Wireless radiator valves.

[Richard_C]

I think its useful to decide of you want your radiator controllers to be able to turn the whole system and/or bits of it on and off, or just turn a radiator or two off at set times. You can achieve that last bit for a lot less money.

The next bit of explanation is basic - no need to read it if you already get all of this stuff.

In a conventional system, the timer/controller says 'hey, its time for some heat now, I've been told to turn it on at 5 pm'. That sends a signal to the room thermostat if you have one. The room thermostat says either 'no need, its warm enough already' or 'too right, its a bit chilly'. If the timer and room thermostat both call for heat, the motorised valve to the CH circuit opens (assuming you have 2 channels and a seperate one for the hot water, or a combi tankless system) the pump starts and cold water begins to flow through the radiators and boiler.

The boiler is at first sight a bit dumb: all it does is say 'well, I've been told to output water at 65 degrees, the water flowing in is only 40 so I had better fire up'. Its not quite that dumb, there is an anti cycling device. Imagine water comes in at 40, fires up. Water gets to 65, water keeps circulating because the timer and room thermostat are telling it to, but if it drops to 64 you don't want it to fire up again - it would be constantly and wastefully on/off with tiny changes in water temperature. So, its programmed with hysterisis - a gap - maybe 5 degrees drop before it will fire again.

So now we have hot water rushing around the CH system and in and out of radiators. If there were no radiator valves that would be it, all the rooms would heat up unitl the room thermostat said 'enough already' and stopped the pump. Room cools, off we go again. That's how it was in my parents house - no TRV's back then.

But with TRVs we can easily adjust room by room, but a TRV is a 'switching off' device not a switching on one. It's only relevant if the pump is running and hot water is circulating through the radiators. Set one to 16 in a bedroom, when it gets to that temperature it shuts that radiator off, saving energy.

You can of course go round and manually adjust the TRVs a couple of times a day in rooms you use intermitttently. That's what I do now. If you don't want to do that you can go full remote, as some here have done, or pick a cheaper middle option.

You can get a stand alone battery operated programmable head to replace the TRV head where it matters. One such is the terrier i-temp from pegler, about £20 although I 'm sure there are others. So if you don't want your bedroom using heat until say 9.30 in the evening you put the times in and tell it you want (say) 18 degrees from that time and nothing before. It won't call for heat if the pump is off like the super clever systems - what it does is turn off the circulation to that radiator so if the system is running anyway that room won't get hot until the time you have set. Saves you running about (or in my case, saves me remembering).

My plan (and its only just got cold enough to start using my recently installed replacement boiler) is to get 2 - one will turn the bedroom off after get-up time until late evening, the other will turn the sitting room off until later in the day so the morning cycle isn't wasting energy by warming a room we are not in.

I don't think £2k of smart full remote will deliver value for me, but £40 on 2 stand alone radiator controllers might repay itself.

The OP speaks of family who leave bedroom TRVs on all the time - this might be a simple solution.

 

[paulrbarnard]

Thanks. I know a bit about that side of things too, having written firmware for a LoRa IoT device a couple of years back, and seen numerous discussions about ZigBee on another forum.
So I'm confident with the RF stuff, the electrical stuff, and a bit of plumbing( which I doubt I'll need). I was , and still am more interested in hands on experience of the system, and the sort of savings that might be possible.
Thanks to all who have contributed so far, please keep it coming if you have first hand experience.
Special thanks for posting the YouTube link.
I'm off to the Scilly's for a few days, but will be resuming looking at this when I get back.

like this? We have a lot of rooms turned off as it's only been my wife and I at home for a while

 

[Spectric]

Another option that I do not think has been mentioned is that rather than use a seperate thermostat and a timer, get a combined timer/stat which then allows you to set a different temperature for each time period and also for each day. The Honeywell CM 907 has six on/off periods per day so if you both work then you can set a low background temperature but then have it come up to a warmer temperature for when you get home. Weekends can be set completely different as you may be at home.

