As donn0128 mentioned, propane boils at a far colder temperature than you're ever going to experience, so heating the tank is fixing a problem that does not exist, normally, unless you have water or butane in the tank. Some vendors have mixed butane in with propane since it's cheaper and, in a warm climate, works as well as propane. JMHO
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I can usually run one unit (generator or furnace) without problems; however, when I attempt to run both, then it is a no go for either after a short period of time.
This is only a problem when drycamping in an ambient temp below 20dF.
Instead of it being a tank supply problem, is there any chance your regulator is freezing up?
One of the symptoms is a reduced flow rate...as in you can run one high flow appliance however if you run two high flow appliances, they are both likely to go out as soon as the line pressure drops. (BTDT recently with the furnace and water heater)
Warming a regulator is a lot easier than warming a tank.
People often assume that if the temperature is above -44°F, then the propane system should work fine. But that's a false assumption.
If the temperature was -44°F, there would be no pressure to move the propane out of the tank. At -30°F, the pressure is only 6.8 PSI. That's right on the borderline for the regulator to even work. At that pressure, the red indicator on the changeover will be out.
But there is one more factor: propane takes 760 BTU per gallon to evaporate. Using propane causes some of the propane to evaporate, chilling the cylinder and the remaining propane. Since the propane is colder than the environment, it begins to pull heat from the environment. The temperature will drop until the incoming heat matches the heat being used to boil the propane. Obviously the amount of the temperature drop depends on how fast the propane is being used. What may not be immediately obvious is that the amount of the temperature drop depends on how full the cylinder is, since the cylinder wall doesn't carry heat very well from the space above the liquid to the liquid. Ever notice the frost on a cylinder? It is only near the liquid level, and not above.
End the end, it's possible to come up with a nice chart like this one:
This chart is from Hydroflame. It shows the BTU/HR capacity for a 20 or 30 lb cylinder at various levels of fill and ambient temperature. Pull propane faster than the value shown in the table, and the regulator will no longer provide the proper pressure and appliances will start to malfunction.
Quote: Propane should flow freely down to about -20.
So last week when the temperature was below -20 how do you suppose my uncle heated his house? Large tank so that the surface area could out-gas (change from liquid to gas do to the reduced pressure in the tank because of use)
For the record the following is from the Silverton Standard & the Miner
Jan 16 low -17
Jan 17 -30
Jan 18 -30
Jan 19 -22
Jan 20 -22
Jan 21 -15
And yes when it gets that cold they don't fill the tanks as full to get a larger surface area.
Ag2000CO wrote: If you were to connect your 2 30# tanks so that both were supplying gas at the same time you would double the surface area that is out-gassing:: double the amount of gas supplied. You would of course be out of gas when you were out of gas (DA) But that beats being cold with full tanks you can't use.
Actually, an auto-changeover valve will draw from both tanks.
For the long boring explanation, feel free to skip
How does the auto changeover work?
There are two regulators: One is set to 10 PSI and that first regulator is part of the auto-changeover. The second regulates down to the 11" water (.47 PSI).
The 10 PSI 1st stage regulator has two valves, one from each cylinder. The first stage regulator will draw out of the cylinder the lever selects first. Once the regulator opens the valve from the 1st cylinder all the way open, it starts opening the valve from the second cylinder. The interstage pressure has to drop to about 5PSI for the second valve to open.
The little red/green indicator is just a pressure gauge connected between the two regulators. It doesn't attach to the changeover mechanism itself. The indicator is green when the pressure is above about 7 PSI out of the first regulator - so if the first cylinder is keeping up, it shows green. If the second cylinder valve has to open and the pressure drops to 5 PSI, the indicator will be red.
The reason there isn't just a hard switchover valve is that when a cylinder is nearly empty, the pressure will drop at higher rates of usage. The small amount of liquid left isn't able to absorb enough heat to boil and keep the pressure up. If a hard switchover was used it would switchover and leave propane behind as soon as the lead cylinder couldn't keep up. By drawing from the lead cylinder as much as it will feed and supplementing to meet demand from the second cylinder, the first cylinder can be boiled dry.
Maybe you can combine a tank heater from Ultra Heat with a jacket from trickewon's link.
They come on at 44°F and turn off at 68°F. They will put a heck of a dent in your 12V battery, so expect to run your generator a lot just to keep the battery up. Don't let yourself git into the situation where you can't start your generator because the battery is dead instead
You may also want to consider a 120V heater and a jacket for the battery too. Battery capacity goes down a lot in the cold. When your generator is running, it can heat and charge the battery. A blanket combined with the large mass of batteries can hold heat overnight.
This might be a quick fix for your problem. Why don't you just buy a 12 volt Electric Blanket at Camping World, there about $15.00. You might need to buy a longer 12 volt cord and adapter. But it would work. Simple fix, and not a lot of money. Good Luck. Happy Camping, Dan & Jill
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mbartlett4 wrote: I have an issue with propane flow in cold weather. After some research, it would appear that I need to heat my propane tanks to facillitate out-gassing.
Could anyone here provide a link to a manufacturer/distributor of propan tank heating blankets?
I bought a heated battery blanket at one of the auto discount stores. One used for diesel engine batteries. It uses about 60Watts at 110V. I wrap it round my 20# propane tank, on my BBQ, which lets me cook outside down to 0F (don't ask me how I know).
If I wanted to use it on the road, I'd buy a 200W inverter and either run it from the cigarette lighter, or wire it in to the 12V supply. The 60W blanket uses 0.6 amps at 110V which calculates to about 7 amps at 12V. Running engine can easily handle that.
Sheff
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