Home heating automation

This is what I have. Will it be a simple swap with Drayton?

deezell wrote: »

If your existing 3 zone system has a single 3 channel controller, the Drayton Kit 3 receiver is a simple swap, box for box. For 3 zones hive requires two receivers, still a simple install.

masterboy123 wrote: »

This is what I have. Will it be a simple swap with Drayton?

A cinch. 3, 5 and 7 on the eph go to 2, 1 and 3 on the wiser. Live and Neutral are reversed.

Posted the below paragraph in the bargains thread after picking up the tado wireless starter kit but might be better to put it here (hoping I bought the right kit for my needs). Currently have a 2 zone house, wired thermostats linked to motorised valves and basic analog rotary clock. Zone 1 = downstairs rads, Zone 2 = upstairs rads + HW cylinder. Goal is to get some room control with smart TRVs as well as hot water control.

'Would anybody know what would be the best way of getting hot water control? As mentioned earlier, our cylinder is upstairs in the same zone as the upstairs rads, i.e. I have no direct hot water control and it currently does not have a stat. I assume a cylinder stat would need to be wired back to the new extension kit that'll replace the old analog clock next to the boiler. How difficult would this wiring job be? Alternatively, if I'm making the old upstairs stat redundant by permanently opening the zone valve could the wiring for that be used instead? Think that would mean any upstairs rads without smart TRVs would heat up also though.'

Redlim wrote: »

Posted the below paragraph in the bargains thread after picking up the tado wireless starter kit but might be better to put it here (hoping I bought the right kit for my needs). Currently have a 2 zone house, wired thermostats linked to motorised valves and basic analog rotary clock. Zone 1 = downstairs rads, Zone 2 = upstairs rads + HW cylinder. Goal is to get some room control with smart TRVs as well as hot water control.

'Would anybody know what would be the best way of getting hot water control? As mentioned earlier, our cylinder is upstairs in the same zone as the upstairs rads, i.e. I have no direct hot water control and it currently does not have a stat. I assume a cylinder stat would need to be wired back to the new extension kit that'll replace the old analog clock next to the boiler. How difficult would this wiring job be? Alternatively, if I'm making the old upstairs stat redundant by permanently opening the zone valve could the wiring for that be used instead? Think that would mean any upstairs rads without smart TRVs would heat up also though.'

A two stat 3 zone system and smart TRVs on upstairs rads would do the trick. Wire the stats as normal to open the motorised valves, but also wire HW call from the ext kit to open the upstairs valve, with smart TRVs on all upstairs valves, they will remain closed until their own schedule calls the motorised valve also and fires the boiler. It's a slight compromise as any TRV call for heat will obviously heat the HW, but you can have HW only using the HW timer while all TRVs are closed and off. Any rad without a TRV upstairs will heat during a HW timer call. Locate the upstairs stat in the landing, if you have a rad on the landing and want to pur a TRV on it, you can assign the Stat as the temperature measuring device for this TRV. So there's better response and no conflict. Make this upstairs stat your main stat.
You can fit a cylinder stat in series with the HW call from the ext. kit, if you can bring the wiring through.
For downstairs just get an extra Tado wall stat, and wire it in place of the existing one. Keep downstairs zone independent.
You could of course just use only one stat, with the main stat downstairs, and the second valve permanently manually open, but then you have a partial single zone system, as all downstairs will heat for any call from a TRV or HW. You have two valves, use them with two stats and keep your zones.
EDIT: I just read your other posts on the bargains thread. It seems your valves are not wired to fire the boiler, they just open at the behest of the old stats, and the old timer is directly connected to fire the boiler. You would need to rectify this, so that the valves own relays are wired to fire the boiler independently for each zone call. Otherwise the Stat relay will only open the valve but not calk the boiler. Even if you revert to a single stat zone, you'll need to do this, as your current wiring was designed to only open the valves, with the boiler firing voltage coming fron the old timer, not the Stat.

Thanks so much for helping me out. I understand the main unit clearly now.

How about the EPH room thermostats (pic attached)? Do I leave them as it is and place the Drayton room thermostats somewhere else?

deezell wrote: »

A cinch. 3, 5 and 7 on the eph go to 2, 1 and 3 on the wiser. Live and Neutral are reversed.

masterboy123 wrote: »

Thanks so much for helping me out. I understand the main unit clearly now.

How about the EPH room thermostats (pic attached)? Do I leave them as it is and place the Drayton room thermostats somewhere else?

