace one on Airstream with least amount of your dual tanks, then go fill that one.

switters 10-26-2020 03:42 PM

Quote:

Originally Posted by Silvr_Bullet (Post 2426353)
Do you have a propane barbecue ? If you have 20 lb tanks fill it and replace one on Airstream with least amount of your dual tanks, then go fill that one.

I don't. We have a direct propane line to our BBQ. There's a place nearby where I can refill a tank when/if necessary, but I was just wondering how likely it is that I'll need to do that given my current tank status and running the furnace at 72F for the next 36 hours?

pcskier 10-26-2020 03:47 PM

Chris here's the math:

Let's be conservative and say you have 5 gallons. That allows some wiggle room because it's harder to get all the propane out of the tank when it's so cold. Plus in your case I wouldn't want to rely on the auto-changeover valve to work when tank #1 runs out, hopefully it will but who knows when it's 8 degrees out.

One gallon of propane contains 91,502 BTUs, giving you 457,510 BTUs. Assuming your furnace is 18,000 BTU (should be, you can look behind the panel outside and it should say, or look in your manual.) Assuming it runs continuously, that gives you about 25 and a half hours of propane. If it runs 30 minutes per hour, you'd have 50 hours. So you have 25 hours at the low end...and the high end depends on how much time it's actually running.

Given that, I'd suggest filling the second tank (you can do so over at the Sinclair in Silver Creek), using that as primary (the auto-changeover arrow pointing at that tank) and use the other tank with 5 gallons as the backup. Giving you 12 gallons, that would be 61 hours of continuous run time...enough to get you into Wednesday night. Plus it likely won't run all the time, especially during the day. You can probably turn the thermostat down a bit as well. As mentioned I had mine set at 57 last night with no issues. Your weak link is the outside shower, did you happen to remove the hose and spray head yesterday? If not, likely toast but maybe not. If so, not an expensive repair. Best bet is to remove the hose and head, and stuff some insulation or even a towel or something in the cavity to help protect the valves that are behind the enclosure.

Dennis C 10-26-2020 03:49 PM

Why did you choose 70 degrees? You might be able to keep things from freezing at a lower temperature level, using less LP gas.

djb75 10-26-2020 03:49 PM

I think you could probably lower your temperature and maybe save some consumption. When I've been caught by freezing temps before winterizing, I've found 40 degrees is sufficient to keep things from freezing.

Silvr_Bullet 10-26-2020 03:50 PM

How much propane does the furnace use?
 
If it were me I would go buy a new tank, if you have that option, do everything you can to avert problems, small price. I agree with others lower setting as suggested.

switters 10-26-2020 03:56 PM

Thanks, everyone! I chose 72 degrees last night because I had just driven through frozen temps and snow for a couple hours and it was going to be 8F overnight. I will definitely turn it down to 55-60F now and I'll go fill up the tank that is at 20% capacity. That should get me through until Wed, when Peter is coming over to help me winterize!

Silvr_Bullet 10-26-2020 04:12 PM

Quote:

Originally Posted by switters (Post 2426369)
Thanks, everyone! I chose 72 degrees last night because I had just driven through frozen temps and snow for a couple hours and it was going to be 8F overnight. I will definitely turn it down to 55-60F now and I'll go fill up the tank that is at 20% capacity. That should get me through until Wed, when Peter is coming over to help me winterize!


I would open all draws, cabinets inside access to inside storage areas and bathroom and spaces where you see water lines to evenly heat vulnerable areas.

switters 10-26-2020 04:22 PM

Quote:

Originally Posted by Silvr_Bullet (Post 2426372)
I would open all draws, cabinets inside access to inside storage areas and bathroom and spaces where you see water lines to evenly heat vulnerable areas.

I've done that and I think it helped. Thanks.

switters 10-26-2020 04:23 PM

Quote:

Originally Posted by pcskier (Post 2426362)
Chris here's the math:

Let's be conservative and say you have 5 gallons. That allows some wiggle room because it's harder to get all the propane out of the tank when it's so cold. Plus in your case I wouldn't want to rely on the auto-changeover valve to work when tank #1 runs out, hopefully it will but who knows when it's 8 degrees out.

