Kickspace/Plinth Heaters

[DJBenson]

Hi

We are currently planning a kitchen refurb but as part of that, we will lose two panel radiators (which are in our 'Kitchen' zone with HR92's on each). I am planning on using kickspace/plinth heaters instead but we'll obviously lose control of the heating in that zone, and I wondered whether there was any way to integrate a zone heated by kickspace heaters into an Evohome setup (whether it is elegant or not).

Any idea's?

I don't think underfloor heating would provide anywhere near enough heat to replace the two units or I would choose that option and an UFH controller so my options are limited. Some of the Myson kickspace heaters can be controlled remotely (wired remote) and I was wondering if that could be incorporated into the Honeywell UFH controller in any way, or simply to add the HR92's to the pipework of the heaters themselves to still give some level of control.

[blowlamp]

Hi

We are currently planning a kitchen refurb but as part of that, we will lose two panel radiators (which are in our 'Kitchen' zone with HR92's on each). I am planning on using kickspace/plinth heaters instead but we'll obviously lose control of the heating in that zone, and I wondered whether there was any way to integrate a zone heated by kickspace heaters into an Evohome setup (whether it is elegant or not).

Any idea's?

I don't think underfloor heating would provide anywhere near enough heat to replace the two units or I would choose that option and an UFH controller so my options are limited. Some of the Myson kickspace heaters can be controlled remotely (wired remote) and I was wondering if that could be incorporated into the Honeywell UFH controller in any way, or simply to add the HR92's to the pipework of the heaters themselves to still give some level of control.

You could switch the fan motor with an Evohome relay, under control from a room thermostat.


Martin.

[DJBenson]

Yes I started to look into this, so I have a BDR91 spare (as my boiler already had one of the older relays so didn't need updating) - if that is wired to the fan it will simply power the entire unit on/off on the control of the wireless thermostat in the room? Actual flow through the pipes however will be determined by any other zone calling for heat I would guess, so there will always be residual heat if there is another zone calling for heat, which I don't think is an issue.

If I have two heaters in the room, that would be two BDR91's? Can a single room stat control multiple BDR91's and is there a limit to the number of relays the Evohome controller can support?

I'm just trying to visualise what it would look like on the display - at present, the two HR92's are grouped into a single zone called 'Kitchen' - could the two BDR91's be grouped similarly?

[mtmcgavock]

Couldn't you just add a Zone valve into the kitchen, after your zone valve have your two kick space heaters. Wire the BDR91 to the zone valve motor (You don't need a S/L to the boiler as you have your boiler relay). Have a thermostat on the wall, and program the kitchen as zone which is controlled by a zone valve and thermostat. When the zone calls for heat the BDR91 will click on, your boiler relay will click on, then the fans on the kick spaces will power up when the flow temperature is hot enough. Simple.

It is basically the same issue as I had with my towel rail circuit.

[DJBenson]

Couldn't you just add a Zone valve into the kitchen, after your zone valve have your two kick space heaters. Wire the BDR91 to the zone valve motor (You don't need a S/L to the boiler as you have your boiler relay). Have a thermostat on the wall, and program the kitchen as zone which is controlled by a zone valve and thermostat. When the zone calls for heat the BDR91 will click on, your boiler relay will click on, then the fans on the kick spaces will power up when the flow temperature is hot enough. Simple.

It is basically the same issue as I had with my towel rail circuit.

Sorry for the noob question but is the BDR91 in your suggestion the one that is already in situ (which would mean running a cable from the kitchen to the garage where the boiler and existing BDR91 is) or a second BDR91 (which to me would make more sense in my head).

[mtmcgavock]

No my suggestion is to have a second BDR91 with the zone valve. The only thing you'd need at the valve then is power.

I had the same issue with my towel rails as I didn't want TRVs on them. So they are on a separate zone valve which is controlled by a wireless stat and BDR91. When you add a zone in the Evohome it will allow you to add it as controlled by a zone valve.

Are you on a traditional system or a combi?

