? on LP heater

DocHeb · Oct 1, 2001

Smaller tanks around here are filled by the pound. Typical Bar-b-que tank, 20 lbs. Larger tanks for heating uses 100 lb. Any idea on the conversions between Pounds, Therms, BTUs and Gallons?

Devildog · Oct 1, 2001

We have had a ventless in the basement for three years and have not had any moisture problem. Does anyone know what causes it(moisture problem). It is used in conjunction to our heat pump and we go through roughly about 200 gals per year.
___________________________________________________
Take care, Jim

2001 B7500 HST 302 Fel R4 Tires, Befco BRB60
Semper Fidelis

Bird · Oct 1, 2001

PaulT, according to my little Operator's Manual for Safe Dispensing of Propane, provided by Ferrellgas, "When the propane liquid is changed into a gas, it will occupy about 270 times the volume as the liquid."

Bird

Bird · Oct 1, 2001

DocHeb, maybe I can provide partial answers. Of course, if you just figure 4 pounds per gallon, you'll be close enough. Have you ever looked at the data plate, or information, on those propane cylinders? I've never understood why people come up with "specialized" terminology instead of using plain English, but the data plate (actually not a plate, but stamped on the cylinder or collar) lists the tare weight (T.W.) of the empty cylinder (empty weight, in other words). Then it lists the water capacity (W.C.) in pounds - don't ask me why - who's ever going to put water in it? So you can multiply the water capacity by 0.42 and determine the propane capacity. Next you can add the propane capacity weight and the tare weight and know what a properly filled cylinder will weigh.

Propane is supposedly 91,547 BTUs per gallon (compared to approx. 120,000 BTUs for gasoline) and, in its vapor state, approximately 2,516 BTUs per cubic foot (compared to 1,040 for natural gas).

And I don't know anything about Therms.

Bird

TWINKLE_TOES · Oct 1, 2001

Bird,

Propane is supposedly 91,547 BTUs per gallon 

You seem to have a flair for the right words/w3tcompact/icons/smile.gif In this case "supposedly " is the exact right word. As an example the U.S. Department of Energy identifies 84,000 BTU's per gallon. The real number is a pressure/temperature (primarily temperature) dependent number. This is the reason why cylinders are not filled to capacity ~80%. The expansion with temperature is significant. In the good old days my propane bill was identified by "therms". Now it's gallons and the equivalancy to heat value (therms) is controlled by requlation. The therm is pretty much transparent to the end user.
Al

TWINKLE_TOES · Oct 1, 2001

Paul,

Aren't liquids "generally" uncompressable. 

Pretty much so, but they do change volume with temperature. Top off your rig on a cold morning and park it in the sun all day and it may overflow. Propane tanks are only filled to about 80% to make room for liquid expansion.

Al

gordon · Oct 1, 2001

Or if you want to cheat you could move the decimal point over on the water column and be pretty darn close as well. Say for a 20 lb cyl is 47.2 ---move it over to the left and you have 4.7 gallons of propane at 100% full. Actually its 4.2 gallons for a tewnty lb cyl (at 80%) but it gets you in the ball park and it's easy to remember. /w3tcompact/icons/smile.gif

Tare wt and the size of cyl is the proper way to fill a dot tank. As you well know. But that stamed label does say alot if you know how to read it on bot a D.O.T. tank and an A.M.S.E. tank as well. Shame they can't put it in english so we all could understand it.

Gordon

bgott · Oct 1, 2001

The byproducts of complete combustion are carbon dioxide and water. Your heat pump is probably dehumidifing the air.

Devildog · Oct 2, 2001

Brad,
Thanks, I forgot to mention we also have a dehunidifier in the basement to. I could'nt figure out when winter camping my truck topper always had so much moisture in the morning. I use one of them vent free little buddy heaters. Now I guess I need to find something else.
____________________________________________________
Take care, Jim

2001 B7500 HST 302 Fel R4 Tires, Befco BRB60
Semper Fidelis