Mixing valve

[marioxp]

I have put mixing valve on boiler to limit the temperature of hot water. After that I have noticed that the water pump starts to work every 1-2 minute. I've also noticed that the water started to flow back out through the water inlet. What could be the cause of this situation?

I tried moving the screw on the valve from minimum to maximum, but it had no effect.

Boat is Bavaria 36 2003.

I have two tanks of 150l, switch valve before pump (I think), water pump with some pressure reservoir...

I don't know where is splitting for cold water and water which is going to boiler.

 

[superheat6k]

I had a similar problem on my last boat when I replaced the calorifier and included a thermo reg vv. Turned out to be the level of the Thermo valve and a dodgy NRVv on the feed to the calorifier. At one point the cold tap in the galley was emitting almost superheated steam !

 

[VicS]

I have put mixing valve on boiler to limit the temperature of hot water. After that I have noticed that the water pump starts to work every 1-2 minute.

There must be a leak somewhere or the valves in the pump are defective allowing water to leak back through the pump

I've also noticed that the water started to flow back out through the water inlet. What could be the cause of this situation?

There should be a non return valve in the cold water feed to the hot water system to prevent this. It is either absent or defective.
There must also be an expansion vessel in the hot water system or rhe calorifier pressure relief valve will lift every time the water is heated
The attached diagram shows a complete pressurised cold and hot water system except for the mixer valve

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