For 20+ years I followed the same procedure as you. The Paloma heater died and I purchased an Excel which does not have a pilot. I decided it was a good time to replace all the hoses, wiring, regulator, solenoid, sniffer, pressure gauge, etc. I hired a propane guy who was recommended to me, but he was a real disaster. I haven't been able to find anyone who understands the propane system on a boat. Of course, propane collecting in the bilge is the problem.
I have two propane hoses from the locker, one for the water heater and one for the stove. Each has a shutoff valve in the propane locker. I connected the propane tank to this plumbing with both valves shut off in the locker and the solenoid on. I used the commercial leak test solution that I purchased. No leaks.
Pressure gauge read 140 lbs. It held 140 lbs for 10 minutes.
After 10 more minutes it read 135lbs. and held at 135 for a total of 40 min
After 40 minutes it slowly began to drop tp 130 lbs.
After 55 min it dropped to 120 lbs.
Atfter 60 minutes it had dropped to 125 lbs.
So, it lost 15 lbs of pressure in 60 minutes
According to Thor's installer, at the same ambient temperature there must be no pressure loss for hours, days, weeks...
Connecting the two hoses is my next step. It seems to me that with a water heater that does not have a pilot this hose must experience no loss in pressure over time. I will always shut off the propane tank when the water heater and/or stove are not in use. When I return to the boat after leaving it for an extended time, the water heater should just fire up right after I turn on the propane tank and the hot water faucet.
I think I understand. Is my explanation and conclusion above correct?
Thanks,
Bob McPeek,NS30C, Pau Hana
San Francisco.