Soldato
Can you take a couple of pics?
Not quite sure what you mean here.
Potentially the one under the stairs is the original 'stat and is just used now as on/off, and the 'stat in the hall has been installed for actual temperature control.
NEST thermostats
- Thread starter Django x2
- Start date
Can you take a couple of pics?
Not quite sure what you mean here.
Potentially the one under the stairs is the original 'stat and is just used now as on/off, and the 'stat in the hall has been installed for actual temperature control.
Associate
I can take some when I'm back but yes what you've said it's right the under the stairs one allows you to turn the heating on and set programmes etc and the hallway one is just a dial to control temperature.
Soldato
Ah OK, if your under-stairs one is a programmer, you will replace this with the HeatLink unit that comes with NEST.
The thermostat bit (the round pretty bit) replaces your hallway stat.
Associate
Ah I see. The pictures I've seen only show the round bit so I thought it may be one unit.
Thanks for the help I think I might pick one up on the way home.
They run in 240v in the UK right?
Soldato
Yes UK systems are 240V and the NEST is compatible with these.
Do you have a combi boiler or do you have a hot water tank with the boiler on a timer to heat the water?
Associate
It's a valiant combi boiler that's only a few years old.
Soldato
OK so your programmer is just a timer for the central heating (nothing to do with hot water) then. In any case the NEST will work, but it's just a question of how you install it.
In the case of a combi, the NEST just replaced the programmer directly. It has live+neutral terminals, and call-for-heat and common terminals. It also has a +12 and Ground for the thermostat, which need to be run to your hall and connected to the dial face.
You will already have cables (either 2 or 3) to the hall for your existing stat, so you can reuse these.
Please be careful etc, standard warnings apply when dealing with mains
In the case of a combi, the NEST just replaced the programmer directly. It has live+neutral terminals, and call-for-heat and common terminals. It also has a +12 and Ground for the thermostat, which need to be run to your hall and connected to the dial face.
You will already have cables (either 2 or 3) to the hall for your existing stat, so you can reuse these.
Please be careful etc, standard warnings apply when dealing with mains
Associate
OK so your programmer is just a timer for the central heating (nothing to do with hot water) then. In any case the NEST will work, but it's just a question of how you install it.
In the case of a combi, the NEST just replaced the programmer directly. It has live+neutral terminals, and call-for-heat and common terminals. It also has a +12 and Ground for the thermostat, which need to be run to your hall and connected to the dial face.
You will already have cables (either 2 or 3) to the hall for your existing stat, so you can reuse these.
Please be careful etc, standard warnings apply when dealing with mains
Thanks GeForce much appreciated!
Soldato
- Joined
- 13 May 2003
- Posts
- 8,845
I'm being really dumb no doubt but I'm having trouble finding the installation guide for the Gen 3 Nest for the UK. I used to be able to find it on their webby but can't today for some reason. The guide I keep finding has no heat link in it for wiring up so I can't compare the wiring to my current thermostat. I can find an old one but that doesn't have the hot water controls in it.
Any help would be much appreciated.
Any help would be much appreciated.
Soldato
Soldato
- Joined
- 13 May 2003
- Posts
- 8,845
Thank you, I kept finding some very different one to that, must have been the international version.
Soldato
- Joined
- 30 Sep 2005
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- 16,549
Yep, if it's any use to anyone I took lots of photos during my installation.
Yeah i'd love to see those, always good to see real install pics, this is the NEST thread - get sharing
Soldato
- Joined
- 30 Sep 2005
- Posts
- 16,549
Yeah i'd love to see those, always good to see real install pics, this is the NEST thread - get sharing
ok, I'll start work on putting a guide together this morning.
Soldato
- Joined
- 30 Sep 2005
- Posts
- 16,549
Nest 3 Installation Guide
================
This guide is indended to help those who are doing a diy self installation of the nest 3 system. It won't be useful for everyone as there are many different types of wiring systems for central heating boilers. My installation was quite straight forward and replaces a Potterton EP2002 timer and a Potterton PRT2 thermostat (240v).
