New boiler, TRV's and weather compensation monitor

Midden82

I'm due to have a new boiler installed, it's not possible in my home to have a heat pump so we're replacing a very old combi boiler for a newer one, but I'm very confused with some conflicting information, I was told that with new regulations that TRVs have to be installed with new boiler installation where TRVs haven't been installed which is fair enough.
But I was told by one company to have a weather compensation monitor installed with my new boiler but I was told by another company that they're a waste of money, so that's question one.
Then I was reading that TRVs are completely pointless if you have a weather compensation monitor, so why is the new regulation to install them?
Then I have chosen to go with a valliant boiler and I don't know if I should get there sensoCOMFORT thermostat but they have discontinued there TRVs so I was looking at Hive and Nest and I don't know which is best as they both have there pros and cons or if I should get there sensoCOMFORT but are there any compatible smart TRVs that work with the valliant system.
I thought I'd done well to have chosen a quality reputable boiler but now i feel like I've fallen down a rabbit hole and I'm spiralling 😪
I suffer with terrible anxiety and depression and the stress is starting to take its toll on me 😪

tacpot12

UK Building regulations required that TRVs be installed on all the radiators except the room that has the central thermostat in it, so you need to have as many any the installer requires. (Not all installers seem to follow the building regs, but will certify the boiler as compliant - go figure!)

TRVs are not completely pointless if the boiler has weather compensation (or load compensation) as they prevent rooms getting above the temperature you want them to regardless of what is happening in the house - e.g. if you haven't opened the door to the room as often as you normally do or if the sun has warmed the room before the heating has gone off. There are various situations in which TRVs will reduce the load on the boiler and save gas. I have weather compensation on my boiler and TRVs everywhere apart from the hallway and bathroom (the installer didn't want to fit one in the bathroom, despite the heating system having an automatic bypass valve, and the thermostat is in the hallway). 

You don't need SmartTRVs. The big advantage of them over dumb ones is that they can call for heat and turn the boiler on via the central thermostat, but I don't think that this is enough of an adantage to look beyond the SensoCOMFORT Thermostat. Vaillant are a good make and the SensoCOMFORT is a good thermostat. It can do either weather compensation or load compensation. Of the two, load compensation is better as it potentially heats you home more quickly. As stated above, TRVs are still a good idea with load compensation (and the building regs require them), so hopefully you can stop worrying and start looking forward to having a warm home this winter.   

ic

I have weather compensation on my boiler - and it absolutely works well with TRVs.  The weather compensation is about constantly and automatically adjusting the flow temp of the water running through the radiators (cooler on mild days, hotter on cold days) - whereas the TRV turns off a rad when the room gets to temp.  Not sure why anybody would have advised otherwise.

Midden82

Thank you so much for your help and advice, I really was getting myself in to a right state chasing myself in to a spin, I suffer badly with my mental health and where once I could handle things such as this, these days I can barely remember what day it is.
So I know I would like the EcoTec plus boiler and the SensoCOMFORT thermostat, as Valliant have discontinued their own make of smart TRVs are you able to recommend a particular make of smart TRVs, as the thermostat will be doing most of the work I don't really need a whole smart system just some compatible ones that will work along side the SensoCOMFORT.
I really can't thank you enough for your help and advice, it has really helped me feel much better.

FreeBear

Not familiar with the SensoCOMFORT thermostat, but I do know a bit about home automation (smart TRVs fit in to that). Unless you have a large home or a complex heating system, you probably don't want/need smart TRVs, and the SensoCOMFORT is a darned expensive "solution". But Nest, Hive, Wiser (and others), whilst being able to tell a Vaillant boiler to fire up, can not control the flow temperature, so if you want smarter control, you're stuck with Vaillant products.

Weather compensation is most certainly worth having - On real cold days, the boiler will run at a higher temperature so that your house heats up at a reasonable rate and maintains the temperature. On warmer days, it dials back the running temperature which equates to lower running costs.

IF it isn't too late to change your mind about installing a Vaillant, I'd suggest looking at Viessmann (either the 050 or 100) - They are OpenTherm* compatible, so you have a much wider choice of programmable thermostats, and they can automatically reduce the heat output right down to 3.2kW. Worcester Bosch Greenstar 4000 and 8000 models will also go as low as 3.2kW (depending on exact model).

