3 channel to 2 channel controller?

Deanicus · 19-11-2015 02:59PM #1

Hey folks

Long story short I have a tado smart thermostat. Due to a mixup when ordering with them several months ago I bought their extension kit thinking it would be compatible with my system.

I since discovered it was not and had held out hope that when they support multiple zones next month it would be possible.

However, having looked at the kit in more detail I can see that it is only a 2 channel controller whilst I have a 3 channel system (Horstmann H37XL. 2xheating, 1xwater with zone 1 being controlled by the tado and zone 2 has 2 normal stats). My fear is that it will never be compatible and I have expensive kit now lying around.

I was just wondering if it is at all possible to wire this so that it controls the 3 channels? Since I am leaving the tado to decide on whether the heating comes on or not, I was thinking I could wire the 2 heat channels into one. Although my fear is that the signal from one would activate the other too. My other thought would be to wire one channel and the hot water to the tado extension kit and leave the horstman controlling the other heating channel. Does this sound plausible?

For reference:

Tado wiring diagram (page 11): https://support.tado.com/hc/de/article_attachments/202119835/tado-Manual-Technical_Documentation_V1.1_EN.pdf

Horstmann wiring: http://www.horstmann.co.uk/files/1713/9867/2108/installer_guide_H37XL-ISeries21.pdf

Thanks for any help you can provide

Deanicus · 19-11-2015 03:16PM

Oh, I should mention that Tado support suggested it was possible but they would not give me any detail on how to wire it. Their explanation was that it was very complicated for a normal user and they could not give out instructions in good conscience in case something went wrong!

I have a good understanding of the issue now but thought I would seek some guidance before giving it a shot

nmacc · 19-11-2015 10:43PM

By my reading of the Tado manual it is, with the extension pack, a 2-zone system, being one heating zone and the extension controlling the hot water.

The reference on page 1 to hot water programmers (UK only) is because continental systems usually have constant hot water or combi systems and they don't usually time the hot water circuit.

The Bridge is simply there to connect your Smart thermostat to the Internet.

On Page 2 it tells you that you will need one Smart stat for each heating zone and these are connected to the heating zones by replacing your existing thermostat with the Tado Smart stats and using your existing wiring from the stat back to the boiler.

This will give you individual control of the heating zones, but if you've got a 3-zone clock at the moment then you've probably got a thermostat on your hot water cylinder. This can still be used with the Extension Pack and the wiring is quite straightforward.

So the quick answer is that what you have will work fine, but only control one room/heating zone and you'll need to buy another Smart stat for your second zone. The wiring is simple and I can send you a diagram if you wish.

Deanicus · 19-11-2015 11:33PM

nmacc wrote: »

By my reading of the Tado manual it is, with the extension pack, a 2-zone system, being one heating zone and the extension controlling the hot water.

The reference on page 1 to hot water programmers (UK only) is because continental systems usually have constant hot water or combi systems and they don't usually time the hot water circuit.

The Bridge is simply there to connect your Smart thermostat to the Internet.

On Page 2 it tells you that you will need one Smart stat for each heating zone and these are connected to the heating zones by replacing your existing thermostat with the Tado Smart stats and using your existing wiring from the stat back to the boiler.

This will give you individual control of the heating zones, but if you've got a 3-zone clock at the moment then you've probably got a thermostat on your hot water cylinder. This can still be used with the Extension Pack and the wiring is quite straightforward.

So the quick answer is that what you have will work fine, but only control one room/heating zone and you'll need to buy another Smart stat for your second zone. The wiring is simple and I can send you a diagram if you wish.

Hi nmacc

If you could send on the wiring diagram that would be great!

Just so I am clear you are saying that with 1 smart thermostat I can control 1 zone and the hot water. If I get a 2nd then I can control both heating zones? Given that the extension kit only has space for 2 channels would that mean wiring both heating channels to the same channel? If that is right then am I correct in saying that with my current setup my standard stats would then be controlling the other zone?

Hope that makes sense!

nmacc · 19-11-2015 11:47PM

Not exactly.

