Suspect Motorised Valve on Central Heating

23 Jan 2018
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United Kingdom
When turning my hot water on, i notice the radiators also get heat.
I've checked my system and i believe it is an S Plan system as i have 2 2-port motorised valves, one for water and one for heat.

When my programmer calls for heat or water i can hear the noise from the motors and the manual lever loosens so i believe the head of valve is working (?).

I did notice when calling for water only that both sides of the motorised valve for heating got hot so it seems the heating valve is maybe stuck open.

Are my suspicions correct or is there anything else i should be checking.

Is this a simple fix if the valve is stuck open? Do i need to replace the complete valve or is there another way to tackle it?

Many thanks!

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The make of valves are honeywell. Will try and find the model but attaching pictures here also.
Picture here showing both valves


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Does the heating valve appear to open and close when heating is turned on and off? When off and closed the little manual lever on the valve should have resistance. It will be free when the valve is open.
if the ch 2port isn’t motoring across then valve itself may be passing. The whole valve body can be replaced or you can get service kits for changing internals only. They can wear down over time or get muck preventing them closing properly.

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