Smart Thermostats

[pcolbeck]

The thermostat in our hall is on its last legs. It keeps requiring recalibrating as it drifts by a couple of degrees.
I was thinking of getting a smart thermostat such as Hive.

The thing is our heating runs of a 300 litre heat-store so the thermostat doesn't actually fire the boiler it just fires the pump for the central heating and the oil boiler kicks in if the heat-store drops by a set number of degrees (controlled by a thermometer probe in the store itself). Or the back boiler on the wood burner heats up the heat-store (and hopefully next year solar panels will do the same)

So would a smart thermostat actually do anything for us bar lettings us turn the heating up and down using Alexa or whatever?

[rafletcher]

Well it would allow you to programme different temperatures for different periods of the day for each day of the week, if that’s something you’d take advantage of.

[Diver300]

Smart thermostats will allow separate control of each room or zone.

[Asterix, the former Gaul.]

How does that work?  Separate sensors? Is programming simple(-ish)?

[DuncanM]

Something like Tado or EvoHome can have smart radiator valves that work like their own mini thermostat and can be programmed independently. They aren't cheap, so you are much better off getting a bundle at the same time as the main unit. Setting the times and temps is in an app and is pretty straightforward.
I'm not sure I believe what the emails I get from Tado say about or efficiency savings though.

[toontra]

Both Tado and Hive smart thermostats have really mixed reviews - many really bad.  That's put me off investing, otherwise I would have jumped a long time ago.

[Diver300]

How does that work?  Separate sensors? Is programming simple(-ish)?

I use the Honeywell Evohome system. It's got separate sensors on each radiator valve, but separate room sensors can be used instead.

[Ham]

Smart stats come into their own when you let them do smarts ("their own" might well be considered to be a small padded room in a deep cellar)


For simple heating they aren't doing that much more than a dumbstat, and they do need a change in mindset to use. You set a target temperature for a given time, and the system will adapt to preheat so that is at the temperature at the target time. If you just transfer from timeswitch to smartswitch, you will actually use more energy, you need to adapt what you really want.

I'm a google fanboi, having received a Starbucks voucher for a free coffee for my soul, Nest was the way for me. Actually, it needs something like a full ecosystem to get the full benefit if that's what you want, so either a google or allow permissions from various sources. After some experimentation, we have enabled a limited number of possible smarts.

One of the cleverest and money saving ones is that it detects when you are away (from a combination of movement sensors and phone location and switches the heating off. Something you would never think to do otherwise. We have limited the preheat, and I've stopped it taking every twiddle Mrs Ham makes to the  temperature as a variance we would like permanently. The learning can also optimise temperatures if you let it. Nest also adapt to outside temperature.

If you want a simple smartswitch to play with, I bought one of these to use for hot water (it isn't the model that accepts an external sensor so it can't) which I would flog for £15 No idea how smart it is, but it is wifi connected so you can switch and control remotely.

[DuncanM]

Both Tado and Hive smart thermostats have really mixed reviews - many really bad.  That's put me off investing, otherwise I would have jumped a long time ago.

I've not had any issues with our Tado system. We don't have any sort of ongoing subscription, but I think if you want all the fancy features like geofencing you have to pay monthly for them. This means that we don't use the smartness much, but we still find it useful because we have 3 floors (townhouse), and the top and the bottom run at very different temperatures, and are used in very different ways (and on different days). We've had it a while (was installed in a hurry because our old thermostat broke, and we put the radiator valve stuff on afterwards - I don't think it would be that beneficial without the radiator valves).

[Kim]

I knitted my own smart thermostat from C code that pulls in data from various other sensors, so I can't make specific recommendations for commercial producs, but the advantages over the traditional thermostat-in-the-hall + timer are roughly:

• Reacts to the average temperature in occupied rooms, rather than just an arbitrary one
• Compensation for outdoor temperature
• Knows when we're out and when we're asleep, and backs off the setpoint accordingly
• Knows when the alarm clock's due to go off, and pre-heats the house accordingly
• Turns the heating off if a door or window (other than that of the bathroom) is open
• Can be told to pre-heat the house in time for us to arrive home
• Ease of adjustment (and one-off 'boost' and 'inhibit' functions) via a simple web page and IRC bot
• Switches off pending manual intervention in response to a fire or carbon monoxide alarm
• No clock to set or timers to program
• No machine-learning, apps or cloud-based services

Conspicuously absent is control of individual radiators via smart TRVs, mainly because there doesn't seem to be a good open landlord-friendly option.  I'm reluctant to invest heavily in someone else's radiators.

Obviously there's a limit to how much integration you can achieve with commercial products, which tend to lean heavily on smartphones as a source of data rather than actual sensors, but hopefully this should give an idea of what sort of thing is achievable.  I'd say the main benefits of any system were ease of tweaking (for increased comfort) and not running excessive heating when you're out.

