Hot water at every faucet - 2002 340 DA

[R-and-R]

I'm getting hot water in both my hot and cold water lines and faucets when the heater is active. I can't find any kind of reverse flow prevention valve, but my heater IS fitted with a temperature regulator that is supposed to mix cold water with hot and then send it to the red lines. My guesses are:
1. The temperature regulator is somehow allowing hot water into the blue lines
or
2. My deteriorating fresh water pump is somehow allowing reverse flow? My water pump sounds a bit sickly when running.

Thoughts?

Rob

 

[bobeast]

Assuming no-one has modified your plumbing, I can't think of anything other than the individual mixer valves at each respective faucet. After running the hot water (only) for a while, feel the two inlet pipes under the sink. One of them should be noticeably warmer. If they are both warm. it points to an internal water heater issue, else, as unlikely as it seems, each of your mixer valves are bad.

 

[Sublimetime]

Just an idea--If your transom shower has both hot and cold turned on, but you have the trigger/on and off on the shower wand/head, and you are not using the transom shower- you now have a common connection between the hot and cold lines. If one is open more than the other, water might be able to backflow thru there.

 

[dlvwill]

I'm getting hot water in both my hot and cold water lines and faucets when the heater is active. I can't find any kind of reverse flow prevention valve, but my heater IS fitted with a temperature regulator that is supposed to mix cold water with hot and then send it to the red lines. My guesses are:
1. The temperature regulator is somehow allowing hot water into the blue lines
or
2. My deteriorating fresh water pump is somehow allowing reverse flow? My water pump sounds a bit sickly when running.

Thoughts?

Rob

I think you're right it would almost have to be the tempering valve at the water heater

 

[rwvw415]

Is this at the dock or after you have run the boat?

 

[Stee6043]

This had happened to me a handful of times. For me it is the result of switching from dock water to tank water without relieving some pressure on the system first. The hot water tank (or pressure tank maybe?) has enough excess pressure when I made the switch that it sent hot water down the cold water lines until everything was equal again.

It was quite temporary...and repeatable.

 

[R-and-R]

Assuming no-one has modified your plumbing, I can't think of anything other than the individual mixer valves at each respective faucet. After running the hot water (only) for a while, feel the two inlet pipes under the sink.bad.

Fair thought, but my boat is older. Individual hot/cold handles at each sink so there’s only a single mix valve at the heater tank.

 

[R-and-R]

Is this at the dock or after you have run the boat?

Both.
Doesn’t seem to matter if the heater was on electric or heat exchanger mode.

 

[R-and-R]

This had happened to me a handful of times. For me it is the result of switching from dock water to tank water without relieving some pressure on the system first. The hot water tank (or pressure tank maybe?) has enough excess pressure when I made the switch that it sent hot water down the cold water lines until everything was equal again.

It was quite temporary...and repeatable.

Interesting.
I’ll have to verify, but I think it happens with either source.

 

[R-and-R]

I think you're right it would almost have to be the tempering valve at the water heater

I’m learning this way, still.

Today I ran water a bit longer, and both sides of faucet went from cold, to hot and back to cold.
They didn’t run long enough to use up all the hot water in the tank.
I think it’s just that the tempering valve has gone wonky.

 

[cfd95]

Thats an anti scalding valve on the hot water heater.
It's probably bad.
The cold to hot is what the valve does on the hot water side if its functioning properly.

 

[northern]

Just an idea--If your transom shower has both hot and cold turned on, but you have the trigger/on and off on the shower wand/head, and you are not using the transom shower- you now have a common connection between the hot and cold lines. If one is open more than the other, water might be able to backflow thru there.

This happened to me. I spent hours trying to figure it out. It turned out to be hot and cold water were on at a shower with the no flow button closed at the head. I was ready to replace the hot water tank unit I found out the problem when I went to use the shower.

 

[R-and-R]

This happened to me. I spent hours trying to figure it out. It turned out to be hot and cold water were on at a shower with the no flow button closed at the head. I was ready to replace the hot water tank unit I found out the problem when I went to use the shower.

Fairly certain mine all closed, but I will double check. Thanks!