Plumber explains what radiator numbers really mean and why you should 'leave it' at 3

[ericmark]

You keep implying that you have solved the secrets of central heating, but you really haven't. The vast majority of people have much simpler systems and they work perfectly well.

Oh no, improved maybe, solved no.

OK maybe a bee in my bonnet, I was told by so many, so many times, you don't fit a TRV to a radiator in an area with a wall thermostat, I believed it. Then I fitted a TRV in my mother's hall, with the wall thermostat, and it cured most of the problems.

So statements like.

TRV's should not be fitted to all radiators, the room where the stat is located, should not be with a TRV, or the heating may not switch off when unnecessary.

Really winds me up. As I now know it is wrong, even with mechanical TRV heads and a non-programmable wall thermostat.

 

[Harry Bloomfield]

Basically TRV heads with *123456 have no place in a modern heating system, they are a left over from a bygone age like the motorised valve, which is not required when using electronic heads on the TRVs. But there are still some people living in the past, and we have to say with mechanical or with electronic to cover both old and new.

Sorry Eric, but you do write some total nonsense. No system can ever be perfect, because there are too many unpredictable variations, besides which, there has to be some cost/benefit involved.

I find it offensive, where you suggest I live in the past - I have a modern, up-to-date boiler, controlled by a very modern, optimised control system. I don't have the TRV T's, not because I cannot afford them, but rather that I do not want that extra cost and complexity in my life, for no extra benefit. My system, as is, does all that I want from a heating system - it keeps my home at a reasonably stable, and comfortable temperature, which all I would expect from any heating system.

You have an obsession with solar panels [1], I made a decision long ago that they had no value for me - the sums just do not add up, the cost of panels, the cost of batteries, the costs of replacement, and they have zero comfort benefit, though might appeal to the gadget freak.

[1] If you doubt you have an obsession with solar, power consumption, and heating system, just look at how frequently you post on these very subjects, and the lengths of those posts.

 

[ericmark]

I have said again and again, every home is different, what works with one home may not work with another.

As to solar panels, I have been saying how I don't like the idea of balcony solar, not supporting it.

As to plumbing, yes I found again, all I had been told about cost to heat DHW with gas or oil compared with electric was not as cut and dried as people make out. I am not saying they are wrong, I am sure there are cases where gas is cheaper, what I am saying, not as cut and dried as has been made out.

 

[denso13]

I was told by so many, so many times, you don't fit a TRV to a radiator in an area with a wall thermostat, I believed it.

That's exactly what Approved Document L says. Again, you have found a quirk that seems to work for you, but it is very much the exception.

 

[Harry Bloomfield]

OK maybe a bee in my bonnet, I was told by so many, so many times, you don't fit a TRV to a radiator in an area with a wall thermostat, I believed it. Then I fitted a TRV in my mother's hall, with the wall thermostat, and it cured most of the problems.

Which completely defies logic - why/how could it possibly?

The normal TRV, is there to limit temperature, the room thermostat is there to switch off the boiler, when heat from it is no longer required. How can the stat work effectively, when the TRV is already limiting the temperature rise?

In early /late summer, the boiler will continue to run, unnecessarily, rather than switching off as it should.

 

[Mister Banks]

Oh no, improved maybe, solved no.

OK maybe a bee in my bonnet, I was told by so many, so many times, you don't fit a TRV to a radiator in an area with a wall thermostat, I believed it. Then I fitted a TRV in my mother's hall, with the wall thermostat, and it cured most of the problems.

So statements like.

Really winds me up. As I now know it is wrong, even with mechanical TRV heads and a non-programmable wall thermostat.

You’re the only person that thinks it’s wrong though.

 

[Harry Bloomfield]

You’re the only person that thinks it’s wrong though.

And unable to explain why it's wrong!

 

[ericmark]

Which completely defies logic - why/how could it possibly?

The TRV and wall thermostat open and fire the boiler when the front door is opened. The radiator rather large get hot, and starts to reheat the hall, at around 16°C the TRV starts to close, but it will not fully close until it reaches 20°C and the wall thermostat is set to 19°C, so on a cold day it will not turn off, and the rest of the TRV's will control other rooms at the temperature set, and the boiler will modulate as it should, but on a warm day it will hit the 19°C and turn off the boiler.