If your current system is working, sell your items on ebay. Mine sold for £100 which covered half the cost of the Nest
Parts you'll need
-------------------
Nest 3 (Obviously)
4 Core Flex Cable (this connects the Nest hub to your central heating)
http://www.diy.com/departments/time-4-core-round-flexible-cable-10mm-3184y-white-5m/188988_BQ.prd
2 Core Flex Cable (this connects the Nest display to the hub)
http://www.diy.com/departments/time-2-core-round-flexible-cable-075mm-2182y-white-5m/188958_BQ.prd
Connector Strips
http://www.diy.com/departments/bq-black-15a-6-way-cable-connector-strip/178055_BQ.prd
Faceplate with flex hole (to replace the hole left from the existing timer)
http://www.diy.com/departments/crab...socket-20a/241865_BQ.prd?icamp=recs&rrec=true
Blanking Faceplate (if you are removing your existing thermostat, I found it easier to mount the Nest somewhere else)
http://www.diy.com/departments/crabtree-1-gang-single-white-blanking-plate/177825_BQ.prd
Electrical tester (for peace of mind before touching wires)
http://www.diy.com/departments/bq-pen-type-voltage-tester/177924_BQ.prd
Usual odds and sods. Screwdriver, drill, wire stripper, masking tape and felt tip pen. You may also require cable trunking to hide the 2-core cable running from the hub to the display.
Step 1 - Working out what on earths going on
=============================
This is probably the most time consuming part of the installation. Once you understand whats what, everything from here on out is a walk in the park.
I'll talk you through my setup, but be mindful that the builders who installed my system actually wired it up wrong in the first place!!! Talk about being professional! This confused me, until I worked it out.
Try to think of it like a computer with inputs and outputs. The live wires are the inputs and outputs which tell the central heating to turn on and off. When you work out which wires are which, the hard part is done.
My system has independent controls for the hot water and central heating. This means that I can have hot water without the radiators coming on and vice versa. The nest 3 is the latest model, and the only one which controls hot water and central heating independently due to the hub having the extra connectors on.
Kitchen = Mains switch > Timer > Boiler
Hallway = Thermostat
Upstairs Bedroom = Water tank, valves, electrical junction box
We will be working in the kitchen and hallway.
The first thing to do is to switch the electrics off. In my case this was as simple as flicking the switch on the kitchen wall. Then you need to remove the front of the timer so you can see the wires.
If you are lucky (like me), there will be a wiring diagram to explain what does what. If not, we can work it out anyway.
There will be quite a few wires in here, but it's quite simple really. The first thing we'll have is the main live feed into the timer. This will be paired up with a negative wire. Identify these two wires first and mark them up. If you struggle, turn the mains back on but turn the timer off. Then press your electrical tester on the wires till you get a light. Mark these wires up (main feed).
Next we need to work out which live wires control the hot water. Again, hopefully they are marked up but if not just unplug one and test to see if you can bring the hot water on. If you can't, then you have found your wire. Mark this up (Live HW). Do the same for the central heating and mark this wire up (Live CH). You will probably notice a small wire which has both ends connected to the timer. This is a live feed jumper. It basically goes from the main live feed into a socket ready to complete the circuit.
Let me explain.
Electrics work on a circuit (basically a circle), when there is a break in the circuit the system is off. In order to turn anything on, you have to complete the circuit by connecting two wires together (flicking the switch). The timer is basically a mutli switch. When you flick the switch for the hot water, it creates the connection which sends the live feed up the house wires to the junction box upstairs which in turn opens the valve to then make a judgement on if it should send the live feed down to the boiler to fire up, or not. This is dependant on temperature of the water tank. You don't want the water getting hotter and hotter. Likewise when you make the switch to turn the central heating on, this creates the connection to send the live feed to the thermostat. This is also a switch, which is actually a dial. You turn the dial to 20c so unless the temperature is less than 20c it will bridge the live feeds to then send the signal back upstairs to the junction box and then back down to the boiler. It's all just switches. It's as simple as that.
Here's the photo showing the back of my timer. NOTE: The black wire in 2 should actually be in 3. I'll imagine it's in 3 for this guide.
N = Main Negative Input
L = Main Live Input
L - 5 = There is a small jumper wire. This basically makes 5 into a live connection.
3 = Hot Water. When you flick the hot water switch, it bridges the gap between L and 3 completing the hot water circuit. When you flick the switch off the connection breaks as it becomes L - 1. Note there is no wire in 1 which is how it breaks the connection.
4 = Central Heating. Again, when you flick the switch to turn on the central heating it creates a connection between 4 and 5. Note 5 is a live feed. When you turn the central heating off, the connection becomes 2 and 5. Since there is no wire in 2, the connection is off.
Hopefully this all makes sense so far!
