Water pump problems

jeffo wrote:
I said earlier that I bypassed the water heater and the cold water worked fine. But I am still having intermittent problems so when I get home I will have to locate the check valve. I don't remember seeing an external check valve, maybe it is in the pump like Old-Biscuit said.
Thanks for all the help

Jeff

Different check valves being discussed.

PUMP------has internal check valve (flapper/diaphragm) that stops backflow thru pump into fresh water tank when using pump or city water.

Water Heater.......nipple on cold inlet or hot outlet (can be on both) that is screwed into WH Tank. It is like the one pictured.
Typically used as a means of isolating flow in/out of WH Tank vs installation of shut-off valves.
(City Water Connection will have same type.............used to stop water from flowing out city water when using pump or city water)

No Flow on HOT side.......bad check valve is usual suspect.
Can be valve that is NOT opening----handle just spins.

With water source ON---OPEN T&P Relief Valve
NO Water Flows out..........problem on COLD inlet side
Water flows out (but not at any faucets) problem on HOT outlet side

I said earlier that I bypassed the water heater and the cold water worked fine. But I am still having intermittent problems so when I get home I will have to locate the check valve. I don't remember seeing an external check valve, maybe it is in the pump like Old-Biscuit said.
Thanks for all the help

Jeff

Artum Snowbird wrote:
The check valve should be near your water pump in line there. When you think about it, the pump pumps up the pressure, but it's the check valve that holds that pressure in your system so it doesn't just bleed back into the water tank.

At the same time, putting shore water on, that check valve is closed to prevent filling the tank. You either dump water into the tank by a gravity fill, or you drive it in by swinging a valve if you connect only with a hose.

Check valves are INTERNAL component of RV water pumps.
In-line check valves are typically installed in pump suction due to bad pump check valve---easy/cheap fix vs pump repair.

OP...

Sometimes a cold water inlet check valve are installed on Water heaters even when it is a 3 valve system. Idea is that as water is heater it expands and the check valve in cold inlet stops hot water from pushing back into cold water system.

The check valves used have cheap plastic internals (plunger/spring/o-ring) and can get clogged up, jammed, o-ring dislodged which can restrict/stop flow of cold water into WH Tank.
Close WH bypass valve-------open T&P Relief Valve with pump on to see if air/water come out of WH tank.



Personally.....I would gut that cold water inlet check valve (remove internals) and run w/o it. Especially with 3 valve system

Check valves are junk, only really needed for winterizing if valving is not provided.
My 3 valve WH doesn't have check valves...........BY OEM and I have no issues with hot/cold etc.

The check valve should be near your water pump in line there. When you think about it, the pump pumps up the pressure, but it's the check valve that holds that pressure in your system so it doesn't just bleed back into the water tank.

At the same time, putting shore water on, that check valve is closed to prevent filling the tank. You either dump water into the tank by a gravity fill, or you drive it in by swinging a valve if you connect only with a hose.

I have had the inlet line apart to clean the screen. It pulls straight up from the tank. I just bypassed the water heater and the cold water seems to work for now. I looked closer at the water heater and it may have a check valve in the bottom line. It just looks like a piece of pipe about 1 1/2" long (no hex)
Maybe it has something keeping it from closing. Not sure what that would do. Guess I will be making a trip to the shower house tonight.

I believe most water systems have a check valve that prevents water from filling the water tank when you are on shore water. In your case, I think that check valve is somehow not closing, so the water pump tries to get water from the tank, but the tank is below the hot water tank, so it takes it from the easiest source.

Find that check valve, change it, and your problems will be over.

Pull the incoming water line at the pump to see if water is getting there.

It's a 3 valve bypass. I have the inlet and outlet valves open and the crossover valve closed. My last rv had check vaves in the water heater lines, this does not appear to have any.

is there a hot water heater bypass valve not turned back after winterizing?

It dosen't have an outside shower.