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hi I’m thinking of changing my thermostat ( Heatmisertouch screen programmable) to a Nest. I currently have an old WB 28cdi RSI and will be replacing it with a Vokera 38kw Combi. Am I right to assume that all the wiring from the new or old boiler goes starlight to the heat link thing ( including power) and the only 2 wires from the heat link to the boiler are the low T1 & T2( low volt). It’s an opentherm boiler. It’s rather challenging! I’ve put a pick up of the current stat wiring.
Cheers
David

99FEEE16-8AAB-4EAB-B890-299D78086346.jpeg


099FA5DC-BB28-429C-A308-6B4923331874.jpeg
 
I would keep the heatmiser maybe update it if it's the old one
 
No idea, I'm afraid.
But thanks for the pic of the thermostat. Yet another installer who has never heard of a backbox lol.
 
No idea, I'm afraid.
But thanks for the pic of the thermostat. Yet another installer who has never heard of a backbox lol.

Each to his own, I could elaborate at how ept I am about using a life support machine in intensive care units and that I have a Doctrare. This site is for DIYers as well. It was a simple request for some general info LOL. However I’ll bow my head to your superior intellect in your own particular field.
 
Each to his own, I could elaborate at how ept I am about using a life support machine in intensive care units and that I have a Doctrare. This site is for DIYers as well. It was a simple request for some general info LOL. However I’ll bow my head to your superior intellect in your own particular field.
He wasn’t meaning you! He was referring to the installer.
Back to your post , keep the Heatmiser, as nest is,a glorified data gathering device.
 
Each to his own, I could elaborate at how ept I am about using a life support machine in intensive care units and that I have a Doctrare. This site is for DIYers as well. It was a simple request for some general info LOL. However I’ll bow my head to your superior intellect in your own particular field.
I could easily throw that sarcasm back on you, but I'll bite my tongue ;)

My point was that I was being sympathetic that, like myself, you've bought a house that comes with electrical installations that are clearly in breach of electrical regulations. It happens often, sadly. And often that sort of mistake is made by people who really ought to know better, i.e. tradesmen!

I can't comment on your original question because I do not have the relevant knowledge, hence saying 'no idea'.

Had I thought that you'd wired that yourself, my comment would have been to the effect that exposed cable cores outside of an enclosure are illegal and dangerous, and so, while you're about it, get a backbox to fit behind whatever you replace that thermostat with and make a real improvement.

Better still, if you are going to do DIY electrics and you do not know that cable cores need to be in a cable sheath or enclosure everywhere, then you really need to get a good textbook on the subject and read it cover to cover before you start. You just won't always get the level of instruction you need from websites. This textbook is quite a good one, I think:
The Electrician's Guide to the 17th Edition of the Iet Wiring Regulations BS 7671: 2008 Incorporating Amendment 3: 2015 and Part P of the Building Regulations
 
I could easily throw that sarcasm back on you, but I'll bite my tongue ;)

My point was that I was being sympathetic that, like myself, you've bought a house that comes with electrical installations that are clearly in breach of electrical regulations. It happens often, sadly. And often that sort of mistake is made by people who really ought to know better, i.e. tradesmen!

I can't comment on your original question because I do not have the relevant knowledge, hence saying 'no idea'.

Had I thought that you'd wired that yourself, my comment would have been to the effect that exposed cable cores outside of an enclosure are illegal and dangerous, and so, while you're about it, get a backbox to fit behind whatever you replace that thermostat with and make a real improvement.

Better still, if you are going to do DIY electrics and you do not know that cable cores need to be in a cable sheath or enclosure everywhere, then you really need to get a good textbook on the subject and read it cover to cover before you start. You just won't always get the level of instruction you need from websites. This textbook is quite a good one, I think:
The Electrician's Guide to the 17th Edition of the Iet Wiring Regulations BS 7671: 2008 Incorporating Amendment 3: 2015 and Part P of the Building Regulations

Thank you for your time. Duly noted. There was no intention to offend. There was beer anyintention to offended. Apologies again.
David
 
Might be best to get the new controls fitted when the boiler goes in
 
It is pretty simple when using the opentherm. I’m pretty sure it will be a wireless connection.

No need to disturb the existing thermostat. Do all the change over with the new boiler installation.

The difficult part is setting and pairing it all up.
 
hi I’m thinking of changing my thermostat ( Heatmisertouch screen programmable) to a Nest. I currently have an old WB 28cdi RSI and will be replacing it with a Vokera 38kw Combi. Am I right to assume that all the wiring from the new or old boiler goes starlight to the heat link thing ( including power) and the only 2 wires from the heat link to the boiler are the low T1 & T2( low volt). It’s an opentherm boiler. It’s rather challenging! I’ve put a pick up of the current stat wiring.
Cheers
David

View attachment 34776

View attachment 34777

Hello David,

Im afraid you are not correct.

T1 and T2 are used to supply the thermosatat from the reciver, thermostat requires a 12v dc to operate but the switching is between stat and reciever is carried wirelessly.

For a combi boiler you woud a 2nd gen nest stat, a 3rd gen would work aswell but it is designed for boilers with cylinders.

See diagram how you would wire a combi boiler.

Thank

5AEC86CC-0211-4E6F-8927-721F240D2EE7.png
 
Hello David,

Im afraid you are not correct.

T1 and T2 are used to supply the thermosatat from the reciver, thermostat requires a 12v dc to operate but the switching is between stat and reciever is carried wirelessly.

