which smart thermostat

[gaz_moose]

I bought the drayton wiser one as suggested. The magic pixies might be responsible for installing it as its illegal for a non gas safe engineer to remove the cover or something like that.

[SimonD]

8 hours ago, -rick- said:

I'm not 100% sure I can fully use opentherm in my setup. I know it's supported with combis but with a S-plan system boiler I need to verify things. Unfortunatetly my installer really ballsed up the wiring and I'm not even running properly as S-Plan right now (there is one signal line to the boiler, not two) and thats before adding opentherm cabling. Royal Mail literally just rang my door and walked away before I could get to it with my delivery of stuff needed to change the wiring over. So guess I now get that delivery on Monday and will be able to report back how things go

 

With eph controls you can run priority hot water using opentherm on an s-plan system. You can also get an additional receiver to install right next to boiler for necessary opentherm communication so no new cabling required.

 

Use the cp4i together with cp4-hw-ot for this. 

 

No subscription fees for the app.

 

I wouldn't touch tado controls ever again after my experiences installing them for a few customers, even the ones I ordered from Europe with opentherm.

 

Hth

[-rick-]

On 22/11/2025 at 17:45, gaz_moose said:

I bought the drayton wiser one as suggested. The magic pixies might be responsible for installing it as its illegal for a non gas safe engineer to remove the cover or something like that.

 

Amazon now selling various packages even cheaper for Black Friday. Whether it's worth the hassle of returning what you ordered is up to you.

 

Magic Pixies have paid me a visit and now everything is up and running and working as expected. Looks like the 2nd Gen Wiser hub has better OpenTherm support. It's a shame in the sense that they don't appear to be backporting changes to the 1st Gen hub. Doesn't really matter to me, though the 2nd gen diagnostic info in the app would be quite useful. I wasn't planning on installing Home Assistant for this but might end up doing so just as I get used to the controls so I have a better idea what's happening.

 

So far the Wiser is running the boiler at the max setpoint temp (control on my boiler) until the room temp is very close to setpoint and then it winds the boiler down. Seen it drop the water temp to 42 so far though overall it spent more time at higher temps than I expected. I've read that it takes a couple of weeks for the system to learn your property and until then its control will be a bit bumpy. We will see. Don't think I'm seeing much cycling though without that diagnostic info and not wanting to stand in front of the boiler for ages it's a bit of a guess based on the noises I'm hearing. Not turned on eco mode (weather compensation based on internet weather) yet. That's the next step after a bit more experimentation without it.

Edited Tuesday at 15:53 by -rick-

[marshian]

On 22/11/2025 at 17:45, gaz_moose said:

I bought the drayton wiser one as suggested. The magic pixies might be responsible for installing it as its illegal for a non gas safe engineer to remove the cover or something like that.

Is your old controller base unit mounted on a universal backplate - sometimes called industry std backplate?

 

If it is a wiser hub should be easy to install no "gas safe" engineer required

 

I replaced my original controller below (library image as the original item got trashed by a toaster - don't ask some people are just stupid)

 

 

With a Danfoss 24/7 digital programmer that had a universal back plate - so I had the headache of working out what the wires did what on the original.

 

No smoke escaped from the wires so once done further swaps of the controller have been isolate power - remove old - replace with new and power up.

 

 

[marshian]

3 hours ago, -rick- said:

 

Amazon now selling various packages even cheaper for Black Friday. Whether it's worth the hassle of returning what you ordered is up to you.

 

Magic Pixies have paid me a visit and now everything is up and running and working as expected. Looks like the 2nd Gen Wiser hub has better OpenTherm support. It's a shame in the sense that they don't appear to be backporting changes to the 1st Gen hub. Doesn't really matter to me, though the 2nd gen diagnostic info in the app would be quite useful. I wasn't planning on installing Home Assistant for this but might end up doing so just as I get used to the controls so I have a better idea what's happening.