[SoreTween]

I really cannot see anything pcolbeck desires to do that requires a 'smart' thermostat. By smart I assume hive, Honeywell or some such IoS is implied. My thermostat allows me to set 6 target temperatures over 6 time ranges Mon-Fri and a different 6 Sat & Sun. It cares not where the heat is sourced, demand is on or off. It is as dumb as rocks whilst being roughly 12x smarter than a single temp+time arrangement. It cost peanuts and maintenance is change the batteries every 18 months or so. Can't be hacked. Can't be bricked by a cloud service bankruptcy. Can't require payments to continue working. WTAF is the attraction of smart IoS?
Kim's solution is, naturally, the bogs dollocks.

[Kim]

After recent xkcd://927 adventures, I'll add that modern boilers/heat pumps/etc support modulation of the flow temperature, which requires a compatible thermostat that speaks something a bit more advanced than dry-contact closure.  OpenTherm is a popular (but, sadly, not popular enough) standard.  Some manufacturers have their own.

If your boiler (or possible future boiler) supports this, there are comfort and efficiency improvements to be made by doing load compensation, rather than the thermostat bluntly calling for heat.

[Auntie Helen]

We have Tuya (Smart Life) radiator valves, separate thermostats and lights/sockets etc.

For us, we have both Alexa and Siri routines to say when the last of us is leaving the house and it turns off all the lights and turns down the radiators. We have “I’m back” routines to fire everything up again. We used to have it linked to both phones leaving the house but this wasn’t great when Klaus’s daughter  was visiting and stayed behind as she got plunged into darkness.

The temperature detection on the rad valves is fairly inaccurate so the separate thermostats are very useful.

[rafletcher]

I really cannot see anything pcolbeck desires to do that requires a 'smart' thermostat. By smart I assume hive, Honeywell or some such IoS is implied. My thermostat allows me to set 6 target temperatures over 6 time ranges Mon-Fri and a different 6 Sat & Sun. It cares not where the heat is sourced, demand is on or off. It is as dumb as rocks whilst being roughly 12x smarter than a single temp+time arrangement. It cost peanuts and maintenance is change the batteries every 18 months or so. Can't be hacked. Can't be bricked by a cloud service bankruptcy. Can't require payments to continue working. WTAF is the attraction of smart IoS?
Kim's solution is, naturally, the bogs dollocks.

This really.  Our stat is just a digital version of the old bimetallic type, bu then we have a small cottage with 2 rooms down and 3 up, and my wife is home all day, so it’s good enough. It’s advantage is the fuzzy logic that lets it learn warm-up times, and the on-off cycles that mean the boiler doesn’t fire constantly and the heat never overshoots the set point. Hysteresis is minimal, rather than 4-6 degrees.

[DuncanM]

It cost peanuts and maintenance is change the batteries every 18 months or so.

We went Tado after the LCD screen died on our Honeywell dumb thermostat meaning we were unable to see what temperature it was set to.  Twice (just out of warranty both times, natch). At £90 each, the 2 dumb (wireless) thermostats cost us almost as much as the basic Tado setup and lasted half as long (combined).
Obviously, mileages vary...

[rogerzilla]

Hive works well but:

1. Centrica now charge for features that used to be free, like historical temperature charts (as if anyone would pay)

2. They really annoyed a lot of customers by withdrawing support for some smart devices (cameras, alarms) very soon after they were last sold.  No support totally bricks them, as Hive are turning off the service centrally.

[robgul]

Hive works well but:

1. Centrica now charge for features that used to be free, like historical temperature charts (as if anyone would pay)

2. They really annoyed a lot of customers by withdrawing support for some smart devices (cameras, alarms) very soon after they were last sold.  No support totally bricks them, as Hive are turning off the service centrally.

+1 for Hive - had it for about 4 years at our previous house (as a deal with new boiler) . . .  been in this house for almost 3 years, had Hive installed to replace existing flakey control system 2 weeks after we moved in - excellent.

We've recently added 3 Hive TRVs to use as "time switches" in rooms we don't use all the time - just heat at specified times (within the overall heating time windows) . . . if the doors are kept closed it all works.    Hive TRVs have had some dubious press but that seems to be where people are using them to control temperatures and use "heat on demand" rather than the way we use them.

... and agreed on the security kit withdrawl - I was poised over the order button when I found out they were binning the service.   The Hive lights and sockets/plugs work a treat too.

[Diver300]

Does anyone know the Honeywell Evohome system in detail?

We've had some underfloor heating added to a few rooms, and there is a new pump and manifold for those rooms. To heat any one of those rooms, the boiler needs to be turned on, the manifold valve needs to be turned on, and the new pump needs to be turned on.

Other rooms (and the hot water) only need the room (or hot water) valve and the boiler to be turned on. If heat is required in any room, or the hot tank needs to be heated, the boiler is needed. The new pump  will only be needed if one of the rooms that has newly acquired underfloor heating needs heat.