 

[MikeJhn]

If you look at my post 50 there is a schematic of my system. I have two leds which come on when the system is calling for hot water or central heating so I can see what is happening. If the rooms and hot water are at the set temperature the boiler is switched off. It is only when a radiator valve or hot water calls for heat that the boiler switches on. I have just looked, cold day outside but boiler is off.

I have complete control of individual room temperatures throughout the week and and the boiler only comes on when there is a demand for heat to heat a room or hot water. The boiler sorts out hot water priority and central heating water temperature based on the outside temperature to maximise efficiency.

If a radiator valve senses a need to switch on it sends a signal to the controller which sends a signal to the bdr91 which switches the boiler on and a signal to the valve to open.

I do not regard it as “a solution looking for a problem”.

You'r first paragraph sounds exactly like my system with a Honywell boiler control unit that lights up when the boiler switches on for the radiators or hot water demand.

I have complete control over individual rooms via the TRV valves and the boiler only comes on when theres is a demand for heat or hot water.

With the Testo gas analyser I have I set my boiler to a real time efficiency of 85%, powers that be say it is only 48% efficient, these being the same power that say you can get 90% efficiency from a condensing boiler, all that I have checked are below 75% when first checked and tweak to 85% or there about's once serviced, I am happy with my boiler as it's over 25 years old and runs like a RR, at my age spending money unnecessarily is wasting beer vouchers.

 

[Spectric]

I am happy with my boiler as it's over 25 years old and runs like a RR,

Unfortunately they don't make boilers like that anymore, yes the days when a boiler would last twenty plus years and it would almost become a member of the family, nice big heavy cast unit that took two people to lift with no electronic's. But now like most things that was not good for the economy and people can now make a very good living out of replacing boilers that in some cases are only six years old, and combi's were like fuel injection replacing carburettors in that added complexity just provided even more income and expense for hard strapped families.

 

[Dibs-h]

I too have the Honeywell Evohome system - runs like a dream. It's been running for 2 years now - and only this week I've had to do a factory reset on the controller & bind the TRV's to it as it just wan't firing up the boiler.

Setting things back up again took 15-30 mins, so no great loss.

I like the fact that only occupied rooms and common areas are heated.

I do keep track of gas usage and worked out after the 1st winter of it being in use that a 6 TRV system would pay for itself in gas savings in 3.5 years (using 2.5p per kWh for gas , which is what I was on then & for this month). Obviously with the jump in gas prices, the savings will be somewhat greater and the payback quicker.

We did have regular TRV heads on all the rads but it really meant heating the whole house, as no one was going to go turning the TRVs up & down round the house.

I saw the Solus system\heads a few weeks ago - but vaguely recall it's limited to 6 heads per controller.

Cheers

Dibs

 

[Jonm]

You'r first paragraph sounds exactly like my system with a Honywell boiler control unit that lights up when the boiler switches on for the radiators or hot water demand.

I have complete control over individual rooms via the TRV valves and the boiler only comes on when theres is a demand for heat or hot water.

With the Testo gas analyser I have I set my boiler to a real time efficiency of 85%, powers that be say it is only 48% efficient, these being the same power that say you can get 90% efficiency from a condensing boiler, all that I have checked are below 75% when first checked and tweak to 85% or there about's once serviced, I am happy with my boiler as it's over 25 years old and runs like a RR, at my age spending money unnecessarily is wasting beer vouchers.

The two led’s I referred to are ones I have added so I can see what signals are being sent from the evohome system to the boiler, so I can see what the boiler is seeing. There are also led‘s on the two Honeywell radio boxes connected to the boiler.