 

So far the Wiser is running the boiler at the max setpoint temp (control on my boiler) until the room temp is very close to setpoint and then it winds the boiler down. Seen it drop the water temp to 42 so far though overall it spent more time at higher temps than I expected. I've read that it takes a couple of weeks for the system to learn your property and until then its control will be a bit bumpy. We will see. Don't think I'm seeing much cycling though without that diagnostic info and not wanting to stand in front of the boiler for ages it's a bit of a guess based on the noises I'm hearing. Not turned on eco mode (weather compensation based on internet weather) yet. That's the next step after a bit more experimentation without it.

 

Having had Wiser for a few years now and gone down the route of smart TRV's and micro control of rooms my advice is keep it really simple if you are running a scheduled heating process (if 24/7 ignore me)

 

1. Set up base programme for Heating and Hot Water like you would an older digital programmer 

2. Device lock the Room Thermostat (so it can't be boosted accidentally - this is a fun game for all the family) and control in the app

3. Make sure the away facility does not apply to HW 

4. Steer clear of ECO and Comfort Modes until you are very comfortable with the system

5. If you notice the boiler being turned off mid cycle - change the boiler type to Oil. 

[-rick-]

10 minutes ago, marshian said:

Is your old controller base unit mounted on a universal backplate - sometimes called industry std backplate?

 

No opentherm connections there. A system boiler may also not be wired for separate CH and DHW signals which limits you to a single water temperature or in the case of the 1st gen wiser and similar prevents Opentherm use if you also want hot water. A competent installer can solve those problems.

[MrPotts]

The “industry standard” backplate will only fit the gen1 Wiser hubr, the gen2 hubr uses a slightly different backplate.

[marshian]

Just now, -rick- said:

 

No opentherm connections there. A system boiler may also not be wired for separate CH and DHW signals which limits you to a single water temperature or in the case of the 1st gen wiser and similar prevents Opentherm use if you also want hot water. A competent installer can solve those problems.

 

Sorry I was directing the question to @gaz_moose

 

My wiser unit isn't connected to the boiler at all - I'm heating 24/7 😉 Boiler is set up with DHWP and WC already

 

Wiser schedule for HW switches the boiler to recharge the cyl via a HW Demand box so there is actually no need to connect Wiser to the boiler.

 

I will eventually connect it again just to use the away function but right now I just use the Viessmann app to do that...

[marshian]

Just now, MrPotts said:

The “industry standard” backplate will only fit the gen1 Wiser hubr, the gen2 hubr uses a slightly different backplate.

 

Was not aware of that - thanks for the heads up

[-rick-]

23 minutes ago, marshian said:

Having had Wiser for a few years now and gone down the route of smart TRV's and micro control of rooms my advice is keep it really simple if you are running a scheduled heating process (if 24/7 ignore me)

 

Still working out which is best. Until the Wiser I've been running on manual boost as required, now exploring other options. One of my rooms has pretty much all its two external walls as not thermally broken aluminium double glazed floor to ceiling sliding doors and is hugely lossy. I don't really use the room so until now I've not be actively controlling the temperature there (just leaving some radiators relatively low and the room gets whatever heat comes from them when the heating is on for the other rooms). This arrangement has its downsides and I'm hoping that the efficiency gain of being able to run the boiler at a lower temp offsets the additional gas that I expect to need to regulate that rooms temperature (early signs not inspiring confidence).

 

Edit: I opened your big boiler journey thread earlier, not (re-)read it all yet but plan to. Thanks!

 

23 minutes ago, marshian said:

4. Steer clear of ECO and Comfort Modes until you are very comfortable with the system

 

Yep

 

23 minutes ago, marshian said:

5. If you notice the boiler being turned off mid cycle - change the boiler type to Oil. 

 

Came across that one in the wiser forums. Opinions are mixed as to whether it's a benefit on a good modulating boiler. (Mine goes from 30kw to 6kw)

Edited Tuesday at 20:20 by -rick-

[JohnMo]

20 minutes ago, -rick- said:

 

No opentherm connections there. A system boiler may also not be wired for separate CH and DHW signals which limits you to a single water temperature or in the case of the 1st gen wiser and similar prevents Opentherm use if you also want hot water. A competent installer can solve those problems.

