Improving my heating controls - going smart - advice welcomed

[danlightbulb]

Hi all,

I currently have a Worcester Bosch Greenstar 25Si combi boiler located in the kitchen with a wireless Drayton Digistat thermostat wall mounted in the hallway. All rads except the bathroom towel rail have a Danfoss TRV.

The boiler with its rotary manual timer:

The Drayton thermostat (no programmable functionality):

The wireless receiver unit which seems to be wired into the boiler:

The TRVs:

I would like new TRVs anyway, as the current ones are stiff, yellowed, and covered in paint splashes. I could go for smart TRVs to give me some zonal control.

I would also like a Google Nest thermostat or similar to replace the existing controls.

I want to DIY this if possible.


Any advice on what I need to do, compatibility issues, would be appreciated.

 

[dirtychinchilla]

Wow, those are some old TRVs!! Danfoss are one of the best manufacturers of TRVs around, although I don't think their smart range is out yet. In reality, most TRVs are rubbish so they're probably much of a muchness.

 

[Deleted User 298457]

You can often grab a Hive including fitting from Amazon for a reasonable price. I'd start there. A British Gas chap will come and install it.

Then for smart TRVs, you just need them in rooms you want specifically cold, or specifically warm - no where else, as it is a waste in reality. I put them on every rad and actually I only cared about the nursery "asking for heat" and then "stopping the heat" once it got to temp. The other 3 TRVs I had, I just let run out of battery as it was superfluous to requirement.

Edit: It is also worth noting that smart TRVs cost so much it will almost never offset your saving in gas.

 

[danlightbulb]

Ok perhaps I ditch the idea of smart TRVs then.

On the thermostat side though, I'm currently trying to find out how to get a device compatible with Worcester Bosch's EMS bus to get proper boiler modulation functionality.

My research so far has pointed me to the Tado system which I've read can communicate via EMS protocol. Has anyone done this or OpenTherm and got good results?

 

[Demon]

Ok perhaps I ditch the idea of smart TRVs then.

On the thermostat side though, I'm currently trying to find out how to get a device compatible with Worcester Bosch's EMS bus to get proper boiler modulation functionality.

My research so far has pointed me to the Tado system which I've read can communicate via EMS protocol. Has anyone done this or OpenTherm and got good results?

I've DIY'd a TADO install,

You boiler looks rather similar to my Worcester Bosch CDI 38, even your wirless stat looks similar! the Tado App does a step by step guide and as you mentioned is connected to my boilers digital control bus.

Effectively I have the same as the "tado° Wireless Smart Thermostat Starter Kit V3+ with water controls", an small internet bridge, a remote room thermostat/control and the boiler/hot water interface box.
Then add as many Tado smart TRVs or other room temperature monitors as you like, I've got 4 TRVs and am adding more now to minimise energy usage, although I am under no ilusion I'm probably lucky to break even in terms of cost.. £150 for the started kit/boiler interface but I do get the TRVs in the sales, so around £45 each. If you are with Bulb, or know anyone with Bulb who doesn't mind burning up their discount code, you can buy 4 TRVs for £43 each after discount.

I don't use their paid service, just the basic free App functionality is fine..

Their CS isn't too bad, they can actually help configure more advanced stuff not available in the app, it just takes a bit of patience to understand/get through and be warned, if your rads are not balanced, the TRVs (this is true for all smart TRVs) struggle to get a proper accurate room temperature, however if balanced, I've found they work well.

The TRVs come with adapaters and have fitted all my TRV bases I've got in the house, but replacing TRVs isn't that hard, although you need to drain the system, refill and add inhibitor etc..

Screwfix have the "TADO V3+ BLACK EDITION WIRELESS HEATING & HOT WATER SMART THERMOSTAT STARTER KIT" which has everything you need, but a black room stat for £99.. (although it's £150 if you want the white thermostat).

 

[danlightbulb]

Effectively I have the same as the "tado° Wireless Smart Thermostat Starter Kit V3+ with water controls", an small internet bridge, a remote room thermostat/control and the boiler/hot water interface box.

Could you elaborate on your configuration please?

I've discovered that the UK version of the v3 wireless interface doesn't support bus control but I can order the EU version which does have it. I believe they used to make a separate bus connection interface, which might be what you have, but this is now discontinued.

I'm particularly interested in how you made the connection to the boiler EMS interface please.

 

[SpellowHouse]

Then for smart TRVs, you just need them in rooms you want specifically cold, or specifically warm - no where else, as it is a waste in reality. I put them on every rad and actually I only cared about the nursery "asking for heat" and then "stopping the heat" once it got to temp. The other 3 TRVs I had, I just let run out of battery as it was superfluous to requirement.

Edit: It is also worth noting that smart TRVs cost so much it will almost never offset your saving in gas.

This is very true. Most homes are just too small to really benefit from zone heating. Not to mention that people are unpredictable - turn the heating off upstairs and I guarantee the kids will want to play up there! This is the same with many of the more complex heating practices. With a business that has set opening and closing times it's easy, but a home is very different. I think this is why some of the really powerful algorithms never made it to domestic heating controllers - the unpredictable nature of the home plays havoc with their control scenarios.

