Water Heater Weirdness

[adt2]

Our 1983 61 CPMY has a "shorty" electric water heater in the starboard engine room. We've noticed that the hot water sorta comes and goes, seemingly at random. I've asked my wife to start keeping a log of when it's hot (i.e. are we on shore power or generator? which generator? how long has the generator been running? etc) but so far there doesn't seem to be any rhyme or reason to it.

We mostly seem to notice it in the galley, but I haven't really experimented to see if it happens elsewhere on the boat yet; the galley is just where we happen to be when we realize there's no hot water. When it IS hot, it's so hot you can't put your hands under it; when it isn't, you can barely get it above room temperature.

Before I go down the rabbit-hole, just wondering if anyone else has come across this and has a fast, easy, and inexpensive solution? [Haha, just kidding. I'd settle for a solution of any kind.]

[Jims43DC]

Our 1983 61 CPMY has a "shorty" electric water heater in the starboard engine room. We've noticed that the hot water sorta comes and goes, seemingly at random. I've asked my wife to start keeping a log of when it's hot (i.e. are we on shore power or generator? which generator? how long has the generator been running? etc) but so far there doesn't seem to be any rhyme or reason to it.

We mostly seem to notice it in the galley, but I haven't really experimented to see if it happens elsewhere on the boat yet; the galley is just where we happen to be when we realize there's no hot water. When it IS hot, it's so hot you can't put your hands under it; when it isn't, you can barely get it above room temperature.

Before I go down the rabbit-hole, just wondering if anyone else has come across this and has a fast, easy, and inexpensive solution? [Haha, just kidding. I'd settle for a solution of any kind.]

When we first got our boat the hot water would come and go trying to take a shower was not fun first hot then cold randomly. chased it down to air in the hot water tank and it acting as a volume tank for the pump being larger then the pressure tank on the galley maid water pump, as soon as I purged the air out of the top of the hot water tank the issue went away. I just lifted the lever on the pressure release until I had all water no air coming out. I am not sure of the make of water heater
but it is contained in a SS box about a foot square. Hope you can get yours fixed as easily as I did

[Pascal]

What kind of water heater? After the water runs cold, does it just starts working on its own?

I doubt it a generator issue. WH are about as basic as they can get so even if the gen was frequency or voltage was off, you d notice other issues before the WH would be affected

It sounds to me like thermostat issue in the WH

[adt2]

It's a Rheem electric unit. I'm not sure we've had trouble with it getting the water hot; I think we've had trouble getting the hot water delivered, if that makes sense. The master shower, for example, has zero hot water - even though the master vanity right next to it has hot water no problem.

Galley usually has hot water, but not always. Midship head usually has hot water (vanity and shower), as does the forward head.

I tried the purge valve on top of the heater and immediately got water coming out, so I don't think I've got air trapped in there.

[SEVEN]

Your Moen shower valve #1200 may need replacing. Easy job.

[adt2]

"...easy job." HAHAHA that's a good one.

Actually I *really* hope it's an easy job. I could use a win. Thanks for the heads up.

[SEVEN]

Go on YouTube and look up how to replace a Moen shower valve. I did all three of mine in less than an hour.

[adt2]

Thanks - you're right, looks pretty simple. Is there a shut-off at each fixture, or do I need to turn off the water somewhere else? I'm assuming the latter, but I haven't really had to do any plumbing on the boat yet so that's just a wild guess.

[Briankinley2004]

Looks like you have it narrowed down to a shower valve. I was going to suggest the thermostat may be bad on the water heater in case anyone else has similar issues.

[SEVEN]

If you’re hooked to shore water, turn it off there if you’re using your pump inside, turn it off on the circuit breaker and you’ll be fine. Drain all of the faucets from the galley to the sinks just to empty out everything.