Motorised valve issue

[Ramrod4]

I seem to have an issue with the motorised valve but not completely sure it's that or what the problem is.
Essentially, when both the heating and hot water are on as far as the programmer is concerned, the hot water is not going to the radiators - only to the hot water tank. If I move the lever on the valve across, the pipe to the radiators, which was cold, immediately becomes hot. But the lever then moves straight back again. I've done some research that suggested that faulty valves are usually evidenced by a floppy lever or a seized lever, but this one actively moves itself back. It's almost as if the programmer is giving it duff instructions. Does anyone have any ideas what might be going on here?

 

[Johntheo5]

Presume it's a mid position valve?, ensure the roomstat is calling for heat?. Does CH on its own work?

 

[ianmcd]

post a pic of the valve there are different makes

 

[Ramrod4]

Yes a mid position valve (honeywell). How would I know if the roomstat is working as it should? CH doesn't work without the hot water on (by design it seems- no idea why)

I've just switched the HW off to answer your question, and after turning it back on the radiators are now warming.

 

[oilhead]

Is this something that has only just happenned or has it always been like this?
It's time to get your multimeter around the junction box. There is a good fault finding chart on the Honeywell website.

 

[Ramrod4]

Is this something that has only just happenned or has it always been like this?
It's time to get your multimeter around the junction box. There is a good fault finding chart on the Honeywell website.

Fairly recent as in a few weeks. Thanks - I will take a look at that. Just wondered if there was a simple explanation.

 

[Johntheo5]

Yes a mid position valve (honeywell). How would I know if the roomstat is working as it should? CH doesn't work without the hot water on (by design it seems- no idea why)

I've just switched the HW off to answer your question, and after turning it back on the radiators are now warming.

So, if you are saying that the HW works OK and the HW+CH (together) work OK but the CH does not work on its own then its more than likely IMO that one of the internal switches that puts power to the orange wire that is only used when CH only is requested has failed.

 

[DP]

So, if you are saying that the HW works OK and the HW+CH (together) work OK but the CH does not work on its own then its more than likely IMO that one of the internal switches that puts power to the orange wire that is only used when CH only is requested has failed.

HW satisfied wire missing or as you say, could be microswitch error

 

[TimboTwo]

What programmer do you have.

 

[Johntheo5]

A very ingenious design.

Electrical Operation
In the Y Plan system, when Hot Water is called for, power to theboiler is provided directly from the cylinder thermostat, the valve is not energised. When Heating is also called for, the Heating ON wire (white) is energisedand the valve will motor to and stop in a mid-position.
If the Hot Water is then satisfied, (either by the programmer orcylinder thermostat) the Hot Water OFF wire (grey) is energised. Because there is still a demand for Heating the valve will then motor towards the Heating Only position and switch a 240V supply onto the boiler. The orange wire only has a 240V supply from the valve when there is a call for Heat in the Heating only position i.e. 240V on white & greywires.
When this Heating demand is satisfied, during a Heating ON period, 50V to 150V (voltage can vary according to the supply) will remain on the orange wire and the valve will continue to be energisedand warm to the touch. Switching Hot Water ON or turning OFF at themains will de-energisethe valve and it will spring return back to the Hot Water only position until thenext demand.

 

[Ramrod4]

So, if you are saying that the HW works OK and the HW+CH (together) work OK but the CH does not work on its own then its more than likely IMO that one of the internal switches that puts power to the orange wire that is only used when CH only is requested has failed.

Apologies for the slow reply - been ruined with covid for a week. It's actually always been like that - by design it seems - I have no idea why.

 

[Ramrod4]

What programmer do you have.

It's a Drayton Lifestyle LP241.

 

[CBW]

It's a Drayton Lifestyle LP241.

Can you (carefully) post a photo of the wiring behind? The programmer should unscrew at the bottom somewhere and then lift off.

 

[Ramrod4]

Can you (carefully) post a photo of the wiring behind? The programmer should unscrew at the bottom somewhere and then lift off.

I can't unfortunately because the conduit for the wiring is firmly fixed in place and prevents screwdriver access.

 

[Johntheo5]

Apologies for the slow reply - been ruined with covid for a week. It's actually always been like that - by design it seems - I have no idea why.

If the CH only works when the HW is on as well then the CH should go off once the cylinder stat is satisfied and only come back in when the cylinder stat calls for cylinder heating again?