Can Hive smart thermostat downstairs be used in conjunction with 'dumb' thermostat upstairs?

HelpfulHints99

Hello all, here's an update with some photos to hopefully explain a bit better.  I think I left some important info out which would have a bearing on the advice you kindly offered.  I also think I may have answered my own question but I'm not sure! (Note to self - ask the right questions and give all the relevant info!)

To answer your questions Bendy_House: 

But, some of what you say doesn't quite make sense, but I think I know what you mean.

You say "I have separate thermostats for upstairs and downstairs but these are not separate zones on my timer control. The upstairs and downstairs radiators are then operated based on the temperature set on the two thermostats. But, for example, I can't select only upstairs or downstairs to be on. The heating is either on or off."

The two comments in bold appear to be mutually exclusive. You say that each house area (upstairs and down) CAN be controlled by their wall stats, but then go on to say you CANNOT select only up or down?

I mean, if you turn the upstairs 'stat down until it's effective 'off' - say at frost setting - then don't the upstairs rads now go cold, whilst the downstairs ones remain hot? You can either control them by their wall stats, or you can not.

Unless what you are actually saying is that the wall stats themselves do not turn the BOILER on and off - the TIMER has to do that? That would make sense.

You ideally need to confirm for us, please: how many motorised valves do you have? Two or three (Surely three - two 'zones' and the hot DHW tank)....

....Unless what you are actually saying is that the wall stats themselves do not turn the BOILER on and off - the TIMER has to do that? That would make sense.

Yes, you are absolutely correct - I can control upstairs and downstairs independently using the wall stats if the heating is on.  I was trying (and failing!) to say that my timer/programmer doesn't have separate zones for upstairs and downstairs that are individually selectable.  Sorry for not being clearer.  

You ideally need to confirm for us, please: how many motorised valves do you have? Two or three (Surely three - two 'zones' and the hot DHW tank)

Yes, I have three motorised valves: 
 a

Ok, a Hive, as you'll know, does BOTH temps AND times. If you fit a Hive to a system that already has a 'timer' (programmer) on it, then you'll have to do one of two things with that existing timer; one is to leave the existing timer 'CH always on' (24 hrs), or the other is to remove and by-pass it.

I have already bought a dual-channel Hive kit to control the hot water as well that comes with Stat, Receiver (to replace the timer/programmer) and Hub.  I'm really sorry for not being clearer about that in my original post as I can see it's an important part of the puzzle and very relevant to the advice being offered.  

So, with that new piece of information - that my downstairs timer/programmer AND downstairs wall stat will be replaced by a Hive receiver and Hive dual channel thermostat - I'll rephrase my original question: 

With a new Hive receiver replacing my existing timer/programmer and a new Hive thermostat replacing my downstairs wall stat, can I leave the old 'dumb' thermostat to control upstairs?  So if I turn on the downstairs heating using new Hive controls, the upstairs will heat depending on whether the upstairs wall stat is calling for heat.  

I think I may have answered my own question by interrogating this a bit more.  I'd be grateful if someone patient could sense-check my thinking!  

The reason for the question and where I have got myself confused is with the wiring in the 'wiring centre'.  My understanding is that currently when 'Central Heating' on is selected it will: 

- Make live 'Central Heating On' wire.
- This CH On wire connects to the wall stat wiring in the wiring centre. 
- If that stat is calling for heat, it completes the circuit, activates the motorised valve and the boiler/water pump and the central heating comes on.  

According to Hive instructions the only change that I need to make in the wiring centre is to bridge where the downstairs wall stat wiring was and therefore directly connect the motorised valve with the 'Central Heating On'. 

That's all fine BUT because I have two wall stats but only one heating zone on my programmer, I think that both my stats are wired into the same connectors in the wiring centre.  

So when 'Central Heating On' wiring is live it connects to wiring from both wall stats and the circuits will complete depending on whether the stat is calling for heat.  If I bridge out in the way Hive recommend, the upstairs wall stat will effectively be bypassed.

So I'm thinking that I need to change the wiring so that the wiring for second dumb wall stat is no longer bypassed by the bridge - if I take the output wire from the upstairs wall stat and the input wire for the upstairs motorised valve and connect these separately from the new 'bridged' downstairs Hive heating wiring, then I think I've answered my own question and I will be able to retain the upstairs 'dumb' wall stat and use it in combination. 

The second way the Smart valves can work is to not only open and close when programmed to, but to ALSO then tell the boiler to fire up. That's clearly better, but it means that this upstairs zone also needs a Hive stat so it controls the upstairs zone valve. Without this, the Smart rad valves couldn't open and close the upstairs zone valve as it would need to. 

