hot water cylinder

[Chiwillie]

Should the return pipe from the hot water cylinder be at least warm?
Have cleaned C/H system and all rads are lovely and hot, the 3 port valve appears to work making the feed to the cylinder hot but the bottom return pipe remains cold and the hot water doesn't get very hot. Any ideas what the problem might be?

 

[stem]

Only if the hot water cylinder thermostat is instructing the boiler to heat the cylinder. If it isn't the pipe will be cold. If your hot water isn't hot enough have you tried turning the cylinder thermostat up?

 

[Chiwillie]

Thanks for that, boiler fires up for a very short time, maybe a minute max, then shuts off, keeps doing that whereas when C?H calls the boiler runs for a long time, could it be an airlock

 

[stem]

The heat required by a hot water cylinder will probably much less than that from a house full of radiators so what you describe would not be unusual.

The temperature of the hot water in the hot water cylinder is controlled by the cylinder thermostat fixed on the side of it. If the thermostat says that more heat is needed, it will position the 3-Port valve such that the cylinder is fed with hot water from the boiler. Once the water reaches the temperature set on the hot water cylinder thermostat the controls will position the valve such that no more heating of the hot water takes place.

The above, of course, assumes that the time controls for heating the hot water are set to be 'on'

If you had an airlock, the hot water wouldn't be heated at all. The clue is in the work 'lock' it would prevent the boiler supplying any heat to the cylinder whatsoever and it would eventually go completely cold.

However, if the 3-Position valve is directing hot water to the hot water cylinder both the flow and return pipes should get hot. Are you sure you have identified the pipes correctly? Cold water from the feed and expansion tank is fed into the bottom of the hot water cylinder and that pipe never gets hot.

 

[Chiwillie]

Have turned C/H off have H/W on constant turned stat to max but boiler only runs for a very short while and keeps repeating itself but return pipe remains cold.

 

[stem]

Have you turned up the cylinder thermostat? Unless the cylinder thermostat is calling for heat, the hot water won't be heated and the motorised valve wont direct any hot water from the boiler to the hot water cylinder.

Have you identified the pipes correctly? The pipe marked 'cold feed from cistern' will never get hot.

I did wonder if it may also be that because of the present cold weather, the majority of the heat is being directed to the radiators instead of the hot water, but if you have turned the central heating off and the hot water still isn't being heated, then that would appear not to be the problem.

 

[Chiwillie]

Cold feed is on the opposite side of the cylinder, been feeling the pipework where it goes into the cupboard/loft where the boiler is and where it connects into the return pipework for the whole system, just thought that the return pipe would have at least got warm. Think I might open the drain valve tomorrow and see if any hot water comes out eventually.

 

[TimboTwo]

Can you post a photo of your cylinder and pipework, please .

 

[stem]

Has it been working satisfactorily in the past and this is a new problem that has recently occurred, or has it always been like this?
Have you changed anything, done any work that could effect the heating system, or installed any new controls or parts?

 

[Chiwillie]

Thanks for your responses, think I may have been a little premature as everything seems ok now,