Simplest solution is to leave them, turned up full so they don't break the circuit loop from the controller to the valves. For tidyness, remove them, (Turn off power, live goes through these), connect the two wires together and insulate, push back into the wall if hollow or else into a dugout recess and plaster over. Put the wireless Drayton over this spot or in a location of your choice.

Alkers

Setup the Drayton wiser kit at home over the weekend, having picked up two multi-zone kits when they were on special on cyber Monday a while back.

We have a combi boiler with only the one physical zone for the heating. Have now got kitchen (2 rads), bedroom and office with the smart TRVs so they can each call for heat independently and fire the boiler and allows great control and flexibility. Have manual TRVs in the main bathroom, hall, spare bedroom and sitting room - so currently spare room and sitting room set down very low as they're not used currently and the hall and main bathroom will obviously hest whenever the boiler is firing.

Very impressed so far, great app to use. We had a pain getting the smart TRVs recognised at the start but found that it was just my phone was dropping from the wiser network as it didn't have internet access, once I copped this and forced it to stay connected, it was a doddle to setup.

Didn't use one of the home hubs or one of the room thermostats so will likely sell them on in the new year.

deezell, that's super helpful really appreciate your help. Also, your edited bit at the end is 100% correct, the valves do not fire the boiler currently. Would both re-wiring bits be awkward for the electrician, i.e. (1) adding a stat + wire from upstairs cylinder to downstairs controller/ext. kit and (2) fixing the wiring to both zone valves so they can each fire the boiler?

In relation to the below quoted bit, are you saying that the HW and upstairs valve would both be wired together to the same point in the ext. kit so that they both come on together (regardless of which one makes the call for heat) and the smart TRVs would ensure the rads don't come on? To give some more info on the layout - there's actually another motorised valve on the pipe to the cylinder but it doesn't really do anything useful at the moment since it's wired to the same upstairs landing stat controlling the valve to the rads. The upstairs piping branches (a) into the rads manifold with a motorised valve as well as (b) into the cylinder with it's own (currently useless) valve. Could this be wired on its own to the ext. kit so it's fully segregated in its own zone?

deezell wrote: »

A two stat 3 zone system and smart TRVs on upstairs rads would do the trick. Wire the stats as normal to open the motorised valves, but also wire HW call from the ext kit to open the upstairs valve, with smart TRVs on all upstairs valves, they will remain closed until their own schedule calls the motorised valve also and fires the boiler.

Thanks so much deezell.
I would prefer to leave the EPH room thermostat on the wall. Would it cause any sort of short circuit? Given the fact other end will be connected to Drayton Wiser main control?

deezell wrote: »

Simplest solution is to leave them, turned up full so they don't break the circuit loop from the controller to the valves. For tidyness, remove them, (Turn off power, live goes through these), connect the two wires together and insulate, push back into the wall if hollow or else into a dugout recess and plaster over. Put the wireless Drayton over this spot or in a location of your choice.

legend99

Hi Deezel,

You had posted a few bits and pieces with myself in about April '19 as I installed Tado - system I had was 3 heating zones (3 floors in the house) and a 4th zone for the HW. I was the guy where we had figured that I couldn't use the Extension kit to both do a Wireless Thermostat and HW control as the two valves in the Hot Press are both spliced to one wire going back to the utility room. We had discussed whether:
1) I should install the extension kit at the boiler end to allow me to switch to a wireless stat set-up as I've noticed our downstairs stat is firing on a lot when the front door opens as it is near the door and our three children think nothing better of going out to rummage for something they have let in the car while leaving the front door wide open - that implied controlling the boiler through it's thermostat only as there is no independent time control and you felt that was ok as it is a good insulated boiler. I did buy the TH16 but never installed it but that would fit in with this solution as I would have additional control on the cylinder beyond a dumb thermostat probe - albeit it a different app.

2) Install the extension kit at the cylinder end which would give me Tado control over the hot water - but at the price of being unable to move the thermostat.

