Current honeywell set up can the nest smart thermo replace it?

[RandomGrinch]

What if I were to ditch the nest and get the hive would I be in the same situation?

Yes, you would be in the same situation.

Also what is currently speaking to my cylinder anyway? Surely it's wired right down to the programmer at the boiler currently as the little receiver at the tank is wireless and only has a wire sitting on the side of the tank for the temperature?

The wireless stat, is how your cylinder is 'speaking' to your controller.
You appear to have an 'S plan' system.
Typically this includes a wired tank stat and room thermostat.
The Honeywell RF2 pack 3, simplifies this setup, by making it wireless.

From this...

To this...

Any change of controller will require a new tank stat and wiring going back to the wiring centre.

Another question, is there something I could potentially get to replace/upgrade the wireless device at the tank that could speak to the nest?

I'm afraid I don't know of such a device, others may - but it wouldn't speak to the nest. It would connect into the wiring centre.

As we've suggested, with this workaround; Nest controls the hot water on and off times, whilst the Honeywell only maintains the overheat cut-off, without the need for any additional work on the cylinder, or additional wiring through new floors.

So basically I'd have to keep the honeywell programmer and run new wires to connect the heatlink that comes with the nest?

Yes...

having terminal 3 (HW ON) of the ST, feed terminal 5 (HW common) of Nest. The wire that was in ST9420C 3, would go into Nest terminal 6 (HW call-for-heat) - the Nest would then have timing authority, when the ST9420C retains over temperature cut-off.

The other connections to Nest, would be made appropriately, with only a Live bridge required to terminal 2 (C/H COM).

The other appropriate connections...
Feed the Heatlink with a Live, Neutral and Earth connection.
The wire that was in ST terminal 4 (C/H ON) would go into Heatlink terminal 3.

 

[monc3]

I have the same, no thermostat on the cylinder, but I am running C Plan, and you seem to be running S Plan, I can see two motorised valves. I don't understand why you want Nest Gen 3, as I am looking to move to Hive as well, as Nest has no ability to link to TRV heads.

I am not good at plumbing, so employed a plumber, who in turn employed a heating engineer, who admitted to me they had not got a clue about how to wire it up. Lucky I did, but had not realised Nest does not link to TRV heads, the instructions I had read said they did, but it seems when google took over Nest support was withdrawn.

Domestic hot water (DHW) during summer was simply timed, the floors in my house mean hard wiring is out, so needs some wireless method if using a thermostat, ½ hour 4 times a week gave me hot water to wash hands, today I use an immersion heater and iboost+ so in summer DHW heated with spare solar energy from the solar panels.

But had I not been an electrical engineer not sure how I would have got it wired up? @stem is normally good at working out what to do, but it is hard to realise what others can understand, and was shocked at the comments made by the heating engineer. Also the Nest help line seemed to just want to send out an engineer to sort problems, I had a simple problem, the central heating was turning on when not called for, it turned out due to anti legionnaires software built into Nest, which could be simply turned off, but Nest help line could not tell me that, found out what it was on here.

With Sonoff wireless relays and other devices there are ways around lack of hard wiring, but for me it was the cost, I looked at wireless options and was looking at £140, and this with no labour costs.

So I would say back to the base line, why do you want Nest? @RandomGrinch makes some good points, the wireless links are already built into the existing system. So may be having both in parallel is the way forward?

Hi Eric, going back on this i ended up returning the nest due to literally no one local being remotely interested in installing it for me.

I'm now looking at hive how are you finding the set up and do you have a cylinder thermostat? I'm thinking surely I'll be fine without one as my current habits are daily 1hr timed for heating the cylinder and boosting it for an hour here and there?

The wireless honeywell thermostat i have at the water tank currently i have no idea if it even works or how to check the temperature so its not like I'd be missing it anyway.

 

[ericmark]

I wonder is this

a wireless transmitter for your domestic hot water (DHW) however you have asked what I have done. To start with the programmer in use was useless it turned out the triple and earth main house to flat with boiler in it, only had two connected cores. So there was no way to get both CH and DHW independently timed without some bus or wireless connection, I used Nest Gen 3 as it has a bus connection so not relying on wireless. Although it can also use wireless and as user no idea which it is using.

I found a wireless thermostat base however no sender why some one would take the sender no idea. The thermostat shown was for the flat not the main house, and we had two pumps, clearly some one thought by selecting which pump is used one could select if house or flat heated, that was not the case, if one pump selected it circulated in reverse direction through the other one.

