Best approach for more LP into our RV...?

[YaddaYadda]

We are all electric at our home.  In the event of a long term grid shutdown, hacking or otherwise, we would like to move into our motor home, especially in cold weather.  MH has a 24 gallon tank and there is a 500 gallon tank by the home which we don't use because it only runs the pool heater.  RV is in a metal shed about 60 feet away and is vented around ceiling.  RV has a gasoline generator and there is a 2000w inverter/chardger. 

I have talked to a licensed contractor who is a gas fitter and knows RV.  He thinks digging a trench to the RV shed and connecting to the 500 gallon tank is the best way to insure there is a long term supply of propane into the RV.  He says he will bypass the RV tank with a tee and pipe in propane directly into the RV for fridge, stove and furnace/water heater.  He says there is no way to refill our 24 gallon tank directly from our 500 gallon tank.  I'm not sure... On another forum it was stated this can be done.  Any comments on this aspect ?

Don't think I want an Extend A Stay or similar.  Or do I ?  Our 500 gallon tank is never used because it runs only to the swimming pool heater.  It is now 80% full. 

I know zilch about propane/regulators/fittings.  Did a search on "propane" and 36 pages of 200+ threads each, showed up.  Aaargh

Any help or suggestions will be appreciated.

 

[NY_Dutch]

The most likely code legal setup would be to run a split two stage regulator with stage 1 installed at the bulk tank, and stage 2 installed near the RV connection. Stage 1 drops the tank pressure down to ~10 PSI for the long run, and stage 2 drops it to the RV's ~0.4 PSI (11" WC) service pressure. The connection from stage 2 to the RV would be made after the existing regulator. A simple 'T' with a ball valve and a quick disconnect on the RV side would work well, with a lockable ball valve at the stage 2 regulator end of the quick disconnect fitted hose to the RV.

 

[Lou Schneider]

Propane isn't stored as a gas, it's stored in liquid form that boils at a very low temperature.  The tank functions like a pressure cooker using pressure to raise the liquid's boiling point.  The pressure in the gas bubble over the liquid is determined by the temperature of the tank, not how much propane is in it, and can range from 80-120 PSI.

As high pressure gas is removed from the bubble, more liquid boils off to maintain the tank pressure.

From there, gas regulators reduce the pressure in either one or two steps to the 0.4 PSI (11 inches water column) used by the appliances.

The point is if you're connecting two propane systems together, it's vital that you join them at similar pressure points.  Connecting the 100-150 PSI tank pressure or 10 PSI intermediate pressure propane from one system to the 0.4 PSI low pressure side of another is a recipe for disaster.

It's good that you are consulting with a professional.  He's familiar with the ins and outs and I'm sure he'll do it correctly.  My preference would be to make the connection at the low pressure (0.4 PSI) side after the regulators, not at the high pressure tank side, as it's easier to seal and control low pressure connections.

As far as filling the motorhomes propane tank from the larger one, you'd have to install a propane dispenser pump to transfer liquid propane from one tank to the other.  It would also be a good idea to learn about propane dispensing as safely filling a propane tank is a little more complicated than filling a gasoline tank.

 

[Frank B]

I hear you!  That is one of the reasons why we park our travel trailer near to our house. it is also why I have a backfeed circuit on our natural gas furnace in the house so that I can power it from our portable generator if need be. (And yes, it was correctly wired by a certified electrician.)


In the event of a services failure, what are the odds of it lasting more than a week or two? I just have four 7 gallon bottles that I keep filled at home. I'm fine for a couple of weeks, even in very low temperatures.

 

[Lou Schneider]

I hear you!  That is one of the reasons why we park our travel trailer near to our house. it is also why I have a backfeed circuit on our natural gas furnace in the house so that I can power it from our portable generator if need be. (And yes, it was correctly wired by a certified electrician.)

I did the same thing when I moved to WA.  Cindy was amazed that my little Honda eu1000i generator would let us run the gas furnace and keep the entire house warm instead of having to huddle around a gas fireplace.

My backfeed circuit consisted of a short cord and a 15 amp socket I installed in a junction box adjacent to the furnace.  When power failed I'd unplug the furnace from the outlet and plug it into an extension cord going to the generator.

 

[Back2PA]

On my previous RV I put a T fitting into the LP system after the onboard regulator. This allowed me to connect to a large propane tank that already had its own residential regulator so no further regulation was necessary. There was ditched black pipe and riser to the RV pad, then a metal flex line to hook to the RV. I just turned off the onboard LP, took the plug out of the T, attached the flex line, turned on the big tank and checked for leaks. Worked great.


I also had an Extenda-stay before the onboard regulator. This setup allowed me to use regulated (such as the big tank) or unregulated (such as 20-100# bottles) external LP sources

 

[Frank B]

I did the same thing when I moved to WA.  Cindy was amazed that my little Honda eu1000i generator would let us run the gas furnace and keep the entire house warm instead of having to huddle around a gas fireplace.

My backfeed circuit consisted of a short cord and a 15 amp socket I installed in a junction box adjacent to the furnace.  When power failed I'd unplug the furnace from the outlet and plug it into an extension cord going to the generator.

That is pretty much exactly what my electrician set up for us.

 

[Utclmjmpr]

  YaDaYaDA,, If your tank is 80% full,, then it is "full".. Propane tanks can only be filled to 80%.>>>Dan

 

[WILDEBILL308]

"Don't think I want an Extend A Stay or similar.  Or do I ?  Our 500 gallon tank is never used because it runs only to the swimming pool heater."
Well that is exactly what you have except with a 500 gal tank not a 40# tank as a source.
" Stage 1 drops the tank pressure down to ~10 PSI for the long run, and stage 2 drops it to the RV's ~0.4 PSI (11" WC) service pressure. The connection from stage 2 to the RV would be made after the existing regulator. A simple 'T' with a ball valve and a quick disconnect on the RV side would work well."
This is good advise. You need to be able to shut off flow from your RV tank so you can use it for a reserve. Just be shure you don't have 2 low preshure regulators on the same line. This will lower the flow to where your stove and furnace won't work.
Adding a big propane tank is very common where people live in their RV in the winter time.
Bill