Wiring a smart thermostat

Pinch Flat

Put this in the elec forum but might be better here

Hi all changing out a 240v thermostat for a smart thermostat. Just wanted to check my approach. The smart thermostat has a four teeminals - L and N for power. There's also 2 dry contact terminals- presuming I just loop the L to the L on the switched contact to switch the boiler on and off when the thermo asks for it?

DGOBS

Would need a little more detail, what way is your current stat wired (and do you have a timer also?)
What brand smart stat you using.

Pinch Flat

DGOBS wrote: »

Would need a little more detail, what way is your current stat wired (and do you have a timer also?)
What brand smart stat you using.

Thanks for the reply

I have a danfoss timer that does both hot water and central heating

https://images.app.goo.gl/XEiKfiA3bdSe1CNf7

Current stat is a danfoss as well

https://images.app.goo.gl/opYFxvf5rMksqaQB7

Live and neutral wired to back of the thermo stat

Pinch Flat

DGOBS wrote: »

Would need a little more detail, what way is your current stat wired (and do you have a timer also?)
What brand smart stat you using.

Thanks for the reply

I have a danfoss timer that does both hot water and central heating

https://images.app.goo.gl/XEiKfiA3bdSe1CNf7

Current stat is a danfoss as well

https://images.app.goo.gl/opYFxvf5rMksqaQB7

Live and neutral wired to back of the thermo stat

DGOBS

So your replacing the time correct (and looping out the stat?)

What are you installing?

Pinch Flat

DGOBS wrote: »

So your replacing the time correct (and looping out the stat?)

What are you installing?

Keeping the danfoss timer and putting in a new smart stat where the thermostat is. Or do I just swap out the timer altogether?

Edit its one of these

https://www.amazon.co.uk/MOES-Thermostat-Temperature-Controller-Electric/dp/B07PKQ75DG

Wearb

Normally you would replace both with your new stat, which has a built in timer. Yes it's most likely that you would loop 4 to 1. I say most likely as I'm not there to see the installation. I presume 4 is coming from a fused spur.

I am only familiar with oil systems. If this is gas, there might be other considerations that I'm unaware of. So proceed with caution.

DGOBS

Original controller is 2 channel (separate hot water) so not enough just to change the stat

Wearb

He could leave the hot water on the programmer and just control the heat with new stat.
Last hive I installed, I wired it in parallel with existing programmer. I didn't have faith in the couple being able to quickly grasp the usage of the new stat.

Pinch Flat

Thanks for the help guys. Sounds a little more complicated than I'd anticipated.

Wondering would one solution be to leave the central heating side "on" permanently on the existing danfoss timer and use the new stat for timing on / off for the boiler to provide hot water to the central heating circuit. As far as I know I can programme the hot water separately on the existing panel as the hot water / central heating circuit is separated.

Wearb

Pinch Flat wrote: »

Thanks for the help guys. Sounds a little more complicated than I'd anticipated.

Wondering would one solution be to leave the central heating side "on" permanently on the existing danfoss timer and use the new stat for timing on / off for the boiler to provide hot water to the central heating circuit. As far as I know I can programme the hot water separately on the existing panel as the hot water / central heating circuit is separated.

That should work (assuming you have a normal S plan system).

Pinch Flat

What you reckon on the live to pin 1. Makes sense in that the neutral and live wired to the live and neutral terminals alone just provides power and no switching ability - I could hear the thermostat click on and off when I programmed it but no movement on the heat.

wizardman

Did you get the single channel? IE Heating only?

Wearb

Pinch Flat wrote: »

What you reckon on the live to pin 1. Makes sense in that the neutral and live wired to the live and neutral terminals alone just provides power and no switching ability - I could hear the thermostat click on and off when I programmed it but no movement on the heat.

1 and 2 are the switching contacts. 3 and 4 are "permanent" live and neutral. Run a jumper from 1 to 4. All assuming it's already wired in a conventional manner.

Pinch Flat

okay so a bit more time with the BH weekend an a 5km lock down since i posted last So the original thermostat was a Flash one, link here: https://www.rvr.ie/products/room-thermostat-1
I wasn't convinced it did work in regulating temperature, but it did click the boiler on and off if you turned the dial.

When I had the boiler replaced a few years back, the guy that did it put in motorised valves in the hot press a so the heating system and hot water is operated separately.

he left back a Danfoss thermostat that was never fitted - this is the one I fitted last weekend to see if I could get some control over the boiler. I now realise it's a 3 wire one, so the boiler is operating but the thermostat is not controlling it. It does click when you turn the dial, but it's obviously not switching the boiler. It is possible to get a 2 wire set up work with 3 wire thermostat by linking Live to Comm?

Photos of both set ups attached. First two images are the Flash, Third is how I wired up the Danfoss Thermostat and the last is my proposed wiring of the new smart stat. I realise my colours are mixed up in the photo

Wearb

What happened to the thermostat that you linked to earlier?

Pinch Flat

Wearb wrote: »

What happened to the thermostat that you linked to earlier?

which one - the flash or the danfoss?

Wearb

Pinch Flat wrote: »

which one - the flash or the danfoss?

This one?

Pinch Flat

Haven't wired this in yet - the fourth image i linked above (ignore my marked up colours in the wiring ) are how I was going to wire it up.

Wearb

I am now mixed up and not sure what you want to know.

Pinch Flat

okay sorry - will remove the new wiring diagram I marked up for my Moes - I've marked this up incorrectly.

Pinch Flat

Okay so here's the mark up of the new moes stat I'm going to fit. The original stat was a flash one, wired up as the first photo in my post from earlier today

Wearb

Pinch Flat wrote: »

Okay so here's the mark up of the new moes stat I'm going to fit. The original stat was a flash one, wired up as the first photo in my post from earlier today

Assuming yellow is live and blue neutral, then you need a feed from from 2 to the boiler.


As I said before, this all assumes everything else is done correctly. If you are not sure get someone who know those things to do it.

Pinch Flat

okay think I Might park this. I was working in the basis of a jumper from 1 to 4, but you reckon i need a feed from 2 to the boiler which I don't understand

DGOBS

You are barking up the wrong tree.

Look at your current stat pictures, and that is not a live an neutral, that is someone using the neutral (blue) wire as the return for live.
So all is at the current stat is a live in, and a live out.

What you need for the stat your intending wiring in, is 240vs live, neutral (both used to power and operate the new stat) and then a switched live in and out to the appliance (yes potentially you can loop common for this purpose, but you don't have the wiring you need to achieve what you want at the current thermostat) I can't see what you want to do working.

the reason your old stat didn't work (properly) is it relies on an anticipator inside the stat for accuracy, but without a neutral it wouldn't work (bet the light never worked either for the same reason)

Sorry

Pinch Flat

Ah grand thanks. those thermostats need a neutral to create some resistant and heat inside to work properly don't they?

might have a look at the danfoss programmable controller. There's a spur beside it that a could probably get power from for the new thermostat but it's in an unheated utility room so the thermostat would be useless located there

DGOBS

Why not purchase something like a HIVE, dual receiver to replace the current timer, then the stat is wireless so put hat where you like, bridge/loop out the old wired stat, and you'll have the Hive hub so you can control remotely from the app if you want.

Pinch Flat

DGOBS wrote: »

Why not purchase something like a HIVE, dual receiver to replace the current timer, then the stat is wireless so put hat where you like, bridge/loop out the old wired stat, and you'll have the Hive hub so you can control remotely from the app if you want.

Yeah sounds like the way to go. Thanks for the help to you and Wearb anyway