What's some ideas on keeping propane flowing in the cold?

HOW COLD IS IT, when this happens........ ?

Reason I ask: Propane vaporises at any temp above someting close to -40 (your choice of C or F) I think it is actually -39F but, well, like I said, something close.

BUTANE,, closer to the freezing point of water (0c/32f)

Some dealers sell lower cost Butane as Propane and pocket the profit (ILLEGAL YES, but they get away with it)

Moisture in the regulator can take out the furnace,, The generator likely sucks liquid propane so that's not and issue.

But if it is cold enough then as the generator (epically) sucks propane out of the tank some of the liquid evaporates to fill the space thus generated with gas,, This causes a general lowering of the temp in the tank, as does the additional evaporation to feed the furnace.. This can be taking the tank down cold enough to cause a problem.

If this is the case adding a small electric lamp shining on the tank (Say 40-100 watts) (Basically a trouble light) might help..

Thogh the idea of somethign that hot in the propane bay concerns me a bit.

I believe Chris is on the right track. The single tank cannot vaporize quickly enough to feed the generator + furnace + water heater + refrigerator + ? I just bought a 150,000 BTU propane heater for heating a shed and the manufacturer recommended a minimum of four 100 pound tanks to feed it, all together in a manifold. I ended up plumbing in a 100 gallon tank into the building.

Hi Chris,

Thanks. Hell's bells I boondock at the lowest temperature on the chart on a regular basis. So far, I've never had to use the tank heater, but I sure feel better having it available.

Those are Fahrenheit. The chart is from a Hydroflame service manual- here is the preceding text:

Hydroflame wrote:
A furnace is a consumer's friend when the outside
temperature gets colder. Unfortunately though, cold is an
enemy of LP gas. The BTU capacity of LP per volume
decreases as the outside temperature gets colder. Therefore,
based on how full the LP tanks are, the ambient temperature
outside and how many BTU's the furnace is, there may not be
enough gas to sustain ignition on the furnace.
Using the charts below, let's say that a 40,000 BTU furnace
won't fire up, and we also know that the 65 lb. LP bottle on
the RV is 40% full and it is 0 degrees F. outside. One's first
thought might be that the burner or valve is bad. However, if
we use the chart, the vaporization capacity of the tank in
these conditions is only 38,500 BTU's. The furnace is not
going to perform very well because there is insufficient BTU
capacity in the tank.
If you were to put an insulated fire resistant blanket over the
tanks and a 75 watt light bulb under that, you would probably
raise the temperature of the bottles 10-20 degrees and
almost double the BTU capacity of the tank. This in turn
would allow the furnace to operate properly. So keep in mind
that a furnace problem is not always a component problem.

Hi Chris,

Are those temperatures C or F?

FWIW, here's a chart of vaporization rates for LP vs temperature.

If the problem is moisture, why would it recover before the temperature went above freezing?

Could it be that the regulator is going bad, so that it doesn't work when the pressure is low? Low temp lowers the propane pressure, and high demand lowers the temp even more (like SDcamperowner said), so if the regulator is marginal, that could explain it.

When the furnace cuts out, will the stove light?

Hi SD,

It boils at a little bit higher temperature. The boiling point is ?42.2 °C (?44.1 °F). Other than that your post is dead to rights.

I would add some heat or bring an extra 40# bottle.

Propanes boiling point is -46f. As that temp. is neared, little vapor will be produced, resulting in low pressure. Understand that the liquid chills as the demand on it increases, so the liquid becomes colder than the ambient temp. Physics pressure dynamics 101.
It is common in the deep south and Mexico to blend butane into propane. Butane has a higher boiling point temp., thus production of vapor/ pressure is reduced at colder temps. It just cannot vaporize fast enough or at all to meet your demand.
Refill up north with pure propane, I bet your issue goes away.