Minimum heat output is important when the house is up to temperature (or very close), as the boiler can tick over keeping the place warm without "short cycling". Short cycling is bad as it is wasteful of gas and increases wear & tear on internal components.

*) OpenTherm is an industry standard to allow thermostats & home automation systems to talk to the boiler. Vaillant's eBus and WB's ems are both proprietary and fewer systems support either. So if you want smart TRVs, OpenTherm is the smarter choice.

Midden82

FreeBear said:

Not familiar with the SensoCOMFORT thermostat, but I do know a bit about home automation (smart TRVs fit in to that). Unless you have a large home or a complex heating system, you probably don't want/need smart TRVs, and the SensoCOMFORT is a darned expensive "solution". But Nest, Hive, Wiser (and others), whilst being able to tell a Vaillant boiler to fire up, can not control the flow temperature, so if you want smarter control, you're stuck with Vaillant products.

Weather compensation is most certainly worth having - On real cold days, the boiler will run at a higher temperature so that your house heats up at a reasonable rate and maintains the temperature. On warmer days, it dials back the running temperature which equates to lower running costs.

IF it isn't too late to change your mind about installing a Vaillant, I'd suggest looking at Viessmann (either the 050 or 100) - They are OpenTherm* compatible, so you have a much wider choice of programmable thermostats, and they can automatically reduce the heat output right down to 3.2kW. Worcester Bosch Greenstar 4000 and 8000 models will also go as low as 3.2kW (depending on exact model).

Minimum heat output is important when the house is up to temperature (or very close), as the boiler can tick over keeping the place warm without "short cycling". Short cycling is bad as it is wasteful of gas and increases wear & tear on internal components.

*) OpenTherm is an industry standard to allow thermostats & home automation systems to talk to the boiler. Vaillant's eBus and WB's ems are both proprietary and fewer systems support either. So if you want smart TRVs, OpenTherm is the smarter choice.

I still have time to change my mind, I was only going with the valliant as it was recommended to me by a family friend who has his own business working with boilers/gas and electrics and so would normally do the maintenance on it.
I'm little stumped now as I don't know what the right answer is.
I guess overall I just want the most efficient, economical, eco friendly, smart capable system that won't cost the earth if it needs maintenance.
I'm not sure what to do now. 😔

Midden82

I should have also mentioned I have agoraphobia so I never leave my home either but I do have a dorma which is always gets incredibly cold in comparison to the rest of my home.

ThisIsWeird

Hi Midden.
My first suggestion is, don't make a decision until you understand it, and are happy with it! Do you have a working boiler at the moment? If so, there's no 'rush'!
A brief explanation of some of the key components you've been told about might help;
Weather Comp: modern boilers work most efficiently when they run cooler - they can then extract more heat from the burner, and the flue gas will barely have any heat left in it as a result. Really good, but on colder days you need to have the boiler running hotter in order to heat your home. That's what the Weather Compensator does - it keeps your boiler running as cool as it can, saving you money, but will turn it up on colder days to 'compensate'. A 'good thing', very worth while.
SensoComfort: no idea - I'll have to look it up... But I'm guessing it's a clever room stat that will give finer control of the boiler. Again, a 'good thing', but the 'OpenTherm' system FreeBear mentioned does similar, so it's available on different makes. (Again, instead of a boiler being told to come on and go off, these controls adjust how much they come on by, trying to keep it down to as little as possible to suit the house, thereby saving you energy - imagine the flame on a gas hob being turned slowly up and down, just to keep things simmering!
TRVs: I'm sure you know, but these control each individual room's temp, quite crudely, but much better than nothing. Setting them to '3', for example, will mean the room will be roughly 19oC. A big drawback with TRVs is that they don't go off or on when you want, unless you turn them by hand. So, what do you do with your bedrooms? After you wake up and get dressed, do you then turn down your TRV? If not, it'll be running all day and eve when your boiler is on - what a waste! Or, if you do turn it off, you then need to remember to turn it back up when you go to bed! And the same goes for every room with a TRV. So, a 'good thing', but not perfect. And that brings us to...
Smart TRVs: these control each room's temp, but can do so via a phone App. You can set a 'schedule' for each room with a SmartTRV, telling your main bedroom, for example, to 'come on at 18oC at 10pm, go down to 14oC at 11.30pm, come back up to 20oC at 7am, and back down to 14oC at 8.30am'. All done automatically. Cool, huh? Fancy an early night? Just pick up your phone, find your 'Main Bedroom' on the list, and scroll the temp up to whatever you want, at whatever time - from your sofa. 
So, a 'good thing', and genuinely useful to have on your most used rooms - sitting, kitchen, main bedroom, study, etc - any room you use on and off most days, at different times. I probably wouldn't bother having them on guest bedrooms, for example; for these, you'd just leave the normal TRV set to guard against frost - '1' or less - and the windows set to ventilate. Then, when a guest comes, you just turn it manually up as and when needed.
Drawbacks to Smart TRVs? They cost around £55 each, and you need to replace their batteries every couple of years. But, they save a lot of faffing about! If you are lazy and don't bother turning your normal bedroom TRV off during the day and eve, that's a lot of gas you are wasting heating a room when it's not needed.
Does the above make sense?

