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

Petriix

Bendo said:

I've had 8 hive smart TRVs for the last 3 or so years.  By themselves,  they are rubbish, I think designed by hive to make you burn more gas.

For the last 12 months I've been driving them with Home Assistant and using a temperature sensor in each room to control them.

Occupied rooms we tend to heat to around 22 degrees,  mainly as the wife suffers from Fibro and it's made worse by cold.

Since using HA to control everything,  we are down from 13000KW gas usage to 10500.

Still got some tweaks to do but can drop that a bit more.

Hard to understand this. What is a 'smart TRV' if it's not a 'temperature sensor', the primary function of which is to turn off the flow of hot water into a specific radiator if heat isn't required at that time? 

Petriix

[Deleted User] said:

Sterlingtimes said:

Situations will differ. We have made considerable savings from using iTRVs.

Here are the problems that we had:

[1] In this large family home, family members forever turned the manual TRVs to the maximum. The temperature was judged by the feel of the radiators.

[2] A north/south temperature gradient. Rooms facing south were hot whilst rooms at the back were cold.

[3] While working from home, gas was turned off during the day and more expensive electricity was used to heat the single room.

Our eight-year average for gas usage is 24,214kWh, and our current 12-month usage is 18,393kWh, a saving of 5,821kWh using iTRVs. More correctly, I would deduct the hot water and cooker usage of 5,821kWh. So radiator saving attributable to Wiser is 13,254/18393 = 0.72, saving 28%.

The system cost £960. 18-month payback is expected. 

I agree: that said, most of the above savings could have been achieved with standard TRVs and a band of willing family members. Willing: by way of example. I was previously on the Octopus’ Agile tariff. I could have a bought a number of devices to turn things on when energy was cheap but the family got used to looking at the next day’s prices and doing it themselves.

Hard to imagine a household all willing and diligently turning their bedroom radiators off 15 minutes before they get up and then back on again 15 minutes before they go to bed. Then who is supposed to turn the living room radiators on and off at either end of the evening? Not impossible to do manually, but highly impractical. 

RonRamsgate

Some manual (keep fit, walk around and alter the settings) trv's have such slow open/close response times the user could feel cold or to hot. Electronic trv's (sit on sofa,tap a screen if necessary) respond much quicker.
Having the ability to control/monitor room temperatures by tapping a screen is so beneficial for some but not always for saving fuel.
The £ cost of the smart gadgets need consideration.
Anything prefixed with the word smart needs consideration, the word could be used as advertising or the next big thing in life everyone needs. Smart motorways, smart meters.....

Central heating is seasonal, getting the annual hot water fuel cost down needs consideration.   

Bendo

Petriix said:

Bendo said:

I've had 8 hive smart TRVs for the last 3 or so years.  By themselves,  they are rubbish, I think designed by hive to make you burn more gas.

For the last 12 months I've been driving them with Home Assistant and using a temperature sensor in each room to control them.

Occupied rooms we tend to heat to around 22 degrees,  mainly as the wife suffers from Fibro and it's made worse by cold.

Since using HA to control everything,  we are down from 13000KW gas usage to 10500.

Still got some tweaks to do but can drop that a bit more.

Hard to understand this. What is a 'smart TRV' if it's not a 'temperature sensor', the primary function of which is to turn off the flow of hot water into a specific radiator if heat isn't required at that time? 

The ability of the temp sensor on the TRV to be accurate is compromised by its position right next to the heat source.  A separate device in the room away from the rad is more accurate.

Sterlingtimes

Bendo said:

The ability of the temp sensor on the TRV to be accurate is compromised by its position right next to the heat source.  A separate device in the room away from the rad is more accurate.

I fully understand your observation. For the most part, my Wiser iTRVs adequately control my room temperatures. However, I have one large, awkward room with two radiators and a study which were difficult to control. I have, in each case, positioned a room thermostat some distance away from radiators that take precedence over these iTRVs. In a perfect installation, I would have an iTRV in every room with an associated room thermostat, which would be cost-prohibitive for the project.

Sterlingtimes

Petriix said:

Hard to imagine a household all willing and diligently turning their bedroom radiators off 15 minutes before they get up and then back on again 15 minutes before they go to bed. Then who is supposed to turn the living room radiators on and off at either end of the evening? Not impossible to do manually, but highly impractical. 

Yes, assuring compliance with eco and cost-saving approaches in a mixed-generation household is impossible. The grandfather, who used to take pleasure turning all thermostats down, now calls for more heat. The millennial has Greta as his goddess but still craves a 30-minute power shower. The Wiser iTRVs conveniently do not display a temperature and have a lock facility within the app, so they are fully functional but dumb.

Bendo

With hindsight,  I could have avoided the Hive TRVs which were about £45 each and bought cheap ones (I picked up 3 Devolo branded z wave ones for £8 each on Amazon a while back).

The temp sensors I'm using are cheap Sonoff ones about £8 each.

Home assistant with lots of automations is great for things like this and certainly works around the (very many) short comings of Hive.

FreeBear

Sterlingtimes said: In a perfect installation, I would have an iTRV in every room with an associated room thermostat, which would be cost-prohibitive for the project.

I had considered using some UFH actuators - These are small wax motors that need very little energy to operate, but are very slow to open/close. Could be wired directly to the home automation system or via an ESP32 relay type wifi board (would still need a mains connection close by). Either would be cheaper than buying off the shelf smart TRVs, and no batteries to replace.

https://prefectcontrols.com/products/local-control/ecostat2-wet-heating/pre9501/

https://waxmotor.com/products/thermo-electric-actuator

wild666

I have to agree with Dolor STRV's only cost more and offer no more of a saving over TRV's that you can set and forget about. STVR's are, IMO, for those with more money than sense.

jennifernil

I rather like our recently fitted smart TRVs and tado system.

Previously we had a time clock plus ordinary TRVs which certainly worked but was not as easy to alter at will.  The time clock was downstairs next to the boiler, and our living rooms and kitchen are upstairs, so altering the times if we were staying up late, or going to bed early,  involved a trip down and up, and at 80-ish we are finding stairs more difficult to negotiate. 

 Nor could we have different rooms heating at different times.    And if we were out and coming home unexpectedly late, we had no way of not having the heating on in an empty house.

Now we can set each radiator to be on at a different time, and we have more precise temperature control.  And we can control the whole system remotely 

In the lounge/diner we have 2 radiators with smart valves and a centrally situated temperature sensor to control them.  The hallways and landing have 4 radiators, with smart TRVs, with one acting as the control one, otherwise each room has its own smart TRV, though there are 3 rooms we rarely use that we have left with manual TRVs as the smart ones are quite expensive.