I've come back to this as we are back with the downstairs zone calling for heating a lot because of the door - so I am going to go with option 1 I think. So I wanted to check if I have this correct:

a) I wire the extension kit with a permanent L and N off the junction box at the boiler;

b) I remove the thermostat from its wired position - I know have a live wire and the wire that would have gone live if the stat passed through a call for heat. I assume that ideally I should try to find the other end of that live wire at the boiler junction box and disconnect it - if that isn't possible I would tie it off in a small termination junction I assume. And I tie any earth wires together as well. So now, that zone valve can't go live as there is no path back to it from the thermostat?

c) I go to the valve for the downstairs zone - and I think I am going to remove the switched live from it (it can't switch to live anyway can it as the circuit is broken at the old thermostat) and I am now going to find that switched live from the CH of the Extension Kit (connection number 4).

d) I then register them with Tado - and ask them to switch the thermostat to be wireless and it then calls to the extension kit - and the extension kit then fires the valve which will in turn call to the boiler?

And I have a hole in the wall in the hall of course. Does that sound correct?!

Thanks a mill

Phew, I'll need to recap on this. You have the benefit of being there, I have to rebuild the virtual setup in my head!. I'll poke back through the old posts, it'll all come back to me then (I hope).

legend99

deezell wrote: »

Phew, I'll need to recap on this. You have the benefit of being there, I have to rebuild the virtual setup in my head!. I'll poke back through the old posts, it'll all come back to me then (I hope).

Eh sorry. I was busy! I suppose the key question is whether I have it correct in terms of how one gets rid of a wired/fixed in place thermostat and makes it wireless.

Apologies!

Someone just went out and got their school back - thermostat dropped from 19.4 to 18.3 - hence I think I might be as well to go wireless. And even at that, I could leave it in that location, if it turned out to be better, but just running wirelessly. But hoping to move it out of the hall.

masterboy123 wrote: »

Thanks so much deezell.
I would prefer to leave the EPH room thermostat on the wall. Would it cause any sort of short circuit? Given the fact other end will be connected to Drayton Wiser main control?

Leave it so. The controller SL to the zone valves goes via these, so you need to effectively short the wires in the old stat. Turning it up full achieves this.

Redlim wrote: »

deezell, that's super helpful really appreciate your help. Also, your edited bit at the end is 100% correct, the valves do not fire the boiler currently. Would both re-wiring bits be awkward for the electrician, i.e. (1) adding a stat + wire from upstairs cylinder to downstairs controller/ext. kit and (2) fixing the wiring to both zone valves so they can each fire the boiler?

In relation to the below quoted bit, are you saying that the HW and upstairs valve would both be wired together to the same point in the ext. kit so that they both come on together (regardless of which one makes the call for heat) and the smart TRVs would ensure the rads don't come on? To give some more info on the layout - there's actually another motorised valve on the pipe to the cylinder but it doesn't really do anything useful at the moment since it's wired to the same upstairs landing stat controlling the valve to the rads. The upstairs piping branches (a) into the rads manifold with a motorised valve as well as (b) into the cylinder with it's own (currently useless) valve. Could this be wired on its own to the ext. kit so it's fully segregated in its own zone?

Yes, this was obviously the intention of the plumbing, but the controls didn't match up. Using an S plan with a valve for each zone insures 3 completely independent zones. With 2 stats and an ext. kit you would have the control system to match the plumbing. All three valves should have relays to call the boiler. The three relay outputs are simply combined together, the relays ensure the zones are independent as no voltage from any zone timer or stat can open the valve of another stat. This is standard S plan wiring, and any electricIan would be able to make the connections from the stats/ext. kit to their respective valves, and from the valve relay outputs combined to the boiler. It would be easy also to introduce a HW cylinder stat into the HW timed valve circuit, to control the max temperature of the HW.

Thanks so much!

I am just waiting for Black Friday deal now. Will let you know how the process goes.

deezell wrote: »

Leave it so. The controller SL to the zone valves goes via these, so you need to effectively short the wires in the old stat. Turning it up full achieves this.

legend99

deezell wrote: »

Phew, I'll need to recap on this. You have the benefit of being there, I have to rebuild the virtual setup in my head!. I'll poke back through the old posts, it'll all come back to me then (I hope).

I sat down tonight and finally mapped it connection by connection on the strip connector blocks in the junction box and I finally have it - used S plan wiring diagrams etc.

The issue I have is that there are 4 zones - 3 CH and 1 HW. For some whacky reason, when we bought the house a few years ago, there was no programmable controller. Just the most basic of clocks in 30 minute blocks where you push in for when you wanted the time on. With your legendary advice, I switched the 3 CH thermostats to Tado, put the clock on 24 hours a day and controlled the zones using the 3 thermostats and their schedules with. The HW has a probe thermostat - I have that set to 60 and your advice was to leave it just call whenever it needed to heat as there was no real need to having time control on it as it had it's own cylinder. I was always uncomfortable allowing potential for the probe thermostat to go belly up and keep calling to heat the water but I bought into your advice, as I said, as you're the King of this forum!

