Replace British Gas UP2 Programmer with Honeywell T6

[poiuytrewq]

Hello everyone, like the subject suggests I try to replace my by UP2 ( Invensys T45 ) with a Honeywell T6 thermostat. The boiler is a Glowworm Fuelsaver 35F.

My UP2 controls both the hot water and heating but the T6 only does central heating. I will not use the hot water - only the central heating to this is okay.

I do not know how to connect the wiring. I thought I did it correctly and powered it on and the boiler did not come on so obviously I had wired it wrong.

The wiring inside the boiler on the chocolate block does not marry up with the wiring diagram in the manual for the boiler.

This is the existing setup:
Programmer:

Thermostat:

Boiler connections:

How it is now:
Thermostat (yellow wire isolated in wago block in backbox)

Programmer location:
(Far left I believe is incoming supply, top two (Rd and Bl) from thermostat which has been confirmed by belling it out - again yellow wire isolated in a wago. There is a chocolate block with L, N and E, coming from a twin and earth and other side is flex which I believe goes to the boiler. The flex that is visible - L,N and earth - the brown bells out to terminal 11 on the boiler but the flex coming into the boiler is 4 core on the boiler picture but here it is just 3 core. There is also a random neutral wire on its own coming into the back box - I have no idea where this is from.

Programmer replacement:
Wired to diagram A which did not work when requesting the boiler to turn on - note terminal B connected to brown as seen far right on photo above.

I have no idea how to connect the wiring up - someone please help me!

 

[stem]

If you have a programmer that controls both stored hot water and central heating the vast majority of such systems will have a motorised valve (or valves) In which case, the programmer and its associated thermostats will be wired to control the motorised valves and will not have any direct connection to the boiler at all. [The motorised valve/s are then what control the boiler] In which case Diagrams A) B) & C) don't apply.

Unfortunately I can't see any of your photos other than the diagrams for the new thermostat. Diagram D) shows the wiring if you have a 2-port motorised valve controlling the central heating.

 

[ianmcd]

If you have a programmer that controls both stored hot water and central heating the vast majority of such systems will have a motorised valve (or valves) In which case, the programmer and its associated thermostats will be wired to control the motorised valves and will not have any direct connection to the boiler at all. [The motorised valve/s are then what control the boiler] In which case Diagrams A) B) & C) don't apply.

Unfortunately I can't see any of your photos other than the diagrams for the new thermostat. Diagram D) shows the wiring if you have a 2-port motorised valve controlling the central heating.

Hey @stem where have you been man , hope all is well with you

 

[poiuytrewq]

Hi @stem, thank you very much for your help!

I think this is motorised valve with its connections:

Above are the connections next to the motorised valve but I do not know what I need to do now with this wiring.
Please help me again!

 

[stem]

Hey @stem where have you been man , hope all is well with you

I've been busy with my real job as a few colleagues have left / retired, and when I have seen a post usually someone has already said what I would have done. Nice to know you missed me

Hi @stem, thank you very much for your help!

I think this is motorised valve with its connections:

Above are the connections next to the motorised valve but I do not know what I need to do now with this wiring.
Please help me again!

Sorry I still can't see your photos.

 

[poiuytrewq]

Hi @stem thanks for getting back and sorry about the pictures not showing - I've made a link to them in numerical order as they appear in this post:

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[poiuytrewq]

Link was removed so pictures uploaded in this reply.

 

[stem]

The wiring would indicate that you have a three port motorised valve, (still no pic of that) so by far the easiest way is to move the wiring from the existing room thermostat to the new receiver box as follows:

1. Existing Honeywell Room thermostat Live wire* goes to receiver box live terminal

2. Existing Honeywell Room thermostat Neutral wire* goes to receiver box neutral terminal

3. Existing Honeywell Room thermostat Switched live wire* goes to receiver box B terminal

Add a wire link to receiver box terminals L and A so that they are electrically connected.

Connect the thermostat to the receiver box T T terminals as shown.

No need to change anything else or make connections to the boiler. The rest of the system should remain exactly as it was originally.

*Convention has it is that Red = L / Blue = N / Yellow = SL. Whilst about 95% of installations follow this convention, not 100% do, so check which terminals the wires at the existing thermostat are connected to make sure this is the case.

The existing programmer needs to be left in place. It will still control the hot water, but the central heating must be set to be permanently on 24/7 to keep the receiver box powered.

 

[poiuytrewq]

Hi Stem,

Thank you so much for your help! I'll try this tonight!

Should I mount the new receiver box above the long chocolate block?

Thanks again!

 

[stem]

You can mount it wherever you wish. Some would mount it where the old room thermostat was being removed from for ease of transferring the wires, but if you don't want it on show, and don't mind rerouting the cable that's OK.

When I said.....

.....The existing programmer needs to be left in place. It will still control the hot water, but the central heating must be set to be permanently on 24/7 to keep the receiver box powered.

As you seem to have disconnected the original programmer, when you reconnect it, if you wanted to prevent anyone inadvertently switching the power to the Receiver Box off at the programmer, moving the red wire from 4 and putting it into L would do that for you. [I hope you made a note of where each wire went, especially the two blues]

The new programmable thermostat would then have full and dedicated control of the central heating. The hot water would continue to work from the programmer.

 

[poiuytrewq]

Thanks Stem!

I've done exactly that and it works perfectly!

Apart from, the boiler is making a constant noise when running now like a big transformer humming - is it possible I've not re-assembled it together correctly? The noise can also be heard from the 3 port valve but it is no where near as loud. If I move the cable going into the valve around the tone changes or is this normal from the valve and unrelated to the boiler?

I have attached some pictures of how it looks now, once again thank you very much for your help!

 

[stem]

From an electrical point of view, as far as the wiring is concerned, nothing has really changed, you have simply swapped one simple on/off switch (old thermostat) for another on/off switch (new thermostat).

As far as I can see everything looks as I would expect it to, and if it's working as it should that points to the wiring being OK. As the noise changes when you move the cable to the motorised valve, I suspect that it may be the synchronous motor inside the valve. Or as you suggest the boiler casing maybe vibrating. [My boiler does this for a while when its been disturbed]

Nice wiring by the way. I wish all so called 'professional' installations looked as good as that.

 

[poiuytrewq]

Thanks Stem,

If it is the synchronous motor in the valve would it explain the boiler making noise too?

Also as you say your boiler does it for a while when its been disturbed - is it normal for the noise to go away on its own?

Thank you very much for the complement - I was also surprised at the state of the terminations when I first looked at doing this!

 

[stem]

My reasoning on that was that maybe the nose was being transmitted from the valve by its interconnecting pipes. If it was the boiler making the noise, I couldn't see why it would it change when you moved the cable from the motorised valve.

My boiler [Baxi] casing rattles when its been removed but usually settles down after a few days. Recently I have assisted it by wedging a sponge between its casing and an adjacent wall . I'm not aware of this being a common thing though, just personal experience.

I'm an electrical engineer so wires and circuits are my thing, the boiler bits and pieces not so much I'm afraid.