Hot water no pressure

[Charlie]

2019 Hawk
Dometic 6 gal. hot water heater

The water heater has been working great for its first 18 months. The water system was drained about a month ago, then I refilled it prior to departure. I ran the water pump with the sink faucet open on hot water, and air was coming out. Eventually I got a trickle of water, and then it stopped entirely. Now I have no hot water available at the sink faucet nor at the outside shower. Cold water pressure is normal at both places.

Yes, the hot water drain valve is closed, and the inlet valve is open. There is no sign of contamination or mineral deposits in any other part of the water system.

Has anyone else seen this?

Thanks!

 

[longhorn1]

With a pressure gauge connected to your hose run water into the city water. It will fill your hot water tank. You can then turn on the hot water faucet and let it run. It sounds like it needs to be primed. Try that.

 

[rando]

I have not seen this before, but may be some debris that has become lodged in the output fitting of the water heater? Have you tried pulling the anode/drain plug on the heater and see what comes out, it is surprising how much precipitate/sediment can build up in there.

 

[Charlie]

I have not seen this before, but may be some debris that has become lodged in the output fitting of the water heater? Have you tried pulling the anode/drain plug on the heater and see what comes out, it is surprising how much precipitate/sediment can build up in there.

Thanks @rando. I plan to pull the drain plug and check for contamination when I get home. But what to do if I find a lot of crud? Getting to the output fitting (I think) involves removing the front of the cabinet. I’ve done that once before and it’s a pain, but if it has to be done I guess I’ll have to do it.

 

[Jon R]

Before tearing the cabinet apart, are you positive that the inlet valve actually is open (as opposed to the handle appearing open but the valve actually being closed or mostly closed)? Is it possible that the handle has slipped or the valve shaft is sheared?

 

[Stan@FourWheel]

Watch this ...

 

[Charlie]

Watch this ...

Thanks Stan. That’s exactly what I did. With the results reported above.

 

[Stan@FourWheel]

If the hot water heater is empty, it sometimes takes 4 or 5 minutes to fill up before the hot water tank is full, and water starts to come out.

If you have water in the tank, the valves are open, the faucet is open, and the water pump is actually pumping water ... and the water never flows out of the faucet, open the cabinet doors or remove a silverware drawer and make sure the hot water heater did not crack from freezing.

If that doesn't work, put some towels inside the cabinets, unhook the water line that hooks up to the hot water sink faucet, and quickly flip the water pump switch on then off to see if water come out? The hot water faucet valve might be stuck closed.

Or if you have the outside hot water shower, go outside, hook up the shower wand, open the hot water valve, turn on the water pump, and see if you can eventually get hot water out of the shower.

Other than that, you could need to take the camper in to an RV dealer, Rocky Mountain FWC in Colorado, or call our service department at 530-666-1442.

Thank you.

 

[Charlie]

Thanks Stan.

Hot water tank doesn’t appear cracked. As I said before, when purging the system I did get air for awhile on the hot water side of the faucet, then a trickle of water, and then it stopped. There is now no water to the faucet _or_ the outside shower, so it sounds like a blockage before or at the hot water manifold.

In a posting that you made in 2010, you mentioned that a check valve could get clogged up with sediment or minerals. That was a long time ago, and the systems may have changed, but I’m beginning to think that something like that is going on. Must be a pretty rare failure, since nobody else is reporting it.

 

[rando]

The check valve seems like a good candidate for a clog. This does seem to be a reasonably common problem in the larger RV universe:
https://liveworkdream.com/2018/08/01/fix-rv-water-heater-check-valve/


PS you are not by any chance an Old Antarctic Explorer are you?

 

[Charlie]

The check valve seems like a good candidate for a clog. This does seem to be a reasonably common problem in the larger RV universe:
https://liveworkdream.com/2018/08/01/fix-rv-water-heater-check-valve/


PS you are not by any chance an Old Antarctic Explorer are you?

Thanks @rando, that is a wealth of info! I’ll check it out when I get home. I guess I should look outside of our local star system for guidance on these problems.

Yes indeed, I was down on the ice, at South Pole in 1985 and McMurdo in 2010. Did we meet there? Perhaps in the Club 90 South

 

[rando]

McMurdo 2010 - I think we were both working on the Concordiasi project.

 

[Charlie]

The check valve seems like a good candidate for a clog. This does seem to be a reasonably common problem in the larger RV universe:
https://liveworkdream.com/2018/08/01/fix-rv-water-heater-check-valve/


PS you are not by any chance an Old Antarctic Explorer are you?

Indeed, it turned out to be a failed check valve. It has a failure mode where it works in exactly the reverse manner than as designed.