Hi billm,
Sounds like the water heater's had a lot of dealer attention - never fun.
A couple of thoughts:
1. sounds like you're running on LP, but the LP burner doesn't reliably light when the thermostat calls for more heat. So you flip the inside switch and then it ignites. Some possible causes, besides what's been replaced include:
- low system gas pressure (maybe just slightly low)
- electrode wire and gap (slightly wide gap maybe?)
- intermittent voltage at the gas valve
- defective gas valve.
2. On the weeping pressure valve, I think I recall a recent thread where someone had this problem due to too much pressure in the water system. I assume you're using a pressure regulator at your city water hose - maybe you need to make sure it's working correctly, or try a different regulator. Also, I think I've heard of pump problems where the system is over-pressurized. Make sure the pump is off.
Sounds like you've already dealt with the air pocket as a potential cause, but here's Suburban's procedure, in case you're doing something different:
- Turn off the water heater, electric or propane.
- Turn off the water sources, i.e. water pump or city water faucet.
- Open a hot water faucet in the RV.
- Pull or open the handle on the P&T relief valve straight out and allow the water to flow out until it stops.
- Allow the P&T relief valve to snap shut, close the hot water faucet, and turn on the water supply. Heat the water to insure proper operation of the P&T relief valve. If it continues to leak, the P&T relief valve is defective.
Another cause of weeping is that the water temp is too high. This seems unlikely since the thermostats have been replaced. But you can measure the temp at the faucet to confirm it's not over 140 degrees.