Hot Water Tap Issue

[Goldie]

I’m in hot water, or more to the point, I’m sometimes not…

When the engine has been running for an hour or so and everything’s got nicely warm (engine is under the galley island where the sinks are) the mixer tap in the galley ceases to provide any water when turned to ‘hot’. Cold works fine, as do both hot and cold in both heads. After a period of cooling, everything returns to normal. It hasn’t always done this so something’s changed recently. I can find no evidence of anything unusual in the piping and as I’m currently on passage, I don’t want to start dismantling things just at the moment. Has anyone else come across something like this? Any suggestions as to cause and solution would be greatly appreciated.

Apologies in advance if I don’t acknowledge any suggestions in timely fashion, I’m offshore with limited connectivity. Many thanks.

 

[RupertW]

The first thing I’d check is to feel the the two pipes going into the mixer tap. One should feel very warm. If it does then the problem is the mixer tap. If it doesn’t then trace the pipe back towards the place where it branches off from the pipes going to the heads and see where it gets cold. My bet is on the tap.

 

[pmagowan]

Perhaps a stressed bit of pipe is kinking when it gets hot and cutting the supply. Or you have some type of mixer valve that is being overly protective when water is very hot

 

[penfold]

If hot feed works in the heads then your galley tap is on the fritz.

 

[Iliade]

I have known the two plastic layers of the hot water pipe to separate from the scrim and the internal one to close off the flow with no evidence from the outside. I would suggest removing the pipe from the tap, but as the water may be at 90ºC I would be very wary of doing so!

 

[penfold]

Be alright if the pump is off and system depressurised by turning on taps in the heads, although care is still advisable.

 

[Goldie]

Thanks all. I’m under sail at the moment and the issue has resolved itself as it always seems to a short time after engine off. What I don’t understand is of the tap is the culprit, why it sorts itself out when the engine is off and it’s presumably cooler? It’s a plain old mixer tap, nothing fancy. I’ll follow your suggestions and investigate further when we get in somewhere in a few days time

Thanks again. No idea why the boxed text!

 

[Iliade]

Does the gallley work when the heads' hot is also on? Maybe the system is becoming over-pressurised and that is stopping the flow?

 

[Boater Sam]

Is this just a mixer tap or a thermostatic mixer tap and is plumbed up the wrong way?