Very strange hot water issue

[RuffLife]

We have an 11 gallon Seaward S-1200 hot water heater.

We just spent our first weekend of the season on-board and on Sunday when I was doing the dishes I noticed that the water was just lukewarm. I turned on just the hot water faucet and the water was warmish with discernible bursts of cold water mixed in.

I then went to the head and tried the hot water faucet there. I let it run for quite a while and the water was not as cold as it was from the cold water tap but it wasn't what you would call warm.

I thought that maybe my husband had used a bunch of hot water before me so I left it for an hour and then went back and ran the galley faucet and then the head faucet with the same results.

Now the strange part. For some reason I decided to experiment by turning on the hot water faucet in the head while running the hot water faucet in the galley. Boom, super hot, scalding water starts flowing in the galley. Cold water coming out of the hot water faucet in the head.

The faucet in the galley is within 2 feet of the water heater. The faucet in the head is a good 10 feet or so.

Clearly the heat element is working because the water that comes out of galley faucet when the head faucet is turned on would give you 3rd degree burns.

Scratching my head over this one.

[tomschauer]

you may have a bad element. When an element fails it usually burns a hole through the casing. This causes the element to continuously heat (bleed to ground) at a reduced wattage, thus causing very slow recovery but very high temps after long periods without water draw.

[After Taxes]

I believe the shut off valves are all open at the water heater. When winterizing, the valves are turned to allow bypassing the heater with antifreeze. Your valves could need a simple adjustment because this happened to me previously. If this is your situation, then the hot water leaving the tank is mixing with cold water and that's why you were getting lukewarm water.

If you personally winterized your heater, you would have set the valves. If the marina technician did it, they probably didn't return valves to correct position.

Good luck and pleasant boating.

[Danno66]

Would take more testing to confirm, but it could be as simple as a defective check valve on the "out" side of the water heater. When this happens, you can get hot water from the cold faucet, and it allows the hot and cold to mix...it really produces some weird results.

Mine stuck open for a few weeks, and about the time I was sick enough of it to fix it, it got unstuck and fixed itself. It's been fine for over a year now....but seriously, it can produce weird and inconsistent results.

[RuffLife]

So after reading your replies and doing some more Google research, I "think" that the problem might be related to our shower issue. We had a leak in the control lever for the shower and while looking for a proper replacement, the plumbing guy capped off the hot & cold lines for the shower lever by joining them with a small piece of tubing.

I found this video on youtube that is for an RV water heater but might explain my issue. https://www.youtube.com/watch?v=IsiXaMEneaY

What they did is they accidentally left both the hot and cold faucets on for their outdoor rinse off shower head and just turned off the flow of water at the shower head itself. This left a connection open between the hot and cold sides of the system allowing the hot and cold water to mix.

The plumber is coming tomorrow and I'm pretty sure he thinks I'm crazy to think that's the issue but I think it just might be. I happen to be female which I find doesn't help my credibility much but I have traced every hose and wire and know every system on this boat. My husband has never had any interest in this kind of stuff but I grew up getting my hands dirty so I committed to doing this when we first bought the boat and it has been a great learning experience.

I will update everyone once we have the new shower control lever installed.

[waybomb]

Cross connecting like that - a bad idea. A plumber did this?
Find another one!

[RuffLife]

Didn't realize until today that this is how he "capped" it off. I asked him about it and he said he didn't have the proper parts with him to cap them individually.

The person is not a plumber but rather someone who does plumbing. Most of the people in this area that work on boats are mechanics who know how to do some other stuff or guys that worked for boat builders. People with actual marine specific certifications are rarer than hen's teeth in this area. Don't even get me started on how hard it is to find an actual certified marine electrician. The Loch Ness Monster would be easier to find.

[bud37]

Good for you to become involved and figure this out.....In my opinion hot and cold water lines are always separate until they get to what ever sink ,appliance etc where they will be mixed accordingly ....now the only other spot would be the water heater bypass if there is one and that would have an isolation valve.

Changes in pressure in either side hot or cold would make one of them overcome the other leading to what you got there it seems....hope this helps or makes it more muddy..

[RuffLife]

Exactly Bud. I am positive that the issue I have been troubleshooting the last two days is actually the result of him connecting the two. The only bright side is that I certainly learn a lot about hot water heaters

[RuffLife]

Well, the fact that he connected the hot and cold is definitely what caused the issue.

Good thing is, I now have a functioning shower again!