Radiators heating when only hot water selected

[jonm01]

I have a glow worm micron 60FF boiler supplying central heating and hot water cylinder, on a fully pumped system. There is a BGMVSP-23 3 position motorised valve and british gas programmer. A problem seems to occur sometimes: If hot water only is selected, the radiators nearest the pump heat, to some extent. This has happened when hot water only has been running, and the heating has been switched on for around an hour, then off. The next time we have HW only, the radiators heat up again. I've looked at the 3 position valve position when this is happening and it is in the correct HW only top position, but still some flow must be reaching the radiators. If I remove the actuator and then replace it, and switch between HW and HW with Heating a few times, it seem to go right, until the next time the heating is used, then the same thing happens. Any suggestions appreciated.

 

[gavinda]

the paddle is sticking on the valve body, or some shiz has built up on the valve seat. tis a simple enough repair, about £30 for the body or less if you use a service kit.

 

[seco services]

More likely the valve spindle is getting stiff and not returning fully to hw position, as it only returns to hw position by a spring in the actuator.

 

[jonm01]

Thanks for the helpful replies, looks like I need to replace the valve body.

 

[gavinda]

Yes. FYI the bgmvsp valve is an ACL mid position valve rebranded by British gas, so you ask for the ACL valve at the merchants. There are others available but you'll need to replace the head as well if you do that.