Replacing 3 Channel Heating and Water system with Tado Wireless V3+ kit

[C0mbat]

I'm creating a new thread as my previous one doesn't quite touch on what I'm potentially now needing to do. This is the old one (that has photos of my wired thermostat wiring):

How to thermostats work

Hi all, I have a gas boiler than is for underfloor heating and hot water (on demand) on the ground floor, heating and a hot water tank on the first floor, and then heating on the second floor. The first and second floor heating and the hot water tank are managed by a Timeguard TRT038N 3...

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I have a Timeguard 3 Channel Programmer that controls heating on the 1st and 2nd floor using two seperate wired thermostats (one on each floor) and then the hot water tank. I've been thinking about replacing them with the Tado for a while and then this week the 2nd floor thermostat stopped working. It actually stops the heating coming on upstairs so I either need to replace it or take the plunge and replace the whole system.

I'm leaning towards the Tado Wireless V3+ kit (only £85 from Screwfix just now plus I have a £10 voucher) plus an extra temperature sensor (unless you can pair wired Tado thermostats with the wireless kit?). However, I'm confused whether the existing 1st floor wired thermostat (the working one) and the 2nd floor thermostat (the malfunctioning one) will cause issues if I just leave them as is? I'd like to leave them as is for now to be honest. The alternative is that I buy two wired Tado thermostats to replace the existing ones but still use the wireless receiver from the Wireless V3+ kit to replace the Timeguard 3 channel programmer but I'm not sure if the wired Tado thermostats work with the wireless kit?

 

[stem]

At the moment you have a Timeguard programmer that provides control of the time the heatig is on, and two room thermostats that provide control of the room temperatures. Smart thermostats Tado / Nest / Hive / Wiser, et al, combine both functions in a single unit controllable via an app. So just changing the Timeguard and keeping the existing thermostats isn't really an option.

You say that the existing the existing 2nd floor thermostat has stopped working, I take it you have had this confirmed and are not just assuming it's the thermostat that's at fault. Generally if a heating zone stops working, in my experience, approximately 90% of the time it's the motorised valve controlling the heating zone that has failed and only 10% of the time it's actually the room thermostat.

You can replace the Timeguard with the Tado wireless kit you reference for HW and CH Zone 1 and a wired Tado for CH Zone 2.

Alternatively Drayton Wiser has a wireless three channel kit that can control two heating zones and hot water. Also available from Screwfix

 

[ericmark]

In hind sight, and hind sight is easy, I likely made the wrong decision when I split my heating into two zones, I have the flat as one zone, and the main house as other zone, each zone has it's own pump and motorised valve, and it's own thermostat, the flat rather a simple bi-metal thermostat, and the main house Nest Gen 3 and Drayton Wiser thermostats in parallel. The Nest Gen 3 does the domestic hot water if required, the Drayton wiser only does room heating.

So your first thing is to decide what is best for you. I am not saying convert all the heating now. What I am saying decide on a final goal, and then decide what to do first.

Today there is no need for a wall thermostat, yes I have two in main house, but if I was today planning from scratch, I would not need one. If I look at my Wiser hub, it can link to both wall thermostats and/or TRV's. So I could use a TRV in every room, and have no wall thermostat, not saying that's the best idea, but it's an option.

I see Wiser does a three zone hub, so can have both zone valves and TRV's, but, an electronic TRV is a zone valve, so why?

The picture shows the circulation of warm air in the room, and the TRV is in about the best place to monitor the return air temperature, it could be on wall opposite to radiator, and it may mean the TRV is set a little lower to what you would set the wall thermostat, but question one has to be, is there some where on the wall opposite where the thermostat can be mounted?

My wall opposite to radiator has 5 Ikea Billy Bookcase units, with doors, so even free standing, no real place to place the wall mounted thermostat. However two radiators in the room at 90º to each other, so there is wall space opposite the other radiator.

But I have nine electronic TRV heads, of which non link to the hubs, as said I have made a mistake, would like to stop you doing the same. The Wiser thermostat is at moment free standing while we decide where it needs to go. The Nest is hard wired, so fitted in the hall, which does not work very well, as hall to slow to cool. However since it also works DHW keeping it.

