Advice on DHW problem

[wytco0]

Hi All I am after a bit of advice about our hot water system, we have a Daikin low temperature Air Source Heat Pump proving DHW and heating, we also have solar thermal which provides additional heating into the hot water tank . It all works well however I am pretty sure we are losing heat from the hot water tank.

Our hot water had a circulation pump which is normally not switched on as we know it takes a lot of heat out of the tank, we switch the pump on for about 1 hour in the morning when we have showers.

The hot water tank is downstairs but our house is upside down with the bedrooms downstairs and the living rooms upstairs, I have noticed that the upstairs taps have hot water almost instantly even though the circulation pump is off. I think that there is some sort of circulation going on even when the pump is off and this seems to cause the ASHP to cycle to top up DHW more often that I think it should.

Does anyone have any idea why this is happening and is there anything we can do to stop it?

 

[ServiceNumpty]

Should be a non return valve on the Hot Water Secondary Circulation circuit.

 

[wytco0]

Should be a non return valve on the Hot Water Secondary Circulation circuit.

OK thanks, I have had a look at the tank, there is a 22mm pipe exiting from the side of the tank about half way up that goes to the circulation pump and another 22mm pipe vertically out of the top of the tank that does not seem to have any valves etc on it and is normally hot to touch. I cannot see anything that looks like a non-return valve.

Any idea where the non-return valve should be ?