Propane question

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Castranova

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Can you approximate how long it'll take two people to go through 2 tanks on a cold camping trip? We would probably use it for some cooking and to keep us at about 68 degrees at night. They are 20 lbs (not sure if that's one tank or together but there are two of them at the front of our Jayco) Thanks! ;)
 

donn

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Too many variables to even make an educated guess.  If you really want to know, look up the BTU per pound for propane and divide that number by your furnaces BTU output.  That will give you a rough estimate of how much propane will be consumed per hour of burn time.
 

Alfa38User

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The same amount of time as 1 person....  ;D

You should get several days provided the days are not  cold. The killer is the 12V supply unless you are plugged in. Those furnaces are heavy 12V users and they like propane almost as much.

Most larger 5th wheels have 2 x 30 lbs propane tanks, a taller tank. They actually weigh about 56lbs each when full, 26lbs when empty.

Many travel trailers have 1 or 2  20lb shorter tanks (commonly used for bar-b-ques) but they could have 30lbs tanks too.

There are about 21622 BTU in 1 lb of propane or about 432440 BTU in a 20 lb bottle. What size is your furnace in BTU?? (Knowing the make and model of the furnace will help calculate the approx. no of hours you can run but that won't tell you anything about the temperature you can maintain.)
 

Lou Schneider

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Your furnace (and other gas appliances) should list their BTU input on the nameplate.  That's how much gas it consumes per hour.

Divide that by the BTU capacity of your tank - as Stu said above, or if you buy propane by the gallon it's about 90,000 BTUs per gallon.

For example, if your furnace is rated at 30,000 BTUs it will use about 1/3 gallon of propane per hour of running time (30,000 / 90,000 = 1/3).  So a 5 gallon propane tank will give you about 15 hours of continuous use, a 7 1/2 gallon tank will last about 21 hours, etc.  Unless you're in extremely cold weather the furnace will not run continuously.

Again, like Stu said, the biggest limitation is your battery capacity to run the furnace blower.  If you're not plugged in the blower can exhaust a single battery overnight.

Your water heater will use about half as much gas, but the burner only operates for a half hour or so to heat a tankfull of water.

Same thing holds true for your stove burners, but they're usually rated around 6000 - 9000 BTUs each.  That's how much gas they use when fully on.  Put them on medium or low flame and they'll use proportionately less.

The refrigerator doesn't use enough gas to worry about - it's somewhere around 1/30th gallon or less per day.
 

Castranova

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Livermore, Colorado
Lou and Alfa38user,
Thank you BOTH so much! Lou, your calculations make TONS of sense and being a former, high school science teach, I understood! Stu, I have FOUR marine batteries on my rig, and keep them charged when NOT plugged in to power with two solar panels on top--I keep the inverter turned on constantly. ."The same amount of time as one user," cracked me up!  :D
I think that the 20lb tanks we have will be plenty for a weekend away. The trick is NOT to try to use any solar power when running the furnace! (I doubt it would last 5 seconds...hahaha) You guys are very helpful and knowledgeable and have helped me with an "educated" guess on how much we'll be using. I will check the furnace out-put tomorrow when the sun comes up and see if I can get closer to a rough estimate on usage. Your comments were very, very helpful! ~Karen  ;D
Hey, if ANYTHING I said above doesn't make sense, or I'm doing something BAD or WRONG, please tell me!!! I take criticism well.  :-\
 

99WinAdventurer37G

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A friend of mine has a TT with two tanks on the front, and they don't switch automatically.  So, he knows when he's at half tank.  If it takes him two days to run through the first one, the second one will last another two days. 

The nice thing is, he just takes it off the TT, and up to the store to fill it up.  I have to break camp and take my entire MH to get more Propane.
 

Icemaker

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99WinAdventurer37G said:
A friend of mine has a TT with two tanks on the front, and they don't switch automatically.  So, he knows when he's at half tank.  If it takes him two days to run through the first one, the second one will last another two days. 

The nice thing is, he just takes it off the TT, and up to the store to fill it up.  I have to break camp and take my entire MH to get more Propane.

I had to do that till I put an "Extend-a-stay" [I believe it's called] that allows me to use up to a 100# bottle for my coach and save the main tank as a back-up while refilling the bottle....works so well I'm putting it on this newer, slightly, coach for the winter..

