Smart controls for my central heating system

[dazzler9000]

Hi all, hope you can help. Central heating systems aren't my strong point and replacing anything at the moment could be risky as the Mrs will not be happy if I break something. I'm trying to limit energy usage for the random days we work from home. Heating the single office room sounds sensible, via smart TRVs.

I'd like to replace my heating system controls with a smart system but I'm stuck on a few things. I have downstairs wet UFH controlled by Heatmiser RF room stats and 6 radiators upstairs. I was planning on making the whole system smart, but for the minute, funds only allow for me to tackle the upstairs.

I was advised by a member on here to look at the Salus range. Listed below is what I currently have and what I think I need. Note, the list below also includes the downstairs but I won't be doing that until the summer.


My current system consists of -

Downstairs
Wet underfloor heating controlled by a Heatmiser UH1-W and 4 x Heatmiser room stats (4 zones).

Upstairs
Vaillant Ecotec Plus 837
Timeguard room stat (hardwired)
Centaurplus C27
6 radiators


I think the replacement would look like this.

Downstairs
1 x Gateway - UG600
4 x SG610RF room stats
1 x KL08RF

Upstairs
1 x RX10RF
1 x SQ610 Think this is right, as the current room stat is hardwired.
6 x TRV10RFM Smart TRV


Below is a diagram of how I think it works (left-hand side) currently and how I think it might look (right-hand side).

The downstairs should be straightforward I'm hoping. The 'KL08RF' should be a straight swap when I get to that.

The upstairs is where I get confused. How does the upstairs heating work with smart TRVs? Do you just set the SQ610 at say 24c and let the smart TRVs regulate the heat in each room?

Do the TRVs communicate with the upstairs SQ610, RX10RF or directly to the gateway UG600.

All a bit confusing for me not being in the trade.

 

[Deleted member 267285]

Salus aren’t usually good from what’s been said, perhaps Tado or Honeywell evo home? Drayton Wiser do TRV heads, but the ufh control is expensive.

 

[dazzler9000]

Salus aren’t usually good from what’s been said, perhaps Tado or Honeywell evo home? Drayton Wiser do TRV heads, but the ufh control is expensive.

Oh really, that's a shame. They seem to have a device to suit most scenarios.....

Any other feedback on Salus?

 

[Heat_this]

Go beyond the hype and look into getting proper controls with weather compensation which will make use of the boiler's modulation capabilities. Vaillant wiring centre VR71 tbc and VR720 SensoComfort would make you achieve this and the latter could be used as thermostat for your radiator zone.
To control remotely, you would need the internet gateway (VR 921 tbc). Depending on the size of the house and the location of the wiring centre and boiler, it might be possible to use wireless control(s), giving the ability to move the radiator thermostat to various rooms.
Also you might want to use vaillant TRVs (VR 50 TBC) in which case they replace the thermostat (which becomes just a programming console) and allow to control temperature and programming at room level. I would contact Vaillant to verify if they recommend this solution.
Your DHW cylinder, assuming there is one, would also benefit since you'd be able to range rate your boiler in accordance to your cylinder's coil rating. This would allow to charge the cylinder at the fastest speed achievable while avoiding cycling.
Regarding the UFH, whichever solution in the future would be connected to the wiring centre for heating demand. A heating curve would also be available in order to manage a motorized valve instead of a manual blending valve so that the heating is adapted to the heat loss which depends as you know on the outdoor temperature. I ll leave it here, the solution would then need some way to control each of the UFH loops.
Hope this will bring food for thought.

 

[dazzler9000]

Go beyond the hype and look into getting proper controls with weather compensation which will make use of the boiler's modulation capabilities. Vaillant wiring centre VR71 tbc and VR720 SensoComfort would make you achieve this and the latter could be used as thermostat for your radiator zone.
To control remotely, you would need the internet gateway (VR 921 tbc). Depending on the size of the house and the location of the wiring centre and boiler, it might be possible to use wireless control(s), giving the ability to move the radiator thermostat to various rooms.
Also you might want to use vaillant TRVs (VR 50 TBC) in which case they replace the thermostat (which becomes just a programming console) and allow to control temperature and programming at room level. I would contact Vaillant to verify if they recommend this solution.
Your DHW cylinder, assuming there is one, would also benefit since you'd be able to range rate your boiler in accordance to your cylinder's coil rating. This would allow to charge the cylinder at the fastest speed achievable while avoiding cycling.
Regarding the UFH, whichever solution in the future would be connected to the wiring centre for heating demand. A heating curve would also be available in order to manage a motorized valve instead of a manual blending valve so that the heating is adapted to the heat loss which depends as you know on the outdoor temperature. I ll leave it here, the solution would then need some way to control each of the UFH loops.
Hope this will bring food for thought.