Midden82

ThisIsWeird said:

Hi Midden.
My first suggestion is, don't make a decision until you understand it, and are happy with it! Do you have a working boiler at the moment? If so, there's no 'rush'!
A brief explanation of some of the key components you've been told about might help;
Weather Comp: modern boilers work most efficiently when they run cooler - they can then extract more heat from the burner, and the flue gas will barely have any heat left in it as a result. Really good, but on colder days you need to have the boiler running hotter in order to heat your home. That's what the Weather Compensator does - it keeps your boiler running as cool as it can, saving you money, but will turn it up on colder days to 'compensate'. A 'good thing', very worth while.
SensoComfort: no idea - I'll have to look it up... But I'm guessing it's a clever room stat that will give finer control of the boiler. Again, a 'good thing', but the 'OpenTherm' system FreeBear mentioned does similar, so it's available on different makes. (Again, instead of a boiler being told to come on and go off, these controls adjust how much they come on by, trying to keep it down to as little as possible to suit the house, thereby saving you energy - imagine the flame on a gas hob being turned slowly up and down, just to keep things simmering!
TRVs: I'm sure you know, but these control each individual room's temp, quite crudely, but much better than nothing. Setting them to '3', for example, will mean the room will be roughly 19oC. A big drawback with TRVs is that they don't go off or on when you want, unless you turn them by hand. So, what do you do with your bedrooms? After you wake up and get dressed, do you then turn down your TRV? If not, it'll be running all day and eve when your boiler is on - what a waste! Or, if you do turn it off, you then need to remember to turn it back up when you go to bed! And the same goes for every room with a TRV. So, a 'good thing', but not perfect. And that brings us to...
Smart TRVs: these control each room's temp, but can do so via a phone App. You can set a 'schedule' for each room with a SmartTRV, telling your main bedroom, for example, to 'come on at 18oC at 10pm, go down to 14oC at 11.30pm, come back up to 20oC at 7am, and back down to 14oC at 8.30am'. All done automatically. Cool, huh? Fancy an early night? Just pick up your phone, find your 'Main Bedroom' on the list, and scroll the temp up to whatever you want, at whatever time - from your sofa. 
So, a 'good thing', and genuinely useful to have on your most used rooms - sitting, kitchen, main bedroom, study, etc - any room you use on and off most days, at different times. I probably wouldn't bother having them on guest bedrooms, for example; for these, you'd just leave the normal TRV set to guard against frost - '1' or less - and the windows set to ventilate. Then, when a guest comes, you just turn it manually up as and when needed.
Drawbacks to Smart TRVs? They cost around £55 each, and you need to replace their batteries every couple of years. But, they save a lot of faffing about! If you are lazy and don't bother turning your normal bedroom TRV off during the day and eve, that's a lot of gas you are wasting heating a room when it's not needed.
Does the above make sense?

May I first say your an absolute angel for writing all that to help me understand, thank you so so much🩷
It did make sense so thank you, I know I can be a bit simple at times and it frustrates people but you explained it all so well, I'm not very smart unless it comes to actually doing something and I only have to watch it once to be able to do it myself but stuff like all this has me stumped.
Thankfully I do have a working boiler currently so I'm very thankful for that, the only reason we are getting a new one is the current one is over 20 years old now and it's being moved to a different room, we have an absolute pea sized kitchen and putting the boiler else where is going to free up so much needed space.
I did have one question though, I'm really sorry as I don't want to take up yet more of your time after you've been so lovely.
But is the "weather compensation" and "OpenTherm" an either or thing as in you can only have one or the other? Or are there makes and models of combi boilers that do both.
I am very keen to have Smart TRVs for all the reasons you explained so I do know and understand that bit.
Thank you again for taking the time to explain it for me.
It's all very daunting as it's a large expenditure that needs to last for many many years and I'm worried and anxious that I will make the wrong choice and mess it all up.