The extension kit has only one channel, not two; it will be used only for the hot water circuit. The Smart thermostat appears to be designed to control the heating using the wiring that goes to your existing thermostats. The water heating part of the Smart thermostat is connected by radio to the extension kit and this is connected to the boiler wiring.

You could put the extension kit where the Horstmann clock is at the moment and connect it to your hot water zone wiring - but you could also put it in the hot press (nor recommended putting electronics in the hot press) and bypass the clock entirely.

I'll explain in more detail tomorrow when I've had a chance to do the sketch.

Deanicus · 19-11-2015 11:56PM

nmacc wrote: »

Not exactly.

The extension kit has only one channel, not two; it will be used only for the hot water circuit. The Smart thermostat appears to be designed to control the heating using the wiring that goes to your existing thermostats. The water heating part of the Smart thermostat is connected by radio to the extension kit and this is connected to the boiler wiring.

You could put the extension kit where the Horstmann clock is at the moment and connect it to your hot water zone wiring - but you could also put it in the hot press (nor recommended putting electronics in the hot press) and bypass the clock entirely.

I'll explain in more detail tomorrow when I've had a chance to do the sketch.

Thanks!

I think I get you. You are right about the smart stat. I simply replaced one of the wall stats with it. On the Horstmann then I set that zone to always on so the smart stat can turn the heating on and off

What you are suggesting then is to remove the hot water wiring from the horstmann and put it into the extension. I'll then be using both with the horstmann still controlling access to the heating and the extension controlling access to the hot water.

Is that right?

No need to respond to this right now. I appreciate your help and look forward to your reply tomorrow

Thanks again

nmacc · 21-11-2015 12:12PM

Sorry Deanicus, I should have got back to you yesterday and I spent about 20 minutes this morning typing up a detailed explanation, but when I tried to post it Boards returned a Database Error and the entire post was lost.

Grrr.

Get back to you later.

nmacc · 21-11-2015 12:16PM

Right, quick and dirty answer.

Select jumper position 2 on the extension kit.

Use the same spur that supplies the Horstmann (important!) and wire L & N to the extension kit.

Connect terminal 3 on the extension to terminal 5 on the Hortstmann. Can be tricky to get the wires neatly into the Horstmann backplate.

Set the Horstmann to OFF for the Hot Water zone. The existing hot water cylinder thermostat will still work.

No diagram needed!

Deanicus · 22-11-2015 02:01AM

nmacc wrote: »

Right, quick and dirty answer.

Select jumper position 2 on the extension kit.

Use the same spur that supplies the Horstmann (important!) and wire L & N to the extension kit.

Connect terminal 3 on the extension to terminal 5 on the Hortstmann. Can be tricky to get the wires neatly into the Horstmann backplate.

Set the Horstmann to OFF for the Hot Water zone. The existing hot water cylinder thermostat will still work.

No diagram needed!

Hi nmacc

Sorry for not getting back sooner. Was taken down with a stomach bug which I inevitably caught off my son!

That seems pretty simple!

Can I just ask a couple of questions? Just for peace of mind

1. I assume the extension overrides the OFF of the horstmann then? My thinking is that the horstmann just sends the signal and the extension will now do that?

2. If there is no spur visible can I just install another on the current wires and run the two feeds off it?

3. What type of wiring would I need to buy? For the power stuff I assume standard blue/brown wiring will do (the two core stuff you can find in Woodies etc). For the actually channel wiring is it special stuff?

4. Finally, I tried taking the horstmann off to have a look at what I was dealing with (mains off of course!) and for the life of me it felt like I was ripping the backplate off so I stopped. Have you ever dealt with them before? Is there a knack to it or is it just brute force?

Thanks a mil for all your help and sorry to bother you again. I am pretty confident in doing it now but didn't want to go complete cowboy and just lash wires together!

nmacc · 22-11-2015 02:53AM

1. Yes. Signal isn't really the right word. The relay in the Horstmann will join terminal 6 which is connected to Live to terminal 5 when the output is on. That means that either the Horstmann or the extension can turn on the hot water, so you need to leave the Horstmann in OFF to avoid it over-riding the Tado extension.

2. The spur is the supply to the existing Horstmann clock and onwards to the boiler. It's usually a single faceplate with a fuse in a slot. The important thing is that it is the source of power to the heating circuit. The easiest way to be sure you have the right one is to take Live and Neutral from the Horstmann.

