Hot water heater problem

Old-Biscuit wrote:
Before messing with the PEX clamps/fittings check the tank nipples.

Your type of valves rarely fail stopping flow when opening.
If they fail it's usually that they don't fully close and leak thru.
When you open hot out valve and get flow then it stops sounds like the symptoms of a check valve problem.

Some rv builders installed check valves even with the 3 valve systems.
Even put them in the cold inlet nipple vs hot outlet nipple.

Next time out to trailer........open WH tank PRV via lever then turn on pump.
If you get steady flow out PRV then cold inlet isn't problem. One less thing to check/worry about. Then you problem is on hot outlet side

He said he had flow from the PRV. The hot supply valve is suspect. Whenever I replace I use 1/4 turn ball valves.

Before messing with the PEX clamps/fittings check the tank nipples.

Your type of valves rarely fail stopping flow when opening.
If they fail it's usually that they don't fully close and leak thru.
When you open hot out valve and get flow then it stops sounds like the symptoms of a check valve problem.

Some rv builders installed check valves even with the 3 valve systems.
Even put them in the cold inlet nipple vs hot outlet nipple.

Next time out to trailer........open WH tank PRV via lever then turn on pump.
If you get steady flow out PRV then cold inlet isn't problem. One less thing to check/worry about. Then you problem is on hot outlet side

Most hardware and home improvement stores carry one of several brands of PEX push-on fittings, including inline shutoff valves, that do not require any tools except a sharp (utility) knife for installation. Common brands include SharkBite, Gater Bite, Watts, and Sea Tech.

Thanks everyone for the advise.

powderman426, I wasn't aware a valve of this type could fail but I really suspect that is what is happening. With all others in their normal operating position, as I open the hot side valve I start to get flow then it suddenly stops.

enblethen, its definately not on the supply (cold) side because I have plenty of flow when opening the blow off valve outside.

Old-Biscuit, I plan to investigate the output fitting on the tank closer but I couldn't find a flow direction stamped on it so I didn't think it would have a check valve in it.

dbbls & RoyB,
The input/output (cold/hot) valves are not the 90 degree shut off type valves. These turn approximately 360 degrees from full open to full close (much like a standard outdoor faucet.

It will be a couple weeks before I can look at it again but hope to solve the issue soon. Any advice on dealing with Pex tubing since I don't have a crimp tool for it?

Michael

This is a pictorial of how the three values work for normal and winterized positions.



Note the values will show which direction the water flow is. Inline is OPEN - across the line is closed.



Hope this helps...

Roy Ken

The two clear valves look like they are partly closed, especially the bottom one. Make sure they are both wide open. Normally the handle should be parallel with the pipe to be open.

It's not necessary for a 3 valve WH system to have a check valve......but all your symptoms point to a jammed check valve in HOT outlet (or the shut off valve isn't opening)

The check valve would be inside that fitting right at tank on HOT out.....probably in the straight fitting vs angled fitting. No check valve in shutoff valve.

Turn off water supply...relieve tank pressure via PRV in outside compartment. Then disconnect the screw fitting on angled piece. Turn on water supply (just crack it open) and see if any flow comes out of top fittings. Bucket/towels to stem water drip/flow.
You can remove internals completely and do without the check valve.

Look closely at the incoming cold water line. It could have a check valve. They don't look like much, just a short nipple on outside but is actually a check valve. It is use to prevent hot water from backing into the cold water line.
You could remove the drain plug and see if you get good water flow into water heater.
Qest check valve

the setup you show doen't have check valves. You may need to unscrew the lines one at a time and check for blockages. its possible one of the globe type valves isn't opening all the way. I would replace them with single throw valves.