One gallon of propane contains 91,502 BTUs, giving you 457,510 BTUs. Assuming your furnace is 18,000 BTU (should be, you can look behind the panel outside and it should say, or look in your manual.) Assuming it runs continuously, that gives you about 25 and a half hours of propane. If it runs 30 minutes per hour, you'd have 50 hours. So you have 25 hours at the low end...and the high end depends on how much time it's actually running.

Given that, I'd suggest filling the second tank (you can do so over at the Sinclair in Silver Creek), using that as primary (the auto-changeover arrow pointing at that tank) and use the other tank with 5 gallons as the backup. Giving you 12 gallons, that would be 61 hours of continuous run time...enough to get you into Wednesday night. Plus it likely won't run all the time, especially during the day. You can probably turn the thermostat down a bit as well. As mentioned I had mine set at 57 last night with no issues. Your weak link is the outside shower, did you happen to remove the hose and spray head yesterday? If not, likely toast but maybe not. If so, not an expensive repair. Best bet is to remove the hose and head, and stuff some insulation or even a towel or something in the cavity to help protect the valves that are behind the enclosure.

I did stuff rags in the outside shower compartment last night, but didn't remove the hose and spray head. I'll do that now.

JohnTF 10-27-2020 10:54 AM

Too many variables to say .
I have lived yr-round , and in MN winters a 30lb tanks can last 2 or 3 days or 5-7 , as is .
But to keep from using too much propane , just like any energy usage .
Is to keep from losing any energy you put in - insulation .
You can keep the entire trailer warm with a pilot light - if no heat leaves the trailer .
In MN RV parks it is state law that you have to skirt trailers in winter .
Skirting makes about 5-10% difference .
You really want to make a difference , cover the top of trailer with insulation , this makes about 50% + improvement .
I do not use fresh water system in winter , but I do use the dain system , and use waterbed heater pad under shower pan / drain .

hhendrix 10-27-2020 11:21 AM

I just winterize, open cabinet doors, and use a small electric heater.

NorthernAir 11-09-2020 12:45 PM

You also need to consider the outside ambient temp. I got caught (Not having winterized the AS.) one fall in Yellowknife when the temp fell between -10C to -15C (14F to 5F). I had the furnace set to about 12C (54F) I was burning through 30 lbs of propane every 48 hrs.

s1000pre 11-09-2020 01:18 PM

I burnt roughly 40% of my 30lb. tank overnight at 70 degrees a couple weeks ago when the temps hit 28 degrees. I use the Mopeka Products tank monitors.

VeloBuckeye 11-09-2020 01:27 PM

Earlier this Spring went through a full 30 lb tank over a 2 night/2 day stay where daytime highs were 45F and nighttime lows were 30F. Thermostat set at 66F. I also use Mopeka Products tank monitors. Tank showed 100% full at beginning of trip and 3% left at end.

Because it was so cold we cooked inside, which used some propane as well, but the furnace was the primary propane hog.

s1000pre 11-09-2020 01:36 PM

Quote:

Originally Posted by VeloBuckeye (Post 2430874)
Earlier this Spring went through a full 30 lb tank over a 2 night/2 day stay where daytime highs were 45F and nighttime lows were 30F. Thermostat set at 66F. I also use Mopeka Products tank monitors. Tank showed 100% full at beginning of trip and 3% left at end.

Because it was so cold we cooked inside, which used some propane as well, but the furnace was the primary propane hog.


I bet that tank was rather frosty!

brick1 11-09-2020 05:27 PM

Although it will vary depending on temp, wind and exposure, a 30 lb tank will last maybe 3.5 days. Tanks only run out in the middle of the night...

Daquenzer 11-09-2020 05:52 PM

Once in Indiana the temps got into the low 20’s for about 4 days. Went through 2 tanks. We used electricity for everything else. I bought an extra tank to have a spare, because about the time you need to fill a tank something will be closed. Murphy loves to show up.

s1000pre 11-10-2020 10:18 AM

Quote:

Originally Posted by brick1 (Post 2430950)
Although it will vary depending on temp, wind and exposure, a 30 lb tank will last maybe 3.5 days. Tanks only run out in the middle of the night...

Just like the batteries in smoke detectors!:lol::lol:


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