Solving the "Dual Tank Auto Change Over w/HP Regulator" Problem

Hi Rabird. Thanks. I took the tanks back off, weighed them again and repeated the process. They remained unchanged with both valves left open, no appliances running. So, no leak. My scale only registers to the half pound....obviously not that accurate. But I guess when I first installed the regulator and tanks and opened the valves, the camper drew enough gas to register that drop.

 

Okay All, Raybird finally provided the reason why check valves won't work. They didn't. If evaporation rate is the same, pressure will be the same. It was obvious, actually, in hind sight!! It was something I had to see and learn for myself. After an hour or so of running the HP stove off both tanks, they began to equalize. The Primary gained .5 lb's!! All the check valves in the system had no effect.
So, I'll now go to plan "B" as suggested by Spridle: Putting in a manual ball valve in the bypass to isolate the tanks. This way, using / setting the ball valve and reserve tank valve (on/off) as required when using the HP stove, I can manage the Primary tank usage (to empty first) and facilitate the auto change over. The real benefit, is not having to physically switch the tanks when the primary tank empties - Just turn two valves and run off the reserve until the Primary can be refilled. I think this is the best solution (so far) to having a functional auto change over system for set ups having a separate HP regulator. Once I retrofit the bypass piping, I'll revert with the final drawing, photos and parts list. Thanks for everyone's input. Ken

 

Spridle, agreed on all. This seems to be the NEXT best way IMHO. That’s how I’m proceeding. I have no fear of any “blow ups”. I’ll just need to remember to close the bypass valve after cooking off the Primary tank and open the reserve tank valve before having too many drinks and retiring for the evening!!! FWIW, based on my tests, The Primary won’t backfill or equalize if I remember to close the bypass valve after cooking. I’ll be trying this set up this week and revert with my results. Now I have to build it!! Regards

 

Bowman......I always carry extra propane and the fittings to connect directly to the HP stove. That wasn't the mission!! Sjm9911......One negative possibility is if you constantly run the HP stove off the secondary or reserve bottle, you could deplete the reserve BEFORE the primary, leaving little , or no reserve gas when the changeover occurs. The goal, in my mind, was to find a way to deplete the primary tank first. This is now manageable.
Last time I checked, anything worth doing requires a little pain. I built it, it works, and I learned some things along the way. I don't consider being aware of your propane system's status, and turning a valve or two, to be such difficult things. The cost was not a factor. I consider the project's time, "time well spent". Do what you will, but If you want a manageable auto change over system W/HP regulator, have the time, the money and some presence of mind, I state again....this works!! If anyone wants to know what it takes to make it, PM me.
Regards, Ken