HR92 and wireless thermostat sensors and actuators in a radiator controlled zone

[bluemike1676]

New to this game so please bear with me if I ask obvious questions !

I am thinking about how radiator valve controlled zones work, especially ones with multiple HR92s and possible a wireless thermostat thrown in. For this scenario assume we have one radiator valve controlled zone with multiple HR92 radiator valves and one wireless thermostat bound to the zone:

• By default with a 'single room zone', then the first temp sensor bound will be the master temp sensor for the zone (could be a HR92 or Wireless Thermostat). The other temp sensors in the zone will be ignored for sensing and also for learning.

• Assume that the evohome controller detects a need for heat from the master temp sensor in the zone. The CH hot water begins to flow but how are the HR92s actuators in the zone controlled ? Do they have local autonomy to control to flow of water to their radiator depending on the temperature measured by that HR92's sensor compared to the set point temperature? Or is it the case that the evohome controller treats the HR92s as dumb and so directly controls the opening and closing of all actuators, including the HR92 actuators ?

• If the zone is categorised as 'multi-room' then Top Brake told me that all the temp sensors in the zone (I assume the wireless thermostat as well as the HR92 temp sensors) become active. When any of them detects a fall below the set point temperature for the zone then I assume the evohome controller will turn on heat for the zone. One may wonder why multi-room is not the default since this seems to offer advantages for single rooms or multiple rooms with more than one HR92, but consider where a wireless thermostat is used or where some HR92s are in unsuitable positions. In that case the single-room mode is probably preferred since the wireless thermostat can then be made master by binding it first or the unsuitable HR92s excluded. Does turning on 'multi-room' have any other effect on the system ?

• If the system has been setup as a sundial S plan system with a BDR91 controlling the heating zone valve and another BDR91 controlling the hot water zone valve, then if heat is demanded by the zone (because the monitored sensor is below the set point for the zone) one assumes the BDR91 connected to the CH zone valve is turned on. If another BDR91 has also been bound to the Boiler Demand function is that also turned on?

• Can a single device, such as a BDR91, be bound for two functions simultaneously, for instance one BDR91 bound as the control for the CH zone valve and the Boiler Demand?

Thanks in advance !

[top brake]

New to this game so please bear with me if I ask obvious questions !

I am thinking about how radiator valve controlled zones work, especially ones with multiple HR92s and possible a wireless thermostat thrown in. For this scenario assume we have one radiator valve controlled zone with multiple HR92 radiator valves and one wireless thermostat bound to the zone:

• By default with a 'single room zone', then the first temp sensor bound will be the master temp sensor for the zone (could be a HR92 or Wireless Thermostat). The other temp sensors in the zone will be ignored for sensing and also for learning.

• Assume that the evohome controller detects a need for heat from the master temp sensor in the zone. The CH hot water begins to flow but how are the HR92s actuators in the zone controlled ? Do they have local autonomy to control to flow of water to their radiator depending on the temperature measured by that HR92's sensor compared to the set point temperature? Or is it the case that the evohome controller treats the HR92s as dumb and so directly controls the opening and closing of all actuators, including the HR92 actuators ?

• If the zone is categorised as 'multi-room' then Top Brake told me that all the temp sensors in the zone (I assume the wireless thermostat as well as the HR92 temp sensors) become active. When any of them detects a fall below the set point temperature for the zone then I assume the evohome controller will turn on heat for the zone. One may wonder why multi-room is not the default since this seems to offer advantages for single rooms or multiple rooms with more than one HR92, but consider where a wireless thermostat is used or where some HR92s are in unsuitable positions. In that case the single-room mode is probably preferred since the wireless thermostat can then be made master by binding it first or the unsuitable HR92s excluded. Does turning on 'multi-room' have any other effect on the system ?

• If the system has been setup as a sundial S plan system with a BDR91 controlling the heating zone valve and another BDR91 controlling the hot water zone valve, then if heat is demanded by the zone (because the monitored sensor is below the set point for the zone) one assumes the BDR91 connected to the CH zone valve is turned on. If another BDR91 has also been bound to the Boiler Demand function is that also turned on?

• Can a single device, such as a BDR91, be bound for two functions simultaneously, for instance one BDR91 bound as the control for the CH zone valve and the Boiler Demand?

Thanks in advance !

rule is one sensor per zone unless you are using HR92

So if you add a wireless thermostat for a zone it can only be single room zone type

regarding your question about using a BDR91 as both Heating and Boiler relay , no this is not correct and will result in heating being switched on when there is hot water demand (boiler relay)

make sense?

have you done youlearn??

[bluemike1676]

rule is one sensor per zone unless you are using HR92

So if you add a wireless thermostat for a zone it can only be single room zone type

regarding your question about using a BDR91 as both Heating and Boiler relay , no this is not correct and will result in heating being switched on when there is hot water demand (boiler relay)

make sense?

have you done youlearn??

Hi top brake,

Thanks for your response but you missed the main part of my question which was "Assume that the evohome controller detects a need for heat from the master temp sensor in the zone. The CH hot water begins to flow but how is the opening/closing of the HR92s actuators in the zone controlled ? Do the HR92s have local autonomy to control to flow of water to their radiator depending on the temperature measured by that HR92's sensor compared to the set point temperature? Or is it the case that the evohome controller treats the HR92s as dumb and so directly controls the opening and closing of all actuators, including the HR92 actuators ?". Do you have any thoughts on this ? Do the HR92s have local autonomy ? Do the HR92s control their valve with local open/close instructions or are all instructions to open/close (even partially) sent from the evohome controller? I must say my tests so far indicate they have local autonomy.

