Heating only comes on when hot water is selected

[luxliners]

My heating only comes on when the hot water is selected on the controller. I have checked the Drayton controller and changed it to pumped and gravity and it makes no difference at all except the boiler fires up on both water and heating is selected on gravity. Where as on pumped it only fires up when the hot water is selected.

I have taken a picture of the wiring behind the controller in case the wiring needs adjusting as can see that the terminals for 1 and 2 are not wired. So not sure if its my wiring configuration or the 3 way valve is stuck. Would love some general advise before I arrange a plumber to attend.

One last thing there is no room stat its an old system so its controller by the rad stats.

 

[CountryFan]

I would be looking at the 3 port valve - they are prone to failure

 

[stem]

The picture seems to show a 3-port valve, but there's no HW off connection to terminal 1 of the programmer, which a mid position 3-port valve would require.

OP, Has it always worked like this? Can you confirm the model of motorised valve you have?

 

[luxliners]

Hi Its a Drayton HSA3 I have added a picture now. I only recently got the property so unsure if the previous occupier just put up with this issue and lived with it. Good point about the wiring so in this it would need a wire to terminal 1 to select the hot water only?

 

[luxliners]

3 port valve.

 

[CountryFan]

Yep, I didn't see that, good spot @stem. @luxliners you have a Danfoss HSA3 (not that the manufacturer will make any difference) and appears to be a mid position valve and would need the hot water off connection for independence. Might be better to upgrade to x2 2 port valves.

 

[luxliners]

Appreciate all your help with this, would this be a big job adding a lead to a hot water connection terminal? Or can it be bridged with the other connectors?

 

[CountryFan]

I don't think it can be bridged and might be an upheaval for adding essentially an extra wire, but upgrading to an S plan (X2 two port valves - yours is known as a Y plan) should be ok.

 

[luxliners]

Brilliant thanks for the help with this, if I was to get a 2 port valve fitted I wouldn't need the wire installing and could I operate independently?

 

[CountryFan]

Brilliant thanks for the help with this, if I was to get a 2 port valve fitted I wouldn't need the wire installing and could I operate independently?

Yes, but as I said, you need x2 - 2 port valves and operate them independently, but you’d also need a room thermostat fitting, but the option of wireless is there too.

 

[stem]

would this be a big job adding a lead to a hot water connection terminal? Or can it be bridged with the other connectors?

It would require a new wire from terminal 1 of the programmer (Hot Water OFF) to the grey wire of the motorised valve. (Hot Water Satisfied)

As @Stuckinarut converting it to two x 2-Port motorised valves is a plumbing exercise, and wouldn't need a new wire running to terminal 1 of the programmer, it would however need new a permanent live supply to both of the 2-Port valves for boiler control [A 3-Port valve doesn't require a permanent live]

It is good practice, as well as as requirement for new systems or a boiler replacement to add a room thermostat. So, whilst it's not ideal not to have one, you could leave it as it is with just the programmer operating the heating as it does now.

Also to be aware of, a 3-Port valve has a built in by-pass function (i.e. one port is always open) if your system requires this facility, it allows the pump to circulate water for a few minutes to cool the boiler once the heating and hot water have gone off. This feature would be lost if converted to two x 2-Port valves, as both could be closed at the same time. Many older systems will have a separate by-pass pipe to provide this facility although I don't see one in your photos, and new boilers often have one built in, so it might not be an issue.

 

[Johntheo5]

This may assist.

 

[luxliners]

Really appreciate the time and effort in replies to this thread many thanks all. I have a much better knowledge of the issue now, I did contact one local plumber who advised the possible work around might be to use a wireless controller to get round the lack of hot water off lead.

 

[Johntheo5]

You say the boiler only fires up (on pumped) when HW is selected on the controller.
If HW&CH selected does the boiler continue to run on CH when the cylinder stat is satisfied?.
If HW only selected does the boiler shut down when the cylinder stat is satisfied?.

 

[gas112]

you havent got an off wire from backplate to 3 port valve so it wont work