3. Yes, regular blue and brown from Woodies will be fine.

4. There are two small screws in the top edge of the Horstmann clock. You need to loosen these screws until they are almost out, then pull the top edge of the clock out and down. The bottom edge of the clock slots into two lugs on the backplate, so don't pull from the bottom. Please note that most clocks of this design actually work in the opposite way and pull from the bottom, but not the Horstmann, so don't make that mistake - pull from the top.

Oh yes, definitely mains off!

Deanicus · 22-11-2015 03:12AM

nmacc wrote: »

1. Yes. Signal isn't really the right word. The relay in the Horstmann will join terminal 6 which is connected to Live to terminal 5 when the output is on. That means that either the Horstmann or the extension can turn on the hot water, so you need to leave the Horstmann in OFF to avoid it over-riding the Tado extension.

2. The spur is the supply to the existing Horstmann clock and onwards to the boiler. It's usually a single faceplate with a fuse in a slot. The important thing is that it is the source of power to the heating circuit. The easiest way to be sure you have the right one is to take Live and Neutral from the Horstmann.

3. Yes, regular blue and brown from Woodies will be fine.

4. There are two small screws in the top edge of the Horstmann clock. You need to loosen these screws until they are almost out, then pull the top edge of the clock out and down. The bottom edge of the clock slots into two lugs on the backplate, so don't pull from the bottom. Please note that most clocks of this design actually work in the opposite way and pull from the bottom, but not the Horstmann, so don't make that mistake - pull from the top.

Oh yes, definitely mains off!

Thanks!

Would I get away with using a 3 core and using the earth wire as the wire to connect terminals 3 & 5?

Re the horstmann, I took the screws off and tried pivoting from the top but it just aint budging. Is the bit where the screws go in to come away too or is that part of the backplate? Its hard to tell!!

Last questions, honest!

Deanicus · 22-11-2015 03:55AM

Forgive my crude photoshop skills but in the attached pic should it come away from the red line or from the wall?

Robbie.G · 22-11-2015 08:48AM

Deanicus wrote: »

Forgive my crude photoshop skills but in the attached pic should it come away from the red line or from the wall?

Unscrew the two fixing screws and pivot it away from wall

nmacc · 22-11-2015 11:22AM

Loosen off those two screws and prise it apart at the red line

Deanicus · 23-11-2015 09:35AM

Thanks very much for all your help.

I'm going to attempt it this weekend so wish me luck

Caoimh1n · 26-11-2015 01:39PM

I would be very interested to see how you get on. I have a similar situation where I ordered tado but later found out that it doesn't really support my setup (3 mechanical timers. 2 for heating, and 1 for hot water), they refer to it as a gravity based system.

I was just going to return it and get the new 3rd generation nest system that does support the water tank, however I prefer the minimal look of the tado and the gps function.

I have 3 apt mechanical timers and a Potterton Promax He plus boiler.

Deanicus · 26-11-2015 01:57PM

Caoimh1n wrote: »

I would be very interested to see how you get on. I have a similar situation where I ordered tado but later found out that it doesn't really support my setup (3 mechanical timers. 2 for heating, and 1 for hot water), they refer to it as a gravity based system.

I was just going to return it and get the new 3rd generation nest system that does support the water tank, however I prefer the minimal look of the tado and the gps function.

I have 3 apt mechanical timers and a Potterton Promax He plus boiler.

I'll let you know alright.

Have you replaced any of the mechanical ones with the tado?

Can you put the hot water on independently of the heating?

Do you have a central programmer which controls all 3 or as your post suggests they are independent timers not connected to each other in any way?

Based on my own knowledge and the help in this thread I think the solution for you might be to replace the hot water timer with the extension kit (assuming no central programmer) and replace both heating timers with tado stats (they are releasing additional stats for multiple zones next month)

Caoimh1n · 26-11-2015 02:31PM

Deanicus wrote:

Based on my own knowledge and the help in this thread I think the solution for you might be to replace the hot water timer with the extension kit (assuming no central programmer) and replace both heating timers with tado stats (they are releasing additional stats for multiple zones next month)

Deanicus wrote:

Do you have a central programmer which controls all 3 or as your post suggests they are independent timers not connected to each other in any way?

