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Ask Jerry Your Own Question
Jerry, Plumber
Category: Plumbing
Satisfied Customers: 760
Experience:  Residential journeyman plumber, over 20 years experience.
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I have an indiect hot water tank which the mains water flows

Customer Question

I have an indiect hot water tank which the mains water flows through via coil and comes out hot to supply the hot taps.
ok. So here is the problem: The tank gets heated in the morning between 4 and 5am by the boiler. However the temperature drops about 0.1degree C per minute ther after. This has just started to happen over the last month. My water meter show no flow on the incomming main. No apparent leaks anywhere. Could I have a problem with the mixer valve on the hot outlet of the tank.
I am an experineved plumber and I have checked all the obvious thing like motorised valves not being in the correct position. But I am not sure how these mixer valves operate.
Submitted: 2 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 2 years ago.
Is it causing a problem?1 degree in 10 minutes is very slight due to standing heat loss from the cylinder.Is the cylinder sat on something cold?
Customer: replied 2 years ago.
No it is very well insulated after a few hours the tank is down to 30 from 55.
Expert:  Andrew Smith replied 2 years ago.
What you may have to check is are you getting heat loss through circulation. With no circulation the flow and return pipes next to the cylinder should both be the same temperature.Check the same with the cold feed and the hot flow and see if you get temperature increase on the outlet when not run for an hour or so.