So I had two motorised valves fitted, and had to set about working out how to wire. I actually made a mistake, and missed out a relay, so house can run without flat getting warm, but not the reverse. However never use flat without house being in use, so never corrected.

With pumps off and valves closed I will get DHW, so Nest can run the boiler only, and unlike the original programmer it can run for ½ hour, minimum with old controller was 1½ hours, it had an option of once or twice a day, where Nest allowed me to have it just 4 times a week, so Mon, Wed, Fri, and Sun and the boiler would actually run for 20 minutes as it would then be too hot on the return as the hot coil not really very efficient at transferring heat. This would give us hot water in the summer, and one hoped it would be hot enough on Mon to stop legionnaires, but never measured the temperature.

In the main this worked, some times would run for extra ½ hour but good enough for warm water at taps. Now I have an iboost+ and solar panels so the DHW is heated with solar in the summer, not as good as hoped as the electric only heats top of tank, so does not really stay hot long enough, I need a longer immersion heater so it heats up more DHW when the sun shines. But only fitted in Sept so not used much before CH was required and I have no way to stop the CH heating the DHW. But the solar only heats the DHW when the battery (3.2 kWh) is full, so does not heat the DHW every day, and the pipe run to the taps means ½ a bowl full of cold water before hot arrives. Had it not been for that, I may have tried to fit some wireless tank thermostat.

By the time my CH switches off, I would think there is enough sun for DHW to be heated by solar. So not doing anything to get the boiler to heat the DHW better.

What I found is a problem is finding out what devices do. My Nest has volt free contacts, so can feed in with N/O and N/C and out using COM, but Hive used 230 volt to com contacts so could not be wired the way I have Nest wired, however it has a software fix, but it was some time before I found there was a software fix.

This is the same with many smart devices, one has no idea what they will do until you buy them, I know Hive uses zigbee, but no idea if only with a Hive zigbee or any zigbee hub.

It is possible I can use google home and my Nest Mini's to use an "If this then that" (IFTTT) routine. So if the current temperature is below target on any TRV then run boiler. But not found out how. At 72 getting a little too old in the tooth to work things like that out. "Hey google turn on landing lights" is about my limit, handy when carrying two cups of coffee.

I am considering a second thermostat in parallel to Nest in the Living room, my problem is doors being left open as cats scratch the carpet if not, means hall gets to warm and turns off CH too early. Best would be Drayton Wiser three channel wall thermostat, but that around £250 before one starts buying the TRV heads.

 

[RandomGrinch]

I wonder is this a wireless transmitter for your domestic hot water (DHW)

As stated before...

The Honeywell RF2 pack 3, has an RF cylinder thermostat.

It is a CS92A wireless tank thermostat.

 

[ericmark]

I have to admit, when the oil fired central heating guy came to service and fit new motorised valves, and said he had no idea how to wire my system up I was rather surprised. Not that I wanted him to rewire it, I had already done that, and all he had to do was fit the motorised valve heads, all pre-wired for him.

However it seems heating engineers as they call themselves, are not trained to over level 3 which is what I consider is needed to call oneself an engineer, although what I learnt to get my degree was not really used, and I would not be able to do all the stuff taught back then.

As an industrial electrician using PLC's and inverter drives was normal, but the domestic scene is only just starting to use the devices we saw in industrial installations some 20 plus years, ago, they label them "Smart" but we called same thing "telemetry" but in 2004 the Part P building regulations stopped electricians swapping between commercial and domestic, the fees to join a competent persons scheme resulted in electricians having to chose, to pay the fees and go domestic, or not pay and go commercial and commercial paid better, so I for one gave up domestic.

So now only work on my own house, I looked at this and at over a £100 it seemed a silly price. I looked at SONOFF relays and these seemed far better priced, I was considering building one, I would likely need some adaptable box to mount it in, but then got solar fitted, so actually paid a lot more for the iboost+ but it means now in summer hot water is free.

So all my ideas to instal a wireless link were shelved as no longer needed it.

But time is money, and likely if not DIY cheaper to fit the Honeywell system to taking the time to design ones own.

 

[monc3]

I have to admit, when the oil fired central heating guy came to service and fit new motorised valves, and said he had no idea how to wire my system up I was rather surprised. Not that I wanted him to rewire it, I had already done that, and all he had to do was fit the motorised valve heads, all pre-wired for him.