Is it possible to program a switch on the Honeywell system to come on for some rooms and not others?

[jdsnape]

Conspicuously absent is control of individual radiators via smart TRVs, mainly because there doesn't seem to be a good open landlord-friendly option.  I'm reluctant to invest heavily in someone else's radiators.

I did something similar to you in our previous house. For TRVs the best I could find were https://www.eq-3.com/products/eqiva.html bluetooth TRVs. They can be manipulated over bluetooth (specifically BLE) and there are various open source utilities for talking to them. I was able to adjust their set point dynamically, as well as poll them for how 'open' they are and use that as a demand signal to operate the heating. I don't know about your radiators, but if you have standard TRVs then these just screw in place and can be easily removed.

[Karla]

My reasons for fitting a Nest were:

1) I was splitting my time three ways between work, mine and Miss Bunbury's places, and work was also being a bit irregular, so my schedule was out the window and the geofenced heating was hugely useful.
2) My boiler was on a different floor to the rest of the flat, so I wanted a wireless controller so I could change the heating without wandering through the communal area in my kecks.  Yes you can get wireless dumb controllers but see (1).

[Diver300]

Does anyone know the Honeywell Evohome system in detail?

We've had some underfloor heating added to a few rooms, and there is a new pump and manifold for those rooms. To heat any one of those rooms, the boiler needs to be turned on, the manifold valve needs to be turned on, and the new pump needs to be turned on.

Other rooms (and the hot water) only need the room (or hot water) valve and the boiler to be turned on. If heat is required in any room, or the hot tank needs to be heated, the boiler is needed. The new pump  will only be needed if one of the rooms that has newly acquired underfloor heating needs heat.

Is it possible to program a switch on the Honeywell system to come on for some rooms and not others?

When I finally got round to phoning the nice people at Honeywell, they told me that their underfloor heating controller has a "pump" output for that very purpose. 5 thermostats and the controller are on order.

I've just taken off the wall the virtually unused Heatmiser equivalent, which was about half the price, but the "professional" that fitted it just wired that to bring on the boiler and ignored the Honeywell controller. That left me with a Honeywell system with 5 rooms not working, and 5 thermostats to go on the wall in the various rooms. The thermostats from Heatmiser are like something out of the 1990s, with a little card to tell you how many times to press each button to program the different temperatures at different times. It is, of course, impossible to actually work out what is going on without a pencil and paper and half an afternoon, and no danger of having features like the ability to copy a program to another day or another room, like the 10 year old Honeywell system can do. The clock setting needs the instructions and needs to be done twice a year for each room. Obviously the Honeywell system doesn't need the clock setting.

The Heatmiser thermostats were the same price as the Honeywell ones, and I'll get next to nothing for them on Ebay.

[robgul]

Hive works well but:

1. Centrica now charge for features that used to be free, like historical temperature charts (as if anyone would pay)

2. They really annoyed a lot of customers by withdrawing support for some smart devices (cameras, alarms) very soon after they were last sold.  No support totally bricks them, as Hive are turning off the service centrally.

+1 for Hive - had it for about 4 years at our previous house (as a deal with new boiler) . . .  been in this house for almost 3 years, had Hive installed to replace existing flakey control system 2 weeks after we moved in - excellent.

We've recently added 3 Hive TRVs to use as "time switches" in rooms we don't use all the time - just heat at specified times (within the overall heating time windows) . . . if the doors are kept closed it all works.    Hive TRVs have had some dubious press but that seems to be where people are using them to control temperatures and use "heat on demand" rather than the way we use them.

... and agreed on the security kit withdrawl - I was poised over the order button when I found out they were binning the service.   The Hive lights and sockets/plugs work a treat too.

As the thread has re-emerged a quick comment - the Hive time-switch rad valve method described worked a treat last winter with a significant reduction in gas consumption (that's Kwh compared year-on-year, not actual cost)

[rogerzilla]

A smart flow thermostat is supposed to save energy if

1. You have a condensing boiler
2. You don't need to heat stored hot water quickly, or to more than hand-hot (the delta-T with a 63 deg flow temperature is too low to get a tank to 60 deg C this side of Xmas).

In practice (2) means it's a no-no for most systems with a hot water tank.  Combis will heat hot water to the same temp regardless, so an external temperature sensor and a smart flow thermostat are worth having..

[Mr Larrington]

I've just had an e-mail from the Mega-Global Chocolate Manufactury of Mountain View, USAnia telling me that:

Google[/b]]
Your thermostat’s Heat Link* is eligible for a replacement by Nest
We’ve identified an issue with your Heat Link, which connects your thermostat to your heating system. This issue could cause your thermostat to lose power unexpectedly.

* which in my case I have not got but had to get added to something in order to control the supply of joules at Schloß von Brandenburg while cat-sitting.