For others reading this. If your system boiler has opentherm. The EPH unit referenced to by @SimonD (up thread) will make your system boiler supply different flow temps via opentherm, so your system becomes priority domestic hot water when using 2x 2 port valves.

[-rick-]

1 minute ago, JohnMo said:

For others reading this. If your system boiler has opentherm. The EPH unit referenced to by @SimonD (up thread) will make your system boiler supply different flow temps via opentherm, so your system becomes priority domestic hot water when using 2x 2 port valves.

 

Yep. Wiser 2nd gen will do that too along with some others, though had I seen @SimonD's recommendation before I bought I may well have gone with EPH.

 

Having said that, having the separate connections may be of use even if your boiler doesn't have opentherm (or a broken version of it). My relatively basic boiler will run the hot water at a hotter temp if triggered by a separate input to the normal heating circuit. It was my fallback position if I had a problem with opentherm.

[marshian]

22 minutes ago, -rick- said:

33 minutes ago, marshian said:

Having had Wiser for a few years now and gone down the route of smart TRV's and micro control of rooms my advice is keep it really simple if you are running a scheduled heating process (if 24/7 ignore me)

 

Still working out which is best. Until the Wiser I've been running on manual boost as required, now exploring other options. One of my rooms has pretty much all its two external walls as not thermally broken aluminium double glazed floor to ceiling sliding doors and is hugely lossy. I don't really use the room so until now I've not be actively controlling the temperature there (just leaving some radiators relatively low and the room gets whatever heat comes from them when the heating is on for the other rooms). This arrangement has its downsides and I'm hoping that the efficiency gain of being able to run the boiler at a lower temp offsets the additional gas that I expect to need to regulate that rooms temperature (early signs not inspiring confidence).

 

Edit: I opened your big boiler journey thread earlier, not (re-)read it all yet but plan to. Thanks!

 

Sounds like you have a similar issue to one of my rooms 

 

Good luck reading the Viessman thread it's taken me a while to get to grips with it!!! It's still got some niggles!!!

 

22 minutes ago, -rick- said:

 

 

 

33 minutes ago, marshian said:

4. Steer clear of ECO and Comfort Modes until you are very comfortable with the system

 

Yep

 

I think they can be good but they also a layer of WTF which can be confusing

 

22 minutes ago, -rick- said:

 

33 minutes ago, marshian said:

5. If you notice the boiler being turned off mid cycle - change the boiler type to Oil. 

 

Came across that one in the wiser forums. Opinions are mixed as to whether it's a benefit on a good modulating boiler. (Mine goes from 30kw to 6kw)

Edited 7 minutes ago by -rick-

 

It's not really anything to do with the boiler ability - more an algorithm in the Wiser control program - it's especially bad with multiple "smart" TRV's and 24/7 heating but it can just as easily do the same with a single room stat 

 

Main Room with thermostat (or multiple rooms with "Smart" TRV's) get close to target temp and Wiser switches off the boiler - it's one of the reasons my Wiser hub doesn't have a connection to the boiler now - I'm running 24/7 with WC and TRV's are set to temp limiters (just above target temp - so it was interpreting that as potential house over heat and shutting down the boiler 

 

Switching it to "oil" reduced the frequency of that intervention - it's just something to bear in mind when setting target temps or placement of the thermostat.

 

I'm still a fan of the Wiser system - I've just dialed out the clever - I don't need or want ECO I'm running flow temps below 35 deg  - I don't need Comfort because I'm not scheduled heating slots and WC is doing all the hard work.

 

The App interface is brilliantly simple just don't try and make it complicated

[SimonD]

22 hours ago, -rick- said:

Having said that, having the separate connections may be of use even if your boiler doesn't have opentherm (or a broken version of it). My relatively basic boiler will run the hot water at a hotter temp if triggered by a separate input to the normal heating circuit. It was my fallback position if I had a problem with opentherm.

 

Yes, there are a few that do. On some, like Ideal, it's used with weather compensation and the manufacturers get a bit sniffy about it if you use it without weather comp. Don't ask me how I know, but they don't always like those who experiment 😏 

 

If you're using something like this with an s plan you'll ideally need a normally open 2 port valve on the ch side to close when you send your 240v call for dhw to boiler.