Also can I just check it one adds a wireless thermostat to a radiator valve controlled zone does the evohome controller know to automatically make it the master sensor regardless of the order in which it is added, ie it might not be the first sensor added?

Yes I have completed the youlearn training about 6 weeks ago but I don't remember this level of detail being covered.

Many thanks,

Mike

[top brake]

Hi top brake,

Thanks for your response but you missed the main part of my question which was "Assume that the evohome controller detects a need for heat from the master temp sensor in the zone. The CH hot water begins to flow but how is the opening/closing of the HR92s actuators in the zone controlled ? Do the HR92s have local autonomy to control to flow of water to their radiator depending on the temperature measured by that HR92's sensor compared to the set point temperature? Or is it the case that the evohome controller treats the HR92s as dumb and so directly controls the opening and closing of all actuators, including the HR92 actuators ?". Do you have any thoughts on this ? Do the HR92s have local autonomy ? Do the HR92s control their valve with local open/close instructions or are all instructions to open/close (even partially) sent from the evohome controller? I must say my tests so far indicate they have local autonomy.

Also can I just check it one adds a wireless thermostat to a radiator valve controlled zone does the evohome controller know to automatically make it the master sensor regardless of the order in which it is added, ie it might not be the first sensor added?

Yes I have completed the youlearn training about 6 weeks ago but I don't remember this level of detail being covered.

Many thanks,

Mike

yes the HR92 have local autonomy

[erik]

Why would you use multi-room in one zone? Why not just make multiple zones? Is it to make it easier to change temp in all rooms at once? Or because there's too many rooms to make a zone for every one of them? Or.. ?

[top brake]

Why would you use multi-room in one zone? Why not just make multiple zones? Is it to make it easier to change temp in all rooms at once? Or because there's too many rooms to make a zone for every one of them? Or.. ?

i see it used to control a group of guest bedrooms at same switchpoints whilst still allowing for individual bedrooms to be locally overriden

indeed, also used when there are more than 12 rooms

[bluemike1676]

yes the HR92 have local autonomy

Hi top brake,

Thanks. Can you also shed any light on the other point '...Also can I just check if one adds a wireless thermostat to a radiator valve controlled zone does the evohome controller know to automatically make the wireless thermostat the master temp sensor for the zone regardless of the order in which it is added, ie it might not be the first sensor added?...'

Many thanks,

Mike

[top brake]

Hi top brake,

Thanks. Can you also shed any light on the other point '...Also can I just check if one adds a wireless thermostat to a radiator valve controlled zone does the evohome controller know to automatically make the wireless thermostat the master temp sensor for the zone regardless of the order in which it is added, ie it might not be the first sensor added?...'

Many thanks,

Mike

If you use a wireless room thermostat it can only be the master, the one and only; ergo you cannot have a multi room zone in such a setup

[erik]

When you add it later on to a zone, then you actually select that you want to change the sensor, so there's no question about being the first or not. Anyway, I would delete/re-create a zone when doing changes like this.

[top brake]

When you add it later on to a zone, then you actually select that you want to change the sensor.

Indeed, that's how I setup such a zone

[HelmutF]

How can I unbind a thermostat from a room/zone without deleting the room/zone? In my bedroom I have two radiators but in the moment I have only one equiped with a HR92. The other one have a normal electronic thermostat. In the future I will add a second HR92 to the room. So I have to create a zone with the two HR92. Is it possible to add a second HR92 without unbinding the first HR92 or can I add the second one, without changing the first HR92.

[bluemike1676]

yes the HR92 have local autonomy

Hi,

I guess this local autonomy explains why we see some odd behaviour in a single room zone with multiple HR92 equipped radiators. For instance it should not be surprising to see HR92s in a single zone with different valve open positions at a point in time (so some radiators are hot and some cold). With local autonomy then one should expect HR92 equipped radiators in a zone to have different valve positions because the valve position of any one HR92 will be determined by the temperature that HR92 is measuring with its local temp sensor (which may not be the master temp sensor for the zone) compared to the set point for the zone.

Mike

[erik]

It should only apply when you set the zone to a multi-room, as far as I know. The default is single room.

[bluemike1676]

It should only apply when you set the zone to a multi-room, as far as I know. The default is single room.

Hi,

If the HR92s are operating autonomously for actuator control (as top brake suggested) then this will apply to a single room zone as much as it would to a multi-room. In fact it should apply equally or not to both types of zones since it is about how the actuators are controlled, not about about how the temp sensors are managed. As far as I understand multi-room is all about how the temp sensors are managed. In a single room then one temp sensor becomes the master, whereas in a multi-room all HR92 sensors are active and being monitored.

Mike

[erik]

In a single room setting, they all act upon the temperature sensing of 1 device. In the multi room setting, they act upon their own temperature sensing. So in single zone, in theory, you could have a HR92 that measures 30 degrees itself, but the master HR92 measures only 15. If the setpoint is 20, both should be open.