ThisIsWeird

Midden82 said:

May I first say your an absolute angel for writing all that to help me understand, thank you so so much🩷
It did make sense so thank you, I know I can be a bit simple at times and it frustrates people but you explained it all so well, I'm not very smart unless it comes to actually doing something and I only have to watch it once to be able to do it myself but stuff like all this has me stumped.
Thankfully I do have a working boiler currently so I'm very thankful for that, the only reason we are getting a new one is the current one is over 20 years old now and it's being moved to a different room, we have an absolute pea sized kitchen and putting the boiler else where is going to free up so much needed space.
I did have one question though, I'm really sorry as I don't want to take up yet more of your time after you've been so lovely.
But is the "weather compensation" and "OpenTherm" an either or thing as in you can only have one or the other? Or are there makes and models of combi boilers that do both.
I am very keen to have Smart TRVs for all the reasons you explained so I do know and understand that bit.
Thank you again for taking the time to explain it for me.
It's all very daunting as it's a large expenditure that needs to last for many many years and I'm worried and anxious that I will make the wrong choice and mess it all up.

You are most welcome, and thank you for your lovely thank you :-)

As far as I know, Weather Comp and Opentherm are quite different things, and used to be separate. I suspect, however, that they may come under the same Smart control system on some boilers.

To be clear - 'Weather Compensation' is simply that - it tells the boiler to go higher or lower to compensate for the outdoor temp. This used to require an outdoor temp sensor. 'Opentherm' is the indoor boiler control, a more complex way for the 'Programmable Room Thermostat' to communicate with the boiler. 

Your current room stat is almost certainly an 'on/off' device, in that all it can do is tell your boiler, "On...on...stay on...that's it...keep going...stay on... Ok! The room has reached temperature! Click! Off! Off! Off, darn you..." sort of thing. 

Opentherm, and other such systems, will instead tell the boiler to adjust it's output depending on how close to the room temp it is; "It's cold! Fire up - full blast! That's it. Niiiice. OOokkaaay, we are getting close to the room temp required; time to back off a wee bit (like turning down a gas hob); that's good, a bit more, sloooowly.. Right - we've reached temp! Try and keep it there, just ticking over". That latter method will save you a small amount on gas consumption, and tend to also give you a more stable room temp. 

Where the two things might overlap is with some Smart systems where the 'weather' is not measured by a sensor fitted outside your house, but is actually taken from weather reports from the Internet. So, that kind of control will most likely have both things going on together.

But FreeBear knows a lot more about this than I do.

FreeBear

ThisIsWeird said: Your current room stat is almost certainly an 'on/off' device, in that all it can do is tell your boiler, "On...on...stay on...that's it...keep going...stay on... Ok! The room has reached temperature! Click! Off! Off! Off, darn you..." sort of thing. 

Opentherm, and other such systems, will instead tell the boiler to adjust it's output depending on how close to the room temp it is; "It's cold! Fire up - full blast! That's it. Niiiice. OOokkaaay, we are getting close to the room temp required; time to back off a wee bit (like turning down a gas hob); that's good, a bit more, sloooowly.. Right - we've reached temp! Try and keep it there, just ticking over". That latter method will save you a small amount on gas consumption, and tend to also give you a more stable room temp. 

Where the two things might overlap is with some Smart systems where the 'weather' is not measured by a sensor fitted outside your house, but is actually taken from weather reports from the Internet. So, that kind of control will most likely have both things going on together.

But FreeBear knows a lot more about this than I do.

Yup, that pretty much explains what OpenTherm does - Virtually all boilers do OpenTherm, but some manufacturers have adopted their own version of it which is incompatible and ties you in to using their controls if you want anything more than basic on/off control.

Weather Compensation is often done by the boiler, so all you need is the external sensor and no additional "smarts". You can also use a smart thermostat to handle weather compensation by pulling data from the internet. But this is reliant on the internet and web site being available 24/7 for the lifetime of your boiler. Then there is the chance that the web site will introduce a subscription to access the data... Stick with an outdoor sensor attached to the house, and keep all the processing local to the boiler & thermostat.