However it seems heating engineers as they call themselves, are not trained to over level 3 which is what I consider is needed to call oneself an engineer, although what I learnt to get my degree was not really used, and I would not be able to do all the stuff taught back then.

As an industrial electrician using PLC's and inverter drives was normal, but the domestic scene is only just starting to use the devices we saw in industrial installations some 20 plus years, ago, they label them "Smart" but we called same thing "telemetry" but in 2004 the Part P building regulations stopped electricians swapping between commercial and domestic, the fees to join a competent persons scheme resulted in electricians having to chose, to pay the fees and go domestic, or not pay and go commercial and commercial paid better, so I for one gave up domestic.

So now only work on my own house, I looked at this View attachment 327965and at over a £100 it seemed a silly price. I looked at SONOFF relays and these seemed far better priced, I was considering building one, I would likely need some adaptable box to mount it in, but then got solar fitted, so actually paid a lot more for the iboost+ but it means now in summer hot water is free.

So all my ideas to instal a wireless link were shelved as no longer needed it.

But time is money, and likely if not DIY cheaper to fit the Honeywell system to taking the time to design ones own.

So nest after all then

Yea thats the device I have. Its a wireless thermostat that I presume came with my honeywell st9420c programmer.

My question is though once I remove the honeywell programmer the cylinder thermostat won't be working anymore which means I'll have no cylinder thermostat.

Do I need a thermostat for the cylinder though?

I only boost my water when I need it and it's on a 1 hour timer daily running at the same times everyday. My understanding is that I can do this with nest as well anyway. Pop it on a timer or use the boost?

 

[monc3]

So nest after all then

Yea thats the device I have. Its a wireless thermostat that I presume came with my honeywell st9420c programmer.

My question is though once I remove the honeywell programmer the cylinder thermostat won't be working anymore which means I'll have no cylinder thermostat.

Do I need a thermostat for the cylinder though?

I only boost my water when I need it and it's on a 1 hour timer daily running at the same times everyday. My understanding is that I can do this with nest as well anyway. Pop it on a timer or use the boos

As stated before...

It is a CS92A wireless tank thermostat.

What do you think RandomGrinch?

 

[ericmark]

With my C Plan if the boiler runs then the DHW heats up. It does not need any valve to open, it will heat up DHW.

But with the S Plan that motorised valve needs to open. So in Summer it is the same as C Plan, and using simple time of 4 x ½ hour per week, it will heat the DHW less than max heat, but enough so no cold water in the pipes, and with also having solar and an emersion heater, don't really need it any more.

However in winter likely there will be a problem, as instead of in my case being heated all the time the central heating is running, it would still only heat 4 x ½ hour per week but instead of having full 19 kW going into the water, it will be cooler as also heating the house, plus the water is colder to start with.

Yes one could add relays so when the CH motorised valve opens so does the DHW, but if adding a relay, then may as well use SONOFF and have it connected that way.

The problem in my mind, is what happens if anything goes wrong. I have this problem now, my son and I know the system and can fault find, but if I wanted to call the local heating guy, he would likely just walk away. I looked for the wiring diagram and have realised I don't have the final one, as the relay is missing.

What I am saying you want standard wiring, even if you can make it work, you don't know what will happen in the future, I went to work abroad at one point, and some thing went wrong with some wiring I had done, and my wife had to wait for my return to get it fixed, nothing wrong with wiring a component had failed, I had thought I was so clever using PLC control, it worked A1, and when I returned a quick look on my PC plugged into the PLC soon showed the fault, but try getting a domestic electrician who can program a PLC, the whole program was double Dutch to them.

So yes I could find a way around the problem, but better to keep it Standard.

 

[RandomGrinch]

What do you think RandomGrinch?

I'm afraid I'm not a heating professional, I'm a technician in a very different field.
I'm unable to comment on whether you can get away with not having a tank stat, in your situation.
However, my opinion is that as @ericmark says, standardisation can be important; not just for you (and any heating engineers trying to fault-find / service your system), but anyone who moves in after you.
The tank stat is also a safety device, and is there for efficiency.

My question is though once I remove the honeywell programmer the cylinder thermostat won't be working anymore which means I'll have no cylinder thermostat.

My question is - why even bother removing the programmer?
My advice, as before - keep it in place, it will be the tank stat for the Nest.
It's not as if the box is on show, its only keeping some mastic company currently.
It seems a small price to pay, leaving a small box to live another day in a cupboard, rather than ripping up your floor for a new cable.

Even then, why not install the Nest, as has been suggested and see how it behaves?