Propane question

MFL wrote:

Chris Bryant wrote:
One caveat- the changeover works on pressure, if it is very cold, the regulator will draw from both cylinders.

Interesting...any rough idea, as to temp, when this will happen?

Jerry

It’s hard to determine- it has to do with temperature, level of liquid lp, and draw on the cylinder. When the level of liquid gets low enough, it cannot absorb enough heat from the air to vaporize the liquid fast enough, and if the cylinder pressure drops below ~20 psi, the reserve cylinder will start feeding as well.



The good part, the furnace and all appliances will keep working, which they might not on a single cylinder, the bad, you can, in the most extreme cases, run both cylinders empty at the same time.

Dick_B wrote:
Haven't found an easy/accurate way to determine the level of the propane in the tank BUT you can tell which tank is empty by tapping on it with a hammer or screwdriver. The empty tank will have a much higher pitch sound and, of course, be much heavier if you try to lift it.

You can also pour hot water over the cylinder in question and feel for the cold line.

Or, loosen the hold down bolt and lift up on the cylinder in question, and if it feels "light" then it's low on propane.

I always open BOTH cylinder valves when I go out and have the lever pointing to the tank I want to draw from.

That way, it will automatically switch over in the middle of the night if that one cylinder runs out..

As long as you CHECK the status of your tanks on a daily basis if you KNOW you are using a lot of gas, you will be fine..

You just need to check it.. I have heard folks will not open the other cylinder so they know when it is empty, then switch over to the other cylinder.. Why do that when it can do it automatically?

I don't winter camp, so I know my rigs gas consumption and I have often come home and found an empty tank, but the auto switch over worked as designed and I just replace the empty cylinder.

Good luck!

Mitch

Dick_B wrote:
Haven't found an easy/accurate way to determine the level of the propane in the tank BUT you can tell which tank is empty by tapping on it with a hammer or screwdriver. The empty tank will have a much higher pitch sound and, of course, be much heavier if you try to lift it.

Consider the pair to be one 'tank'. When the regulator indicator is green you are over half full and generally good for 24 hours minimum. If the regulator indicates red you are below half capacity and just go fill the cylinder indicated by the lever. Move the lever to the other cylinder at some point in the fill process. You will never run out. Check the indicator more often during heavy use.

I purchased a little gadget recommended by moderator jplante4, to check level of my tanks. It is about the size of your finger, and is pressed against the side of tank to check. Looking at Chris's pic above of tanks, when pressed just above level it lights red, and at level and lower it lights green. It actually works quite well, IMO. Sorry no picture, but a search may bring up thread that discussed it. IIRC it was around $25.

Jerry

Chris Bryant wrote:
One caveat- the changeover works on pressure, if it is very cold, the regulator will draw from both cylinders.

And just how does this work? Never saw this in 35 year of RVing.

Ken

TXiceman wrote:

Chris Bryant wrote:
One caveat- the changeover works on pressure, if it is very cold, the regulator will draw from both cylinders.

And just how does this work? Never saw this in 35 year of RVing.

Ken

Due to lower vaporization rate at low temperatures. Low being well below freezing. Generally I doubt you would be more than 5% into the reserve when the primary cylinder goes empty. Exception might be heavy use such as running a propane generator with a heavy load.

Here is a pic of the gadget/propane level checker I mentioned earlier.



Jerry

I used two clothes pins, one painted green, one painted red. It worked :)

TXiceman wrote:

Chris Bryant wrote:
One caveat- the changeover works on pressure, if it is very cold, the regulator will draw from both cylinders.

And just how does this work? Never saw this in 35 year of RVing.

Ken

At zero degrees, a half full 30 lb cylinder will not supply a 35 k btu furnace, as it cannot absorb enough heat from the surroundin* air.

Chris, Propane, AKA R-290. at zero pressure is -43.7 degF. At 0 degF it has a pressure of 24 psig, which is well above the 11 in of water column that is required to operate the appliances in an RV. See chart at
http://virtualmark.net/wx/pressure.htmhttp://virtualmark.net/wx/pressure.htm

If you get so low, that the boil off is this critical, you can always put a 100 Watt light bulb in the compartment with the tanks.

Ken