Thanks, as you say, you've certainly brought some new ideas to the table. Albeit, rather expensive from a quick google.....

I don't have a DHW cylinder at present.

The house is a 3-bed detached, with 2 bathrooms, not massive. I currently have Heatmiser stats using RF without issue.

I have another thread on here discussing my potential lack of insulation under my UFH. It takes so long to get my downstairs up to temp, the boiler is running nonstop all day. I'm investigating how to improve this by potentially using closed-cell spray foam under the suspended floor. Lots to do!

Anything to improve the running of the UFH would be good. It just doesn't seem like the best use of energy, by supplying hot water to the UFH, which then has to mix with cold . I'm just clueless and don't know who to ask. I could contact a local company that specialises in central heating but I'm concerned they would sell me the wrong system! Do Vaillant do system designs themselves?

 

[sxturbo]

Don't bother with the Honeywell evohome, it's really poorly supported now, the trvs are almost impossible to get hold of, Honeywell are just flogging a dead horse at this point, it's a shame as it could be very good but Honeywell are arrogant buggers who don't care, since the pandemic they've basically shut it down.

You would be best off with the Drayton wiser system,

Even the evohomeshop.com has moved away from the Honeywell evohome due to the now poor service and lack of availability and are now recommending the Drayton wiser.

The wiser system has much newer technology and Drayton have spent considerable time and effort providing regular updates to the system and software and their customer service is top notch should any issues be encountered.

To get the best out of a smart heating system and if your boiler can support it, running it in opentherm mode would provide the optimum efficiency, with hot water set as priority.

Personally I'm not a fan of the tado system as they are slowly making everything subscription based which imo negates any savings that may be had and I just don't think a heating system in your home once you've paid for it should then be dictated with a monthly cost to use it to it's optimum.

Edit: just read the thread properly you have a vaillant boiler, on these you would be best sticking with vaillant smart controls as per heat_this advice.

I think there is an opentherm adapter module you can buy for the vaillant from Netherlands (it's not officially available in the UK) which allows other smart systems to control the boiler at it's maximum efficiency, but there has been cases where vaillant have refused warranty if this module is installed as it's not officially available in the UK.

 

[Heat_this]

Don’t rush your idea for smart TRVs. They will not make you make much or any economies if they cannot control heating demand from the boiler.
As noted by sxturbo, Vaillant boilers are not natively compatible with the OpenTherm protocol. I cannot advise for the module which can be purchased from the Netherlands as I don’t have experience with it.
If you’re after efficiency gains with a ROI in short/medium term, I think you should hold off, take a step back to think about the design. Possibly with a specialist if you don’t want the headaches.
I d start with searching for an answer on the following:
What is your home estimated heat loss per room?
What is the minimum output of your boiler?
What is your UFH output per room (at design temperature, that is ~-2°c outdoors depending on your location)?
What is each of your radiator’s power (at delta T 40)?
Once power potential requirement for each room is known/estimated, work out what are your total minimum and maximum power requirements when heating is required depending on day, time of day, circumstances.
Once you have answers on these, you will have the right ingredients to think of a design to maximize efficiency and make the most of smart controls.
Regarding your UFH, what is under the suspended floor? A cellar? Is that room gaining temperature when your UFH is on?
Is that beneficial in any way at all or not?

 

[muggles]

Salus aren’t usually good from what’s been said, perhaps Tado or Honeywell evo home? Drayton Wiser do TRV heads, but the ufh control is expensive.

