Hot water tank not heating despite both feed and return from boiler/pump hot....

the whole system is working 3 port valve does the right thing when told, thermostat on water tank does switch on and off if turned manualy, pump is working, heating to rads works but....no hot water.

Hot water does flow into the tank and out of return pipe. both pipes get hot, too hot to hold for very long but water in tank not heating

There is valve on the return pipe, currently this is fully open, should this be closed to restrict the flow ? or is there some other problem.

Any advice appreciated?

Reply to
davem
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The valve could be broken in the mostly closed position (especially if it a gate valve).

To hot to hold for very long (about 50-55C) the flow should be scarcely touchable say around 70C and the return at least as hot as it is now. So may be boiler thermostat nees to go higher.

Are there any dripping HW taps?

Reply to
Ed Sirett

Or is the tank just scaled up so much that its not transferring heat properly?

Reply to
The Natural Philosopher

New tank. Probably not worth trying to descale as it must be quite old. If it's not old, then you may have been heating the water up much hotter than required.

Reply to
Andrew Gabriel

If the heat exchanger is effective, the return will come out at close to the temp of the water in the tank, ie cool, and not hot. If it comes out hot, theres little heat transfer to the tank of water. Presumably either heavy scale or some kind of slime growth etc in the tank. Time to replace the tank probably.

NT

Reply to
meow2222

thanks for these comments, I shoudl add that ti was working fine about a week ago before i fitted a new 3 port valve, the new valve works as does the stop c*ck on the return pipe, as did the heat transfer.

could air be preventing the heat transfer ?

could air be trapped within the heat exchanger?

is so how to get it out?

Reply to
davem

no

not really

the only other option I can think of is maybe its a very slow recovery coil (very old tank) and youve got a hot water leak somewhere, so the thing doesnt get a chance to heat up.

Cant say I really know exactly what the prob is tho.

NT

Reply to
meow2222

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