 

No such thing as a free lunch unfortunately.

 

I used to do this stuff regularly until I saw the light and just moved to installing Viessmanns on  4 pipe. Life got a lot easier from then on - I'd regularly save myself a day.

Edited Wednesday at 18:38 by SimonD

[-rick-]

11 minutes ago, SimonD said:

Yes, there are a few that do. On some, like Ideal, it's used with weather compensation and the manufacturers get a bit sniffy about it if you use it without weather comp. Don't ask me how I know, but they don't always like those who experiment 😏 

 

Hmm, well I've just booked my service with them, would you expect their engineer to question it? So far the boiler is doing exactly what is asked of it. I may have other issues to raise with my overall system in due course but so far the boiler is fine.

 

11 minutes ago, SimonD said:

If you're using something like this with an s plan you'll ideally need a normally open 2 port valve on the ch side to close when you send your 240v call for dhw to boiler.

 

I've looked into this and I can get an add-on relay (I think Salus make a nicely packaged one for the purpose), but for now I'm doing poor mans PDHW by just not scheduling them both to come on at the same time. Edit to clarify: my system has two NO valves (and a pressure release bypass).

 

11 minutes ago, SimonD said:

No such thing as a free lunch unfortunately.

 

I used to do this stuff regularly until I saw the light and just moved to installing Viessmanns on  4 pipe. Life got a lot easier from then on - I'd regularly save myself a day.

 

I have no interest in investing extra money in this property (really want to sell it asap but can't right now due to cladding issues) so focussed on maximising what I have. Needed to replace the controller anyway as my Honeywell broke and while I was able to repair it, I don't trust my soldering skills (or the quality of the replacement capacitors) as a long term fix.

Edited Wednesday at 18:50 by -rick-

[marshian]

2 minutes ago, SimonD said:

If you're using something like this with an s plan you'll ideally need a normally open 2 port valve on the dhw side to close when you send your 240v call for dhw to boiler.

Mine is set up with

 

normally open on the CH side

 

normally closed on HW side

 

call for HW opens the normally closed on the HW and signal from the now open HW valve tells the CH valve to close

 

but I guess it can be done in other ways

I liked the simplicity of valves being exercised all year (ie in summer when the CH valve would do nothing for months) and both valves only consuming any power during the short HW recharge period

[SimonD]

2 minutes ago, -rick- said:

Hmm, well I've just booked my service with them, would you expect their engineer to question it?

 

I doubt they'll notice on a service. It's  likely only on repair or warranty work they might find out.

[-rick-]

2 minutes ago, SimonD said:

I doubt they'll notice on a service. It's  likely only on repair or warranty work they might find out.

 

Hmm, this is a 'warranty reestablishment' service, because I'm apparently a few weeks late booking the service. They are supposed to fully take it apart and check everything. Edit: I had thought I was out of warranty but apparently I have 1 more year so it was worth the extra £30 to keep the warranty.

Edited Wednesday at 18:52 by -rick-

[SimonD]

4 minutes ago, marshian said:

normally open on the CH side

 Yes, that's what I meant to write. You caught me before I edited 😊

[marshian]

2 minutes ago, SimonD said:

 Yes, that's what I meant to write. You caught me before I edited 😊

Sorry about that - I’ll see if I can delete my post

[SimonD]

27 minutes ago, -rick- said:

 

Hmm, this is a 'warranty reestablishment' service, because I'm apparently a few weeks late booking the service. They are supposed to fully take it apart and check everything. Edit: I had thought I was out of warranty but apparently I have 1 more year so it was worth the extra £30 to keep the warranty.

 I don't recall what boiler you have but I seriously doubt they'll check the wiring. For tests they'll usually use the check programs and might ask you to turn  your heating on so there's flow through the system.

[-rick-]

Quick update from me. I'm just in the process of returning the package I ordered and replacing it with a different one (Multizone Kit 2 to Thermostat Kit 3). Reason being the TRVs are utterly useless. I knew smart TRVs weren't hugely useful and the only reason I got them is because I have a high heat loss area (subject to high solar gain when the sun is out) and low heat loss area and I wanted either area to be able to call for heat.

