New boiler and Thermostatic radiator valves

nofoollikeold

1. Manual radiator valves (wheel head valves) are not on or off.  As they close they restrict the flow of hot water from full flow to no flow.  On a properly balanced system, full flow will give maximum heat from the radiator.  Reduced flow will reduce the heat lost from the radiator to the room, and will result in a cooler room.
2. However, manual radiator valves tend to leak if they are constantly used, whereas the construction of TRVs avoids these problems.  No reason why manual valves shouldn't be built to stand constant use, but they generally aren't.  There are some notable exceptions like the old Pegler valves. 
 

BUFF

Manxman_in_exile said:

Thanks everybody.

BUFF said:

On a totally new install they are a requirement.
On a replacement install they are not (highly advisable though hence why they are a requirement for a new install)...

Yes.  I've since spoken to our local council's building control people and they've told me that they are required if new radiators have been installed, but not if the boiler has simply been replaced, (as in our case).

Ebe_Scrooge said:

Quite apart from any rules 'n' regulations, TRVs are a good idea. ... But a simple TRV is a purely mechanical device, pretty cheap to buy, and makes life so much easier.  At the simplest, in a conventional setup you've got a thermostat somewhere that control the overall temperature.  Then you just adjust the TRV in each room to suit your preference.  Maybe the living room is turned up full, the kitchen is on half, bathhroom on three-quarters, bedroom on a quarter, any unused rooms set to the lowest setting just to stop any damp.  Makes it very easy to adjust different rooms to different temperatures, depending on your lifestyle and preferences, for not much money.

Manxman_in_exile said:

Is their some particular benefit in radiators turning themselves on and off - which is what I presume thermostatic valves do - rather than controlling it yourself?

It just means you don't have to go round adjusting each rad as the temperature changes.  Set the TRV up, set it to a temperature you want in each room, and it'll look after the rest for you...

I understand that.  But how much of a benefit are TRVs over simply manually turning radiators on and off?  We are two people living in a house with ten radiators - can't we simply turn radiators on and off in the rooms we are using or not using?  I can see that TRVs are "convenient", but are they really a benefit worth paying for?

I also appreciate that TRVs may be a requirement on new builds, but I wonder if that's because there is a view that people these days don't have the common sense only to use the energy they need?  (Or are perhaps lazy?).  I don't waste electricity if I don't require it so I turn off anything I'm not using.  (I don't for instance ever leave anything on standby.  Everything is turned off if it's not bring used.)  If I don't want to waste gas by heating rooms we aren't using, manually turning a radiator off is not a great inconvenience to me, and having a TRV do it automatically doesn't seem like a significant benefit.  But maybe I'm looking at it entirely wrongly...

BUFF said:

...Did you get a new programmer/room 'stat when you had the new boiler install?
A modern room 'stat is likely to do a far better job with a modern boiler than an old one & therefore save you gas consumption & hence money.

Well yes - we got a new smart programable thermostat that independently controls heating and hot water.  But it's a single, central thermostat.  Should we have had (or do we need) a thermostat in each room?

Incidentally, the reason I framed my question the way I did (are TRVs required rather than are they advisable) is because I wanted to check if the advice we'd received had been correct.  It would seem that strictly speaking it was correct, although it may not have been entirely complete.

Thanks again!

You don't need a room 'stat (although, depending upon the control system, it is possible to) in each room. For most that would be overkill.
Similarly, you don't need a TRV in a room but they are highly advisable (except for the room where your room 'stat is). They will let you set your different rooms to be at different temps. automatically - convenient & energy saving. Just a shame that you didn't have them done whilst the system was drained down for the boiler change.

Apodemus

nofoollikeold said:

2. However, manual radiator valves tend to leak if they are constantly used, whereas the construction of TRVs avoids these problems.  No reason why manual valves shouldn't be built to stand constant use, but they generally aren't.  There are some notable exceptions like the old Pegler valves. 
 

  While I agree in general terms with this, I look after a property where the three remaining 53 year old manual valves are fine, while the only new rad in the house, has a leaking TRV!

MoreProbs

Manxman_in_exile said:

But how much of a benefit are TRVs over simply manually turning radiators on and off?  We are two people living in a house with ten radiators - can't we simply turn radiators on and off in the rooms we are using or not using?  I can see that TRVs are "convenient", but are they really a benefit worth paying for?

Thanks again!

The main difference between manual and TRV valves is that the latter will only open as far as it has been set to, and heat the room to only that temp. So if you have one in a bedroom and you want that room to be only at 17 degrees, a TRV will get that room up to that temperature quickly, and then hold it there.

How would you do this with a manual valve? If you only open the manual valve a small amount, the radiator will take an age to heat the room, and will then carry on heating it slowly regardless of the room's temperature. If you open a manual valve fully, it'll heat the room quickly but then the temperature will swing well above what you want. They are very crude devices. As crude as the operator.

If you are happy to keep chasing your tail, running around your house monitoring each room's temperature and turning manual valves up and down, then you'll be fine. But TRVs are far better, and should be more energy efficient.

TRVs still require some manual intervention so that they come on only when required, but at least you'll know the rooms will heat up more quickly, and then stay at that temperature.

'Smart' TRVs are the ultimate solution but require a much larger financial outlay.