Installing an additional room thermostat

[csj]

I have a simple central heating system with a traditional Baxi Solo 2 60RS boiler supplying heat to radiators around the house.


The room thermostat is located in the main bedroom and so calls for heat
only when the temperature in that room requires. When heat is required this
thermostat is wired so that it simply switches the pump on or off.


I would like to have the thermostat located in the lounge (it wasn't placed
there originally because radiators were not initially installed in the
lounge/dining room) and it would be a relatively simple task to just move the
thermostat and retain the wiring as present.


However, I'm thinking that I might wish to leave the existing thermostat
where it is and install a similar additional room thermostat in the living
room and connect it up in the exact manner as the esisting one using the
same connectors in the junction box beside the boiler.


I could see that this would mean that if neither thermostat is calling for heat
the pump would not turn on


Am I right, though, in thinking that if the bedroom thermostat is turned right
down and the lounge one turned up to call for heat that this would turn the
pump on. Similarly, if the bedroom one is turned up to call for heat and the
lounge is turned right down the same would apply and again the pump would
switch on.


What, though if both thermostats are turned right up so that they are both
calling for heat. Would this allow tthe pump to come on until the
temperature has reached the desired temperature(s) in both rooms or would
this, somehow, cause a fuse to blow or cause even worse damage.

 

[telectrix]

add 2nd stat. in parallel, then either stat. calling for heat will activate the pump. at the end of the day, the stat. is just a switch.

 

[MDJ]

you can have as many stats as you wish on a heating system, providing a switch wire goes back to the valve or boiler whatever the system requires it will work, the problem will be if rad valves are not used some rooms they could be boiling hot and others still calling for heat, if you have radvalves on all radiators then they will stop the heat even if a stat in a different room still calls for it, however IMO I would have just one stat wired from a time clock, set it to 30 c and let the rad valves do the job and the stat is there due to a legal requirement now for all new heating systems, it is a fail safe device and most of the time are not actually used for heat control, as mentioned whack it up to it's highest temperature, let the time clock and rad valves control the heating and the system will run better in a house that is IMO.

 

[snowhead]

What, though if both thermostats are turned right up so that they are both
calling for heat. Would this allow tthe pump to come on until the
temperature has reached the desired temperature(s) in both rooms or would
this, somehow, cause a fuse to blow or cause even worse damage.

The pump will run until both stats are satisfied, no fuse problems involved.

 

[csj]

Thanks for all your comments - that's been very useful.

 

[csj]

One further question - what thickness wire do I need for a room thermostat, 1.0 or 1.5mm. The wire going into my existing thermostat is thick (presumably 1.5mm) but the one going into the junction box is thinner (presumably 1.0mm). The wires go under floorboards in a bedroom so I assume that they've been connected together somewhere using different thickness cable. The colours are exactly the same: blue (I assume to be neutral), green (assume earth), red (assume live) and yellow (which I assume is switched live).

Thanks again.

 

[SYKRAPS]

The problem with this is that you have now way of controling the room with the higher ambient temperature if a 2 room stats with no zone valves are installed.

 

[SYKRAPS]

Your best bet IMO if you do not want to alter the pipework by adding valves would be to install a wireless room stat to control the pump set up,this way you can move the stat from room to room as you desire and control the system that way.

1mm cable is fine for a hard wired room stat btw.

 

[csj]

I did consider a wireless thermostat but my local plumber who is installing extra radiators for me said that they were good for about 2 years but then tended to break down. So, I thought I would stick with a manual Drayron RS1 thermostat.

 

[SYKRAPS]

I did consider a wireless thermostat but my local plumber who is installing extra radiators for me said that they were good for about 2 years but then tended to break down. So, I thought I would stick with a manual Drayron RS1 thermostat.

All depends on which one you buy, as usuall Honeywell are fairly good

 

[Kiers1970]

Plumbers never heard of Batteries? (had this the other day)

 

[snowhead]

Plumbers never heard of Batteries? (had this the other day)

Funny that, I have to change the batteries in my Programmable stat every 2 years.
And it doesn't warn me, the display just starts flashing like it's broken!!

 

[rsp84]

Id say 1 room stat, and rest of rooms with rad trvs. you only required seperate room stats if the system is split, say on two floors if the property is large.