So ask yourself, what do you want? Is there any point splitting a home into two zones, in my main house, we have one upstairs room as an office, and another as a craft room, plus the two bedrooms, so spiting up/down for me would not work. Each room has it's own TRV and I am now trying to reach them all to change the batteries. The eQ-3 were cheap, £15 each in 2019, I bought five, the batteries only last a year in them, and bluetooth not wifi. The Energenie were far more expensive, bought as pairs, one has failed (carpet fitters killed it) so batteries last around 2 years, and it was claimed to work with Nest (they don't) about £40 each. The damaged one replaced with Kasa, which is the best of the three, but although 4 do connect with wifi so can set anywhere in the world, they do not connect to either of my hubs.

My idea is to get Wiser TRV's for key rooms, like wife's bedroom, and move the existing down into the flat. I really don't get the idea of two zones, when I had children at home, so 4 bedrooms used as bedrooms, the children would go to bedrooms to do homework, so from 4 pm both down and upstairs rooms were used, so no point in up/down zones.

The wiser three channel is a lot more expensive to two channel, and two channel more expensive to single channel, and over one channel, it seems the OpenTherm option may not work correctly, and second channel is for domestic hot water (DHW) so to have two zones needs the three channel version. Personally can't turn off DHW (C Plan) and rarely use oil to heat DHW in the summer, as solar does that, and DHW takes two days to cool, so simple timed DHW is all that is required. So single channel Wiser Hub.

So what are your aims, I can only talk about my aims and mistakes, as don't know what your aims are.

 

[C0mbat]

At the moment you have a Timeguard programmer that provides control of the time the heatig is on, and two room thermostats that provide control of the room temperatures. Smart thermostats Tado / Nest / Hive / Wiser, et al, combine both functions in a single unit controllable via an app. So just changing the Timeguard and keeping the existing thermostats isn't really an option.

You say that the existing the existing 2nd floor thermostat has stopped working, I take it you have had this confirmed and are not just assuming it's the thermostat that's at fault. Generally if a heating zone stops working, in my experience, approximately 90% of the time it's the motorised valve controlling the heating zone that has failed and only 10% of the time it's actually the room thermostat.

You can replace the Timeguard with the Tado wireless kit you reference for HW and CH Zone 1 and a wired Tado for CH Zone 2.

Alternatively Drayton Wiser has a wireless three channel kit that can control two heating zones and hot water. Also available from Screwfix

Thanks for your response. The reason that I think that it's the thermostat unit is because the light on it was flickering on and off a lot when I was turning the dial the other day. Then the light just went off and hasn't come back on. You could still make a case for it being something else but I'm not sure how I would check. Is there a way of by passing the thermostat and checking if the heating still works?

 

[C0mbat]

In hind sight, and hind sight is easy, I likely made the wrong decision when I split my heating into two zones, I have the flat as one zone, and the main house as other zone, each zone has it's own pump and motorised valve, and it's own thermostat, the flat rather a simple bi-metal thermostat, and the main house Nest Gen 3 and Drayton Wiser thermostats in parallel. The Nest Gen 3 does the domestic hot water if required, the Drayton wiser only does room heating.

So your first thing is to decide what is best for you. I am not saying convert all the heating now. What I am saying decide on a final goal, and then decide what to do first.

Today there is no need for a wall thermostat, yes I have two in main house, but if I was today planning from scratch, I would not need one. If I look at my Wiser hub, it can link to both wall thermostats and/or TRV's. So I could use a TRV in every room, and have no wall thermostat, not saying that's the best idea, but it's an option.

I see Wiser does a three zone hub, so can have both zone valves and TRV's, but, an electronic TRV is a zone valve, so why?

The View attachment 362114 picture shows the circulation of warm air in the room, and the TRV is in about the best place to monitor the return air temperature, it could be on wall opposite to radiator, and it may mean the TRV is set a little lower to what you would set the wall thermostat, but question one has to be, is there some where on the wall opposite where the thermostat can be mounted?

My wall opposite to radiator has 5 Ikea Billy Bookcase units, with doors, so even free standing, no real place to place the wall mounted thermostat. However two radiators in the room at 90º to each other, so there is wall space opposite the other radiator.

But I have nine electronic TRV heads, of which non link to the hubs, as said I have made a mistake, would like to stop you doing the same. The Wiser thermostat is at moment free standing while we decide where it needs to go. The Nest is hard wired, so fitted in the hall, which does not work very well, as hall to slow to cool. However since it also works DHW keeping it.

