CH Thermostats in hallway - why?
Discussion
Just getting quotes for new boiler and every plumber wants to put a wall-mounted thermostat in the hallway. I've had many heating systems in different houses over the years and I've always found wall-mounted thermostats ineffectual so I'm hoping soeone can tell me why we have them.
All of my radiators have thermostatic valves (TRVs) so each room temp can be separetly controlled.
I understand that the main difference between a thermostat in the hall and a TRV is that the thermostat can switch the heating on/off according to the ambient temperature and the TRVs cannot.
All the plumbers have said put the thermostat in the coolest part of the house and make sure that the radiator in that area does not have a TRV and is left fully open. So the thermostat will keep putting the heating on because it is located in the coolest part of the house!!! But all the other radiators which are controlled by TRVs will still keep having hot water pushed through to them on the basis that as long as the hallway is cold then the thermostat keeps switching the heating on - and they sell this system as an energy saving plan!!!
Am I going nuts? Where's the sense in that? surely it's more sensible to just control your heating on radiator TRVs?
All of my radiators have thermostatic valves (TRVs) so each room temp can be separetly controlled.
I understand that the main difference between a thermostat in the hall and a TRV is that the thermostat can switch the heating on/off according to the ambient temperature and the TRVs cannot.
All the plumbers have said put the thermostat in the coolest part of the house and make sure that the radiator in that area does not have a TRV and is left fully open. So the thermostat will keep putting the heating on because it is located in the coolest part of the house!!! But all the other radiators which are controlled by TRVs will still keep having hot water pushed through to them on the basis that as long as the hallway is cold then the thermostat keeps switching the heating on - and they sell this system as an energy saving plan!!!
Am I going nuts? Where's the sense in that? surely it's more sensible to just control your heating on radiator TRVs?
as far as i`m aware its a legal requirement, our hall rad had a trv but when it stopped the heated water had no were to go so tripped the boiler, when we removed the trv from the hall rad the boiler had a circuit to pump water round and no trip.
digi thermostat much better than old bimetal type aswell.
Ray
digi thermostat much better than old bimetal type aswell.
Ray
S6PNJ said:
martinalex said:
So the thermostat will keep putting the heating on because it is located in the coolest part of the house!!!
Erm, 
set it to a lower temperature then?Think it's all part [placing them next to outside door in hallway etc] part of the old "f
k you" attitude of the plumbing trade myself....If you lower the hall thermostat - it knocks out the room TRVs hence the whole house will be colder and not just the hall.
I think one of the plumbers did imply it was 'building regs' but I'm not convinced - sounded more like it had to be ticked off the boiler manufacturer's sales checklist.
He actually said the manufacturer will look at the check list and ask why a thermostat isn't fitted, then with a bit of whistling through teeth - suggested it might affect the warranty!
Seems unlikely - I would have thought a hall themostat is more likely to result in constant on/offs for the boiler - heating up a single hall radiator causing extra wear on the boiler.
I think one of the plumbers did imply it was 'building regs' but I'm not convinced - sounded more like it had to be ticked off the boiler manufacturer's sales checklist.
He actually said the manufacturer will look at the check list and ask why a thermostat isn't fitted, then with a bit of whistling through teeth - suggested it might affect the warranty!
Seems unlikely - I would have thought a hall themostat is more likely to result in constant on/offs for the boiler - heating up a single hall radiator causing extra wear on the boiler.
our stat was in the hallway near the front door, with people coming in/out it was all over the place during winter
So I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
So I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
When TRV's reach the desired temp they close. So if the boiler's on and the house is warm enough, the system will have nowhere to pump the water. You should have a small bypass just in case, but normally it'll make noises and shorten the life of the pump.
Also, if the house is up to temp, you want the boiler to turn off. TRV's are mechanical, so there's no way for the boiler to recognize that all rooms are warm enough. Hence the need for one radiator which doesn't have a TRV, and a roomstat to tell the boiler that the house is warm enough.
I've recently had a new boiler, some independant under floor heating, a wood burning stove and TRV's on all but one radiator. I have a roomstat in the centre of the downstairs hall, and the no-TRV radiator 8' away in the hall. I'm struggling with getting it to stay on long enough to heat the house, as I now have to have the roomstat up around 20 to stop the hall radiator turning the whole thing off too quickly.
