Can Smart Thermostat replace my poorly located old-style programmer?

grassmarket

The CH/HW programmer in our new house is inconveniently located in a cupboard in integral garage - alongside the newish Vaillant gas boiler & large Megaflow HW tank (inc. immersion heater). Problem: don’t fancy going out there in the cold weather to adjust or override the timer! 

Rather than drill a big hole & redecorate, just to relocate programmer inside house - is a smart thermostat the better solution? The house has 2 area thermostats for up & downstairs zones - does that complicate things? Is Tado the best option for a Vaillant boiler? Having read some other advice on the forums, it seems that Vaillant boilers have OpenTherm & work best with Tado - is that right? There are TRVs on most rads, but we don’t really want to get involved in smart controls on these. We just want to be able to adjust the main programmer from the warmth & comfort of indoors. & maybe occasionally switch it on/off when away from home. 

Any advice would be much appreciated, many thanks.

deano2099

For a Tado yes, you get the Wireless kit and it will come with a replacement for your programmer which doesn't have any buttons, just a couple of status lights. Then you get a thermostat that can either replace your existing thermostat or go somewhere else (but either you need to get the old thermostat disconnected) as it's wireless/battery powered. You can use that or the app to control the system. Only thing to note is the programmer will need access to your WiFi so you'll need to be sure you can get a signal in the garage.
Other smart systems may work differently.

Edit - just noticed you have two thermostats, doesn't complicate it as Tado does multi-zone systems, but you'll need a second wired or wireless thermostat from them to replace the second one also.

ChaunceyGardiner

the programmer will need access to your WiFi

The wireless receiver and thermostats communicate via radio, not Wi-Fi.

For OpenTherm, you'll need to buy the older extension kit, or purchase a wireless receiver from Europe. The UK market wireless receiver doesn't support it.

BUFF

as per above the current UK version of the Tado wireless extension does not do modulation (it lacks the contacts that used to support it) - for some reason (they say that nobody used it) they removed them from the UK wireless extension only (the wired thermostat still has it). https://community.tado.com/en-gb/discussion/14049/tado-should-bring-back-modulation-to-their-wireless-thermostat
Afaik they do need access to your internet access as Tado is effectively cloud-based for scheduling etc. although you can have local, manual input (off/on, change temp) in the event the internet connection goes down.
Tado Smart AC does need WiFi, heating not.

As for your Vaillant boiler it may also depend upon which exact boiler you have (or you may need some form of adapter module) - Vaillant, Viessmann & Worcester all have their own proprietary ebus communications protocols in some boilers.

Also have a look at the Drayton Wiser system (or no doubt Vaillant will have their own).

[Deleted User]

Opentherm control isn’t simply ‘plug and play’ on an existing set up. Your programmer/controller will most likely be 230volts: Opentherm is a low voltage control protocol.

By way of example, in my previous home I installed an Atag boiler which works happily with Opentherm. However, to make it work, I had to purchase an Opentherm Bridge for my smart control and then wire the Bridge directly to the 2 low voltage terminals on the boiler PCB. The smart controller communicated with the Bridge using Zigbee wifi. Clearly, the high voltage connections to the boiler need to be disconnected.

Not all Valliant boilers sold in the UK come with the Opentherm connections. I know that some Valliant owners have had to purchase an additional board from the EU where Opentherm is standard.

It is also worth pointing out that the Opentherm protocol is very loose in its application. For example, when there is a HW cylinder re-heating demand, Opentherm will demand 93C as the boiler temperature. The boiler itself should limit this to the TMaxSet temperature in the boiler: not all boilers apply this limit.

Is it worth it? Yes, if you can get it to work properly. I have seen Opentherm control as being similar to driving through a city with all the traffic lights on green. One of its key advantages is that it reduces the frequency of boiler on/off cycling.

grassmarket

ChaunceyGardiner said:

the programmer will need access to your WiFi

The wireless receiver and thermostats communicate via radio, not Wi-Fi.

For OpenTherm, you'll need to buy the older extension kit, or purchase a wireless receiver from Europe. The UK market wireless receiver doesn't support it.

ChaunceyGardiner said:

the programmer will need access to your WiFi

The wireless receiver and thermostats communicate via radio, not Wi-Fi.

For OpenTherm, you'll need to buy the older extension kit, or purchase a wireless receiver from Europe. The UK market wireless receiver doesn't support it.

Understood - receiver & thermostats in the home communicate with each other via radio - thanks. But I communicate with the receiver via Wifi. So I think that Deono2099 was just warning me that the receiver - which I (no doubt incorrectly) called a programmer - needs to be able to connect to my Wifi, so that I can communicate with it. If so, then answer = yes, there’s a perfectly good Wifi connection in the garage. So all good, I hope.

ChaunceyGardiner

But I communicate with the receiver via Wifi. So I think that Deono2099 was just warning me that the receiver - which I (no doubt incorrectly) called a programmer - needs to be able to connect to my Wifi, so that I can communicate with it.

Sorry, perhaps I wasn't clear. A separate component, the Tado bridge, connects to your router, via an ethernet connection. It then communicates with all the other Tado devices via a proprietary radio signal. Wi-Fi isn't involved at any stage.

deano2099

I thought it was all done on WiFi but never looked at it in that much detail and appear to be wrong. 

You're not wrong to call it a programmer. What you have at the moment is a programmer. With the Tado system you replace that with a receiver which serves the same purpose, but I guess it would be weird to call it a programmer as you'd be setting programmes on the app instead and they just get sent to it.

[Deleted User]

For info:

https://myboiler.com/opentherm/vaillant-opentherm/

Note the warranty implications.

Have you considered Valliant’s own control systems:

https://www.vaillant.co.uk/for-installers/products/controls-and-thermostats/

grassmarket

CG - thanks for that explanation. But now that you’ve mentioned Ethernet connections - I’m really confused! Do you mean that in the Tado setup, a device/gateway is physically connected to the router, with all the other devices communicating with it via radio? If so - what’s physically connected to the boiler & how do I communicate with it? Do I communicate with gateway via Wifi & then gateway communicates with boiler device via radio? 

All we’re looking for is a way to control our CH/HW programmer (currently in the garage) without having to go outside to do it - other than drilling a big hole in the wall & relocate the programmer inside the house. Is a smart thermostat a reasonable way to solve that problem?

As for Tado, OpenTherm etc - I neither want nor don’t want them. I just want some advice about what I should have in my setup to make it work right.

grassmarket

Buff - thanks for your input; unfortunately I don’t understand most of it! Modulation? 

Perhaps I should investigate the Vaillant options, as suggested by Dolor.