 

[chris murphy]

you can have as many stats as you wish on a heating system, providing a switch wire goes back to the valve or boiler whatever the system requires it will work, the problem will be if rad valves are not used some rooms they could be boiling hot and others still calling for heat, if you have radvalves on all radiators then they will stop the heat even if a stat in a different room still calls for it, however IMO I would have just one stat wired from a time clock, set it to 30 c and let the rad valves do the job and the stat is there due to a legal requirement now for all new heating systems, it is a fail safe device and most of the time are not actually used for heat control, as mentioned whack it up to it's highest temperature, let the time clock and rad valves control the heating and the system will run better in a house that is IMO.

"Hello MJD",


I don`t mean this to offend You - I`m sure that you are an Expert Electrician - But You should NOT be advising people on your `ideas` on how to `Control` / Run their Central Heating - especially NOT that:


Room Thermostats should be `Turned Up to 30 Degrees` - AND: `the stat is there due to a legal requirement` - AND: ` it is a fail safe device and most of the time are not actually used for heat control`


What You have advised in those statements would cause the Boiler to `Cycle` - to keep firing `ON & OFF` to satisfy the BOILER THERMOSTAT - when the Heating was On - irrespective of the Room Temperatures or TRV`s [Thermostatic Radiator Valves] - this is NOT the way to `Control` a Heating System.

This would be a big waste of Gas / Money.

When you write about `rad valves` either being used or not being used I presume that you mean Thermostatic Radiator Valves / TRV`s - as ALL Radiators should have `rad valves` on either end of the radiator.


I am a Heating Engineer - your statements as quoted above really could not be more incorrect.


I have NOT written this to attack You personally - BUT - As a Heating Engineer I could not let those statements go unchallenged / uncorrected - for the benefit of other Members / Readers.


I hope that You won`t take offence to this.

Regards,


Chris - Heating Engineer

 

[electric will]

Deleted post,

 

[Geordie Spark]

I agree with Chris - post #14.

If as the op has said he's got a plumber in to add extra rads. now would be a good opportunity to add 2 zone valves to allow for the upstairs & downstairs radiators to in separate zones and therefore be independently controlled via separate thermostats - one upstairs & one downstairs.

Each Thermostat would operate the relevant zone valve which would then operate its own switch to fire the boiler.

This would give heat downstairs only, heat upstairs only of if both thermostats are calling for heat, downstairs and upstairs together.

It's neither difficult nor too expensive to do.

 

[MDJ]

"Hello MJD",


I don`t mean this to offend You - I`m sure that you are an Expert Electrician - But You should NOT be advising people on your `ideas` on how to `Control` / Run their Central Heating - especially NOT that:


Room Thermostats should be `Turned Up to 30 Degrees` - AND: `the stat is there due to a legal requirement` - AND: ` it is a fail safe device and most of the time are not actually used for heat control`


What You have advised in those statements would cause the Boiler to `Cycle` - to keep firing `ON & OFF` to satisfy the BOILER THERMOSTAT - when the Heating was On - irrespective of the Room Temperatures or TRV`s [Thermostatic Radiator Valves] - this is NOT the way to `Control` a Heating System.

This would be a big waste of Gas / Money.

When you write about `rad valves` either being used or not being used I presume that you mean Thermostatic Radiator Valves / TRV`s - as ALL Radiators should have `rad valves` on either end of the radiator.


I am a Heating Engineer - your statements as quoted above really could not be more incorrect.


I have NOT written this to attack You personally - BUT - As a Heating Engineer I could not let those statements go unchallenged / uncorrected - for the benefit of other Members / Readers.


I hope that You won`t take offence to this.

Regards,


Chris - Heating Engineer

No need for a room stat at all IMO, the rad valves can call for heat, the timer will dictate when the customer wants the boiler to run, the stat has to be there for legal reasons, years ago stats were not used at all, in old cottages for example a stat would be installed and the area where it was housed when warm in the area the the stat would stop calling for heat and the rest of the old cottage would be freezing cold, unless you had stats in every room which is a bit of a joke really, I have worked on one or 2000 I suppose over the years and wouldn't install stats in every room myself.

 

[MDJ]

I agree with Chris - post #14.

If as the op has said he's got a plumber in to add extra rads. now would be a good opportunity to add 2 zone valves to allow for the upstairs & downstairs radiators to in separate zones and therefore be independently controlled via separate thermostats - one upstairs & one downstairs.

Each Thermostat would operate the relevant zone valve which would then operate its own switch to fire the boiler.

This would give heat downstairs only, heat upstairs only of if both thermostats are calling for heat, downstairs and upstairs together.

It's neither difficult nor too expensive to do.

If split up and down and via the method you have just mentioned then yes quite right a good method, I agree with this.

 

[MDJ]

"Hello MJD",

I hope that You won`t take offence to this.