 

[Harry Bloomfield]

The radiator rather large get hot, and starts to reheat the hall, at around 16°C the TRV starts to close, but it will not fully close until it reaches 20°C and the wall thermostat is set to 19°C, so on a cold day it will not turn off, and the rest of the TRV's will control other rooms at the temperature set, and the boiler will modulate as it should, but on a warm day it will hit the 19°C and turn off the boiler.

Both 'fighting', to be in charge of the heating, so neither is able to work to a satisfactory level.

 

[ericmark]

Both 'fighting', to be in charge of the heating, so neither is able to work to a satisfactory level.

I would agree the settings are important, and it means non-programmable wall thermostat locked to a set temperature with a mechanical TRV head also locked to a set temperature, the thermostat I used,

had stops to limit the range, so these were used to lock it. And they worked in unison together, no fighting involved.

Once we move to programmable, then we may as well link the TRV head and wall thermostat.

I had intended to do that, I had 4 Energenie TRV heads in the house, which said they would work with a Nest thermostat. And I had intended to swap to Nest.

But by time I moved to this house, Nest had been bought out by Google, and the TRV heads would no longer link in a meaning full way. So this house now installed Wiser, so the TRV head can be linked to the wall thermostat by assigning them to the same room. Not that I have done that, as still using the old TRV heads.

However, single voice command, will change the two TRV heads and wall thermostat in living room to the temperature required, not used it, other than to see if it works, but what can be easier than simply saying hey google set living room to 22 degrees?

 

[denso13]

but what can be easier than simply saying hey google set living room to 22 degrees?

Saying "hey Alexa, turn my Hive up to 22".

 

[ericmark]

Saying "hey Alexa, turn my Hive up to 22".

But that would only turn up Hive units, and would turn them up in the whole house. "hey Alexa, turn living room up to 22" would be better.

I don't know how Hive works now? In the past if the wall thermostat showed over 22°C then it would not accept a demand for heat from the TRV heads, has that changed? Also does Hive group devices, with Wiser if a wall thermostat and TRV are in the same room, it links them, so the wall thermostat tells the TRV what to do.

So with Wiser, no question, should fit TRV in same room as thermostat.

This is what I see as a problem, so much depends on make and type of thermostat and TRV there is no longer a simple answer, I tend to assume if someone says they have fitted Hive, Wiser, Tado, etc. That it is all Hive, Wiser, Tado, etc. but that is wrong, people do try to mix and match, including myself, as we still have bits from failed systems, my Energenie cost around £80 a pair, and Wiser around £45 each, so I know it would be better to have all Wiser, but it is down to is it worth it?

I have eight non Wiser electronic TRV heads, I am not about to spend out £360 for very little gain. I find if a Wiser TRV is fitted in the worst bedroom, then the boiler is running when other bedrooms are calling for heat. I have considered fitting a wall thermostat in the coldest bedroom, linked to the TRV, as the TRV next to a cold wall.

But, simple statements without qualifying like you should not have TRV in same room as a wall thermostat, is clearly wrong. I have two TRVs and a wall thermostat in the same room, and they work fine. Even when each one is a different make.

 

[denso13]

But that would only turn up Hive units, and would turn them up in the whole house.

Yes, in a properly designed system that is how it works. Micro controlling each room is madness, IMHO, and can do more harm than good.

But, simple statements without qualifying like you should not have TRV in same room as a wall thermostat, is clearly wrong.

Of course it isn't, it's in the guidance to the Building Regs.

I have two TRVs and a wall thermostat in the same room, and they work fine. Even when each one is a different make.

Great.

 

[Harry Bloomfield]

But, simple statements without qualifying like you should not have TRV in same room as a wall thermostat, is clearly wrong. I have two TRVs and a wall thermostat in the same room, and they work fine. Even when each one is a different make.

That is rather like having two drivers, controlling the one vehicle - it is doomed to failure.

 

[ericmark]

That is rather like having two drivers, controlling the one vehicle - it is doomed to failure.

Driver and steersman, standard way to move large loads, and it works well.

Of course it isn't, it's in the guidance to the Building Regs.

ii. An individual thermostatic room control for each heat emitter, such as a thermostatic radiator valve, on all heat emitters outside the room that contains the thermostat.
Thermostatic radiator valves should not be used in the same room as the thermostat.

OK, but still does not make sense, it says a thermostat should not be used in a room with a thermostat, only way that can be done, is to have no thermostat in the room.

Think this is actually better than the law on import of peanuts as being complete gobbledygook.

Sorry, I have made a mistake, that is from the approved document not the law, I must hunt further.