Step 2 = Install the Nest Hub
===================
Ensure all cables are labelled up, then remove them along with the timer from the kicthen wall. You will be left with a hole and labelled up wires.
Ensure you keep the little jumper wire as we'll need it later.
Thread the four core flex cable through the faceplate
Connect using a connector block one wire from the 4-core cable to the water feed (label it up HW)
Connect using a connector block one wire from the 4-core cable to the central heating feed (label it up CH)
Connect all the main live and negative feeds to the back of the faceplate
Connect one wire from the 4-core cable to the live connector on the faceplate (label it up Live)
Connect one wire from the 4-core cable to the negative connector on the faceplate (label it up Neg)
Screw the faceplate to the wall
You now have a 4-core cable coming from the wall (Live, Negative, HW, CH)
Connect the 4-core cable to the Nest Hub
Live - L
Neg - N
CH - 3
HW - 6
Little jumper wire from L - 2
We'll also need another jumper wire L - 5 (you may have one after step 3)
Now connect the 2-core cable to T1 and T2 (make a note which colours are in which)
Step 3 - Bypass existing Thermostat
=======================
Remove the thermostat from the wall and identify the two live wires and the negative. Join the two live wires together using a connector block. Connect an empty connector block onto the negative wire.
Install the blanking faceplate.
Step 4 - Install the Nest Display
====================
Run your 2-core cable to where ever you want to install the display. I found the hallway wall which backs onto the kitchen a good place. Drill a hole through the wall into the kitchen. Thread the 2-core cable through and connect T1 and T2 into the display. Fix to the wall.
Step 5 - Finishing Up
=============
Install cable trunking if desired. I decided to use a strip of no-nails tape to stick the hub to the wall, rather than drilling holes into tiles.
Configure display. Connect to Wifi and install the mobile app.
================
This guide is indended to help those who are doing a diy self installation of the nest 3 system. It won't be useful for everyone as there are many different types of wiring systems for central heating boilers. My installation was quite straight forward and replaces a Potterton EP2002 timer and a Potterton PRT2 thermostat (240v).
If your current system is working, sell your items on ebay. Mine sold for £100 which covered half the cost of the Nest
Parts you'll need
-------------------
Nest 3 (Obviously)
4 Core Flex Cable (this connects the Nest hub to your central heating)
http://www.diy.com/departments/time-4-core-round-flexible-cable-10mm-3184y-white-5m/188988_BQ.prd
2 Core Flex Cable (this connects the Nest display to the hub)
http://www.diy.com/departments/time-2-core-round-flexible-cable-075mm-2182y-white-5m/188958_BQ.prd
Connector Strips
http://www.diy.com/departments/bq-black-15a-6-way-cable-connector-strip/178055_BQ.prd
Faceplate with flex hole (to replace the hole left from the existing timer)
http://www.diy.com/departments/crab...socket-20a/241865_BQ.prd?icamp=recs&rrec=true
Blanking Faceplate (if you are removing your existing thermostat, I found it easier to mount the Nest somewhere else)
http://www.diy.com/departments/crabtree-1-gang-single-white-blanking-plate/177825_BQ.prd
Electrical tester (for peace of mind before touching wires)
http://www.diy.com/departments/bq-pen-type-voltage-tester/177924_BQ.prd
Usual odds and sods. Screwdriver, drill, wire stripper, masking tape and felt tip pen. You may also require cable trunking to hide the 2-core cable running from the hub to the display.
Step 1 - Working out what on earths going on
=============================
This is probably the most time consuming part of the installation. Once you understand whats what, everything from here on out is a walk in the park.
I'll talk you through my setup, but be mindful that the builders who installed my system actually wired it up wrong in the first place!!! Talk about being professional! This confused me, until I worked it out.
Try to think of it like a computer with inputs and outputs. The live wires are the inputs and outputs which tell the central heating to turn on and off. When you work out which wires are which, the hard part is done.
My system has independent controls for the hot water and central heating. This means that I can have hot water without the radiators coming on and vice versa. The nest 3 is the latest model, and the only one which controls hot water and central heating independently due to the hub having the extra connectors on.
Kitchen = Mains switch > Timer > Boiler
Hallway = Thermostat
Upstairs Bedroom = Water tank, valves, electrical junction box
We will be working in the kitchen and hallway.
The first thing to do is to switch the electrics off. In my case this was as simple as flicking the switch on the kitchen wall. Then you need to remove the front of the timer so you can see the wires.