Regards,


Chris - Heating Engineer

Not at all Chris, appreciate the view, after reading geordies reply after yours I see a very good point there.

 

[chris murphy]

Not at all Chris, appreciate the view, after reading geordies reply after yours I see a very good point there.

"Hello MJD",

Thanks for not taking offence to what I wrote - it was not meant to just contradict You - I felt that I had to put a Heating Engineers point of view.

This message is NOT to irritate You further - I hope that You don`t mind Me explaining in a bit more detail for the benefit of other Members / Readers:


What You stated about having seen countless Heating Systems that did NOT have a Room Thermostat is doubtless correct - BUT that was never the correct way to Install / Control a Heating System.

Your example of the `Old Cottage` where the Room Thermostat turned Off the Boiler before the Cottage could Heat Up indicates that the Room Thermostat`s location OR possibly an incorrectly sized Radiator in the area where the Room Thermostat was located - or a bit of both - was the reason for that very frequent `Fault` relating to a System not operating at the correct `Heat Up` process.

This is an indication that this Heating System was NOT designed and installed by a Heating Engineer - OR that these systems were installed in the `Dark Ages` of Domestic Central Heating - the 1970`s !

Systems that were installed in Homes in the 1970`s - when `normal` Homes first started to have Central Heating - were almost invariably installed by Companies and `Plumbers` who really had NO Idea about Energy Efficiency and the correct control of those Heating Systems - also Gas was relatively Cheap / Affordable in those Days.

Those were the Days before Zone Valves were readily available and there were `Mechanical Control Valves` for Hot Water Cylinder Heating / Primary Flow Control - E.G: `Cytrol Valves` and other Manufacturers Mechanical Valves - however Room Thermostats were available.

This also applied to MANY Heating Installations throughout the subsequent Decades - Companies were installing Heating Systems with ONLY Thermostatic Radiator Valves and Programmers / Timeswitches right up to the Legislation for Energy Efficiency / Part L of the Building Regulations - `Conservation of Heat and Power` - that still did NOT mean that this was correct.

These next details are dealing with the Heating ONLY - for purposes of clarity I don`t want to have to keep including things like `If the Hot Water Cylinder heat requirement is satisfied` etc. in My explanations.


When a Heating System has Thermostatic Radiator Valves and NO Room Thermostat the Boiler is `ON` all of the time that the Programmer / Timeswitch [depending on the system] Setting is `ON` - Irrespective of whether ALL of the Thermostatic Radiator Valves are CLOSED or not the Boiler will keep `Cycling` ON and OFF to keep satisfying the setting on the Boiler Thermostat - this uses Gas unnecessarily - hardly an Energy Efficient System.

So imagine that ALL of the Rooms heat requirements / TRV`s are satisfied at any particular time [however unlikely] - the Boiler will keep firing ON and OFF to keep the water in the Heating System Pipework and Boiler Heat Exchanger at the Temperature as set on the Boiler Thermostat - what a waste of Gas and Money for the Householder.


If there is a Room Thermostat AND Thermostatic Radiator Valves on all Radiators EXCEPT in the location where the Room Thermostat is located [this Radiator should ideally have two lockshield radiator valves] - when the Room`s heat requirement as set on the TRV`s are satisfied the TRV`s will close down stopping the Flow to the Radiators thus saving heat production for each Room where the TRV has closed down.

When the area where the Room Thermostat reaches the temperature as set on the Room Thermostat the stat will shut down the Boiler - stopping the `Cycling` / firing to keep the Boiler Thermostat satisfied by unnecessarily heating the water in the system Pipework and Boiler Heat Exchanger.

In My own Home - depending upon how Cold the outside Temperature is - this period when the Boiler is NOT firing / `cycling` could be anything from 30 Minutes to an Hour - if I did not have a Room Thermostat the Boiler would have fired up probably between 5 and 10 times during that period of time / Hour.

It is of course VERY important that ALL the Radiators are Calculated correctly - especially the Radiator where the Room Thermostat is located - that Radiator MUST be correct in order that the Heating System can supply the correct `Heat Up Time`for the whole Home / premises - as otherwise the Heating System would not operate correctly / efficiently.


I hope that this may be helpful to other Members / Readers.


Regards,


Chris - Heating Engineer

 

[SYKRAPS]

"Hello MJD",

Thanks for not taking offence to what I wrote - it was not meant to just contradict You - I felt that I had to put a Heating Engineers point of view.

