Drayton Zone Valve Actuator ZA6 not reading Danfoss Programmer??

8 Nov 2021
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United Kingdom
Hi Everyone,

Very new here and made an account for some advice and guidance. Here's hoping you can help!

I have a Worcester Greenstar 40cdi system boiler that is hard wired to a Danfoss FP715Si 2-Channel programmer for heating and hot water.

The boiler has a Danfoss HPA2 actuator and a Drayton ZA6 Zone valve actuator.

Initial problem - No Hot Water

HW stopped working, even when I switched the HW programme to ON / ALLDAY / +1HR. The boiler wouldn't fire up - no green burner light. CH was fine - I have that to ALLDAY - I am a carer for my mother so if its too warm she can control it via the iflo thermostat.

So initially no HW but CH was fine.

I had a look at the boiler which is located upstairs and moved the Danfoss HPA2 valve to manual, it clicked in place and within seconds the boiler fired up. 20 mins later we had Hot water - fabulous.

Not rocket science, So I figured the HPA2 is faulty, went out and purchased a new one, wired it up (Amateur handy man but I work with cars), I followed the previous wiring and hey presto works fine on all settings ON / AUTO / ALLDAY etc.

New Problem - No Central Heating

However, since replacing the Danfoss HPA2 now there's no CH. I re-checked the wiring - all good and neat.

I switched the HW to off and tried the CH programme on all the usual settings ON / ALLDAY /+1HR to see if the radiators and pipes would heat up - Nothing.

Upon investigation, when I move the Drayton ZA6 to manual it switches on. Great. But now the radiators only get hot if the HW is on and the Drayton ZA6 has to stay on manual.

If the HW is switched to ALLDAY then the CH will come on ALLDAY from 8am - 9pm (as per the first and last HW programmed times) If the HW is only on for +1hr then CH only comes on for 1hr and so on etc you get the drift.

Now the question is...

Do I have a faulty programmer? I don't think so - do correct me if I'm wrong - because the boiler fires up when the HW programme is selected.

Do I need a new Drayton ZA6 Zone Valve Actuator?

Would really appreciate if you could help me out here and help me work out what's going on?

Many thanks everyone.
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Inside the motorised valve is a microswitch that when the valve opens, the switch is made and hey presto the boiler fires up. With some valves the switch is triggered when the manual lever is operated (as it would appear from your description of the Danfoss) with others it isn't.

From your post I suspect that the CH valve (Drayton) is manually opened by the lever but the switch isn't made, so it's then relying on the HW valve to trigger the boiler.

Failure of the CH valve to open could be due to any of the following: Failure of the heating channel of the programmer / failure of the room thermostat / failure of the valve motor / wiring fault. The best way to check is for someone who can use a multimeter safely to test between the brown and blue wires of the motorised valve for 230V when the heating should be on. If there's 230V present the valve and it doesn't open, it's faulty (most common culprit). If not, it's the programmer, room thermostat or wiring, which can also be tested with the aforesaid multimeter.

Unlucky for both CH and HW to fail at the same time, I would initially suspect that something was disturbed when you changed the first valve, but as you've checked that already...
Hi Stem,

Many thanks for your reply! Really uber helpful

Now, the brown and blue wires... Do i need to open the Drayton to test the wires or do you mean the brown and blue wires coming out of the Drayton connected to the fuse box?
No need to open the actuator, just test the terminals that the brown and blue wires are connected to. (IE the wires visible at the end of the cable as per the photo) Obviously don't disconnect them though. It should be in a junction box or wiring centre, not a fuse box.

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Ah yes the junction fuse box is what I was meaning - thanks for the correction, and thanks for the explanation. I'll get them checked and report back!

Sooo... Looks like a school boy error but the brown wire from the Drayton isn't connected! How on earth did i miss that!

Now the question is where do i connect it too. Obviously after I switch the mains elecy off.


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I'm really racking my brain here. Clearly my wiring and observation skills are some what to be desired! But atleast, with thanks to your help, we may have found the culprit!

I took pics before i started fiddling around - lo and behold I can't see the journey of the brown wire from the drayton! How?? Clearly my photography is somewhat to be desired too!

The red 'X' is the Drayton wire and the white arrow points to the the non-connected brown wire in question. The black wire next to it, which is out of focus, leads to the Danfoss


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Last edited:
I re-checked the wiring - all good and neat..


The brown wire from the central heating motorised valve should be connected to the switched live wire from the room thermostat. Unfortunately there are no standard colours for the wire or which terminal it's connected to. Those choices are down to the personal preferences of the original installer.

It can be traced physically from the thermostat, or with a multimeter. The required terminal will be 'live' when the heating should be 'on' and not 'live' when the room thermostat is turned down, or CH at the programmer turned off. That's the terminal where the brown wire should go.
Thanks a mill for this.

I shall report back shortly

I fiddled around and wasn't sure which terminal the brown wire should go. The boiler is upstairs with programmer / thermostat downstairs. Wasn't confident tracing wires and I don't own a multimeter.

I kept looking back at the pics i took before I 'rewired' the danfoss and couldn't work out the journey of the BW. Just my luck.

Long story short called out a sparky that was recommended by a friend - took him no time to work it out, traced the brown wire to the live and voila. So far so good, the CH is coming on independently on all functions.

Will keep my eye on it. Fingers crossed that should be it.

Thank you for you're time and advice Stem. :) very appreciated


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