So I'm thinking that if I fit Hive TRVs to the upstairs bedrooms, providing the upstairs wall stat is set to max and so calling for heat, those smart TRVs can also communicate with the new Hive receiver and turn the heating on when they need heat.      

Anyone who's made it this far - THANK YOU.  Would appreciate it if anyone could advise on whether I've reached the right or wrong conclusion!

Many thanks

J

BUFF

You may not want to hear this ...
Can you return the Hive gear?
Honestly, I think that Drayton Wiser would be a better solution for you going forward. 

Apodemus

BUFF said:

You may not want to hear this ...
Can you return the Hive gear?
Honestly, I think that Drayton Wiser would be a better solution for you going forward. 

I think this is probably correct. 

Hive can do multi-zones, but I believe you need a second thermostat and a second receiver to do it properly.  In theory, they seem to sell a mutizone kit - they talk about it on their website - but I can't see it on their product page.  I think in the OP's case, they would also need to reconfigure their wiring centre so that the second receiver was able to control the upstairs zone valve.  I've seen this working in practice and when set up properly it allows both zones to work completely independently, with either of the Hive thermostats calling for heat from the boiler and only the correct zone being heated.

But the plan of setting the upstairs wall stat to its max and using smart rad valves sounds like a reasonable work-around.  You could probably manually lock the zone valve in the open position instead of using the wall thermostat.

For the main thermostat, it might be easier to "bridge" at the wall stat rather than in the wiring centre and you could also take that approach to the upstairs wall stat as well.

HelpfulHints99

Many thanks for the follow-ups.  I haven't opened the Hive kit yet so returning it is an option.  I'll take another look at the Drayton stuff as suggested.  Without wishing to take up any more of your time, could you summarise why you think it would be a better solution to help me get my head round your suggestion?

Thanks again, really appreciate the wise words - it's already been super-helpful.

All the best
J  

Apodemus

HH99, I'm no expert on this, but my understanding is that with Hive, you are limited to two channels per receiver - normally Heating and Hot Water.  So if you want to have two zones for the Heating, you have to add a second receiver and second thermostat.  The Drayton systom does a three-channel Hub, so you can more easily control Hot Water, Heating Zone 1 (+ Thermostat) and Heating Zone 2 (+Thermostat) from the one installation.

Hive can do it, but you need extra kit and really know what you are doing at installation. 

...Or you can do the workaround that you are suggesting, which leaves you essentially operating as a single zone system.  It will work, but I don't think you will be able to have the upstairs heating if the downstairs Thermostat has reached its desired temperature. 

HelpfulHints99

For the main thermostat, it might be easier to "bridge" at the wall stat rather than in the wiring centre and you could also take that approach to the upstairs wall stat as well.

Apodemus - I've just realised what you meant by this - super smart idea, thank you! 

BUFF

HelpfulHints99 said:

Many thanks for the follow-ups.  I haven't opened the Hive kit yet so returning it is an option.  I'll take another look at the Drayton stuff as suggested.  Without wishing to take up any more of your time, could you summarise why you think it would be a better solution to help me get my head round your suggestion?

Thanks again, really appreciate the wise words - it's already been super-helpful.

All the best
J  

I think that it's a better (e.g. even though much improved over earlier generations I don't think that Hive V3 supports OpenTherm), neater (e.g. can run more than 1 thermostat from a single hub) system.

I also believe that the support/warranty from Drayton will be better plus Hive have already shown a willingness to withdraw from areas (N. America) & products (e.g. cameras, security).
Whilst Hive is an offshoot of Centrica, Drayton is part of a much larger group of companies in the electrical/heating/energy management arena, Schneider Electric.

The caveat is to order the right kit to start with.

Sadly, you may have now missed the best  Black Friday/Cyber Monday deals.

Apodemus

HelpfulHints99 said:

For the main thermostat, it might be easier to "bridge" at the wall stat rather than in the wiring centre and you could also take that approach to the upstairs wall stat as well.

Apodemus - I've just realised what you meant by this - super smart idea, thank you! 

Your situation might be simpler, but my wiring centre is a real mess of connections, reconnections, terminal blocks and insulating tape, as it was updated by a really poor electrician who thought it better to leave the old wiring in place and patch  a new programmer into the old wiring rather than rewiring it properly.  In contrast, the thermostat is much simpler, with plenty of space to see what you are doing and connect the bridge across the two terminals.