This sounds like a brain-teaser offered up by a radio show.

However, I will bite. On the surface of things, it makes no sense. The water tank temperature should be about what the water temperature of your sea water is. I hope it’s not due to global warming!

The route from the water tank to the pump is quite short, also quite short from the pump to your sink. Your engine room might make water a little warm in the pipes, but not that much. My best guess is that the mixing mechanism in the faucet is broken. However, that would not explain why the filtered water is also hot. 

So I’m stumped. What I would do is turn the water pump off, depressurize the system, and then disconnect the cold water hose from the faucet, under the sink. Turn the water pump back on, with a bucket to catch the water. See if it’s cold, if so, then replace the faucet. If hot, then trace it back and make sure somebody didn’t alter the hoses. 

You’re not by any chance in the Bermuda Triangle?

Sorry for my poor attempts at humor, I do believe your description. It’s just a bit of a stumper.

Tom Peacock

SM 240 Aletes

Martinique

On Jan 3, 2020, at 5:26 PM, JOSE PRIETO <prietomd11@...> wrote:

Hello guys,

I have a problem that maybe some of you have already had, and can help me.

When using the kitchen faucet, my wife complained that the water was too hot, even in the position that she always used the mixer handle.

I went to check and realized that the water was really very hot regardless the tap handle position. I also verify that the hot water was returning through the cold water pipe.
I checked the filtered tap on the side and it was also coming out of hot water (supposedly it should only be cold).

Only after some time with the tap handle in the cold position did the water return to normal (cold), but it was enough to return to the intermediate position that the water overheated and the cold water pipe became hot again.

Any suggestion?

Thank you in advance.

Jose Prieto SY Wayag SM323