For a combi boiler you woud a 2nd gen nest stat, a 3rd gen would work aswell but it is designed for boilers with cylinders.

See diagram how you would wire a combi boiler.

Thank

View attachment 34815
Thanks mate

I’m at a loss to how confusing this is!!
The current system I have is my boiler when installed by BG has a programmer (British Gas UT1) in the airing cupboard and that was then linked to a analogue thermostat in the hall ( 240v). The thermostat was removed and replaced with a Heatmiser programmer thermostat (digital). The old programmer in the cupboard was set to constantly on ( acting as a simple connector bloc I assume) and all the controls were then set up by the Heatmiser where the thermostat used to be. Now I’ve got 240 in the Heatmiser wiring when I only need low voltage for the Nest. I thought I could disconnect the wiring from the boiler utalise two wires, remove the old British Gas programmer and connect the two wires together to provide T1 & T2 to where the current Heatmiser is and connect to the nest. The heat link would be wired as is in the diagram to the boiler as it would normally be?
Did that make any sense?
David
 
Thanks mate

I’m at a loss to how confusing this is!!
The current system I have is my boiler when installed by BG has a programmer (British Gas UT1) in the airing cupboard and that was then linked to a analogue thermostat in the hall ( 240v). The thermostat was removed and replaced with a Heatmiser programmer thermostat (digital). The old programmer in the cupboard was set to constantly on ( acting as a simple connector bloc I assume) and all the controls were then set up by the Heatmiser where the thermostat used to be. Now I’ve got 240 in the Heatmiser wiring when I only need low voltage for the Nest. I thought I could disconnect the wiring from the boiler utalise two wires, remove the old British Gas programmer and connect the two wires together to provide T1 & T2 to where the current Heatmiser is and connect to the nest. The heat link would be wired as is in the diagram to the boiler as it would normally be?
Did that make any sense?
David

It does make sense to me but you have not understood my post.

You have T1 and T2 on heat link and stat now the heat link has transformer built in 240vac to 12vdc.

So you would need2 cables from heat link to stat.

Nest comes with usb charger but you need to buy a stand for it.


Thanks
 
No problem, thanks, The picture I sent was the existing Heatmiser but that 240v. The boiler goes through an old British Gas programmer and the Heatmiser was an addition instead of the old thermostat in the hall. The old BG programmer is constantly on like a connector block and the Heatmiser does all the work but is 240. I thought disconnect all the wiring to the house, find two common wires for T1 &T2 and run them from the heat link to the stat? Does that sound right? There’s only low volt to the stat as it’s coming from the heat link which has been reduced down?
 
Thanks mate

I’m at a loss to how confusing this is!!
The current system I have is my boiler when installed by BG has a programmer (British Gas UT1) in the airing cupboard and that was then linked to a analogue thermostat in the hall ( 240v). The thermostat was removed and replaced with a Heatmiser programmer thermostat (digital). The old programmer in the cupboard was set to constantly on ( acting as a simple connector bloc I assume) and all the controls were then set up by the Heatmiser where the thermostat used to be. Now I’ve got 240 in the Heatmiser wiring when I only need low voltage for the Nest. I thought I could disconnect the wiring from the boiler utalise two wires, remove the old British Gas programmer and connect the two wires together to provide T1 & T2 to where the current Heatmiser is and connect to the nest. The heat link would be wired as is in the diagram to the boiler as it would normally be?
Did that make any sense?
David

Yep, that made perfect sense. Ditch the old programmer and heatmeiser stat and reuse cables so your heat link will be in your cupboard sending 12v to your stat. Job done

As a foot note though. Heatmeiser also allows you to set up parameters based on outside temperature if you have a WiFi enabled stat but I’m guessing the old stat is more basic and not one of the neo range?
 
Thanks mate

I’m at a loss to how confusing this is!!
The current system I have is my boiler when installed by BG has a programmer (British Gas UT1) in the airing cupboard and that was then linked to a analogue thermostat in the hall ( 240v). The thermostat was removed and replaced with a Heatmiser programmer thermostat (digital). The old programmer in the cupboard was set to constantly on ( acting as a simple connector bloc I assume) and all the controls were then set up by the Heatmiser where the thermostat used to be. Now I’ve got 240 in the Heatmiser wiring when I only need low voltage for the Nest. I thought I could disconnect the wiring from the boiler utalise two wires, remove the old British Gas programmer and connect the two wires together to provide T1 & T2 to where the current Heatmiser is and connect to the nest. The heat link would be wired as is in the diagram to the boiler as it would normally be?
Did that make any sense?
David

Yep, that made perfect sense. Ditch the old programmer and heatmeiser stat and reuse cables so your heat link will be in your cupboard sending 12v to your stat. Job done

As a foot note though. Heatmeiser also allows you to set up parameters based on outside temperature if you have a WiFi enabled stat but I’m guessing the old stat is more basic and not one of the neo range?
 
Yep, that made perfect sense. Ditch the old programmer and heatmeiser stat and reuse cables so your heat link will be in your cupboard sending 12v to your stat. Job done

As a foot note though. Heatmeiser also allows you to set up parameters based on outside temperature if you have a WiFi enabled stat but I’m guessing the old stat is more basic and not one of the neo range?
Thanks mate. It never occurred to me to put the heat link where the programmer was in the up stairs coluboard instead of where the boiler is in the garage. The wiring makes a little more sense now.
 

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