 

[mikej460]

We have an old, now obsolete German made FHT wifi system in our house. The house is zoned using wall mounted programmable thermostats that each instruct one or up to 4 motorised radiator valves to partially or fully open/close. Each thermostat is then networked to a central hub that connects to the boiler. Once all thermostats have reached their pre-programmed temperature the hub switches the boiler into standby (as long as the hot water tank has reached its temperature). Each thermostat can be programmed to a desired temperature at any time period on any day. It has worked well over the years but it is complicated, it isn't intuitive and if something goes out of kilter and needs changing then I have to do it using the manual. I have no idea how much this saves us and I installed it when we moved from a dilapidated oil boiler to a biomass and the whole system has saved us a small fortune in oil. I've programmed it to keep all rooms to a minimum 17 degrees 24/7 with bedroom and bathroom coming on to heat to 20 degrees every morning and evening, spare bedrooms run cooler. Downstairs the kitchen, hall and lounge come on each morning and the lounge stays on all day and evening at 20 degrees. In warmer months I simply programme the boiler differently and it overrides the thermostat system; this simply stops the boiler from starting and going into standby once the hot water tank is up to temperature. My wife can't operate it other than knowing how to press a thermostat override button if she's wants to work in a cooler room. The batteries in the valves and thermostats last a very long time, at least 2 years.

 

[DBT85]

Well I just pumped in for a Wiser kit (saved £12 on it with that ebay voucher over the price anywhere else) and 12 valves. £625 all in. We have a large bungalow so may end up needing a smart plug and I can see us getting at least one extra wall stat for our bedroom. We cook about £1500 worth of oil a year.

Lets see where we end up.

 

[MikeJhn]

I do keep track of gas usage and worked out after the 1st winter of it being in use that a 6 TRV system would pay for itself in gas savings in 3.5 years (using 2.5p per kWh for gas , which is what I was on then & for this month). Obviously with the jump in gas prices, the savings will be somewhat greater and the payback quicker.

Don't understand that statement, if Gas has jumped presumably upwards in cost your saving on usage will go down, or have I missed something?

 

[DBT85]

Don't understand that statement, if Gas has jumped presumably upwards in cost your saving on usage will go down, or have I missed something?

If it was 100 units of fuel at 1p per, and you now used only 50, you'd save 50p.
If it was 100 units of fuel at 3p per and you now only used 50, you'd save £1.50.

Since prices only ever seem to go up, the short term pain of buying a thing that saves energy invariably pays for itself faster than initially calculated as rarely do people include inflated energy costs in their calculations.

 

[MikeJhn]

Arn't statistics wonderful, they can prove anything you want!

 

[DBT85]

Arn't statistics wonderful, they can prove anything you want!

If you disagree Mike then lets discuss it.

 

[Jonm]

Arn't statistics wonderful, they can prove anything you want!

Dbt85 has helpfully given you a very good mathematical calculation showing why “with the jump in gas prices, the savings will be somewhat greater and the payback quicker”, to help you understand the issue. No statistics involved.

 

[Dibs-h]

For anyone interested - I paid £110 for the EvoHome controller & boiler relay and £50 per TRV head (6 heads), giving a total of £410. I didn't go for the pre-packaged sets as I was able to get better pricing by getting bits from separate suppliers.

My gas usage in prior years without the EvoHome, was approx 31,000kWh. For the last few years since having the EvoHome system in place, the average (over 3yrs) has been 26,500kWh, giving a reduction of 4500kWh.

For me an approximate payback of 4 yrs is enough to do something. Obviously different strokes for different folks.

Cheers

Dibs

 

[Just4Fun]

For anyone interested - I paid £110 for the EvoHome controller & boiler relay and £50 per TRV head (6 heads), giving a total of £410.

If you have 6 TRV heads does that mean you have 6 radiators? Or do you have additional radiators to which you did not fit TRV heads?

My gas usage in prior years without the EvoHome, was approx 31,000kWh.

6 Radiators is a modest heating system, implying that you don't live in a large old stately home, so I am surprised that your gas usage has been so high. Why do you think that is? You are using more energy than we are but we have a larger heating system in a colder climate.

For the last few years since having the EvoHome system in place, the average (over 3yrs) has been 26,500kWh, giving a reduction of 4500kWh.