 

[jpaul]

(could have been in the optimize my combi thread ...)

what is the heating pump ? is it modulating and going to back off the flow if most of the zones are off .... so that the return temperature is low giving opportunity for optimal efficiency.

 

[danlightbulb]

turn the heating off upstairs and I guarantee the kids will want to play up there!

Isn't that the point though? In a normal system if your heating is off and someone wants heat in a room just turning up the trv won't do anything, you'd have to turn the heating on as well. Whereas with a smart trv you can use it directly to activate the boiler for that room without touching the main programmer.

 

[squerble]

Getting your home fully kitted out with smart TRVs is nothing other than ultimate control. Only half-fitting the house with smart TRVs is bad, as the boiler coming on to heat the smart TRV requesting heat will also be sending that heat to every radiator without a smart TRV, wiping out any saving.

It looks like a well-balanced system with a sensible schedule is the best way to save money. Not possible for everyone, of course, but for most it'll likely work out.

 

[danlightbulb]

It looks like a well-balanced system with a sensible schedule is the best way to save money. Not possible for everyone, of course, but for most it'll likely work out.

As long as I invest in a control system that can accommodate smart TRVs in the future then I can start with the thermostat and app control and see how that goes.

The frontrunner at the moment is the Tado system but Im really keen to hear more from @Demon because it sounds like he has done exactly what I want to do in terms of making a Tado to EMS connection on the boiler. Don't let me down Demon!

 

[413x]

I have full tado too.
I did it all myself.
Every radiator bar towel rail and downstairs hall has one.

Caveat. I have a tank.

I removed our control unit and replaced with tado unit (wiring was provided by app)

I removed old analogue wall thermostat and bridged the wires (always on)

Now the Tado control unit calls for CH or HW as a direct replacement to the old one.

Any one TRV can turn the boiler on.
HW is obviously same method. If it's requested it comes on.

I bought a V2 box from ebay so I get the geofencing for free!


Why did I get this?
Old stat was useless. Set to 20? Comes on at 17.goes off at 23.
Where stat was is east facing. My office room is west.
Heating would come on while my room was baking.
Heating would go off when my room was cold.
Tado has certainly solved that.

We also both WFH. So 9-5 we are in our offices. 5-10 living room and kitchen.
Then obviously bedroom.

That's basic schedule

Geo fencing is nice in that of we go away heating is all automated too.

 

[danlightbulb]

I have full tado too.
I did it all myself.
Every radiator bar towel rail and downstairs hall has one.

Caveat. I have a tank.

I removed our control unit and replaced with tado unit (wiring was provided by app)

I removed old analogue wall thermostat and bridged the wires (always on)

Now the Tado control unit calls for CH or HW as a direct replacement to the old one.

Any one TRV can turn the boiler on.
HW is obviously same method. If it's requested it comes on.

I bought a V2 box from ebay so I get the geofencing for free!

What boiler do you have and did you wire into the flow modulating functionality?

 

[413x]

What boiler do you have and did you wire into the flow modulating functionality?

Um. I have no idea. I doubt it.

This is an old potterton something or other.
As far as I'm aware the pump and boiler come on and off and that is all the smart stuff controls.

I believe it's a potterton suprima

 

[squerble]

Um. I have no idea. I doubt it.

This is an old potterton something or other.
As far as I'm aware the pump and boiler come on and off and that is all the smart stuff controls.

I believe it's a potterton suprima

A quick Google suggests these models don't have OpenTherm capability so it'll just work in an on/off fashion @danlightbulb

@danlightbulb Also, it's flow temperature modulation via OpenTherm. The heating pump is what would modulate flow rate, be it the one in the boiler or elsewhere on the heating loop.

 

[413x]

A quick Google suggests these models don't have OpenTherm capability so it'll just work in an on/off fashion @danlightbulb

@danlightbulb Also, it's flow temperature modulation via OpenTherm. The heating pump is what would modulate flow rate, be it the one in the boiler or elsewhere on the heating loop.

Thought as much. It's old and basic. The service guy said he liked them. Reliable.

Bet it's inefficient as hell!

 

[danlightbulb]

A quick Google suggests these models don't have OpenTherm capability so it'll just work in an on/off fashion @danlightbulb

@danlightbulb Also, it's flow temperature modulation via OpenTherm. The heating pump is what would modulate flow rate, be it the one in the boiler or elsewhere on the heating loop.

Yeah Ive developed my understanding of it over the past couple of days.

What I need to do is decide whether its worth trying to get a device, likely the Tado, to connect to the EMS bus on my Worcester Bosch boiler. To do this I need to buy the EU version of the device and get it shipped here. Or I can buy the UK version which doesn't support EMS bus link so I'd have to wire it using switched live approach. To connect via EMS I would also have to open my boiler case to make the connection. That's why im interested in @Demon and what he did to wire this up.

Its £200 for the EU version or £100 for the UK starter pack currently on screwfix.

