BTU's in a propane bottle?? Anyone??

[davenpete]

Hi,

I want to use a 10,000BTU propane, non-vented, wall mount radiant heater. Having an all eletric home means no gas tank outside.

Can anyone tell me how long I might be able to run one of these at full

10,000BTU from a standard BBQ propane tank.

Are we talking hours days or weeks??

Thanks

[Dave, I can't do that]

Thanks Doug,

I did a few searches but your "heat content" was the key, I got so many hits it was useless with the searches I did. DUH!! Slapping myself on the forehead.

I will see if the tank is marked with "gallons."

Given the gallons though, what do I do with them and 90K/gal? I think the tanks are around 5 gallons. I'll go look.

I need to look up exactly what BTU is, (other than British Thermal Units ;-O), but is that rating for the heater per hour or minute or what?

Thanks so far though.

Dave

[Brian V]

Standard tank 20#

4.24# per gallon 20/4.24=4.72 gallons 4.72*91547=432101.84 btu per 20# tank 432101.84/10000= 43.2 hrs running at full blast

[Marc]

Good ol' Google: definition BTU The amount of heat required to raise 1-lb of water 1-degF

[Doug Miller]

That's 10,000 BTU per hour, by the way.

Google search on [propane "heat content"]. You should find 91,500 BTU per gallon. How many gallons in the tank? Do the math.

[boden]

A 20# cylinder contains about 4.8 gallons of propane. This will give you a total capacity of 441,600 BTU. You can get 30 to 33 hours of operation IF the outside temperature is above +10F. If the temperature drops below +10F you're out of luck.

As the propane boils in the cylinder it gets cooler. If the outside temperature is warm enough enough heat will flow into the cylinder to enable the boiling (vaporization of propane) to continue. For a 20# cylinder, 25% full, 10,000 BTU/hr is the maximum rate at which you can extract propane for heating. If the fuel is butane the time is quite a bit less.

Boden

[e-mail] wrote:

[Drifter]

If I remember correctly, 1 lb of liquid propane has somewhere in the neighborhood of 20,000 BTU of energy stored.

A stock propane tank for a grill is usually 20-30 lb of propane so you'd get a total of somewhere in the neighborhood of 400k to 600k BTU

So if your heater generates roughly 10,000 BTU per hour you should be able to get around 40-60 hrs of use on a standard "gas grill" type propane cyl.

This is all, of course, the roughest of calculations and your mileage may (and probably will) vary greatly.

Drifter "I've been here, I've been there..."

[Doug Miller]

Like I said in my initial response... it's per hour.

Tank holds 'x' gallons. One gallon supplies 90K BTU. Heater burns 10K BTU per hour. Do the math.

[Stormin Mormon]

A small infared heater is supposed to put out 3,500 BTU for 7 hours on a one pound (16 ounce) propane bottle. Hope that's of some help.

[Stormin Mormon]

A BTU, British thermal Unit, is the ammount of heat necessary to raise one pound of tea (well, really water) one degree farenheit.

As opposed to a calorie which is the heat needed to raise a gram of water one degee centigrade.

[Edwin Pawlowski]

252 calories = 1 Btu

100,000 Btu = 1 therm

[George E. Cawthon]

The standard tank is 20# or 5 gallons. With the new valves they can only put 4.5 gallons in the tank.

[Dave, I can't do that]

Thanks Brian,

Thanks to everyone who responded. Concencus seems to be about 40 hours or in that vicinity.

I'll check with my insurance agent on the gas bottle inside. I can always drill a hole through the wall and run a hose with bottle outside on the patio.

As to the few comments on non-vented they are as safe as any other form of heating. Modern ones have an ODS (Oxygen Depletion Sensor) that shuts gas off before CO gets too high. Of course I would still have a Nighthawk CO sensor which actually has a readout of the levels rather than just a warning beeper if too high.

Thanks again guys, I will wive it a shot.

Dave

[Bob G.]

I do not follow the above reasoning...about what the outside tempature ....the freezing temp of Propane is like minus 400 or so degrees....not really sure but real real low...and the boiling point is about Minus

40 degrees...

Again I just do not understand ...it boils yes...and the resulting vapor is what you burn... If the outside

Sorry but this old guy is not a rocket scientest by any means...but I can tell you that you can store a 20 pound cylinder of propane in your house hold freezer and the propane will still be well above its boiling tempature... ============================

That said... I heat my shop with Propane....(116,000 BTU gas furnace converted to burn propane)... I burn about 300 gallons...of propane a year...

Bob G.

[Jim Elbrecht]

So would his fire insurance company. It is illegal, too. [anything over 1 pound of LP has to remain outside.]

I love my ventless propane heater-- but for the sake of yourself & any humans you hold dear, have the gas company hook it up for you. [mine charged less for the installation than I would have paid for the parts at the local borg. also- LP gas is cheaper delivered in bulk than carted around in those BBQ bottles.]

Jim

[Joseph Meehan]

I would personally worry about having one of those tanks inside the house with temporary hoses hooking it up.

[Wayne Whitney]

Yes, absolutely. I think the issue is one of rates--if you are trying to draw propane out too quickly, the environment around the tank may not be able to supply enough heat quickly enough to keep up with the heat requirement to boil the liquid propane.

Cheers, Wayne

[Goedjn]

Unless of course, you're eating them (the calories), in which case, they're one thousand times as big.

[Robertm]

Some states still have code from 30 years ago and still deem unvented to be unsafe. Safe or not, you must stay within the code. Some states allow only small unvented heaters in a sleeping area but ok for larger unvented in non-sleeping areas. Aside from CO, unvented burns any particles or fumes in the room and vents that to the room so California has declared them to be a cancer causing agent. From experience, don't light them for a few days after using oil based paint or contact cement. Long after the danger of explosive fumes has gone, the byproducts of combustion can still be nasty. Liquid Nails will emit fumes for two weeks that when burned cause an irritating cough.

Bob

[Edwin Pawlowski]

This just begs the question: How many Btus in a fart? The gas is methane so it heating value