Hot water, cold radiators

[tanswel]

I have a horstmann 3 way valve and can only get the radiators hot by holding/wedging the arm across to the side. If I release pressure, the heating stops working. Please help - wife complaining!!!

 

[Blagard]

Sounds like the motor has gone. But it is a Horstmann so swap it for something a bit more reliable. I use Honeywell and the Honeywell V4073A 3 Port Motorised Valve should work OK. Cable colours are standard.

I believe the head design on the Horstmann changed so unless you known if yours is the current model , just buying a replacement head is risky.


As a temporary:
You should be able to manually lock it in the mid position for venting purposes. Often just a case of press it across against the spring then press it down toward the pipe as it tries to return and it should latch onto a keep.

That will hold it open but the boiler will only run while your hot water cylinder needs heating. If you have a cylinder stat it may shut it all down


Just in case it is not the valve can you test the room stat and programmer to make sure they are trying to switch the CH on?

Edit I'll leave this one to MANDATE

 

[MANDATE]

Providing the wiring has not been tampered with and power is present on the valves 'white' wire when CH is selected, it most likely the motor that needs replacing.
There are four sets of micro switch contacts in the actuator head and one of these sets switchs power from the white wire to the motor, so there is a slight chance the contacts have failed, so check motor first.