What You stated about having seen countless Heating Systems that did NOT have a Room Thermostat is doubtless correct - BUT that was never the correct way to Install / Control a Heating System.

Systems that were installed in Homes in the 1970`s - when `normal` / working class Homes first started to have Central Heating - were almost invariably installed by Companies and `Plumbers` who really had NO Idea about Energy Efficiency and the correct control of those Heating Systems - also Gas was relatively Cheap / Affordable in those Days.

Those were the Days before Zone Valves were readily available and there were `Mechanical Control Valves` for Hot Water Cylinder Heating / Primary Flow Control - E.G: `Cytrol Valves` and other Manufacturers Mechanical Valves - however Room Thermostats were available.

This also applied to MANY Heating Installations throughtout the subsequent Decades - Companies were installing Heating Systems with ONLY Thermostatic Radiator Valves and Programmers / Timeswitches right up to the Legislation for Energy Efficiency / Part L of the Building Regulations - `Conservation of Heat and Power` - that still did NOT mean that this was correct.

These next details are dealing with the Heating ONLY - for purposes of clarity I don`t want to have to keep including things like `If the Hot Water Cylinder heat requirement is satisfied` etc. in My explanations.


When a Heating System has Thermostatic Radiator Valves and NO Room Thermostat the Boiler is `ON` all of the time that the Programmer / Timeswitch [depending on the system] Setting is `ON` - Irrespective of whether ALL of the Thermostatic Radiator Valves are CLOSED or not the Boiler will keep `Cycling` ON and OFF to keep satisfying the setting on the Boiler Thermostat - this uses Gas unnecessarily - hardly an Energy Efficient System.

So imagine that ALL of the Rooms heat requirements / TRV`s are satisfied at any particular time [however unlikely] - the Boiler will keep firing ON and OFF to keep the water in the Heating Syatem Pipework and Boiler Heat Exchanger at the Temperature as set on the Boiler Thermostat - what a waste of Gas and Money for the Householder.


If there is a Room Thermostat AND Thermostatic Radiator Valves on all Radiators EXCEPT in the location where the Room Thermostat is located [this Radiator should ideally have two lockshield radiator valves] - when the Room`s heat requirement as set on the TRV is satisfied the TRV will close down stopping the Flow to the Radiator thus saving heat production for each Room - when the area where the Room Thermostat reaches the temperature as set on the Room Thermostat the stat will shut down the Boiler - stopping the `Cycling` / firing to keep the Boiler Thermostat satisfied by unnecessarily heating the water in the system Pipework and Boiler Heat Exchanger.


It is of course VERY important that ALL the Radiators are Calculated correctly - especially the Radiator where the Room Thermostat is located - as otherwise the Heating System would not operate efficiently.


I hope that this may be helpful to other Members / Readers.


Regards,


Chris - Heating Engineer

Your comments make sense and are correct IMO, but how would you suggest the OP should remedy the issue that is present in his situation if he does not want to alter the pipework and install zoning?

I suggested earlier in the thread that the only way that I could see of coming up with a practicable remedy would be a portable wireless stat, IYO would this satisfy Part L?

Regards SYKRAPS.

 

[chris murphy]

Your comments make sense and are correct IMO, but how would you suggest the OP should remedy the issue that is present in his situation if he does not want to alter the pipework and install zoning?

I suggested earlier in the thread that the only way that I could see of coming up with a practicable remedy would be a portable wireless stat, IYO would this satisfy Part L?

Regards SYKRAPS.

"Hello SYKRAPS",


The OP`s post is basically just asking if He can wire up another Room Thermostat - I thought that this had been answered by a couple of Members.

With regard to satisfying Part L of the Building Regulations by fitting / using a wireless Room Thermostat which could be moved around the Home - Absolutely NOT.

BUT your suggestion might be a good idea for the OP`s immediate requirements - ?

The facts of adhering to Part L where it relates to Heating Systems Controls are very simple:

You MUST have the Controls - Programmers / Timeswitches [system appropriate] - Room Thermostat [VITAL] preferably Programmable Room Thermostats - Zone Valves [to Zone the Heating system / for Cylinder] - Thermostatic Radiator Valves - Cylinder Thermostat [and possibly a Frost Thermostat and Pipe Thermostat for Boilers in locations which could become very cold].


ONLY with the necessary Controls can a Heating System both operate correctly / with energy efficiency and adhere to Part L of the Building Regulations - there are NO `short cuts`.


I would hope that My `Comments` about Heating Systems `make sense and are correct` - as I am a Heating Engineer.


