Faulty Zone Valve?

[helmpost]

My daughter has just moved into a property. There is a known CH problem that I am trying to resolve.

Hot water works but the radiators also heat up
Hot water does not work at all

Checks show that the heating zone valve (Honeywell V4043) has been set to manual - permanently on. Setting this back to auto does not solve the problem.

I have changed the controller. No difference
I have checked that the room start is switching (it is) and that there is a 240v supply on the cable when the heating is switched on. I have further found that this 240V supply appears on the blue wire of the heating zone vale. The V4043 does nothing when the heating is switched on, the pump does not operate and the boiler (Glow Worm Fuel Saver F) does not turn on.

Can someone advise the sequence of events when a zone valve should operate? Are there additional contacts on the V4043 that should sent current to the boiler and pump? In short, is it likely that a faulty V4043 would cause the problem?

Grateful for any views and suggestions

Brian

 

[ollski]

Are there 2 of them?, the 4043 is normally installed as an s plan system ie one valve for heating and another for hot water.

 

[helmpost]

Ollski

Yes there are two. The DHW works fine. When called, DHW valve opens, boiler and pump operate properly.

In design, the flow from the pump is split into two paths, one for the DHW and one for the HTG. When the DHW is on, water passes through both valves. When HTG is called, no response from HTG valve, pump or boiler. In essence then, can only get HTG by calling DHW!

Regards, Brian

 

[ollski]

Sounds lik ethe actuator on the heating valve is knackered so they have manually latched it open so the heating comes on whenever there is a call for water...may just need a new motor but it depends where the power is getting to.

 

[helmpost]

Ollski

The spec for the V4043 states that the de energised position for the valve should be OFF but clearly this is not happening since water is passing through the valve when the HTG is OFF. At a guess it looks like it has "failed open" if such a thing were possible ... ? or the wiring is incorrect. I have the circuit diagram from Honeywell so up with the floorboards again.


Regards, Brian

 

[ollski]

Thats because the lever has been moved over and hooked into the manual position to keep it open.

 

[ChrisR]

flow from the pump is split into two paths, one for the DHW and one for the HTG. When the DHW is on, water passes through both valves.

That appears to be contradictory.
The split should be before the valves, so only one is used for each function.

 

[helmpost]

To be clear

DHW working correctly

Heating not working at all when switched to HTG
When switched to DHW, water flowing through both DHW and HTG valves.

Initially found the HTG valve switched over and latched to "Open" and thought this was the problem so switched the lever back to "Auto" but problem remains so in effect, whatever the position of the lever, water flowing through HTG valve when DHW is switched on - that's why I believe that the HTG valve may have failed "Open".

And yes, the DHW and HTG circuits is split after the pump and before the valves.

Regards, Brian