George
 

John From Detroit

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99 had it right, Just open one tank, when you run out pull that tank, open the other one (Assuming you have a proper change over valve so you do not vent the 2nd tank) and get the 1st one refilled, , Then replace it, when tank 2 runs dry switch over and open the valve on tank one, Pull tank 2 and refill it.

You can run forever that way

In fact when I was growing up we ran the kitchen that way (3 tanks 100 pounders) for .... Well,,, 20 years.
 

Alfa38User

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Just an FYI, 4 batteries is good!!. However, the so-called 'marine' batteries are not the best deep discharge type batteries around as many of them are intended to start the boat engines as well. The best type of deep discharge batteries are golf cart batteries. Many of us still use the cheaper and more readily available marine type successfully though!!

As long as a tank does not run out at 3:00A, (as mine did, LOL) manual switching works well to prevent accidentally running out of propane. Darn, it was cold out there!!!!

And, would that be a CONVERTER, rather than an inverter?? Converter= 120V to 12V; Inverter = 12V to 120V in most rigs. Either type can have a battery charge function but the small inverters, used to power a TV, do not!!
 

Castranova

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Hi Stu,
Thank you so much for the comments! The "inverter/converter?" says "Sine Wave" and is located in the front panel of the trailer. I believe it's to convert the solar power into 12V to use in the camper? Not sure. Doesn't the solar simply keep the batteries charged and nothing more? I appreciate this! :D
 

Gary RV_Wizard

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If the solar panel is a larger one, it will have a regulator for charging the batteries. Smaller ones, e.g. 15-20 watts, won't have a regulator. Battery charging is all that a solar panel does.

A converter makes 12v power from shore power (120vac) for use in lieu of battery power. It is basically a battery charger.

An inverter makes 120vac from 12v battery power.  They are not usually found in trailers, at least not as standard equipment, but one may have been added.  The fact that you have 4 batteries also suggests an upgrade.  "Sine wave" implies the device is an inverter, since only alternating current power has a sine wave. An inverter uses a huge amount of 12v power to produce a small amount of 120vac. The 12v amperage is 10x the output 120v amperage (as a science teacher, you will remember Conservation of Energy, i.e. that input watts must equal output watts).

The amount of propane (and 12v power) you use depends entirely on the amount of runtime of the furnace, and that in turn depends temperature differential. If it's in the 30's and you keep the interior at 68, expect the furnace to run 50-75% of the time. RVs do not retain heat well at all!
 

Greg H.

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We just got back from a cold weekend at Shenandoah National Park, so i've got a bit of real world data for you.  We left with 2 twenty lb tanks, one full, the other 3/4 full.  We stayed for three nights with lows in the upper 30's to low 40's.  We have a single 130 AH battery (20 hr rate) that was fully charged upon leaving.  The site had no electricity hookup.  We ran our generator (onan 2500) for 10 hours total during daily generator hours (5 hrs/day) mostly to keep the battery as far over 50% as we could so that we could run the heater later at night during quiet hours.  In addition, we cooked with the gas stove twice a day and ran the water heater for a few hours each day.  Tank one, the 3/4 full one, 'ran out' one the second day, first thing in the morning when I started the Jenny at 8:00 am.  I switched over to the second one, used it for 5 hrs on Sunday... It 'ran out' at 8 am on Monday morning. 

Upon filling each tank when we returned, I found each to be 1/4 or a bit more full prior to filling.  It turns out that they appeared empty to the Jenny because the rate of vaporization could not keep up with the generator's demand due to the cold.  See attached blurb (item 4) from my troubleshooting guide.

So, I had about 1/2 tank left between the two after a long, bitter cold, blustery, rainy weekend.

Lessons learned: get another battery or two, add a solar panel or two (though they would not have helped much this trip), find a source of heat that does not require electricity (Quartz wave heater), and don't count on the full tank of propane for the generator in colder temps.