It's worth noting that the roomstat should be in the same airspace as the non-TRV rad, because if there's a closed door in the way it won't work. I'm going to experiment with a wireless roomstat in the upstairs hall, to slow down the switch-off.
Also, if the house is up to temp, you want the boiler to turn off. TRV's are mechanical, so there's no way for the boiler to recognize that all rooms are warm enough. Hence the need for one radiator which doesn't have a TRV, and a roomstat to tell the boiler that the house is warm enough.
I've recently had a new boiler, some independant under floor heating, a wood burning stove and TRV's on all but one radiator. I have a roomstat in the centre of the downstairs hall, and the no-TRV radiator 8' away in the hall. I'm struggling with getting it to stay on long enough to heat the house, as I now have to have the roomstat up around 20 to stop the hall radiator turning the whole thing off too quickly.
It's worth noting that the roomstat should be in the same airspace as the non-TRV rad, because if there's a closed door in the way it won't work. I'm going to experiment with a wireless roomstat in the upstairs hall, to slow down the switch-off.
bogie said:
our stat was in the hallway near the front door, with people coming in/out it was all over the place during winter
So I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial and you change the temperature of the whole house achieving this
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
Edited to aid understanding.So I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial and you change the temperature of the whole house achieving this
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
I reckon that the interaction between the TRVs and the main thermostat is a little different. Each TRV will effectively close off the flow of hot water to each radiator if the temp in that room is high enough.
So, if your boiler is just on a timer, you could be heating water and pumping it around your system for no reason if your rooms are all warm enough and your TRVs are all closed. (Hopefully you do have at least one rad without a TRV to make sure the boiler doesn't trip.)
If you DO have a room stat and a radiator without a TRV closest to it then it will still be getting heat even when all the other rads are "off" and (assuming that the room stat setting is sensible) the stat will switch off the CH system, thus saving energy.
Personally, having lived in a couple of places that used TRVs only, I found it a right pain, especially when the weather changed, having to fiddle about with all the TRVs to get the temp I wanted.
Now I have a wall stat (even though it's an old fashioned bimetallic one) I barely have to touch anything and when I do, it's usually just to roll the stat up or down a degree or two.
So, if your boiler is just on a timer, you could be heating water and pumping it around your system for no reason if your rooms are all warm enough and your TRVs are all closed. (Hopefully you do have at least one rad without a TRV to make sure the boiler doesn't trip.)
If you DO have a room stat and a radiator without a TRV closest to it then it will still be getting heat even when all the other rads are "off" and (assuming that the room stat setting is sensible) the stat will switch off the CH system, thus saving energy.
Personally, having lived in a couple of places that used TRVs only, I found it a right pain, especially when the weather changed, having to fiddle about with all the TRVs to get the temp I wanted.
Now I have a wall stat (even though it's an old fashioned bimetallic one) I barely have to touch anything and when I do, it's usually just to roll the stat up or down a degree or two.
It IS a requirement of the Building Regulations Part 'L', yes, however it has long been proven to be the most efficient way to control space heating in a domestic situation. The reason stats are placed in the hall is because they need to be sited in the space with most air-changes an hour and with an exterior door it's the most likely. It's also the place which it isn't particularly inconvenient to get hot LAST. This is important, of course, so that all the TRVs get hot water when required.
A system with ALL TRVs will cycle via the bypass far more which is simply burning fuel.
A system with ALL TRVs will cycle via the bypass far more which is simply burning fuel.
The benefit of TRVs is not to stop the boiler from firing up. It is top stop heat being wasted in areas that don't need it. Think of TRVs as cruise control for the heating system and the thermostat as the ignition key. The TRVs only allow heat where it's needed and the thermostat making sure the engine's running.
If your thermostat is still turning on the boiler when all the TRVs are closed then you have a set-up issue. You need to check the settings (temperature on the dila) or set-up (location).
For ultimate efficency each room would need to have a 'stat and the radiator supplied from a manifold - like underfloor heating. However, this is a lot of wiring and, frankly, Joe Public wouldn't accept the additional cost.
If your thermostat is still turning on the boiler when all the TRVs are closed then you have a set-up issue. You need to check the settings (temperature on the dila) or set-up (location).