If you are lucky (like me), there will be a wiring diagram to explain what does what. If not, we can work it out anyway.
There will be quite a few wires in here, but it's quite simple really. The first thing we'll have is the main live feed into the timer. This will be paired up with a negative wire. Identify these two wires first and mark them up. If you struggle, turn the mains back on but turn the timer off. Then press your electrical tester on the wires till you get a light. Mark these wires up (main feed).
Next we need to work out which live wires control the hot water. Again, hopefully they are marked up but if not just unplug one and test to see if you can bring the hot water on. If you can't, then you have found your wire. Mark this up (Live HW). Do the same for the central heating and mark this wire up (Live CH). You will probably notice a small wire which has both ends connected to the timer. This is a live feed jumper. It basically goes from the main live feed into a socket ready to complete the circuit.
Let me explain.
Electrics work on a circuit (basically a circle), when there is a break in the circuit the system is off. In order to turn anything on, you have to complete the circuit by connecting two wires together (flicking the switch). The timer is basically a mutli switch. When you flick the switch for the hot water, it creates the connection which sends the live feed up the house wires to the junction box upstairs which in turn opens the valve to then make a judgement on if it should send the live feed down to the boiler to fire up, or not. This is dependant on temperature of the water tank. You don't want the water getting hotter and hotter. Likewise when you make the switch to turn the central heating on, this creates the connection to send the live feed to the thermostat. This is also a switch, which is actually a dial. You turn the dial to 20c so unless the temperature is less than 20c it will bridge the live feeds to then send the signal back upstairs to the junction box and then back down to the boiler. It's all just switches. It's as simple as that.
Here's the photo showing the back of my timer. NOTE: The black wire in 2 should actually be in 3. I'll imagine it's in 3 for this guide.
N = Main Negative Input
L = Main Live Input
L - 5 = There is a small jumper wire. This basically makes 5 into a live connection.
3 = Hot Water. When you flick the hot water switch, it bridges the gap between L and 3 completing the hot water circuit. When you flick the switch off the connection breaks as it becomes L - 1. Note there is no wire in 1 which is how it breaks the connection.
4 = Central Heating. Again, when you flick the switch to turn on the central heating it creates a connection between 4 and 5. Note 5 is a live feed. When you turn the central heating off, the connection becomes 2 and 5. Since there is no wire in 2, the connection is off.
Hopefully this all makes sense so far!
Step 2 = Install the Nest Hub
===================
Ensure all cables are labelled up, then remove them along with the timer from the kicthen wall. You will be left with a hole and labelled up wires.
Ensure you keep the little jumper wire as we'll need it later.
Thread the four core flex cable through the faceplate
Connect using a connector block one wire from the 4-core cable to the water feed (label it up HW)
Connect using a connector block one wire from the 4-core cable to the central heating feed (label it up CH)
Connect all the main live and negative feeds to the back of the faceplate
Connect one wire from the 4-core cable to the live connector on the faceplate (label it up Live)
Connect one wire from the 4-core cable to the negative connector on the faceplate (label it up Neg)
Screw the faceplate to the wall
You now have a 4-core cable coming from the wall (Live, Negative, HW, CH)
Connect the 4-core cable to the Nest Hub
Live - L
Neg - N
CH - 3
HW - 6
Little jumper wire from L - 2
We'll also need another jumper wire L - 5 (you may have one after step 3)
Now connect the 2-core cable to T1 and T2 (make a note which colours are in which)
Step 3 - Bypass existing Thermostat
=======================
Remove the thermostat from the wall and identify the two live wires and the negative. Join the two live wires together using a connector block. Connect an empty connector block onto the negative wire.
Install the blanking faceplate.
Step 4 - Install the Nest Display
====================
Run your 2-core cable to where ever you want to install the display. I found the hallway wall which backs onto the kitchen a good place. Drill a hole through the wall into the kitchen. Thread the 2-core cable through and connect T1 and T2 into the display. Fix to the wall.
Step 5 - Finishing Up
=============
Install cable trunking if desired. I decided to use a strip of no-nails tape to stick the hub to the wall, rather than drilling holes into tiles.
Configure display. Connect to Wifi and install the mobile app.
Last edited:
Caporegime
- Joined
- 21 Jun 2006
- Posts
- 38,372
Brilliant guide Glen8. Sure it will help a lot of people out there.
Soldato
Very nicely written. How did your hot water ever work with that wire in 2 instead of 3?!