Installing Smart Thermostat

[purpleozzie1]

Hi Guys,

I inherited a Salus wireless thermostat when we moved into this house two years ago and it's awful. Never reads the correct temperature and a pain to program and pair with our Worcester salus boiler.

I'd like to install a smart thermostat, either a nest or hive, but I don't think this house has ever had a wall mounted Thermostat.

Is it possible to install one myself, I have basic knowledge of wiring and electrics.

Or is this best left to the experts.

Also, do you need to hardwire a smart thermostat or can I somehow bypass the houses internal wiring?

Amy help would be appreciated..

Cheers,

 

[RandomGrinch]

Is it possible to install one myself, I have basic knowledge of wiring and electrics.

What is the model of your boiler and can we have a photo of the front panel?
It sounds as if you have a boiler with an integral wireless Salus receiver.

If there hasn't been an external thermostat installed previously, whether a new stat is a DIY install, depends on the boiler. Often with modern boilers, reaching the wiring terminals, involves removing the cover; this may form part of the room sealing of the boiler - a job for a registered gas installer.

Also, do you need to hardwire a smart thermostat or can I somehow bypass the houses internal wiring?

I'm afraid I don't really understand the question.
Usually, a Hive receiver or a Nest Heatlink would be connected by a short length of cable and mounted near the boiler.
The wireless thermostat itself, could then be mounted where it is required.
The Nest Heatlink has an option to use a cable to power the thermostat, but as you don't have any existing cable to re-utilise, this would have to be new anyway.

 

[purpleozzie1]

 

[ericmark]

The central heating is normally controlled by TRV (thermostatic radiator valve) which being on the radiator are in an ideal position to monitor the return air temperature, however they have a problem, in that the basic unit can't turn the boiler on/off, it can by the return water temperature turn it up/down, but in the basic form there is no electrical connection, so we use some sort of hub/thermostat to switch whole system on and off.

There are two basic ways to control the boiler, on/off or up/down, the boiler of yesteryear was either on or off, but the modern gas boiler (not oil in the main) can today turn up/down, and to gain the latent heat from the flue gases, it is important it is allowed to turn up/down, it will work on/off but not as efficiently.

So the idea is to select a room, on the ground floor as heat raises, with no south facing windows, or the sun can warm the room, and of course no alternative heating, and keep on the cool side so on warm days it will turn heating off before the home get too hot, and no TRV in that room, and to be frank, most homes there is no such room.

So in the main we use a compromise. And in that compromise we have to include cost. So the likes of Honeywell Evohome or Drayton Wiser have electronic heads on the TRV's and a hub, so the TRV's control the boiler, and the hub has the option of using OpenTherm so it slowly turns the boiler up/down so gaining most of the latent heat. But they are not cheap, so we look at near enough engineering.

This may be a mixture of TRV heads and wall thermostats, Wiser can do this, or only some of the TRV's linked, I use eQ-3 heads which are programmable but do not link to either my Nest Gen 3 or the Wiser. The Nest Gen 3 did not do what it said on the packet, it will not link in a meaning full way to the TRV heads.

But it does depend on your life style and design of your house, there is no best system. But you need to be aware of the failing of each system, and decide will this be a problem for you.

Nest has OpenTherm but will not link to TRV heads, and the geofencing only allows Eco and Comfort temperatures to be set, no option as to distance away from home, it will work with both phone and PC.

Hive is simple on/off, it will not connect to ebus, it does connect to TRV heads, as long as the thermostat is in a room cooler than 22ºC.

Wiser does have OpenTherm, it does connect to TRV heads, and/or wall thermostats, will not work with PC on phone or tablet, using IFTTT but not tried the geofencing so can't say how it works.

Evohome was likely the first of the TRV head linked systems, and has a central control panel has the option of OpenTherm not used it, so can't comment further.

Tado OpenTherm version was withdrawn from UK, think it still can be got, but info when I looked was rather low.

Tapo/Kasa/TP-link do seem to do a system, but could not find a wireless thermostat, the TRV head works well, but lack of wireless wall thermostat resulted in my not continuing with that system.

Energenie/Mihome TRV heads were claimed to work with Nest, but seemed the wrong way around, the TRV should tell hub what to do, not the thermostat tell the TRV heads what to do, they have their own wall thermostat, but hard wired, so no good for me.

Maybe others can add to what I have found, I use at the moment a mixture with an oil fired boiler, so no OpenTherm, of Energenie, Kasa, and eQ-3 TRV heads, and Nest Gen 3 and Wiser single channel thermostats. Former wall mounted, latter free standing.

I am careful that all central heating is either from the same UPS backed FCU or battery, so if I loose grid supply my central heating continues to work.

 

[ericmark]

I have no idea if the Salus unit can be removed, think it connects to ebus, so not really a DIY job.