Regards,

Chris - Heating Engineer

 

[electric will]

Deleted post

 

[SYKRAPS]

"Hello SYKRAPS",


The OP`s post is basically just asking if He can wire up another Room Thermostat - I thought that this had been answered by a couple of Members.

With regard to that satisfying Part L of the Building Regulations by fitting / using a wireless Room Thermostat which could be moved around the Home - Absolutely NOT.

BUT your suggestion might be a good idea for the OP`s immediate requirements - ?

The facts of adhering to Part L where it relates to Heating Systems Controls are very simple:

You MUST have the Controls - Programmers / Timeswitches [system appropriate] - Room Thermostat [VITAL] preferably Programmable Room Thermostats - Zone Valves [to Zone the Heating system / for Cylinder] - Thermostatic Radiator Valves - Cylinder Thermostat [and possibly a Frost Thermostat and Pipe Thermostat for Boilers in locations which could become very cold].


ONLY with the necessary Controls can a Heating System both operate correctly / with energy efficiency and adhere to Part L of the Building Regulations - there are NO `short cuts`.


I would hope that My `Comments` about Heating Systems `make sense and are correct` - as I am a Heating Engineer.


Regards,

Chris - Heating Engineer

Thanks Chris

 

[chris murphy]

"Hello again SYKRAPS",

No problem - I hope that My Posts on the Forum about Heating and Gas matters are helpful to Members and other readers - as that is My primary reason for being involved on the Forum - as a SMALL `Pay Back` to the Forum / Members / Electricians - for being helped with a wiring enquiry by topquark about a Year ago.


Regards,


Chris


P.S. - It looks like I have upset electric will ? - Deleted Posts 2 Nights running.

 

[Geordie Spark]

If split up and down and via the method you have just mentioned then yes quite right a good method, I agree with this.

Thank you MDJ

That is exactly what I meant & is how the heating in my own house is done but I use Programmable Room Stats - one upstairs & one downstairs - and have removed the normal time clock from the boiler.

The Programmable Room Stats do the job of the timer and allow for different temperatures to be selected & maintained at different times of the day and night for both floors. It's very flexible and works well.

 

[csj]

Thanks again for all the comments (including the controversies that my initial query seem to have stirred up).

For your information, I eventually installed a Celect (£25) remote room thermostat which now works fine. I installed it in parallel with my existing non-remote bedroom thermostat and only managed to blow one 13A plug fuse in doing so (but had made sure that only the pump and not the boiler was not connected in case of very expensive mistakes).

The instruction guide was pretty pathetic and I had to figure out the wiring mainly from basics. Reading reviews on Amazon of even more expensive ones like Honeywell seems to indicate that instruction guides are not very well presented on most of them. This is possibly because many (most?) of them are manufactured in the Far East where English is not the first language.

Anyway, all's well that ends well and I'm quite happy with what I achieved.

 

[chris murphy]

Thanks again for all the comments (including the controversies that my initial query seem to have stirred up).

For your information, I eventually installed a Celect (£25) remote room thermostat which now works fine. I installed it in parallel with my existing non-remote bedroom thermostat and only managed to blow one 13A plug fuse in doing so (but had made sure that only the pump and not the boiler was not connected in case of very expensive mistakes).

The instruction guide was pretty pathetic and I had to figure out the wiring mainly from basics. Reading reviews on Amazon of even more expensive ones like Honeywell seems to indicate that instruction guides are not very well presented on most of them. This is possibly because many (most?) of them are manufactured in the Far East where English is not the first language.

Anyway, all's well that ends well and I'm quite happy with what I achieved.

"Hello csj",


Thanks for posting what You decided upon to make your Heating System `more controllable` regarding Temperature Control.

I hope the details that I and the other Members wrote were helpful to You.

There should have been no controversy about the Installation and use of a Room Thermostat - although your Heating System is NOT installed as one of the `Normal` Configurations regarding Timed and Temperature Controls.

I am sure that Honeywell Controls have clear Installation / Wiring Instructions - I would rate them as `World Leaders` in Heating Controls - although when I wanted to get a Battery operated Programmable Room Thermostat for My own Home they did not have one that could be wired with just 2 Cores [existing Stat cable] and I had to go for a Horstmann Programmable Room Thermostat.

Horstmann is a recognised Manufacturer of good quality Heating Controls - and I had to ask on here about the `Wiring Diagram` for that - but it was because I am not an Electrician that I wanted to check what the Diagram showed.


Glad to read that You now have better Temperature Control of your Home`s Heating System.


Regards,


Chris - Heating Engineer