Deanicus wrote:

Can you put the hot water on independently of the heating?

Deanicus wrote:

Have you replaced any of the mechanical ones with the tado?

Hi Deanicus , thanks for your reply. I haven't received my tado yet (ordered it last friday), but I only ordered the starter kit, so will have to look in to ordering the extension kit.

To answer your questions, yes the water can be used independently, the timers are independent of each other (1 for upstairs heat, 1 for downstairs heat, and 1 for the hot water) however the water one needs to be on for the heat to work.

Deanicus · 26-11-2015 02:50PM

Caoimh1n wrote: »

Hi Deanicus , thanks for your reply. I haven't received my tado yet (ordered it last friday), but I only ordered the starter kit, so will have to look in to ordering the extension kit.

To answer your questions, yes the water can be used independently, the timers are independent of each other (1 for upstairs heat, 1 for downstairs heat, and 1 for the hot water) however the water one needs to be on for the heat to work.

Yeah I am pretty sure you need the extension kit to control any hot water, regardless of the system you have.

When you get the stat you login and they give you instructions on how to install it. If you had the kit they might have given you the instructions on how to do that one.

Nmacc on this thread knows a lot more about these things than I do but I do wonder whether the fact that the water needs to be on will affect the compatibility with the extension kit

Caoimh1n · 26-11-2015 03:40PM

Deanicus wrote:

Nmacc on this thread knows a lot more about these things than I do but I do wonder whether the fact that the water needs to be on will affect the compatibility with the extension kit

Yeah, kinda got that vibe from their customer services. They didn't really give me a difinitive answer. I'll look more in to it, but I know the new nest system will work out of the box. If there's a black Friday deal I might just go that way, but I'm still interested to see if you get yours working.

Deanicus · 26-11-2015 03:45PM

Caoimh1n wrote: »

Yeah, kinda got that vibe from their customer services. They didn't really give me a difinitive answer. I'll look more in to it, but I know the new nest system will work out of the box. If there's a black Friday deal I might just go that way, but I'm still interested to see if you get yours working.

I'm hoping to do it this weekend so will post back when I do.

I know the new Nest supports hot water but I think tado is still cheaper (obviously if it doesn't work for you then cost doesn't make a difference).

The deciding factor for me was certainly the geofencing. Nest is great but it only guesses whether you are home or not based on your previous behaviour. Any deviation from that whether that be changing shifts, bad traffic, good traffic etc and Nest will take a while to figure it out or you will have to put the heating/water on manually

To me that defeats the purpose. I like how tado knows where I am and adjusts the heating accordingly. I can turn it on and not worry about it ever again

Caoimh1n · 26-11-2015 04:56PM

Deanicus wrote:

To me that defeats the purpose. I like how tado knows where I am and adjusts the heating accordingly. I can turn it on and not worry about it ever again

Yeah, that's exactly why I would prefer Tado over nest, so hopefully...

nmacc · 26-11-2015 05:03PM

There's no good reason that I can see why the Tado shouldn't work with your set-up Caomh1n.

The individual Tado Smart stat has a single wired output to control one circuit. Adding the extension kit provides two benefits:

1. It adds hot water timed control
2. It makes the wired connection to the heating system into a wireless one (assuming you are within range)

You could wire up the extension kit to replace the hot water timer and one of the zone timers, leaving one timer in place for the remaining zone.

The fact that you need the hot water on for the boiler to run suggests that your wiring may need a little work for everything to run smoothly.

Caoimh1n · 26-11-2015 08:38PM

nmacc wrote:

There's no good reason that I can see why the Tado shouldn't work with your set-up Caomh1n.

The individual Tado Smart stat has a single wired output to control one circuit. Adding the extension kit provides two benefits:

1. It adds hot water timed control 2. It makes the wired connection to the heating system into a wireless one (assuming you are within range)

You could wire up the extension kit to replace the hot water timer and one of the zone timers, leaving one timer in place for the remaining zone.

The fact that you need the hot water on for the boiler to run suggests that your wiring may need a little work for everything to run smoothly.