So that was the last 18 months. I always had an extension kit. Never opened it. Forgot to try to return it until after the date. So obviously that ext kit can either control a zone or offer extra control on the hot water. BUT. The live feed from the clock coming only feeds three wires. One to the downstairs Stat. One to the first floor Stat. But the third white is the live feed from the clock to both the second floor and the cylinder. So if I use the ext kit for that wire I'm putting the timing on both the CH on floor 2 and the HW zone. I also don't know how it would interact if the relevant thermostat didnt need heat? But I assume as the valves, which are independent, would only call when they needed heat that they would split there. However of course, if I only feed that joined wire from say 6am to 8am for hot water, then the CH zone for floor 2 wouldn't be able to come on outside those 2 hours. So doesn't make sense. So I had decided to go sonoff on the cylinder for no other reason than to know the temp of the water - which Tado wouldn't tell me anyway as they don't have a HW thermostat (they don't seem to care too much re hot water but maybe that's cause Germany has combi boilers or something?)

So I've decided, because of the issues in the hall and the kids being incapable of closing the front door, that I'll use the Ext Kit only for the wireless capability. So I'll take out ground floor stat and make it wireless and move it to tv room I think. I know the wiring now. Permanent live and neutral to the ext kit. Disconnect the feed from the clock to the wired location just to avoid unnecessary live wire in the wall. Then power the valve for the ground floor off pin 4 in the ext kit as the old wire going back to it from the wired stat location can never be live now.

Does that make sense? You have any views on moving stat from hall?

Tks!

deezell - thanks again for the great advice.

The below quote is from your response to my initial post. Does this still apply? From what I've read Tado seems to have a flaw in that if a TRV calls for heat but the wall thermostat for that zone hasn't opened its zone valve then there's a problem, i.e. the TRV cannot both fire the boiler AND request the zone valve to open. Is this the same with Drayton Wiser also? If DW was able to manage this better maybe I'd be better off cancelling my Tado wireless starter kit order.

deezell wrote: »

For downstairs just get an extra Tado wall stat, and wire it in place of the existing one. Keep downstairs zone independent.... You have two valves, use them with two stats and keep your zones.

digiman

I currently have 2 Nest Thermostats to control hot-water, ground floor and first floor. I'm planning to have an attic conversion done early next year so want to be able to control that floor separately.

Downstairs I have the following radiators:
Kitchen/living area with 2 radiators
Dining room with 1 radiator
Downstairs toilet with 1 radiator
Hall with 1 radiator, radiator is right beside the front door.

Upstairs I have the following:
2 heated towel rails in the bathrooms
4 bedrooms with a radiator each

Attic conversion would have the following
Office with 1 radiator
Bedroom with 1 radiator

I plan to sell the 2 Nest thermostats and replace with possibly a Honeywell Evohome or somethings similar that will give individual heating control per room and also heat the hot water tank. Also I do have an Eddie diverter to heat the hot water, works well during the summer but currently it's not doing anything - just adding incase it's relevant.

Couple of questions
1) In kitchen/living area do I need to put a thermostat on each radiator?
2) Can towel rails take a thermostat? Is there much need?
3) Is there any device that can tell the temperature of the hotwater tank and display it in the app?

I'm using Google home so would like to be able to use that to control the rooms but not a deal breaker.

Happy to spend whatever I need on this to get a really good system.

Any recommendations?

planck26

paulgrogan.eu wrote: »

As a recent convert of a very basic system to full Tado, you're in for the world of pleasure I can assure you. I did my install over the summer and it's been great since. Like you I bought up the parts when they were on various cyber / black sales etc, and probably got nearly 50% off it all. In terms of the TRV's, watch for deals on the quatro packs (4 packs). I have smart TRV's on all my rads and it's amazing, well worth the investment, but did so when they were on sale.