So ask yourself, what do you want? Is there any point splitting a home into two zones, in my main house, we have one upstairs room as an office, and another as a craft room, plus the two bedrooms, so spiting up/down for me would not work. Each room has it's own TRV and I am now trying to reach them all to change the batteries. The eQ-3 were cheap, £15 each in 2019, I bought five, the batteries only last a year in them, and bluetooth not wifi. The Energenie were far more expensive, bought as pairs, one has failed (carpet fitters killed it) so batteries last around 2 years, and it was claimed to work with Nest (they don't) about £40 each. The damaged one replaced with Kasa, which is the best of the three, but although 4 do connect with wifi so can set anywhere in the world, they do not connect to either of my hubs.

My idea is to get Wiser TRV's for key rooms, like wife's bedroom, and move the existing down into the flat. I really don't get the idea of two zones, when I had children at home, so 4 bedrooms used as bedrooms, the children would go to bedrooms to do homework, so from 4 pm both down and upstairs rooms were used, so no point in up/down zones.

The wiser three channel is a lot more expensive to two channel, and two channel more expensive to single channel, and over one channel, it seems the OpenTherm option may not work correctly, and second channel is for domestic hot water (DHW) so to have two zones needs the three channel version. Personally can't turn off DHW (C Plan) and rarely use oil to heat DHW in the summer, as solar does that, and DHW takes two days to cool, so simple timed DHW is all that is required. So single channel Wiser Hub.

So what are your aims, I can only talk about my aims and mistakes, as don't know what your aims are.

Hi, thanks for your detailed response. I get what you're saying but I'm pretty happy with the two heating zones. There's one for the 1st floor and one for the 2nd floor. I rarely need the 1st floor heating but regularly need the 2nd floor heating as that is where I work from. You could make a case for a single zone with TRV heads to control the radiators but it seems counter intuitive to try and achieve the same thing as it would cost me extra money to switch back to a single zone plus then more on TRVs. So sticking to what I have seems by far the cheapest option but it also fits my use case very well. Furthermore, using TRVs actually still uses energy because you've actually got the heating zone valve open and it's heating the pipes around your house but just not necessarily specific radiators right?

 

[ericmark]

I think your right looking at cost to fit linked electronic TRV heads.

However, with all TRV's closed the by-pass valve opens, so water only circulates to by-pass valve and back, and in some cases by-pass valve is inside the boiler.

And once one valve opens, it goes from boiler to that radiator and back, it does not have to heat up all pipe work.

And the whole idea is for the boiler to modulate, (turn down) and once fully modulated start a mark/space ratio, and for that to work efficiently
you want analogue control, and zone valves are simple on/off, so each time the valve opens the boiler starts all over again setting how much to modulate unless using something like OpenTherm so thermostat sets output.

EPH do a thermostat for use with zone valves and OpenTherm, but that means one set of wires to zone valve and another set to boiler. Wiser I think is the same. Since I have oil, so boiler does not modulate, I have not looked fully into this.

 

[stem]

The reason that I think that it's the thermostat unit is because the light on it was flickering on and off a lot when I was turning the dial the other day. Then the light just went off and hasn't come back on. You could still make a case for it being something else but I'm not sure how I would check. Is there a way of by passing the thermostat and checking if the heating still works?

That does sound like the thermostat. The easiest test is to connect the thermostat's live and switched live wires together. That takes the thermostat out of the circuit and if the heating comes on then then it will confirm there is a problem with the thermostat.

With regard to your photo of the thermostat wiring, the live will be the brown wire in terminal 1 and the switched live the grey in terminal 3.

 

[C0mbat]

That does sound like the thermostat. The easiest test is to connect the thermostat's live and switched live wires together. That takes the thermostat out of the circuit and if the heating comes on then then it will confirm there is a problem with the thermostat.

With regard to your photo of the thermostat wiring, the live will be the brown wire in terminal 1 and the switched live the grey in terminal 3.

View attachment 362451

Thanks for your response on his. I actually got the Tado V3+ Wireless kit (plus an extra wired thermostat). In the instructions there are steps to decommission an existing wired thermostat and replace it with the wireless one. The attached instructions have a set of images that line up with what you've suggested. The connector blocks will connect the live and switched live in order to bypass it. I just want to double check something though.

You're saying that the brown going in to terminal 1 is live and the grey in terminal 3 is switched live? Do I just throw away the brown wire that is connecting 3 to 5? And what is the black wire then? Neutral? And there's no Earth? I'm confused and worried about misunderstanding which wire is which and blowing something up lol.