Boiler won't output DHW & CH at the same time.

[radiohe4d]

Info:
Worcester Greenstar Heatslave
Drayton MA1 Mid Position Valve Actuator

Summary:
Had to replace the valve actuator as the old one was sticking. Wired up the new one with the same pinout as the original. Tested but got the following failed outcome;
Off = DHW
Water On = DHW
Heating On = CH + DHW (makes clicking sound)
Both On = CH

Boiler Hell:
We only moved in a few months ago and haven't needed the heating much, but we did notice it was coming on at random or when water was run. Worked out that the valve was sticking, removed it and only got around to replacing it today.

The boiler had a full service at the start of this year (2020) and had the PRV, Pump and fuel lines replaced.

So I after the actuator failed to move to the expected positions I thought must have always been wired wrong (as i matched the previous wiring). So I hunted out the Greenstar and Drayton manuals and tried to figure out what wires did what. A multimeter, a lot of cursing and 6 hours later, I managed to map what the boiler outputs and matched it to what the actuator does.

I've now got the DHW and CH working separately. But for the life of me I can't figure out how to get them to run both at the same time (actuator at mid position, yenno, the whole damn point of the £70 hole in my pocket!).

I've got pictures if it'll help but I'll not spam until theyre needed.

Boiler => Actuator Wiring:
Blue => Blue
Green => Green
Grey => Orange
Orange => Grey
Brown => White

Boiler Output Voltage For States:
These don't make much sense to me. Both On shouldn't be the same as Water only?

Off
Grey = 0v
Orange = 0v
Brown = 0v

Water
Grey = 240v
Orange = 240v
Brown = 30v

Heating
Grey = 0v
Orange = 240v
Brown = 240v

Both
Grey = 240v
Orange = 240v
Brown = 30v

Actuator Position Settings:
I manually tested the actuator with switches connected to a wall socket to determine how to set each position. 240v was applied to white, grey or both white & grey wires. The Orange wire outputs various voltages based on position.

DHW (default position)
Grey
Orange = 0v

Mid
White
Orange = 60v

CH
Grey + White
Orange = 240v

Conclusion:
I'm pretty experienced with electronics but have little to no experience with boilers and heating systems.
I am however confident that the diverter valve is functioning correctly, the actuator isn't faulty as from my successful manual position testing and that I hate boilers 1000 times more than I did yesterday.

I'll admit that I'm pretty lucky to have everything else working, so I am counting my blessings there but I can't walk away when it's so close to working 100% correctly.

Apologies for the long post but hopefully I've talked enough that someone out there will somehow know exactly what I'm talking about.

Cheers,
Brian.

 

[ianmcd]

pics would be best, your ramblings make no sense, sounds like you have not wired in the HW off properly

 

[dilalio]

Grey is NOT permanent live.

 

[oilhead]

It is a combi. It will not run in mid position. You will get either heating or hot water, and if you have both selected, it will prioritise getting the heatstore up to temperature before giving you heating.

 

[Gasguru]

It sounds like you're tying to bodge on an off the shelf Drayton mid position valve rather than buying the correct Worcester part which is a simple diverter valve (ie. diverts the primary water to either the rads or heatbank).

 

[dilalio]

OP. Sounds like you're trying to convince us you know what's wrong and how to fix it... But it's just muddying the waters.

What controls do you have?

 

[radiohe4d]

Lol, so posting too little information on this forum gets negative responses, so I tried to be a thorough as possible but apparently that's even worse

@ianmcd
I've posted loads of photos. Hope that helps.

@dilalio
Grey isn't live when both DHW & CH are off. If that's still wrong, how should it be wired?

@oilhead
Thanks for that, I didnt know combis couldn't do both at the same time. I've only ever had separate boiler and hot water. The pre existing mid position valve sent me down the wrong path.

@Gasguru
As I said above, I replaced the exact diverter that I found in the boiler. I didn't try to bodge anything. I would have bought the original Worcester if I knew one even existed.

@dilalio
I'm not trying to convince anyone of anything. I tried to give as much information as possible from what I've tried so far and what outcomes I got.
I'm only here to ask for help.
I don't know what you mean by what controls I have. I've posted photos that may be of some help.

IMG_20200906_002706~01

• radiohe4d
• 6 Sep 2020

IMG_20200906_125703

• radiohe4d
• 6 Sep 2020

IMG_20200906_125726

• radiohe4d
• 6 Sep 2020

IMG_20200906_125732

• radiohe4d
• 6 Sep 2020

IMG_20200906_125747

• radiohe4d
• 6 Sep 2020

IMG_20200906_125756

• radiohe4d
• 6 Sep 2020

IMG_20200906_125822

• radiohe4d
• 6 Sep 2020

IMG_20200906_125826

• radiohe4d
• 6 Sep 2020

IMG_20200905_230420

• radiohe4d
• 6 Sep 2020

IMG_20200906_002706~01

• radiohe4d
• 6 Sep 2020

 

[ianmcd]

That image there, it is not very clear , that connector is used to join the multi core cable when replacing the valve actuator, cant really tell but it looks wrong, can you straighten out the cable at the top and post another pic so we can see what is connected to what

 

[radiohe4d]

Yea sorry about that, not the clearest

I've added some more photos and labeled them as best I could.

This current wiring let's the heating and hot water work separately but not together. I tried other configurations of orange, white and grey and non of them did anything the right way. This was the only way that worked.
Wiring the colors to match like for like, with brown matched to white, was how the old one was wired but neither the old nor the new actuator worked properly with that wiring.

Maybe oilhead is right and this particular boiler doesn't have a mid position output?

Cheers
Brian.

 

[Gasguru]

The heating and hot water are not designed to work together...a DHW demand and replenishing the heatbank always has priority.

For the sanity of yourself and any future eng. working on the boiler buy the proper diverter part no. 87161087230
Perhaps a previous owner of repair tech has tried to be clever...

Check the wiring diagram fully but in theory connecting boiler brown (motor Live) to the actuator grey & white will result in the motor winding fully to the heating position.
And connecting boiler grey to actuator orange will obtain the Live feed once the valve has motored. ie. replicate the end switch in the proper diverter actuator.

If the wiring isn't perfect on a mid-position the motor can become magnetised and stick...

 

[oilhead]

I think you; findif you have amid position actuator, if you simulate theCH only position, i.e just power the brown then it will work as a diverter. Just make the white safe and ignore it.

 

[Gasguru]

Er..no brown on a mid-pos.
An end microswitch is required to operate the pump....hence powering both the grey & white and using the the orange to simulate the switch.
And as for trying to get the boiler to have heating and hot water...too late in the day to get my head round the relays etc...

 

[oilhead]

The micro switch is operated when the the motor opens. The PCB feeds the grey, energising the orange to fire burner and pump.White opens the valve I think so put that where brown is in PCB. ( was getting confused with H.well) I've not adapted a Drayton Actuator, but have done the Danfoss HSA3 on Boulter Combi's. At 5 o'clock on Christmas Eve, you have to try and do something

 

[oilhead]

O.P., if you have a mid position actuator, you may as well try and use it as it is paid for. Now you know the boiler does not do 'mid position', the orange and grey are the same as your old actuator, and make the switch when the live feed opens the valve fully.

 

[radiohe4d]

Thanks for the help guys! I've learnt a lot and things are making sense now

@Gasguru thanks for finding the part no. for the original part. I'll see how this Drayton works out and if it quits working I'll definitely replace it with the oem part.

@oilhead Yea I think you're right, best to give this Drayton a go and hope it lasts. Knowing that the boiler can't do mid position has made things make sense now.

Cheers!