Nest wireless with Gen 3 uses a USB supply, the internal battery does not last long, so getting it to work with UPS (uninterruptible power supply) could be a challenge.

But simple method is use electronic TRV heads. The eQ-3 was bluetooth, so need to be close, but in 2019 cost me £15 each, so cheap, and you can set manually, the Energenie has no manual options, needs a hub, uses IFTTT and have tried using the geofencing, but the anti-hysteresis software is OTT so did not really work with geofencing, the Kasa was to replace a damaged Energenie it has worked well, it has loads of info from the phone, including charts as to how it has preformed, it was maybe a mistake for me, but wanted one which used internet not bluetooth, and Kasa will work with phone.

The eQ-3 does not show current, only target temperature, the current and target temperature display I found helped setting the lock shield valves.

 

[RandomGrinch]

Your Greenstar 30i ErP has a cover that does form part of the room sealing of the boiler. You should get an RGI to install the connections, or get the boiler checked by them afterwards.
If for example, a Hive for combi.(single channel) was to be connected..

The link wire to LR heating would be removed.
Using a 3 core and earth cable;
The L and N to the Hive receiver would connect to terminals 3 L and N on the boiler.
LR heating on terminal 4, would connect to Hive terminal 3.
A link would be added between L and terminal 1 on the Hive.
The earth connections would be made, and the switch on the Salus receiver would be turned to permanently on.

Alternatively, you could use Worcesters proprietary EMS controls, these allow for better control of the boilers modulation.
Your boiler does not support OpenTherm.

Hive is simple on/off,

Not quite; it, and many other on/off smart stats, are load compensating smart stats, that can use on/off control as a form of long period, pulse width modulation to make some efficiency gains, although not quite as much as an OT, or EMS modulating controller.

 

[purpleozzie1]

I am so confused right now.. Basically it's a 3 bed semi and every room is generally the same temperature.. I don't work to a set schedule work from home a couple of times a week but could be different days, sometimes I'm out till 7 sometimes I'll be home by 3.. All over the place, hence why I was looking for a smart learning system..

What system would work best for this and how much would a pro charge to install??

 

[RandomGrinch]

I am so confused right now..

You don't need to overthink this (Eric has a certain way with words!). A Hive, or Nest will probably suit your needs - after all, anything is better than a Salus.

I'm afraid I don't know what the costs would be for an install.

 

[denso13]

What system would work best for this

As above, simple Hive or Nest, gas safe person to remove and fit case.

 

[purpleozzie1]

That's what I'm thinking.. I assumed a smart thermostat would be easy to install.. how easy is it to replace salus receiver with nest/hive receiver and can I just plug the thermostat into the wall socket??

 

[denso13]

and can I just plug the thermostat into the wall socket??

No, you need to get someone in, about £300 all in.

 

[ericmark]

Not quite; it, and many other on/off smart stats, are load compensating smart stats, that can use on/off control as a form of long period, pulse width modulation to make some efficiency gains, although not quite as much as an OT, or EMS modulating controller.

Mother had the thermostat shown fitted to a Worcester Bosch boiler which also used a mark/space system to stop over shooting, and was completely inappropriate for the boiler. Each time the boiler was externally turned off, it would start again setting the amount of modulation required to gain the latent heat.

I am so confused right now.. Basically it's a 3 bed semi and every room is generally the same temperature.. I don't work to a set schedule work from home a couple of times a week but could be different days, sometimes I'm out till 7 sometimes I'll be home by 3.. All over the place, hence why I was looking for a smart learning system..

What system would work best for this and how much would a pro charge to install??

Not surprised, my old house worked, so never looked at central heating, it was not until I went to look after my mother, in a house with doors, that I came across central heating that did not work as required, and found after a lot of messing around, simply fitting a TRV in the hall, with the wall thermostat, cured my problems.

So do you want geofencing (it works out when your mobile phone is within set distance from home and turns up the temperature automatically) or a manual system where you need to look at phone and alter settings?

And which is likely to hinge on recovery time, how long it takes to reheat the home. I found my home is too large to reheat all rooms together when I return home, and I would set a sequence, first the kitchen, then dinning room, then living room, and finally bedrooms. Nest would turn up the heating far too late, so I had to manually turn up heating, but used the geofencing to turn down the heating.

There is also a huge difference heating 17ºC to 20ºC to heating 10ºC to 20ºC, old house, heating off, so 10ºC turn on central heating and the 4.5 kW gas fire and living room was warm in ½ an hour, this house it would take a couple of hours, so this house don't turn it off, I turn it down, so held at 17ºC when away.

 

[purpleozzie1]

Hiya,


Just got a quote for £80 on my builder to fit it all.. Does.this sound about right?

 

[ericmark]

Seems too cheap. Hive, Nest, Wiser cost more than that to buy, without fitting.

 

[purpleozzie1]

That's just the fitting.. I'll supply the nest..