[DJBenson]

It's a combi

[DBMandrake]

Couldn't you just add a Zone valve into the kitchen, after your zone valve have your two kick space heaters. Wire the BDR91 to the zone valve motor (You don't need a S/L to the boiler as you have your boiler relay). Have a thermostat on the wall, and program the kitchen as zone which is controlled by a zone valve and thermostat. When the zone calls for heat the BDR91 will click on, your boiler relay will click on, then the fans on the kick spaces will power up when the flow temperature is hot enough. Simple.

It is basically the same issue as I had with my towel rail circuit.

Something to keep in mind with this approach is a BDR91 configured as a zone valve for a zone will perform TPI modulation - so when the temperature is near the set point it will switch on and off in every (by default) 10 minute cycle.

Whether this is a problem or not depends on whether the fans mind being constantly switched on and off or whether they make enough noise that them stopping and starting would annoy you!

[mtmcgavock]

So you will just need your additional relay wired to the zone valve and leave your BDR91 as a boiler relay like you currently have it.

Yes DBMandrake is correct it will use TPI, so whether this annoys you or not will be up to you. I have mine set on 3 cycles an hour so that it reduces this issue. Also the fans will only run when the flow temperature is there not when the thermostat clicks on/off.

[bruce_miranda]

Can you change the cycles per BDR91 used as a zone valve?

[DBMandrake]

Can you change the cycles per BDR91 used as a zone valve?

Nope. It's one synchronised system wide cycle rate. And you only have the option to change it from the default of 10 minutes if you have a boiler control relay configured. Otherwise you're stuck with the default as the setting is inaccessible.

[paulockenden]

Does the 'boiler relay' setting also affect the cycle rates of BDR91s connected as zone controllers?

[DBMandrake]

Does the 'boiler relay' setting also affect the cycle rates of BDR91s connected as zone controllers?

As far as I know, yes.

It wouldn't make sense for a zone relay for an individual zone to have a different cycle rate that wasn't synchronised with the cycle rate of the overall system CH zone valve (in an S/Y-plan) or the boiler control relay - otherwise it would spend a significant (and semi-random) amount of its time open when the main heating zone valve was closed or when the boiler was in an off part of its cycle. As they drifted in and out of sync the amount of heat transferred would fluctuate greatly.

For it to work properly the turn-on times of the boiler relay, CH zone valve and individual zone valves need to be synchronised, and the total cycle lengths need to be equal so that the next turn-on happens together. Then, whichever is on for the shortest time in that cycle controls the effective amount of heat reaching that zone. And depending on what other zones are doing, either the zone valve will have the shortest on time (high heat demand elsewhere) or the boiler/CH valve will have the shorter on time. (No heat demand elsewhere)

[mtmcgavock]

As DBMandrake I too assumed that it would use TPI and use the settings from the EvoHome Controller. However you can set TPI settings on the wireless stats when they are being used as a normal wireless roomstat, whether you can alter this once it is paired to the EvoHome controller I don't know or if you are able to alter it whether it takes any notice.

On another note is whether it actually applies TPI to it due to being a Zone, in affect it's just like another HR92 being told to open or close. I haven't sat and watch what mine does and the towel circuit isn't usually on for that long, especially in summer.

[DBMandrake]

However you can set TPI settings on the wireless stats when they are being used as a normal wireless roomstat, whether you can alter this once it is paired to the EvoHome controller I don't know or if you are able to alter it whether it takes any notice.

Wall stats bound directly to a BDR91 act as a TPI controller, (they generate the head demand) so you can adjust things like the TPI cycle time. When you bind them to an Evohome however they only act as a temperature sensor and a set point controller, so some of the functionality is disabled. You'll notice this if you go through the configuration menus of a DTS92 that is bound to an Evohome controller - most of the parameters are locked out and can't be adjusted including the TPI ones.

On another note is whether it actually applies TPI to it due to being a Zone, in affect it's just like another HR92 being told to open or close.

An HR92 is a proportional device, a BDR91 isn't, so you need TPI to get any sort of proportional temperature control.

It's not just zone valves that you can proportionally control with TPI, it's also electric radiator actuators like the MT4-230-NC.