IDK if this is going to get any responses, but if you have any experience with using propane with a portable generator maybe you can explain what’s going on.
So I got a big generator, I previously only used gas, but as this was new and dual fuel, it seemed like propane might be a big win. Propane as far as I know doesn’t get old like ethanol gas does, won’t gum up small engine carbs like gas does.
However, it had some downsides - the tanks are not able to just have an extra gas can to refill while the generator is running if needed, and for some reason I can’t tell the manual gives 0 estimated runtime with propane, but lots for the gas fuel. Ok, well some searching found a Y connector with a kind of switch/indicator that is supposed to auto failover to the second connected tank if the first one empties so you can then change out the tank while the generator is running.
Now my problem. Power goes out last night, it’s 20F and I fire up the new generator for the first time. First hour, no issue, however it then starts almost stalling out and then restarting over and over again. I go look at it seems like the “switch” indicated it tried to change tanks but… maybe didn’t? It went straight up and down, not pointed to the other side (though IDK if I actually understand the switch, there were like 0 instructions with it from Amazon). OK, I’ll just figure out which tank is empty (wondering how it went empty in like an hour on a 20lb tank) and move the switch to the other one and then change out the tank with my spare. Did all this, no change. Cannot get the generator to run right, and cause constant brownouts to my house and the generator makes a sound like it’s backfiring every so often. I give up on backup power for the night.
Today, I go look at it again, and it starts up and runs fine today at 43F. However I haven’t put a load on it, but it wasn’t running right without a load last night, so I don’t think it was overloading the generator (and I know it wouldn’t given earlier uses when it was warmer). OK, well lets at least use the valves on the top of the 20lb tanks to test the switch over thing. I tried turning off one of the tanks (right), the one the switch / arrow is pointing towards. Nada, generator keeps running, switch doesn’t do anything. I turn off left and generator stalls out. Weird. I then reset, restart, and try turning off the left tank - no change keeps running. I then re-open left and close right, no change, generator keeps running. Just to not lose my mind, I also close left and as expected generator stalls out.
Ok, so - do I have a worthless amazon transfer thingy, is the propane just not working at 20F or below? This seems really weird as I have a 500 gallon tank for my entire life for heat and stove and it got down to like -15F a few times with no issue.(I asked my provider, they say they can’t hook up the portable generator, or even provide me a propane hose / valve/ anything I could hook it up to.) The 20lb tanks are brand new… So some googling seems to say maybe the tanks need to be warmer? I could get some tank heaters I guess and plug them into the generator also assuming it can run long enough for the heater to do anything and bootstrap stuff when it’s cold. However, I’m also concerned about not having any estimate how long it should run from what should be 40lbs of propane. I don’t know if the first tank leaked over the months since I set it up (the other 2 didn’t), but 1 hour seems really fast to run out, and I would expect at least 8 hours when the gas tank is supposed to be good for 18.
So - do I just give up on propane for this generator? It seems silly to keep propane for the warm months and then switch to gas for the winter…
Hot Air balloon pilot here. I burn up to 60 gallons of propane, twice a day, if weather and passengers permit.
The vapor pressure of propane at 20F is 55PSI, but if you’re drawing it off fast, the temperature in the tank can plummet, and the vapor pressure can drop a lot.
I use waterbed heaters wrapped around my tanks, and preheat to 83F. That gives me 150PSI at the burners. I have redundant thermostats ensuring the temperature does not exceed that set point.
Heat tape, for keeping water lines from freezing, could hold your tanks around 40-50F. Put a couple wraps of tape very low on the tank (you want to warm the liquid, not the vapor) and use Saran wrap to secure. Wrap blankets or fiberglass insulation around everything.
Larger tanks have greater thermal mass; drawing a given amount of vapor from a tiny tank will lower its temperature (and thus pressure) far more than the same amount of vapor from a large tank. Maybe try a 30# or 100# tank?
I’d plumb it into the house lines. The propane supplier won’t, but a plumber will.
I have no experience with dual fuel generators, but I have experience using propane for hours in cold weather. Propane is a liquid that evaporates into gas. Evaporation cools the system (that’s why we sweat). When you run a propane tank in cold weather for a long time, the evaporation slows down until the propane freezes entirely, even though the ambient temp is above the freezing point of propane at that pressure.
Easiest way around it is to keep your backup tank in a heated area, or to find a way to keep the tank warm, like submerging it in a tank of warm water.
This is the right answer. As LP gas converts from a liquid to a gas in the tank the latent heat of vaporization is provided by cooling the bulk of the liquid. Eventually, the liquid becomes so cold that it will not evaporate, it will not become a gas. You cannot use more of it until there is enough heat input to evaporate the fuel. This can happen in warmer weather when the withdrawal rate is too great, so that even then, you have to provide supplemental energy, heat, to allow the liquid to vaporize. LP gas, commonly “propane” but typically a blend of propane and butane, is difficult to use in cold weather for exactly this reason.
I have experienced this in hot weather using one of those propane-fueled things for burning weeds, with a small 1lb tank. When running it full bore the tank gets super cold and eventually can’t provide enough gas to keep the flame going until it warms back up.
