Will Smart Raiator Thermostats help reduce my heating bills, are they worth it?

Petriix

Anything that reduces the demand for heat objectively saves you money. Exactly how much and whether or not it's worth it compared to the expense of installing the equipment is a different question.

There's a very lazy tendency to claim that running a boiler to heat a smaller volume of water would be less efficient and therefore cost more; that's a non-sequitur with the first part potentially being true with it being very unlikely (but not impossible) for the second part to be right. The overwhelming likelihood is that a boiler running less efficiently will still use less gas because it's putting out less energy overall.

The picture is very much complicated by subtleties of how the system is configured and used with people often failing to maximise the potential savings through misunderstanding the system.

Smart TRVs are most effective when you have significant separation between the different areas of the house and when they are used. In my house they could work really well because, most of the time, only one room is in use. If we could program it so that the bedrooms got a short blast before getting up and again before bed, that would be a significant saving over heating them whenever the rest of the house is heated. Likewise, only heating the back room while Mrs Petriix is working home alone most days would be better than heating the whole house (including the bedrooms).

I say 'could' because, at £70 each for the 6 TRVs required, it's unclear whether I could make a saving overall. Perhaps if current prices stick around but almost certainly not if they return to sensible levels in the medium term. The entire gas bill for my house (including hot water and cooking) was around £400 for 2022.

[Deleted User]

Petriix said:

Anything that reduces the demand for heat objectively saves you money. Exactly how much and whether or not it's worth it compared to the expense of installing the equipment is a different question.

There's a very lazy tendency to claim that running a boiler to heat a smaller volume of water would be less efficient and therefore cost more; that's a non-sequitur with the first part potentially being true with it being very unlikely (but not impossible) for the second part to be right. The overwhelming likelihood is that a boiler running less efficiently will still use less gas because it's putting out less energy overall.

The picture is very much complicated by subtleties of how the system is configured and used with people often failing to maximise the potential savings through misunderstanding the system.

Smart TRVs are most effective when you have significant separation between the different areas of the house and when they are used. In my house they could work really well because, most of the time, only one room is in use. If we could program it so that the bedrooms got a short blast before getting up and again before bed, that would be a significant saving over heating them whenever the rest of the house is heated. Likewise, only heating the back room while Mrs Petriix is working home alone most days would be better than heating the whole house (including the bedrooms).

I say 'could' because, at £70 each for the 6 TRVs required, it's unclear whether I could make a saving overall. Perhaps if current prices stick around but almost certainly not if they return to sensible levels in the medium term. The entire gas bill for my house (including hot water and cooking) was around £400 for 2022.

My evidence is based on 5 years with Honeywell Evohome (18 smart TRVs). We spent £1500 on Evohome and have saved very little on our heating bill.

BEIS has collated the results from a number of international academic studies. At the end of the day, it is a personal decision whether to buy smart controls.  We no longer have smart TRVs.

Rob5342

You do have to be careful how you use them. With Tado the electronic radiator valves can call for heat and turn the boiler on. If you have a room with a radiator that's a bit undersized that has a Tado valve on then that room can be calling for heat and make a room without an electronic valve a lot warmer than normal

Rob5342

Alnat1 said:

Rob5342 said:

We have them in a few rooms and they are great for comfort and convenince. We have the bedrooms set to 18 most of the time so they are cool to sleep in but they come up to 21 for an hour in the morning and even so it's nice and warm when we get up and go to bed. We have the lounge set to 21 during the day but it goes down to 18 overnight.

18C is cool to sleep in? I'd personally want to open the window if the bedroom was that warm or I'd be awake all night.

Lounge is 17.5C in the day, bedrooms around 14-15C. Heating off overnight unless below 0C outside, then it stays on with lounge thermostat at 14.5C which will let the bedroom heat up a bit now and then.

I always find 21 just right if I'm wearing a t-shirt, if it was 18 I'd need to put a jumper on. I can't be alone as the Tado app puts 18 as the lower limit of comfort

[Deleted User]

From a BEAMA report last year. Not a smart TRV in sight:

Leon_W

I see the OP hasn't been back yet but everyone is presuming it's a Baxi gas back boiler like the Bermuda. Perhaps it might be a solid fuel Baxi Burnall with a back burner which is a whole different kettle of fish ?