 

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Gary RV_Wizard

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A 2500 watt LP generator can consume a lot of propane. Onan says about 0.3 gal/hr with no load and 0.4 gal/hr at 50% load (1250 watts).  A 20 lb LP tank contains 4.1 gallons of propane, but you seldom get to use it all, especially in cold weather. So 10 hours of generator runtime is about 3/4's of a 20# tank all by itself.
 

denmarc

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Gary RV Roamer said:
The amount of propane (and 12v power) you use depends entirely on the amount of runtime of the furnace, and that in turn depends temperature differential. If it's in the 30's and you keep the interior at 68, expect the furnace to run 50-75% of the time. RVs do not retain heat well at all!

I can attest to this also.  I use my TT and heat with propane throughout the Fall and sometimes into early Winter.  Power and propane consumption is your biggest concern.  In MI, the nights lately have been getting down into the lower 30's already in the area my TT is parked.  I have a 100# tank as a main, with a 30# as a standby (auto-switchover) to give me time to get the main refilled.  After 3 weekends of use off of the main, I have a little less than half of the 100# left to burn.  The furnace is off during the day.
 

Castranova

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Livermore, Colorado
Thanks for helping me calculate what we'll be needing for 4 nights and 5 days on the road this upcoming trip. The tanks appear to be two 20lbs.

Yes, the sine-wave inverter is on constantly, and it has been for about 5 days but we don't have full-sun and batteries seem to be charged fully, and simply keep equalizing at this point.

Thanks Gary, Denmark, and Greg for the recent in-put, because it made more sense to me when trying to decide if I should purchase another heat-source. I decided to keep the small electric, fire-place heater turned on during the night, and let the propane kick in when the furnace feels the inner temp gets too cold. We will be in Saratoga, WYO and the night time temps will grace 30, I'm sure.
Gary, the up-grade includes the sine wave inverter, two solar panels, and inside there's a small dialogue box that shows a steady, red light or the light is blinking in intervals depending on  batteries charge. It set the last guy back @ $1,800. If I'm informed, I am realizing the solar is only a way to keep the batteries charged up, not much else, but that could come in handy without any electric hook-ups around. I still can't turn the lights on after it being on for 5 days, so that says something too. :-[ Kind of Embarrassing.~Karen
 

denmarc

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Castranova said:
I still can't turn the lights on after it being on for 5 days, so that says something too. :-[ Kind of Embarrassing.~Karen

FOR CRYING OUT LOUD!...Don't be embarrassed!  Do what we do...
You try it out, and if it doesn't work...you ask questions.  Read the answers, try it out again, keep fingers crossed.

If it still doesn't work, ask again.  Simple as that.  Many on this forum love a basic challenge.



 

Icemaker

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denmarc said:
FOR CRYING OUT LOUD!...Don't be embarrassed!  Do what we do...
You try it out, and if it doesn't work...you ask questions.  Read the answers, try it out again, keep fingers crossed.

If it still doesn't work, ask again.  Simple as that.  Many on this forum love a basic challenge.

Absolutely ...I think i I didn't like a challenge I'd have to sell my coach....

George
 

PJ Stough

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In order to save battery power when boondocking we bought one of these three years ago, and we love it!

http://www.amazon.com/World-KWP112-000-BTU-Vent-Free-Infrared/dp/B000KKO4PW/ref=sr_1_6?ie=UTF8&qid=1350336986&sr=8-6&keywords=kozy+world+heater

We also purchased 20' of hose and a regulator.  We hook it up to a 20 lb tank outside the motorhome, and run the hose inside.  Just like having a fireplace in the motorhome!

Paul
 

Gary RV_Wizard

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I decided to keep the small electric, fire-place heater turned on during the night,

I'm confused - how are you going to run an electric heater if you don't have shore power?  And if you do have shore power, the inverter doesn't need to run (except perhaps if it is also the charger) and the batteries won't discharge no matter what you do (the charging system will supply all your 12v needs).
 

Castranova

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Livermore, Colorado
Gary,
I would only run the EL heater which is one of those ceramic jobbers, if I'm plugged into shore power--simply to save propane. My inverter can put out 110V if I need it, but I bet I'll really never use it much. I suppose it would be handy for an outdoor light? What do most people use them for?

The batteries are all good, but what WASn'T good was the small fuse that offers some type of surge protection. It was corroded and I had the entire wire and small fuse holder replaced today. it fixed the entire rig!

Do you know where I can get a heavy duty surge protector?

Thanks! :)
 
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