Just on this particular point here, Deezell is 100% here, however I do have a large kitchen like yours and I'm finding a little snag in that the TRV I use to monitor the temp gets blocked if one of the doors is left open and thus doesn't read right. I could use another stat, but I'm having issues with it dropping offline due to its distance from the Bridge (to be solved soon). However overall I feel the wireless sensor that they've recently released is a great offering and something that I'm going to move too, as I think it will allow me to just have a more central location for my temp sensor and also given it's such a large room, for anyone visiting it will offer an easy to find location to adjust that room's temp. Tado have a deal on these at the moment so that's just worth keeping in mind.

But again what Deezell is saying is 100% accurate and will work.

Paul

Thanks for this - makes sense that the wireless room stat would do a better job than the TRV alone, so I'll keep an eye out for one of those.

Also, I've noticed a newer version of the Tado Starter Kit V3+ with HW control is now available, and at a slightly lower price. Not clear to me if there are any significant differences - has anyone any views on this?
https://www.amazon.co.uk/tado°-Wireless-Thermostat-Starter-Assistant/dp/B08LP1LS5T/ref=sr_1_2_sspa?crid=3LF6G09FM0JM0&dchild=1&keywords=tado+starter+kit&qid=1606298270&sprefix=tado+%2Caps%2C170&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFTVEVSUzIyMVRaUEUmZW5jcnlwdGVkSWQ9QTAwNTYwMTIxVlhLMjNPMERPV1I5JmVuY3J5cHRlZEFkSWQ9QTA4MjY0NDAxWERLT09JNDVHTldKJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

baldshin

Despite getting some great advice on here, which very nearly did the job, I ended up having to get a Nest Pro to install my thermostat.

However, there have been problems since day one, so checking if anyone else has seen this before.

1. When heating is turned on, the boiler fires, but the rads won't heat unless I also turn on the hot water boost.

2. The hot water boost doesn't work at all, turning it on simply turns on the heat pump (?), but the boiler itself does nothing.

3. Our heating now seems to have a mind of its own. If I have the heat set to off, it could randomly come on on its own. Been woken in the middle of the night to a boiling hot house. Nest app and thermostat both showing as heating not on, and no schedules set either.

Have been promised by the Nest Pro he'd call multiple times to fix, but this has been going on month now. This thing is costing us more in gas, not less!

Gregor Samsa

I'm no expert, but it sounds like it's wired up wrong. I'd consider getting someone else to come and take a look at it - if the Pro wired it up wrong the first time, I wouldn't trust them to fix it. I can understand that you'd want them to come back and fix it with no charge, but sometimes it's better to cut your losses and was your hands of the problem, and anyway, it seems they have no intention of coming back, and meanwhile you're losing money and enduring hassle.

Clareman

I'd be giving him 1 last chance to call to fix it but warn him that you are going to lodge a complaint with Nest if he doesn't call in the next 2 days. I'd probably be lodging a complaint anyway

Redlim wrote: »

deezell - thanks again for the great advice.

The below quote is from your response to my initial post. Does this still apply? From what I've read Tado seems to have a flaw in that if a TRV calls for heat but the wall thermostat for that zone hasn't opened its zone valve then there's a problem, i.e. the TRV cannot both fire the boiler AND request the zone valve to open. Is this the same with Drayton Wiser also? If DW was able to manage this better maybe I'd be better off cancelling my Tado wireless starter kit order.

A TRV can be associated with a particular Tado stat, so that when the TRV opens, the stat relay will close to call the boiler, even though the stat itself may be satisfied and not calling for heat. It's a compromise if there are other open non TRV radiators in the the stats zone, as these will heat when the TRV radiator calls for heat. Ideally, all rads have smart TRVs, the stat now just acts as a zone valve/boiler relay on behalf of all TRVs in it's zone, and the stat's own temperature sensor is either unused, or is assigned as the measuring device for the TRV equipped rad situated in the same physical space or room as the stat.
Tado support can configure this remotely for you, if you describe which TRVs are inside a particular stat's zone.
Drayton operates on a similar basis afaik, TRVs are associated with a particular wireless relay. The logic is a little easier to get your head around, as drayton stats are just wireless sensors like their TRVs, whereas Tado stats have the relay built in, and can be both sensor for their own location, and relay for TRV locations.
When a star relay or a TRV call to that relay powers a zone valve open, the SL to the boiler comes from the zone valves's own internal relay. The SL from the stat does not go directly to the boiler except in a single zone system, or in certain pumped/gravity CH/HW installations where no zone valves are fitted.

deezell wrote: »

A TRV can be...

Really appreciate all your help and for taking the time to help me understand my heating system. The advice you give to people on here is unbelievable and your patience is even better!