BUFF

As already mentioned results will vary according to the building, the heating system & user behaviour.
Iirc the 1 major study that I saw has it at about 3% overall compared to standard TRVs - but results varied massively by user incl. some that used more not less.

Imo to get the max benefit you need to have a complete "smart" control system from boiler to programmer/room 'stat & all TRVs - but that comes at considerable cost (especially the multiple TRVs) which may take a long time to recoup especially if you are a low user to start with.

Alnat1

Did I read somewhere that the smart TRVs are battery powered and you're forever having to change them, adding to cost?

FreeBear

Dolor said:

FreeBear said:

Dolor said:

ThisIsWeird said:

To answer your Q, it's 'yes'.

It should be a statement of the bleedin' obvious that if you have fewer radiators running, you will consume less gas. So you either run around the house turning the valves up and down as required, or you just - wastefully - keep heating the whole house.

Smart valves come into their own with rooms that only require heating at certain times, of which bedrooms are probably the best example. These generally only need a bit of heat a short while before bedtime, and first thing in the morning. You may also want a lower level of heat all night, tho' that's why gawd gave us duvets.

So, how do you currently control the heat in your bedrooms? 

I beg to differ. Smart TRVs offer no additional savings over standard TRVs. They just offer more owner convenience at a much higher procurement cost. If there were significant additional energy savings to be made, smart TRVs would be made mandatory for new builds which is not the case.

The downside of shutting off too many rooms is that you end up with an over-sized and inefficient boiler that rarely condenses and continually cycles. I have a 4 bed home with 2 heating zone valves and manual TRVs. I leave the unused rooms set at 15C and the rest at 20C. Our gas usage for the past 12 months has been 4481kWh.

The OP has a Baxi back boiler, so it won't be condensing (unless it is a BBU 15 HE). Have (had) an ancient Baxi here, and I would agree that smart TRVs will not make for any significant savings over regular TRVs. A couple of things that will save gas though is to shut off the gas during the summer - The pilot light will be using something in the region of 2000KWh each year. Fit a smarter control system such as a Drayton Wiser that allows for different temperatures throughout the course of the day - Potentially, 10-15% saving there.

I've gone from an annual gas consumption of 8000KWh with the Baxi down to under 4000KWh with a smart control, regular TRVs on most radiators, and shutting the gas off during the summer. Due to circumstances beyond my control, having a new combi boiler fitted next month, and am replumbing the heating system & DHW in preparation. With the addition of some new radiators, I'm hoping gas consumption will remain under 4000KWh p.a..

Go for Opentherm control if you can. It is mandated in The Netherlands. The best analogy is someone driving across London with traffic lights varying from go to stop. Opentherm cleverly modulates the boiler output to try to get you across London with all the lights on green! That is, it reduces boiler cycling than enhances efficiency and extends boiler life.

One step ahead of you on that - One of the primary specs when shopping for a new boiler was OpenTherm compatibility so that I could integrate it with my home automation system (Home Assistant and an ESP32 thermostat+shield).

Pretty much all modern boilers will modulate the output when coupled with a smarter thermostat. Vaillant and Worcester Bosch certainly do, but they both use their own proprietary bus (there is an open source EMS-ESP32 project for WB, but I'd rather not be debugging a reverse engineered protocol).

Took delivery of the OT shield over the weekend, and just waiting for an ESP32-S3 board to turn up. Once all the bits are in place, I can start playing.

[Deleted User]

BUFF said:

As already mentioned results will vary according to the building, the heating system & user behaviour.
Iirc the 1 major study that I saw has it at about 3% overall compared to standard TRVs - but results varied massively by user incl. some that used more not less.

Imo to get the max benefit you need to have a complete "smart" control system from boiler to programmer/room 'stat & all TRVs - but that comes at considerable cost (especially the multiple TRVs) which may take a long time to recoup especially if you are a low user to start with.

Having sold a house with a complete Evohome system, the EPC allowance was exactly the same as it would be for a home with 2 zones and standard TRVs. When I queried this with BRE the organisation that produces the EPC database that assessors use, the response was ‘ all savings for smart heating controls are based on manufacturer tests. If a manufacturer is prepared to make its controls available for independent testing then the test data will be included in the EPC database.’