Putting your 4,500kWh in perspective, I spent about 3,000 euros in (I think) 2005 to fit 90 solar evacuated tubes mainly to supplement our heating(*). These contribute about 7,000kWh p.a. so your TRVs are giving more bang for your buck than I get from my solar.

(*) During the summer they provide hot water, but our non-heating season is rather short. This year the last snowfall before summer was 6 May and the first snowfall after summer was 20 October, so for most of the year I have the solar kit switched to heating use.

 

[Jonm]

I was told by a plumber about one of his customers who had a large house with a system which was under sized in terms of pipe work and boiler. He fitted the Evohome system and was able to heat the occupied rooms to a higher temperature. The customer was apparently very satisfied.

I used to own a large listed building. Cost a fortune to heat, had thermostatic valves but as others have said, the family had no concept of how to use them, If the room is not warm enough then turn them up to maximum.

With the Evohome system if a room is not warm enough, then turn a dial on the top and there is a digital display of the temperature, my wife can use it. she has even been known to then turn it down if the room gets too hot! On the next programming cycle the valve is reset. From that point of view the digital display is much better. It would have saved me a fortune in my old house.

My wife is perfectly capable of programming the system but has absolutely no interest in doing so. Bit similar to me and ironing.

 

[Dibs-h]

If you have 6 TRV heads does that mean you have 6 radiators? Or do you have additional radiators to which you did not fit TRV heads?

6 TRV heads - living room, dining room & bedrooms have them on. Kitchen, downstairs WC & bathroom don't. They just have the regular TRV heads except the WC which is the bypass radiator. The large hallway is also a regular TRV - if that one had an EvoHome TRV, it would be forever turning the heating off as it's near the outside door (would register drafts as the door is used & turn that rad off a lot).

Then there's a few other rooms that aren't really used that have regular TRV's set so the room isn't cold but isn't toasty either.

6 Radiators is a modest heating system, implying that you don't live in a large old stately home, so I am surprised that your gas usage has been so high. Why do you think that is? You are using more energy than we are but we have a larger heating system in a colder climate.

It's a 110yr old house with 10 foot ceilings and not really energy efficient but something I'm working on.

Putting your 4,500kWh in perspective, I spent about 3,000 euros in (I think) 2005 to fit 90 solar evacuated tubes mainly to supplement our heating(*). These contribute about 7,000kWh p.a. so your TRVs are giving more bang for your buck than I get from my solar.

(*) During the summer they provide hot water, but our non-heating season is rather short. This year the last snowfall before summer was 6 May and the first snowfall after summer was 20 October, so for most of the year I have the solar kit switched to heating use.

They're on my list of things in the future.

Cheers

Dibs

 

[Dibs-h]

With the Evohome system if a room is not warm enough, then turn a dial on the top and there is a digital display of the temperature, my wife can use it. she has even been known to then turn it down if the room gets too hot! On the next programming cycle the valve is reset. From that point of view the digital display is much better. It would have saved me a fortune in my old house.

You can disable the "local" override on the EvoHome TRV's on a zone by zone basis if you wish.

My wife is perfectly capable of programming the system but has absolutely no interest in doing so.

Don't get me started on that bit...the number of times I've driven her car and asked her (who's sat in the front passenger seat) what the noise is that I can hear & the answer has always been the same.."What noise?".

 

[John Brown]

Another option that I do not think has been mentioned is that rather than use a seperate thermostat and a timer, get a combined timer/stat which then allows you to set a different temperature for each time period and also for each day. The Honeywell CM 907 has six on/off periods per day so if you both work then you can set a low background temperature but then have it come up to a warmer temperature for when you get home. Weekends can be set completely different as you may be at home.

Thanks. We already have that. It's the control over individual rooms I'm after.

like this? We have a lot of rooms turned off as it's only been my wife and I at home for a while
View attachment 121087View attachment 121088

That's interesting. I was avoiding Tado, as I think thay were the ones who'd changed to a subscription system, although I could be wrong.