Their smart home kit is excellent, I've fitted several systems now and very happy to recommend it

 

[Deleted member 267285]

Their smart home kit is excellent, I've fitted several systems now and very happy to recommend it

Thanks, I knew someone had used them before and recommended them, thought it was you but not 100%.

 

[Heat_this]

Their smart home kit is excellent, I've fitted several systems now and very happy to recommend it

@muggles Hi Andrew,
Can you explain what you mean exactly by excellent? How does it integrate with the boiler?
If it doesn't, that means the boiler needs to be kept artificially on heating demand at all times for the radiator circuit which burns fuel. What might be saved on one side could generate bigger losses on the other (fuel cost, boiler cycling wear, circulating pump electricity). In other words, how do you manage the boiler part?
Thanks

 

[Heat_this]

@dazzler9000 If the heating topic is of interest to you, I would advise you to review the following document which covers and explains many of the concepts that are good to understand prior to get on the market for so called "smart" controls:
https://www.gov.uk/government/consultations/improving-boiler-standards-and-efficiency

 

[dazzler9000]

@dazzler9000 If the heating topic is of interest to you, I would advise you to review the following document which covers and explains many of the concepts that are good to understand prior to get on the market for so called "smart" controls:
https://www.gov.uk/government/consultations/improving-boiler-standards-and-efficiency

Thanks very much. Sorry, I haven't responded, I'm still stuck t work . It seems I have lots to read/learn. Let me digest and I'll no doubt be back with some questions.

 

[muggles]

@muggles Hi Andrew,
Can you explain what you mean exactly by excellent? How does it integrate with the boiler?
If it doesn't, that means the boiler needs to be kept artificially on heating demand at all times for the radiator circuit which burns fuel. What might be saved on one side could generate bigger losses on the other (fuel cost, boiler cycling wear, circulating pump electricity). In other words, how do you manage the boiler part?
Thanks

The RX10RF component provides boiler switching. Currently only on/off but I'm told OpenTherm is coming

 

[dazzler9000]

I stumbled across a Nest thermostat video on YouTube. I'd always steered away from these for some reason as I assumed they wouldn't work for me needing to control downstairs UFH and upstairs radiators but I think they do as they have a hot water connection. It looks like they also support opentherm.

Could I just stick in a Nest G3/heatlink in place of the Centaurplus C27 and Timegiard room stat? Would this enable me to control the rads upstairs and the UFH downstairs?

Don’t rush your idea for smart TRVs. They will not make you make much or any economies if they cannot control heating demand from the boiler.
As noted by sxturbo, Vaillant boilers are not natively compatible with the OpenTherm protocol. I cannot advise for the module which can be purchased from the Netherlands as I don’t have experience with it.
If you’re after efficiency gains with a ROI in short/medium term, I think you should hold off, take a step back to think about the design. Possibly with a specialist if you don’t want the headaches.
I d start with searching for an answer on the following:
What is your home estimated heat loss per room?
What is the minimum output of your boiler?
What is your UFH output per room (at design temperature, that is ~-2°c outdoors depending on your location)?
What is each of your radiator’s power (at delta T 40)?
Once power potential requirement for each room is known/estimated, work out what are your total minimum and maximum power requirements when heating is required depending on day, time of day, circumstances.
Once you have answers on these, you will have the right ingredients to think of a design to maximize efficiency and make the most of smart controls.
Regarding your UFH, what is under the suspended floor? A cellar? Is that room gaining temperature when your UFH is on?
Is that beneficial in any way at all or not?

I have another thread active at the moment, where I've just found out that my wet UFH system I inherited when I moved in, doesn't appear to be insulated. It looks like my UFH water pipes just sit on floorboards (hard to be 100% sure without ripping up the top flooring surface, but I've pretty much concluded as much) and then there is a suspended floor under my house (outdoor space). Half my heat is going under my house, Consequently, I'm not overly keen on wasting energy on its at the moment and I'm relying on a wood-burning stove for downstairs heat.

If I did install a nest, I'd still need the ability to use the UFH if I was desperate.

My plan is to rip up the downstairs floor at some point and insulate (if the wife doesn't kill me first).

 

[Mister Banks]

Do you have a combi boiler, Nest only supports combi boilers with Opentherm. I think you will need two Nest thermostats if you have two heating zones.