Thanks nmacc, I wonder would it be possible to combine the two heat timers in to one and treat the house as one zone?

As far as the wiring goes, unfortunately I wouldn't know where to start. I'm sure I could quite easily get a copy of the boiler wiring diagrams, but I'm not sure if I'd know which wires to change/add.

nmacc · 26-11-2015 09:05PM

Unfortunately the boiler wiring diagram wouldn't help. I have one of those.

It's really the layout of the plumbing and wiring together, such as how the cylinder coil is fed, how the motor valves are set up, etc.

Not easy to figure out remotely.

Caoimh1n · 27-11-2015 07:29AM

nmacc wrote:

It's really the layout of the plumbing and wiring together, such as how the cylinder coil is fed, how the motor valves are set up, etc.

Ah, ok. I'll have to weigh up the options of getting someone to install it.

Thank you for your advise.

Caoimh1n · 27-11-2015 07:53PM

Just out of interest nmacc, would you know of anyone around the Dundalk area that would be able to make those changes?

Deanicus · 28-11-2015 02:21PM

Hey lads. See picture below

So I installed it last night. Not my neatest work. I gave a lot of extra slack in the wire in case I messed up trimming the wires (I dont have a proper wire cutters)

I also have an allergic reaction to drilling through my walls as it is steel frame and it never goes smoothly hence the over wiring. I just stuck it up using those sticky picture hangers.

I had a bit of an issue getting it to pair with the tado bridge. I called customer support and it took about 45 mins to get it all working. Had to change the channel the bridge was broadcasting on in order to connect the extension. This then disconnected the thermostat so had a round of getting that connected.

So far it seems to be working i.e. no mains trips!. I haven't had the chance to test it properly. I had the water on last night before I started and it was still hot this morning so not sure if that was just holding since last night or the tado heated it back up a bit. The water though was suspiciously hotter than I would have thought so I am worried that I did something wrong and it is constantly on. I have turned the water off altogether now and will test later, first that it is cold or at least lukewarm and then will test if it is heating up when I tell it to.

Just an interesting side note, one of the first questions they asked me was how I got it working on a triple relay system. Told them I had some help from a genius!

Deanicus · 28-11-2015 02:24PM

I also want to thank nmacc and Robbie G for the help and advice. Couldn't have done it without you!!

Caoimh1n, report back on how you get on. If you have any questions etc then I am more than happy to help. Whilst nmacc is clearly the genius here I do understand it all a lot better than I did so I might be able to help in some small way.

Have to give back somehow!

Deanicus · 28-11-2015 03:22PM

Ok I'm pretty sure I done goofed. Water seems to be on constantly

Nmacc, I couldn't find the spur for the live (it just seemed to be a wire coming out from the wall) so I wired the extension into the live and neutral terminals of the horstmann thinking it would be easier to do it that way than put in my own spur. There was another live wire in there for some reason so I thought it must be ok to do that.

Having re-read your post you did say it was important to use the same spur as the horstmann but I thought you meant that as in make sure I am getting the correct power as opposed to "don't wire it into the terminals on the horstmann"

I think I know what is happening. For the thermostat to control the heating I have to leave that heating channel as always on on the horstmann.

I think by doing that it is drawing power as such. Since the extension is hooked into the same part it is also then receiving this without asking for it which then kicks the hot water on.

I tested this by turning off all channels on the horstmann. I then set the tado and extension to off. I turned the heating channel back on. Since both tado devices were not looking to turn anything on then nothing should have happened. However very shortly after I turned the heating channel back on the boiler started up. Presumably to heat the water or at least that is my guess.

Nmacc, do this sound correct to you? If I wire the live and neutral away from the horstmann terminal should it then work as expected?

If thats not it could I bypass the horstmann water channel altogether and wire it directly into the extension?

Sorry for hassling you again nmacc. Caoimh1n, best not ask me for advice so!

Deanicus · 28-11-2015 06:21PM

Ok, sorry to be posting yet again

The mystery deepens.

The heating is on despite the tado thermostat saying it shouldn't be on. So it seems when I put the channel on as before it is overriding the tado

3 channel to 2 channel controller?

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