 

[Demon]

Could you elaborate on your configuration please?

I've discovered that the UK version of the v3 wireless interface doesn't support bus control but I can order the EU version which does have it. I believe they used to make a separate bus connection interface, which might be what you have, but this is now discontinued.

I'm particularly interested in how you made the connection to the boiler EMS interface please.

Sure,
Originally I had the basic starter kit (just internet bridge + wireless thermostat), this was wired from my old wall thermostat to the boiler, where I wired the other end as a normal manual thermostat (i.e. mains voltage)..

Later on when we had a load of building work done they removed the wall with the old thermostat on, so basically I had no wiring at all, so I bought this:

tado° Extension Kit (Add-On) - Hot Water Control & Dual Channel Wireless Receiver For tado° Smart Thermostats : Amazon.co.uk: DIY & Tools

Shop tado° Extension Kit (Add-On) - Hot Water Control & Dual Channel Wireless Receiver For tado° Smart Thermostats. Free delivery on eligible orders of £20 or more.

www.amazon.co.uk

"tado° Extension Kit (Add-On) - Hot Water Control & Dual Channel Wireless Receiver"

That kit has the "A | - | +" connections on the right hand side, the installation instructions (just checked via the Tado App and confirmed) wire the + and - from the Tado to the "BB" connection on my CDi Greenstar 38 Combi which is the EMS bus as far as I am aware.

Spoiler: App Instructions

They don't do that extension kit anymore, but I see what you mean, the EU version of the V3+ kit has the same connections as I have, the UK version has some cut down version without the "A | - | +" connections..

Mine works a treat and added hot water control as well (although I don't need that) the TADO app and installation method through a lovely wizard is 10/10 from me!

The other tip is I removed the DT20RF programmer from the boiler previously and found loads of installers sell the little blank covers for a few quid on ebay, they must have left over from installs, this neatens up the boiler with no ugly controller on show.

 

[danlightbulb]

They don't do that extension kit anymore, but I see what you mean, the EU version of the V3+ kit has the same connections as I have, the UK version has some cut down version without the "A | - | +" connections..

Mine works a treat and added hot water control as well (although I don't need that) the TADO app and installation method through a lovely wizard is 10/10 from me!

The other tip is I removed the DT20RF programmer from the boiler previously and found loads of installers sell the little blank covers for a few quid on ebay, they must have left over from installs, this neatens up the boiler with no ugly controller on show.

Thanks for replying that sounds perfect to what I want to do.

I do have to open up the boiler front cover though, which strictly speaking is not allowed. Was this easy to do and access the terminals?

Did you have to go through the setup menu to activate a certain mode on the Tado stat?

Thanks for the tip to blank off the mechanical rotary timer with a blanking plate, that sounds ideal as well. Would you know what to search for please?


Do you think its worth £100 extra to get the EMS interface?

 

[Demon]

Thanks for replying that sounds perfect to what I want to do.

I do have to open up the boiler front cover though, which strictly speaking is not allowed. Was this easy to do and access the terminals?

Did you have to go through the setup menu to activate a certain mode on the Tado stat?

Thanks for the tip to blank off the mechanical rotary timer with a blanking plate, that sounds ideal as well. Would you know what to search for please?


Do you think its worth £100 extra to get the EMS interface?

Assuming yours is similar to mine, the TADO app wizard is very detailed, it gets you to power off, it takes you through taking the front panel off, dropping the control section down etc, where to route the cable, how to connect.. Fairly easy.

It's absolutely fine to take the front cover off IMO, the Worcester Bosch is really well designed for service, the control panel is hinged so it all comes down and is easy to access. I don't think TADO would offer the installation guide in the App if it wasn't appropriate.

For the blanking panel, I just searched 'Worcester Bosch Blank Panel' .. there is one (a bit pricey) on there now (https://www.ebay.co.uk/itm/125524680247).

And as for EMS, I don't know, I'm a techy person, so when I saw it was using the EMS to control the boiler I just prefer that over the on/off basic AC switching.. There is some debate on if it actually works correctly, but I'm happy knowing I've done what I can and never think 'What if?"
Knowing what I know now, and that the Tado stuff has continued to work well etc, I would pay the extra, although on the Tado shop, it's £199 (https://uk.shop.tado.com/products/wireless-smart-thermostat-starter-kit-v3-eu-version) which is only £50 more than the normal 'white' version anyway?


On the subject of TRVs and usefulness of this, well, having been in the house for 14 years, I have plenty of historical evidence of gas usage, and it dropped nearly 20% from the moment I installed TADO and has stayed lower since..
We have Smart TRVs in the bedrooms only at the moment and downstairs with manual TRVs and the wireless thermostat.. We only want the bedrooms warm in the morning when we wake up for 30 minutes, the rest of the day they are off, so in a morning all the house is heated quickly.. then during the day or evening, the heating will only come on for downstairs only, the bedrooms are all off.. Without the Smart Controls the bedrooms would heat to their manually set TRV setting every time the downstairs was being heated, which was pointless as we are all downstairs.