Posted on 01/06/2014 12:27:07 PM PST by virgil283
Absolutely will. Each gallon of propane burned will generate 6.8 pounds of water vapor. If combustion is not vented to the outside, this large amount of water vapor will raise the humidity inside. How much the humidity goes up is dependent on a number of factors, basically how leaky the structure is to air.
If no leakage of air occurs to the outside, in a 10,000 cubic foot structure (1000 square feet x 10' ceiling), burning 5 pounds of propane will generate ~30 grains of water vapor per pound of air.
That 30 grains per pound will raise the relative humidity at 70F from 50% to 77%, high enough to grow mold nicely.
Burning 10 pounds of propane would raise RH to 99%.
Oh, boy, will it ever. The house I live in now is a cabin on a lake, and originally was built without any central heating, only an UNVENTED wall propane heater upstairs.
When I bought the place I learned that the insulation in the ceiling (home-built cathedral ceiling, so it was about four inches from the roof) had become completely sodden and was ruined. Had to peel the roof off, replace the spacers according to code, and the insulation, and put the roof back on. Next thing I did was central heat.
It's nice and toasty now, temps outside about 18F. How they survived the winter here I'll never know.
Never, but some of the more sophisticated systems for controlling fresh air supply into large office building use them. Measure the ventilation air needed instead of just adding it per some present formula. Can save VERY large amounts of money by not having to cool, heat or dehumidify unencessary fresh air.
What happened there is something I didn’t address in my little calculation.
Relative humidity won’t go up evenly, it will get MUCH higher in the cooler spaces and will condense onto and soak into cooler materials.
It’s actually pretty easy to control, with some attention to detail, as you have VERY dry air outside to mix with your inside air and bring down its humidity.
But I highly recommend venting combustion heaters to the outside, if used for more than very short periods.
Thinking of getting the rest of the place re-insulated. I think it'd pay for itself pretty quickly. Just have to figure out what options to go with.
Accck. Do NOT give any credence to the calculations in #61. They suffer from the dreaded misplace decimal syndrome.
Burning 5 pounds of propane will increase the grains of moisture in the air by 10x the amount in the calculations, which means it’s going to be raining inside before you finish the burn.
Burning one pound of unvented propane would bring RH to very nearly 100%.
Sorry bout that.
We bought two CO (not CO2) detectors on Amazon when we bought a house with a propane gas log ventless fireplace, which gives good heat. We crack a window in that room and turn on the ceiling fans the send the warm air up to hit the ceiling and then be forced down. Works great to supplement our regular HVAC system when the furnaces are working hard. (Here in E. TN it’s now 0 degrees.)
The house is over 5,000 sq. ft., and the floor plan allows the heat to flow to make things tolerable on both levels.
I’m afraid of any of the portable heaters. (Ex BIL died in his sleep because of a portable gas heater.) I was leary of this gas FP, but after four years I guess it’s OK.
So that’s a “NAY” on the rust eaten hibachi with wet charcoal?
:)
You can purchase vent free propane heaters at most hardware stores. The issue is that you have to have a large supply to run a 30,000 BTU unit. A 20lb. tank won’t cut it.
$4.95 per gallon Kero works out to $36.68 per million BTUs.
Most propane delivered by truck is in the $2.60/gallon range. This would be $28.57 per million BTUs.
Here's how I come up with these figures:
Kerosene has 135,000 BTUs in a gallon. There are 7.41 “135,000s” in 1 million. 7.41 X $4.95 = $36.6795 MM/BTU.
Propane has 91,000 BTUs in a gallon. There are 10.99 “91,000s” in 1 million. 10.99 X $2.60 = $28.574 per million BTUs.
A $19 twenty pound tank with an actual 20 pounds of propane (propane weighs 4.2 pounds per gallon or 84 gallons in a 20 pound tank) is somewhere north of $62 MM/BTUs.
It would be unusual for a 20 pound cylinder to be filled to more than 19 pounds, so the cost would approach $70 MM.
See post # 72.
Propane all the way. Only smells when the tank is low, better heat, more convenient all around.
I have used propane to heat my house for 35 years. It’s the way to go. Make sure whatever heater you get has an ODS(oxygen depletion system) on it. You can’t go wrong with Dearborn heaters.
Thanks Eric, you make all that seem simple.....and easy to understand.
“84 gallons in a 20 pound tank”
The internet hates for people to use math on it! From my experience there muxt be some person actively transposing numbers and moving decimals in any math work posted on it.
@ $1/pound, 21,000 BTU/lb.
I get $47.60/MBTU for a 20 pound tank.
Time spent in the woods with your Dad or Granddad (or Son or Grandson) is a precious gift from God.
Double bonus for Dad, he could smoke his pipe driving out and back on the tractor without grief from Mom.
Someday I’ll get a little closer to that life.
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