Now I must keep my eyes peeled for a black Friday deal for a second wall stat and some TRVs

Clareman wrote: »

I'd be giving him 1 last chance to call to fix it but warn him that you are going to lodge a complaint with Nest if he doesn't call in the next 2 days. I'd probably be lodging a complaint anyway

Don't be too hard or expect too much from these 'Pro' installers. I'd read somewhere that many are just hastily trained up cable installers working for a well known Knetwork installation contractor.
I looked back at our previous posts, I see I had concluded that your system was a 2 zone gravity system, with HW only or HW plus CH.
This requires a special arrangement of a 2 zone HW plus CH controller, and I suggested your Grasslin controller had a switchable gravity mode in order to work with your system. The Nest does not have a gravity mode switch, but does have 2 pole volt free relays for HW and CH switching, and I provided a wiring diagram to operate the Nest heatlink relay in gravity mode. From your description of the operation of your system now, it seems that the 'Pro' wired your Nest in Amateur mode. Follow the last diagram I posted. It will solve your problem. Here it is again.

Clareman

deezell wrote: »

Don't be too hard or expect too much from these 'Pro' installers. I'd read somewhere that many are just hastily trained up cable installers working for a well known Knetwork installation contractor.

Sorry but I have to disagree, they were paid for a service that wasn't done right, probably over €100 and there's an additional cost of the additional gas that's being used, if you pay for a professional service you should expect a professional service and if you get the run around afterwards you should be allowed complain.

If I pay for something I expect what I paid for so I don't think it's being too hard on anyone to expect that, if they haven't been trained properly that's not good enough for a professional service imo.

digiman wrote: »

I currently have 2 Nest Thermostats to control hot-water, ground floor and first floor. I'm planning to have an attic conversion done early next year so want to be able to control that floor separately....
....I plan to sell the 2 Nest thermostats and replace with possibly a Honeywell Evohome or somethings similar that will give individual heating control per room and also heat the hot water tank. Also I do have an Eddie diverter to heat the hot water, works well during the summer but currently it's not doing anything - just adding incase it's relevant.

Couple of questions
1) In kitchen/living area do I need to put a thermostat on each radiator?
2) Can towel rails take a thermostat? Is there much need?
3) Is there any device that can tell the temperature of the hotwater tank and display it in the app?

I'm using Google home so would like to be able to use that to control the rooms but not a deal breaker.

Happy to spend whatever I need on this to get a really good system.

Any recommendations?

If money is no object, go for the Evohome. A 12 rad max kit plus the HW relay system with HW temperature sensor and display will do everything you ask for about €1k, installation not included.
If your rads already have manual TRVs, then its a technical install, no plumbing required. If your rads have screw tap like valves, each rad will need one TRV valve body to take a TRV head. A job for the plumber while he installs your attic plumbing.
I count 13 rads, so you may need to leave a selected rad open, which will heat for any TRV activity in its zone. Towel rail might suit, its normal to have one rad open in a full TRV installation so the circuit is never fully closed. Some towel rails may have awkward connections for a TRV valve body, or it may look unsightly on the rail. You will need to latch your existing CH motorised zone valves to permanently open, but the HW zone valve can be retained.
The Eddie will continue to function as normal, though you will now be able to see the Hot water temperature rise associated with diverted solar PV energy from the Eddie.

1. You will need a TRV per rad, otherwise open rads will heat for any room call.
2. See above.

3. Evohome HW control has a temperature sensor.

baldshin

deezell wrote: »

Don't be too hard or expect too much from these 'Pro' installers. I'd read somewhere that many are just hastily trained up cable installers working for a well known Knetwork installation contractor.
I looked back at our previous posts, I see I had concluded that your system was a 2 zone gravity system, with HW only or HW plus CH.
This requires a special arrangement of a 2 zone HW plus CH controller, and I suggested your Grasslin controller had a switchable gravity mode in order to work with your system. The Nest does not have a gravity mode switch, but does have 2 pole volt free relays for HW and CH switching, and I provided a wiring diagram to operate the Nest heatlink relay in gravity mode. From your description of the operation of your system now, it seems that the 'Pro' wired your Nest in Amateur mode. Follow the last diagram I posted. It will solve your problem. Here it is again.

Here's how he has it wired up. Certainly differently to your diagram. I've emailed them back and requested a refund and will possibly have a look myself at sorting tomorrow if time allows.