Boulter Camray 5 Oil Combi - Nest Wiring Query

[CountryHome]

Hello!

I'm looking for some assistance with installing a Nest Heat Link and Thermostat to my old Boulter Camray 5 combi boiler.

I have a programmer fitted to the boiler which is original as far as I can tell, with the programmer and wiring diagram shown in the images below.

I'm confused as the Nest Heat Link wiring diagram (also below) shows multiple wires for both HW and CH, while my current programmer is only using 1 for each.

Ideally I'd like to simply disconnect the wires from the old programmer, and use them to feed the Heat Link - but perhaps there's more to it?

Any guidance would be much appreciated!

 

[RandomGrinch]

Ideally I'd like to simply disconnect the wires from the old programmer, and use them to feed the Heat Link - but perhaps there's more to it?

Have you investigated the wiring behind your existing stat?
I believe it's hooked up using spade connectors...

(Image from... https://www.trustapart.co.uk/product/glowworm-programmer-control-s202918/ )

It may be necessary to adapt, or change the existing cable to connect up the Nest.

I'm confused as the Nest Heat Link wiring diagram (also below) shows multiple wires for both HW and CH, while my current programmer is only using 1 for each.

Your existing programmer has built-in links between Live and the common connections of its relays.
The Nest Heat link has 'Voltage free" contacts - this means we have to make the links ourselves.

You would connect...
L on your existing controller to L on the Heat link
N to N
Heating On to Heat link terminal 3
(Heating call for heat NO)

If there is a connection to Water On (although you have a combi), it would attach to Heat link terminal 6
(Hot water call for heat NO)

Additionally, you would require two short link wires, to connect L and the common terminals 2 and 5 on the Heat link.

Oil burners may have higher current loads to switch, than gas boilers.
In this case, your existing controller can switch 2(1)A (2A resistive, 1A inductive) in total.

The Nest can handle 3(1)A, which is fine.

 

[CountryHome]

Have you investigated the wiring behind your existing stat?
I believe it's hooked up using spade connectors...

Thank you very much for your detailed advice, it's much appreciated!

The wiring is tucked away and hard to see, but you're right - I had planned on cutting the spade connections off and just re-terminating the wires ready for the Heat Link.

I had not even considered the amperage on the controller, I expected low amp coms - I'll double check my ancient programmer is 2(1)A.

I'm going to follow your advice and hook it up this evening, will report back with how it goes.

Thanks again.

 

[RandomGrinch]

I had planned on cutting the spade connections off and just re-terminating the wires ready for the Heat Link.

As long as you can keep the connections safe - i.e. using some strain relief on the new cable and covering the gap left by the old controller - then go for it!

If you are connecting the Nest thermostat to the Heat link using T1 and T2, the Nest will also need an earth connection.

I'm going to follow your advice and hook it up this evening, will report back with how it goes.

Good luck

 

[CountryHome]

Thanks again, RandomGrinch!

I've hooked the Heat Link up to the boiler, and it seems happy - so thanks for the great advice.

The only thing I am confused about is the hot water - setting the Nest thermostat to 'Combi' or 'System' didn't give me independent hot water control, which the boiler was previously capable of (it has a small hot water tank built-in).

I've changed the boiler type to 'Other', which has allowed for hot water control within the Nest app. However it's heating the hot water, but reporting the hot water as 'off' in the app. When I press boost, the hot water remains on. I can't seem to get it to stop heating the water tank.

The hot water does switch off once the boiler has determined the tank is at the correct temperature.

The central heating is off in the Nest app, in case that's useful context.

Not sure if this is something you've come across before?

 

[RandomGrinch]

I've hooked the Heat Link up to the boiler, and it seems happy

Well done!

The only thing I am confused about is the hot water - setting the Nest thermostat to 'Combi' or 'System'

As you've found, the combi setting won't allow hot water control.
But the system setting should give independent control.

Are you sure you have got a link between L and the common terminal 5, and your hot water call for heat is on terminal 6?
Or could there be any loose strands of wire bridging the terminals - they are quite tightly packed within the heatlink.

I will have another look at the app in a bit, 5o see if I've missed anything!

 

[CountryHome]

Are you sure you have got a link between L and the common terminal 5, and your hot water call for heat is on terminal 6?
Or could there be any loose strands of wire bridging the terminals - they are quite tightly packed within the heatlink.

Thanks RandomGrinch!

I've double checked, all the cables are seated nicely - I thought the same, so spliced the additional live wire that connects to the CH and HW terminals with a wago connector, as the Heat Link terminals are definitely on the small side.

The hot water seems to have settled down - I haven't noticed it firing up while the Nest reports it as 'off', so maybe I jumped the gun and it was simply part of the set up process of the Nest?

Thanks again for your help, really appreciate the effort you've gone to!

 

[RandomGrinch]

The hot water seems to have settled down - I haven't noticed it firing up while the Nest reports it as 'off', so maybe I jumped the gun and it was simply part of the set up process of the Nest?

We'll wait and see!
I note that the default evening hot water on time, is from 16:00 to 22:00 - I wonder if that had anything to do with it

Anyway, enjoy the Nest!

 

[CountryHome]

We'll wait and see!
I note that the default evening hot water on time, is from 16:00 to 22:00 - I wonder if that had anything to do with it

Anyway, enjoy the Nest!

Ah, I hadn't changed any default settings - it could well be down to the schedule then! I'll soon find out.

Need to figure all that out next, but sure beats pressing buttons on the tiny LCD programmer I used to have

Cheers.