Nest Smart Thermostat V3

night.owl

Hello

I am thinking of buying the above.

I have a combi boiler being a flexicom 30cx and a thermastat 240v being a T6360B

The thermastat seems to have a 240v live, neatral and a call for heat, 3 wires in total. The thermostat is in the hall way, so not great. I am thinking of removing this and putting the heat link in its place, it would cover the hole up and i think its viable because of the 240v available at the old thermostat. The new thermostat i would put in the living area somewhere. Can anyone confirm if this is viable and if not, why ?. I beleive from reading that its easy to connect the heatlink to the boiler, near the boiler but i was thinking if i dont touch any wiring on the boiler, due to having 240v at the thermastat, i should be able to simply use this.

Points 1, 2 and 3 are used on existing thermastat with 1 being live, 2 being neutral and 3 being call for heat.

Please advise thank you

Brummie85

Already discussed elsewhere.

https://www.diynot.com/diy/threads/glowworm-flexicom-30cx-and-nest-v3-thermostat.494097/

night.owl

Hello.

The link shows the way to wire it up if you want the heat link by thr boiler but as i have 240v thermastat, i was thinking of removing the thermostat and putting the heat link on the wall in its place using the live, neutral and call for heat wires the 230v thermastat has. Is this viable ?.

Thank you

night.owl

Basically i dont see a reason that without touching any wiring on the boiler i cannot remove the thermastat on the wall and:

Use the permanent live and neutral to the heat link, then the remaining wire (call for heat) - with a small jumper wire between the live and common on the heat link. ?

Perhaps my 240v thermastat is not normal but if this is viable, it sounds a good idea and means if i move, i just have to put the old thermostat back on wall.

Brummie85

Both Nest and Glowworm show how to replace an existing mains voltage stat. Looking at their instructions, I think you are right with the idea of bridging the Live and Common within the Heat Link.

Pages 8 - 13 & Page 32 may prove useful for you from this document from Nest. For replacing an existing control running at mains voltage, they suggest a jumper between the Live and Common connections. They specify a cable 55mm in length and 0.75mm csa.

https://nest.com/support/images/misc-assets/Nest-Thermostat-Installation-Guide-UK.pdf

I'm assuming you aren't going to hard wire in the Nest thermostat as well, so some of their guide isn't relevant for your work. I'm waiting to install my Nest after the boiler has been moved, but the main appeal was being able to plug the thermostat in any room and use it wirelessly with the Heat Link. That does away with all the bits about wiring in T1 and T2 and mounting the stat to the wall.

Glow Worm show a jumper or link in Diagram 10.3 (skip to Page 25 to see it) for wiring in external controls. Your 3rd wire would be for R on the boiler. Please also note that they include and link in an anti-frost stat for this mode of control. I'm not sure if the Nest will be able to provide an anti-frost function as part of it's operation.

https://www.glow-worm.co.uk/glow-worm/flexicom-cx-157167.pdf

If you're unhappy with the location of your current stat because of it's performance and would prefer to locate the heat link closer to the boiler. There isn't really anything stopping you from doing so. The cable and bits to make it look tidy wouldn't be expensive. You could simply disconnect the existing thermostat wires, stick the connections in a terminal block and leave them tucked away tidy ready to reinstate them if you wish to take the Nest with you later.

night.owl

Thank you Brummie85

Now i just need to figure out if to go for the V3 or the newly announced nest e uk.

I like the look of the V3 better....

Brummie85

The Nest E has been around since January or a bit earlier, but they're only just deciding to release it here now.

If you're wanting to run it at 230-240v, I don't think the E would be suitable anyhow. The Heat Link will take a mains voltage, but the E wants to run like the V3 Thermostat (when hard wired) at the lower voltages. I suspect putting 230v to an E would ruin it. But as said, you could always leave your existent stat in place and disconnected, placing the E where you want.

ashe

Few benefits to the E in the uk. In the states it’s significantly cheaper but here the price difference is so slim it’s hard to see who they’re aiming it at.

Brummie85

ashe wrote: »

Few benefits to the E in the uk. In the states it’s significantly cheaper but here the price difference is so slim it’s hard to see who they’re aiming it at.

The E will most likely be pitched for new build housing developments, or social housing refurbishment projects and people replacing the boiler in their homes (a lot of these online quote sites will give a free smart stat as part of the boiler deal). Nest will offer some chunky discounts to get the market share and to shift the E in the required volumes to make it worth selling, whilst the normal version will continue to be developed and sold as the premium model.

Probably why they've priced it so similarly to the regular Nest. Consumers will buy the better version because it's not much more, whilst they can (on paper, at least) offer large discounts to everyone else and still make a healthy profit.