Thermostat dead/powered off troubleshooting

[triangularmonkey]

Hello,

I have a hive hub wireless receiver that's all of a sudden dead. Not sure how long as I haven't needed to turn on the heating for quite some time, thank god for summer?

Below the receiver is the boiler fused switch. I've turned the boiler on/off a few times and no luck. Just to rule out a dodgy receiver, I remounted the old British Gas manual thermostat. Surprise surprise, that's now also dead. So, I'm suspecting something is up/funny with the wiring or socket.

I've looked at the wiring visually and can't see any disturbance or damage. Any other steps I can check please?

 

[DP]

I've looked at the wiring visually and can't see any disturbance or damage. Any other steps I can check please?

Looking at it will not do much.
Get a multimeter and test.
What is the fuse rating in the spur?

 

[triangularmonkey]

Looking at it will not do much.
Get a multimeter and test.
What is the fuse rating in the spur?

Hi DP.

It's a three amp. Even at that low power, I only have a very cheap unfused multimeter so I'm a bit worried about testing live wires. Perhaps I'll try the continuity between the faceplate pins the receiver goes into with the exposed wire ends at the terminal in the boiler. I'm still inclined to turn off the power at the main fuse board as I think it sits on a 20/25 amp breaker!

Would some pictures be helpful?

 

[ericmark]

There are two Hives, linking 1 to 3 on single channel, or L to 4 on twin channel should make the boiler run. And wiring a standard lamp to L and N will show if there is power to the thermostat.

But the problem as always is, was it wired correctly to start with? We had bi-metal thermostats for years which did not need power to make them work, so it was all too common to only run two wires to the thermostat, on upgrading some way needed to be found to power them, and I have seen all sorts of fixes, including using the earth wire as a live.

One thing which does seem to throw the DIY repair, is the motorised valve, it is common for the thermostat to work the valve not the boiler, and then a microswitch in the valve in turn works the boiler.

And pictures are good, I note not UK, so not sure of practices in your country.

 

[triangularmonkey]

So I've had a chance to do some testing. On the boiler, the live (behind the fuse) is indeed live so all is well there. The boiler is running any way. On the junction box, the brown wire is also live. The white wire out the back runs to the boiler. Finally, on the face plate for the receiver there are no live wires, so none of that works. Any thoughts?

 

[garygooner]

Hi I think the supply to face plate is feed from terminal 2 off boiler is there power there also why would someone use earth wire and sleeve to link live and common.

 

[CBW]

@DP is correct, you need to make sure that there’s live being fed to the Hive backplate. Testing continuity won’t do much.

 

[dilalio]

Get rid of it and replace with a decent smart controller/stat instead of a glorified on/off switch.

 

[RandomGrinch]

As mentioned by @garygooner, the power for the stat is currently supplied by the white wire from terminal 2 of the boiler.
Is there 230V on the white wire?

Also (possibly unconsequentially), there appears to be an additional cable connected to the control side of the junction box - this was often the case when a timer and thermostat were mounted separately.
Do you know where this cable goes to?

 

[triangularmonkey]

Hi I think the supply to face plate is feed from terminal 2 off boiler is there power there also why would someone use earth wire and sleeve to link live and common.

Clearly there's something bad going on with the boiler. The voltage detector is showing no reading from the white wire (terminal two on the connector box in the boiler) that then feeds up to the face plate (becomes the red wire there) So it's a boiler hang up - Potterton Combi Pro Plus HE 28 A if anyone's got experience with those. About to replace it any way with a W Greenstar 4000

 

[RandomGrinch]

The voltage detector is showing no reading from the white wire (terminal two on the connector box in the boiler) that then feeds up to the face plate (becomes the red wire there) So it's a boiler hang up -

There are only two components between the brown incoming live of the boiler and the white wire - the fuse (presumably ok, as the boiler is on), and the selector switch...

So my money is on a faulty selector switch.
A replacement is even available from Screwfix...

Baxi 248095 Switch Selector - Screwfix

Order online at Screwfix.com. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

However, for an easy workaround, we could try moving the white wire...

 

[Johnmdc]

Have you set the selector switch on the boiler to water only?
Because if you have it kills the power to terminal 2.

 

[triangularmonkey]

There are only two components between the brown incoming live of the boiler and the white wire - the fuse (presumably ok, as the boiler is on), and the selector switch...

View attachment 347877
So my money is on a faulty selector switch.
A replacement is even available from Screwfix...

Baxi 248095 Switch Selector - Screwfix

Order online at Screwfix.com. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

However, for an easy workaround, we could try moving the white wire...

View attachment 347879

I don't know if it's any coincidence, but the boiler's been outputting E20 when I try and run a shower. No showers for a fortnight, the joys of living alone!

Apparently E20 relates to a bad thermistor sensor. It's a £3 part so I'll try fitting that and see what happens. My actual heating engineer also reckons the diverter valve is sticky/corroded and and wanting replacement but I'll also need a gasket/seal set which is apparently hard to come by. Either way the outlook it's not looking good for this lovely boiler, seems the lot is starting to give out. Designed/forced obsolescence perhaps! I'll give what you've suggest a go for the sake of curiosity at the very least. I really doubt I'll still have this boiler by the time it actually gets cold, though. Many thanks

 

[DP]

Clearly there's something bad going on with the boiler. The voltage detector is showing no reading from the white wire (terminal two on the connector box in the boiler) that then feeds up to the face plate (becomes the red wire there) So it's a boiler hang up - Potterton Combi Pro Plus HE 28 A if anyone's got experience with those. About to replace it any way with a W Greenstar 4000

Why would you take out a solid build boiler and instal a boiler with plastic parts

 

[DP]

There are only two components between the brown incoming live of the boiler and the white wire - the fuse (presumably ok, as the boiler is on), and the selector switch...

View attachment 347877
So my money is on a faulty selector switch.
A replacement is even available from Screwfix...

Baxi 248095 Switch Selector - Screwfix

Order online at Screwfix.com. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

However, for an easy workaround, we could try moving the white wire...

View attachment 347879

Or the switch is in HW only mode