Another actuator issue.

[hobbes748]

Afternoon!

The actuator on our downstairs heating loop has become stuck in the open position (so the boiler was constantly on heating up downstairs), even though the thermostat isn't requesting the actuator open. It's not mechanically stuck - it closes normally if you cut the power to it. Thinking it was just a knackered actuator I replaced it with a new one - which went straight to open too and stayed there. So unless I was very unlucky and bought a new actuator that just happens to have the same issue as the one I've just replaced, it's not an actuator fault.

It's Hive thermostats we have. I've tried disconnecting the receiver - no difference. I've tried swapping the upstairs and downstairs receivers over (my thinking being if its a fault lies with the receiver/thermostat the upstairs actuator would develop the issue instead of the downstairs one. Nope, no change.

Anyone know what this could be? I've called a couple of heating engineers, but they're not keen on coming out until after the new year.

Thanks in advance.

 

[Exedon]

Sounds a bit obvious but you've got a permanent live somewhere.
Have you got a multimeter and are competent to use it ?

 

[ianmcd]

post a pic of the wiring inside the wiring centre

 

[Harry Bloomfield]

If not a wiring or other issue - Try tapping the hive receiver, with the power to it turned off, it might just be welded up contacts in the relay.

 

[hobbes748]

Sounds a bit obvious but you've got a permanent live somewhere.
Have you got a multimeter and are competent to use it ?

Yeah, I'd half-sussed it was getting power from somewhere it shouldn't be. I do have a multimeter, but I'm not 100% confident/competent to go poking round with AC unsupervised. Happy to fire in if somebody tells me where.

I'd sketched out a schematic of the wiring (attached) to try and get my head round what's going on and noticed that the 2 actuators had common connections and wondered if the one working correctly was sending some sort of cross-feed to the other one making it open. Tried swapping the unaffected one out - no difference.

Just noticed my drawing is missing a black wire coming from the bottom left to '12' at the top of the page.

 

[hobbes748]

post a pic of the wiring inside the wiring centre

I've attached a diagram in the previous post. A1+A2 are the Actuators, R1 + R2 are the receivers. It's A1 that's giving me grief.

 

[Johntheo5]

Afternoon!

The actuator on our downstairs heating loop has become stuck in the open position (so the boiler was constantly on heating up downstairs), even though the thermostat isn't requesting the actuator open. It's not mechanically stuck - it closes normally if you cut the power to it. Thinking it was just a knackered actuator I replaced it with a new one - which went straight to open too and stayed there. So unless I was very unlucky and bought a new actuator that just happens to have the same issue as the one I've just replaced, it's not an actuator fault.

It's Hive thermostats we have. I've tried disconnecting the receiver - no difference. I've tried swapping the upstairs and downstairs receivers over (my thinking being if its a fault lies with the receiver/thermostat the upstairs actuator would develop the issue instead of the downstairs one. Nope, no change.

Anyone know what this could be? I've called a couple of heating engineers, but they're not keen on coming out until after the new year.

Thanks in advance.

Is this a 2 port motorized valve?.

 

[noddy997]

From my recent experience, check the wires - take them out of the connector blocks etc and check the copper is clean and that there is sleeving on all wires

 

[hobbes748]

Is this a 2 port motorized valve?.

Yeah, they're both 2 port valves.

 

[hobbes748]

From my recent experience, check the wires - take them out of the connector blocks etc and check the copper is clean and that there is sleeving on all wires

OK, I'll give that a shot. I did give them all a tug to make sure nothing's loose, but I'll give them a proper check in the morning when everyone else is out and I can get a bit of quiet to concentrate.

 

[noddy997]

OK, I'll give that a shot. I did give them all a tug to make sure nothing's loose, but I'll give them a proper check in the morning when everyone else is out and I can get a bit of quiet to concentrate.

If copper isn't clean then there will be poor conductivity or if there are other metallic objects in close proximity they could cause a short circuit too.

 

[Johnmdc]

Do you have a frost thermostat somewhere?

 

[BlueLoo]

If they are stuck open, are they Myson?
The plastic goes brittle after a while if so and can cause the latch to catch.

Just snap the plastic off.

 

[ianmcd]

I've attached a diagram in the previous post. A1+A2 are the Actuators, R1 + R2 are the receivers. It's A1 that's giving me grief.

Well if you mean that drawn diagram, you have both browns from A1 and A2 joined together which is completely wrong

 

[hobbes748]

Well if you mean that drawn diagram, you have both browns from A1 and A2 joined together which is completely wrong

Morning.

Hope everyone had a good Christmas.

Sorry - maybe it's the quality of the photo, but they don't. The brown from A1 connects to grey from R1 and also the brown that goes back to the boiler (which I think is where the issue lies)...

Without doing a thing, the heating cured itself for a day or so, but then began the same thing again. I noticed it was most likely to start it's s***t in the middle of the night when it's really cold, making me get up and dressed to go into the garage to turn the boiler off. I now think it's possibly an issue with the frost protection. If what I've read on t'internet is correct, my external temp sensor flicks a switch to send power up that brown wire that's joined to A1/R1, which opens A1 and starts the heating cycle. Then when the warm water comes back, the pipe thermostat clamped the return pipe above the boiler is supposed to cut that live feed - which I don't think it's doing. So as a test I've disconnected the brown twin 'n' earth that connects to A1/R1 to see what happens. It's only been a day or so, but so far it's been working just fine.

If it is the pipe thermostat or the external sensor, is it worth replacing or should I just do without it? There is no external pipework and the boiler is sited in an internal garage?