Help... intermittent hot water issue

[SJB060685]

When the roomstat calls for heat and with hot water off the valve should motor over to CH and supply a 230 volts live to burner switch live (orange cable). If the valve is stuck or the switch inside actuator head has failed then you won't get 230 volts to boiler and pump.
I apologise for not reading all previous comments.

 

[Larches]

Thanks, I think if I've understood that correctly then it does suggest the MA1 is at fault, as the roomstat clearly shows it's calling for heat and yet the valve remains on 'W' until I use the manual override lever to shift it to 'H'. So presumably either the valve keeps on sticking, or perhaps more likely it's the actuator switch having failed - either way I certainly get the impression it's the motorised valve that needs repairing or replacing.

 

[Larches]

The saga continues... I took off the actuator head and took some pliers to the spindle on the valve to see if it would turn. It's just a little stiff, but definitely not stuck. I then did a quick test with the head still off to see if it managed to rotate when it had no resistance (i.e. without being attached to the valve), and it did nothing when the room stat called for heat - just remained stubbornly at 'W'. I thought to myself that maybe the motor had packed in. So I goes and gets a replacement motor and guess what... exactly the same thing happens. So that's ruddy annoying. What I did notice though is that there's a slight buzz from the motor whilst the room stat is calling for heat - I could hear it and also felt the vibration, so it seemed like it was trying to do something, but even with the motor freed from the assembly it still doesn't turn.

So again, it seemed like the motor is dodgy, but what are the odds of an unused replacement motor (genuine Drayton, sealed packet) being faulty in the same way? Made me wonder if there could be something wrong with the circuit board, although it looks simple enough, and there must be some power getting to the motor (the buzz/vibration stops as soon as the room stat turns off again).

Seeing as I still don't have a multimeter (for now, although I'm beginning to wonder if it might be worth getting one - and learning how to use it ) I've no idea what to do next really, short of stumping up for a whole new head unit and hoping for the best. If anyone has either a theory as to what's going on or experience of this issue then, as ever, I'd be grateful for any further tips (as you can tell, I'm reluctant to give in and call a heating engineer as it feels like something I should be able to sort out myself, but it may yet come to that...).

 

[Aquarius]

Do you have the battery version of Danfoss or mains voltage?

 

[SJB060685]

Before you spend any more money on the valve I would get a multimeter to check what is where, it doesn't have to be an expensive one. I've had a quick read through from old comments, so forgive me if I've forgot something (a lot comes through this forum each day). Is your problem no hot water or no heating? I'm getting mixed messages from recent comments.

 

[Larches]

Do you have the battery version of Danfoss or mains voltage?

It's the battery one.
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Before you spend any more money on the valve I would get a multimeter to check what is where, it doesn't have to be an expensive one. I've had a quick read through from old comments, so forgive me if I've forgot something (a lot comes through this forum each day). Is your problem no hot water or no heating? I'm getting mixed messages from recent comments.

Sorry, yes, it has been a bit convoluted as the initial problem was the HW not coming on, which I've now resolved (with a new programmer), but in the meantime the heating stopped coming on. I thought at first that the two things may be related, but I'm now reasonably sure they aren't (maybe I should have moved this bit to a new thread!). We now have the hot water coming on automatically as per its schedule, but the heating fails to do so when tested (obviously we're not actually using the CH at the moment, but just keen to get it working before the weather gets colder).

 

[SJB060685]

I would pop down to your local screwfix or toolstation and get a cheap multimeter, as i said it doesn't need to be expensive, you'd probably get one for around £15-£20.
From there I would be looking for 230 volts between a neutral and the white wire on the actuator head. What that tells you will allow you to go from there.

 

[Aquarius]

Does it need batteries in the thermostat? Have you checked the batteries, and are they alkaline?

 

[Larches]

Does it need batteries in the thermostat? Have you checked the batteries, and are they alkaline?

Yes, they're Energizer alkalines, replaced not that long ago. I think the thermostat is working fine - I can hear it click on (and the flame symbol appears) when I notch up the set temperature, and as mentioned, the actuator motor responds with this slight buzzing, and then stops when the thermostat clicks off again. As per @SJB060685, sounds like some electrical diagnosis required on the actuator head.