For ultimate efficency each room would need to have a 'stat and the radiator supplied from a manifold - like underfloor heating. However, this is a lot of wiring and, frankly, Joe Public wouldn't accept the additional cost.
mk1fan said:
The benefit of TRVs is not to stop the boiler from firing up. It is top stop heat being wasted in areas that don't need it. Think of TRVs as cruise control for the heating system and the thermostat as the ignition key. The TRVs only allow heat where it's needed and the thermostat making sure the engine's running.
If your thermostat is still turning on the boiler when all the TRVs are closed then you have a set-up issue. You need to check the settings (temperature on the dila) or set-up (location).
For ultimate efficency each room would need to have a 'stat and the radiator supplied from a manifold - like underfloor heating. However, this is a lot of wiring and, frankly, Joe Public wouldn't accept the additional cost.
Still heating the primaries to the manifold... If your thermostat is still turning on the boiler when all the TRVs are closed then you have a set-up issue. You need to check the settings (temperature on the dila) or set-up (location).
For ultimate efficency each room would need to have a 'stat and the radiator supplied from a manifold - like underfloor heating. However, this is a lot of wiring and, frankly, Joe Public wouldn't accept the additional cost.
A zone valve for each room opened by a stat, using the microswitch to fire the boiler??
bogie said:
our stat was in the hallway near the front door, with people coming in/out it was all over the place during winter
So I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
+1 thats what we had installedSo I changed my wall stat for a wireless room one. They are about £70 upwards depending on how fancy you want the programmer
so you can have the stat module sat next to you and carry it around the house if you wish...and set different temp ranges for day/night etc
then the room you are in, is at the temperature you set on the dial
far better for general use, then of course use TRVs to control far rooms, bedrooms, bathrooms etc
I'm still confused with this. In my last house we had a combi boiler running about 10 radiators over 3 floors. All radiators, apart from the top floor bathroom, had TRVs. There was no room thermostat. I don't use the timer at all -just switch the boiler on when I'm cold and off when I'm hot. I adjust the temp in each room using the TRV.
There was no room thermostat but the boiler didn't just run on and on. It would run until all the rads reached their temperatures on the TRVs and then cut out. It would then start up again when the temperature dropped. I could hear it going on and off.
What am I missing here? Does the boiler have an internal/integrated thermostat? Otherwise how did it switch itself off and on again?
If the room thermostat is the ignition then a boiler without a room thermostat shouldn't be able to do this - should it?
I still don't get how heating an empty hallway can be shown to save energy when compared to just using TRVs and keeping the doors to the rooms closed.
I really would like to understand this as I'm buying a new boiler/system and at the moment I can't see the need for a thermostat.
There was no room thermostat but the boiler didn't just run on and on. It would run until all the rads reached their temperatures on the TRVs and then cut out. It would then start up again when the temperature dropped. I could hear it going on and off.
What am I missing here? Does the boiler have an internal/integrated thermostat? Otherwise how did it switch itself off and on again?
If the room thermostat is the ignition then a boiler without a room thermostat shouldn't be able to do this - should it?
I still don't get how heating an empty hallway can be shown to save energy when compared to just using TRVs and keeping the doors to the rooms closed.
I really would like to understand this as I'm buying a new boiler/system and at the moment I can't see the need for a thermostat.
Either way you are heating the hall way aren't you? Or are you proposing not having a radiator in it? Both ways will work, except that the roomstat will turn the boiler off instead of the boiler pumping 'round water at flow temperature in a loop via the bypass until the boiler thermostat senses it. A properly designed heating system is more efficient..as above, it's also essential for Part 'L'.
The problem you face with no thermostat is the pump will run continuously until the heating is switched off.
As each TRV shuts, you are creating more resistance, thus putting the pump under strain. If you have a bypass fitted it will reduce the strain to some effect.
Boilers have an internal thermostat that shut the burner off when the desired temperature of the water in the system is reached. But the pump will still run and waste heat around the bypass.
A room thermostat switches the heating off completely, including the pump. So you lengthen the life of the pump and save gas.
As each TRV shuts, you are creating more resistance, thus putting the pump under strain. If you have a bypass fitted it will reduce the strain to some effect.
Boilers have an internal thermostat that shut the burner off when the desired temperature of the water in the system is reached. But the pump will still run and waste heat around the bypass.
A room thermostat switches the heating off completely, including the pump. So you lengthen the life of the pump and save gas.
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