Problem with old back boiler - HELP PLEASE! Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Amberflame]

I wonder if an expert could help with my problem, i have an old style back boiler which for some time now will not run the hot water and central heating seperately ie, to have the central heating on the hot water must be on.
We do have it serviced and last time the engineer fixed it but not long after it stopped working seperately again. Does anyone know why this is as i would like to be able to have knowledge of the problem and how it should be fixed before i call an engineer again.

[gasmick]

hi it sounds like a problem with the motorized valve, its only that that can seperate the 2, it perhaps needs a new motor fitting ,, the other thing it can be are the control stats, one for the water and one for the heating,
or even the programmer not working properly

mick

[Steve the gas]

Hi,

You prolly have a problem with your motorised valve, to check this, lock the slider into the manual position.
Could be a programmer fault, but hey lets check the MV first.

Hth

[htg engineer]

It'll be the actuator or 3 port valve at fault. Remove the actuator and check the spindle on the valve moves freely. Replace the actautor and all should work well.


htg

[Amberflame]

Thanks for your replies obviously there are a couple of options so could you tell me where the Motorised valve can be found. Is this mext to the water tank and the pump, if so we had this replaced last time not even a year ago.

Were is the actuator located and 3 port valve?

[htg engineer]

The actuator/motorised head sits on top of the three port valve, normally located near the pump if the pump is in the airing cupboard - the 3 port valve will be there too.

Did they change the valve and actuator ? probably not - if they only change the motorised part it may be that the valve is seized.

If the spindle cannot move freely - when the head trys to turn the spindle - the aperture becomes rounded and will start to slip on the spindle.

Change the actuator again - the same will happen.

You need to hange the 3 port valve and motorised head.

htg