 

The TRVs are useless because their temperature algorithm is totally divorced from reality.

 

Heating on: Room 18C, measure 23C

Heating off: Room 16C, measure 13C

 

The Thermostat Kit 3 is technically a dual zone kit and the second zone doesn't work with Opentherm so I don't plan to use it. However, I believe you can configure two of the Smart Thermostats to control the same heating zone and this is the cheapest way to achieve two calls for heat within the first gen ecosystem (it's also on significant discount right now so I will end up spending less - even though it was the more expensive option when I was originally ordering).

 

If it hadn't taken me so long to get the system up and running I would have given it a bit more time and seen if Wiser support would trade the two TRVs for the extra Thermostat. But they haven't responded to my support case yet and my returns window on the original order is about to expire so I'm forced into quick action.

 

Still trying to get my heating system into shape. The system was on full bore for the entirety of yesterday and didn't get the high heat loss area above 21.5. Been attempting to balance things today that does seem to have made an improvement but a bit too early to tell (especially as it's warmer outside).

[SimonD]

18 hours ago, -rick- said:

The Thermostat Kit 3 is technically a dual zone kit and the second zone doesn't work with Opentherm so I don't plan to use it.

 I know you're in the Wiser ecosystem now, but for future reference the EPH controls can do multiple zones via Opentherm as each additional zone is paired to a master hub controller.

 

I've always argued that it's not the heat source that's important but the control strategy and mechanism. With gas systems I always seem to have struggled with getting the system control as I like it, even in my own house where I ended up with a pragmatic solution that was okay, it was efficient, but not amazing. I think this is down to the split between heat source and controller manufacturer and how they decide to implement their control ideology and this causes problems. This is particularly the case with in the gas market.

 

I've now completed 2 full system designs and installations of heat pumps where I'm fully responsible for the systems and have to say that with using the manufacturers control packs of course, the control element is just fantastic. Both have required very little time and only small adjustments to WC and room influence, including a tweak to a couple of normal trvs. From this, I have so become a convert to heat pump systems, I really don't want to work with gas any more.

 

Integrated manufacturer controls are a big player, but I also suspect there are a few other fundamentals in the systems that improve things on this front.

 

Anyway, just an aside, while I'm on the topic. I'll get my coat ☺️

 

 

 

 

[-rick-]

40 minutes ago, SimonD said:

 I know you're in the Wiser ecosystem now, but for future reference the EPH controls can do multiple zones via Opentherm as each additional zone is paired to a master hub controller.

 

I'm not fully committed yet. Did look at those EPH controls you recommended before reordering the Wiser system. The EPH would have required another re-wire of the wiring centre and cost at least twice as much. One of the benefits of reordering now is that I now benefit from the extended return times Amazon gives you around Christmas. So I've got months to get to grips with the Wiser system and still have the option of changing my mind.

 

So far its mostly working for me, couple of niggles that I'm trying to work out if its me misunderstanding something, a bug or intentional design but I don't think anything show stopping (given workarounds I've discovered).

 

Todays task is installing Home Assistant to access the debug info. Shame that appears to be the easiest way to get it.

 

My biggest concern right now is how much scope there is for me to run low and slow and heat the whole place is with the existing radiators. Half the flat the system can easily cope, the other half seems more difficult.

 

40 minutes ago, SimonD said:

Integrated manufacturer controls are a big player, but I also suspect there are a few other fundamentals in the systems that improve things on this front.

 

Heatpumps being funamentally low and slow and the controls being designed around that vs boilers where low and slow is a new thing grafted on must mean there is a lot of technical debt/legacy that gets in the way.

[JohnMo]

2 minutes ago, -rick- said:

boilers where low and slow is a new thing grafted on must mean there is a lot of technical debt/legacy that gets in the way.

Sorry not exactly new - European manufactures have been designing boiler for low and slow weather compensated, room compensated heating systems for decades. UK manufactures offer drummed down technically poor boilers, manufacturing and installing, with the basis of design being S and Y plan heating systems, they should have been banned the day condensing boilers were mandated, a few decades ago.