Hive heating questions...

[Mottie]

Our heating system is working fine but sitting here bored I was considering 'tinkering'!

All rads apart from the lounge have TRV4 valves. I have a Honeywell DT90E room stat in the lounge. I manually adjust the TRV's. In the morning when we get up, I have the two rads in the kitchen diner on from 5.30 until about 8.00. (the heating is set to come on at 5.30) I also have them on between 5.00 and 6.30 when we are having tea.

I put the main bedroom one on around 10.00pm until 11.00 as I like a warm bedroom to go to sleep in but I don’t want to wake up to a warm room - gives me a headache!

I have the second bedroom to come on at 5.30 until 7.00 am as Mrs Mottie gets dressed and puts her slap on in that bedroom so as not to wake me (very considerate ).

And that’s it. Obviously they all only work depending on the heating being on and when the system is calling for heat, controlled by the room stat. If I were to replace the TRV's on all the rads (except the lounge) with hive Wifi TRV’s, as I see it, that will just allow my lazy fat arse to stay in the chair longer with no need to manually go round adjusting them. We already have a hive hub for the lights. I get all that.

Now, if I were to get the hive smart thermostat kit, I understand I can control that remotely but does that replace the controller? (Honeywell ST9400C)

My main question is, if the controller is replaced, on cold nights could I have the bedrooms and kitchen heating on low with all other rads off even if the thermostat in the lounge was not calling for heat?

I hope I’ve explained that clearly!

 

[Brigadier]

Don't fiddle, and count your blessings that you have heating and hot water!

Our combi threw a total strop (after being sulky for months) and has downed tools completely.
We've been without heating, and having cold showers, since last week
Joe is not coming out until Thursday

 

[bernardgreen]

and having cold showers, since last week

Time to consider a cylinder with an immersion heater.

 

[denso13]

Time to consider a cylinder with an immersion heater.

And a generator on stand by in case of a power cut. Heck, better with spare generator just in case.

 

[ericmark]

I have 9 programmable TRV heads, 4 energenie, and 5 eQ-3 bluetooth. But first Hive, that's a special odd one out as it has a "demand for heat" system that will turn on the wall thermostat even if the room the wall thermostat is in is warm enough if any of the TRV heads call for heat for ½ hour.

Honeywell evohome also have wall thermostat linked to TRV heads, and also Drayton Wiser, and Tado, although not quite the same way, and Nest did work with energenie but have removed their support, so I would say big question, do the TRV heads need to be linked to the wall thermostat?

I have found setting the same program on the wall thermostat to TRV heads works, a little thought, hall TRV set 2°C lower to wall thermostat in the hall, I have found since wall thermostat higher and closer to centre of house, it always shows it warmer than hall TRV. But clearly every home will be slightly different. But the wall thermostat turns down 0.5°C an hour before any TRV head asks for a higher temperature, and back up 0.5°C when the TRV heads change, that seems to be enough to get the boiler running when there is a change.

So from what has happened in the two houses I have lived in with programmable TRV heads, I would say no does not need to be linked, a little thought when setting is all that is required.

However my old DT2 thermostat only had for changes per day the replacement slightly better with 6 changes, so although I have no problem with Nest Gen 3 setting multiple 0.5°C changes with other thermostats it may be a problem. I think there is a limit with the eQ-3 heads I use, but unaware of any limit with the energenie heads.

However the energenie heads do have a problem, the anti hysteresis software is too good, set to 16°C over night, and 20°C in the morning at 7 am it was 11 am before the room finally hit 20°C, so would set at 22°C at 7 am and 20°C at 8 am and it would be at 20°C from 8 am onwards, this of course messes up that 0.5°C set on the wall thermostat, if the wall thermostat warms up too quick, then not enough time for the TRV head to adjust to new temperature.

The other problem was in mothers house the TRV was on the return, this at first resulted in over shooting, so I would look at the current and target on the TRV if the target was over current open lock shield a touch, and if under close it a touch, once set it seemed to run A1.

So that was OK with the energenie, but the eQ-3 only shows target temperature, it does not show current, so a little harder to set. With two radiators in a room you need the bluetooth version of eQ-3 cost me £15 each, with a single radiator the non bluetooth will do the same job, seen at £10 each, however it is easier to program with app, than direct on to TRV head, however I like being able to alter without my phone, I walk into a room, and press the eco/comfort button and it swaps setting so easy, or press dial and get boost, that was a big problem with the energenie you needed a hub to set them and also the app on your phone, so a visitor could not alter temperature.

Also the eQ-3 has open window/door feature handy when unloading food.

 

[stem]

My main question is, if the controller is replaced, on cold nights could I have the bedrooms and kitchen heating on low with all other rads off even if the thermostat in the lounge was not calling for heat?

The issue is more about the pipework which would need to provide two separate heating Zones. In your case that would mean the bedroom and kitchen radiators connected together as one circuit and the others radiators piped up as a separate circuit. Each circuit would then be controlled by an independent motorised valve connected to its own appropriately located room thermostat.

If you search this forum you will find many posts relating to Hive Multi Zone installations. In fact Zoned heating systems are now a building regulations requirement for new builds. The Zones are split as sleeping and living areas.

My father (plumber) and I designed and installed a 5 Zone system in my parents bungalow in the 1980's when I was training as an electrical engineer. So they're not new.

Alternatively, systems such as Honeywell evohome use thermostatic radiator valves which will control each room individually directly from the radiators.

 

[ericmark]

The building regulations definition of zones seems to be a problem, some government information from county councils seems to say a TRV forms a zone, and with a motorised TRV I really can't see how you could class it any different to a motorised valve as really that is what it is.

The problem as I see it is for a gas modulating boiler to work efficient it needs to modulate, and for it to modulate the flow needs to be gradually altered not on/off or some device needs to remember what rate of output is required, it seems the EPH thermostats can work OpenTherm as master/slave so as long as the boiler is OpenTherm enabled then you can work the system efficiently with zones. Would love to be corrected, but as far as I am aware, only EPH do OpenTherm master/slave configured thermostats so unless boiler is OpenTherm and you use EPH thermostats I can see no way of ensuring the boiler does not start at flat out. And in the main running flat out means not running efficiently.

To use zone valves as in this house, one for main house central heating and one for granny flat central heating makes sense as the granny flat seldom heated, and it stops the house or flat from having warm radiators in the summer when using the boiler for domestic hot water, but room by room zones makes much more sense for main house, although since my wife does not seem to understand the concept of have doors on rooms you can close so that room is not heated. Comes of living in an open plan house for 30 years.

 

[Mottie]

I think I’ll leave it - just keep on turning them on and off as required! Thanks all.

 

[Bodd]

Hive no idea