Honeywell motorised valve playing up.

[Leo]

Good afternoon – I am really stuck with a diagnosis here and hope to get your help.

The system has 2 Honeywell V4043H1056 motorised valves. Their outside levers are both set to “auto”. No problems at all with the Central Heating valve or the programmer (ST6400C). The issue is with the hot water valve: When the heating or the hot water have not been on for many hours, the programmer will send a signal to the hot water valve, the valve will “try” to kick into action (makes a noise) but the inside arm of the valve that is supposed to press on the inside little button to trigger the boiler, does not actually reach the little button! If, on the other hand the boiler has been on recently, when the programmer sends the signal, the hot water valve kicks in and works fine. When it doesn’t work, I just click on the programmer’s “override” off-on repeatedly until the valve does finally work. So:

1. Summer day, heating is not on during the night or day, at 4:30pm when the water tries to start, the valve fails and the boiler does not receive a signal. I have to manually try to start the water.
2. Cold day, heating is on during the day, water starts at 4:30pm without issues.

I find it incredibly strange that the boiler having been on recently has any bearing on a valve’s internal arm reaching its full clicking position or not!
I thought of replacing the top part of the valve (the part of the gears) but then again this works perfectly fine when the system is more frequently on. Any recommendations?

Thanks very much

 

[Masood]

Welcome to the forum Leo. The arm is made of very thin metal, and the cogs (teeth) cut into it are prone to stripping, allowing the arm to slip off the brass cogwheel that rotates to move the arm.

Why it works when the system is hot - I can only surmise that the heat conducted down the pipe is allowing the metal components to expand enough to force a better contact, making the arm move without slipping.

 

[Best]

As above, ^^ they tend to work intermittently due to teeth worn on arm, plus the arm seems to be very loose. Not great those Honeywell valves I think and looks like you will need a new Honeywell actuator, or have someone replace the entire valve with another brand if you wanted. Centre Brand motorised valves are a lot cheaper.
Danfoss - avoid! Drayton break inside after a few years. I actually think Myson, which are a cheap valve, seem reasonable.

 

[Billy Bob Bob]

gone over to EPH same much stronger,also a EPH head will fit directly to a honeywell body but you need the newer version of the EPH valve to do it

 

[Leo]

Thank you everyone for your suggestions and prompt advise. So, just to check I am on the right track: I have this valve V4043H1056 and it seems that the power head replacement for it, Honeywell brand, is 40003916-001.

I found it at £50 in Amazon incl delivery - https://www.amazon.co.uk/Honeywell-...903295&sr=8-1&keywords=honeywell+40003916-001

Does this sound about right?