Time Controller [UT2 / LP711] not in control

[silentcontributor]

Hi folks,

Just recently bought our first house, and having a wee heating issue.

The timeswitch (a British Gas UT2 / LP711) is working as expected, but it isn't controlling the heating. It seems to be set correctly, and shows that it's asking for heat at the correct settings, but isn't effecting the boiler at all.

Instead, the thermostat - a bog-standard Honeywell analogue job (one channel, 230V) - is completely controlling everything - if it clicks low, heating comes on & visa versa.

The wiring from the backplate of the controller to the backplate of the thermostat seems to be as follows:
1 (common) -> 2
2 (off) - no connector
3 (on) -> 1
4 (unlabelled) -> 3

Do you happen to see an obvious mistake in the wiring?

Thanks,
Tim.

 

[Deleted member 267285]

Are you sure that’s correct? How have you checked? 2 on a Honeywell is usually Neutral, 1 is usually Live from programmer/time switch and 3 call for heat.

 

[Mister Banks]

Hi folks,

Just recently bought our first house, and having a wee heating issue.

The timeswitch (a British Gas UT2 / LP711) is working as expected, but it isn't controlling the heating. It seems to be set correctly, and shows that it's asking for heat at the correct settings, but isn't effecting the boiler at all.

Instead, the thermostat - a bog-standard Honeywell analogue job (one channel, 230V) - is completely controlling everything - if it clicks low, heating comes on & visa versa.

The wiring from the backplate of the controller to the backplate of the thermostat seems to be as follows:
1 (common) -> 2
2 (off) - no connector
3 (on) -> 1
4 (unlabelled) -> 3

Do you happen to see an obvious mistake in the wiring?

Thanks,
Tim.

The programmer only provides power to the thermostat based on a timed program. The thermostat decides if heat is required and controls the zone valve which in turn turns on the boiler. According to your post this is what is happening so it is working as expected.

 

[silentcontributor]

The programmer only provides power to the thermostat based on a timed program. The thermostat decides if heat is required and controls the zone valve which in turn turns on the boiler. According to your post this is what is happening so it is working as expected.

The thermostat can always call for heat, regardless of the settings on the timer (it's completely controlling everything, with no regard for the timer). I'm pretty sure that's not what I've dealt with in any other house/setting and isn't how it's designed to work!

 

[silentcontributor]

Are you sure that’s correct? How have you checked? 2 on a Honeywell is usually Neutral, 1 is usually Live from programmer/time switch and 3 call for heat.

I'm not very sure and that's part of the issue! I've traced the wires as best I can and think I may have reached the depth of my current ability - not very deep, as it turns out.

I was already thinking of replacing the control system with a Hive controller, but if there's an underlying issue that I can't solve then I'll need some help from a professional.

 

[RandomGrinch]

The wiring from the backplate of the controller to the backplate of the thermostat seems to be as follows:
1 (common) -> 2
2 (off) - no connector
3 (on) -> 1
4 (unlabelled) -> 3

Can you show us pictures of the wiring behind the UT2 and Honeywell stat?

 

[Mister Banks]

What type of system do you have, s plan, y plan or something else. Do you have a wiring centre.

 

[RandomGrinch]

What type of system do you have, s plan, y plan or something else. Do you have a wiring centre.

The UT2 is single channel, so I'm guessing it's a combi, and possibly (depending on the wiring), somebody has bypassed it - making the Honeywell 'stat a very simple on/off controller?