TRVs

Grandad2b

Sorry, this may sound very dumb...

My heating system was originally installed when the house was built (1960s). However there are no TRVs anywhere so I have basic questions.

I understand the principle of TRVs and I guess they're an improvement on manually opening and closing rad valves. But what is the difference between a basic cheap model from e.g. toolstation and one of the more expensive brands - are you paying for the name or are there real benefits? 

Secondly, how do I work out how much they're going to save?

Third part of the question - what are the upgrade paths available? 

ThisIsWeird

Hi G'dad.
First check what type of CH plumbing system you have - do you know what a one-pipe system would look like? The two pipes that supply your radiator, is there also a pipe that joins them, running under the rad?
Differences between TRVs. Essentially it comes down to build quality. Also aesthetics - cheap ones can look cheap, and you'll certainly pay for 'designer'. Finally it's whether they are bi-directional, Ie can be fitted either end - they'll operate properly regardless of the water flow direction going through them.
Having said that, not all cheapies are bad, or costly ones good. And I suspect all modern TRVs will now be 'bi' (but, if you can, still fit them to the 'flow' end).
The principle behind a TRV is that is prevents the room from being over-heated, which would be a waste. 'Manually' adjusting a basic rad valve does not provide this control, at least not unless you sit beside the rad constantly adjusting it. 
Even with TRVs - a significant improvement over manual - they still need to be manually adjusted to obtain the actual room warmth you want, and to turn them on and off when required. They just provide a stable, chosen, temp once set, so should provide more comfort, and obvious energy savings too. 
A good example of where they hugely score over 'manual' valves will be in rooms prone to fluctuating temp swings, say from doors being opened a lot, or from solar gain through a south-facing window. With a manual valve set in one position to get the rad 'nicely warm', if the room cools down more than usual - doors being opened - the rad's output won't change to compensate. The TRV's will. Similarly if the sun blazes through your window midday, your stupid manual valve will still keep the rad chugging out.
To fit them will require your CH system to be drained down. Then it's usually a straight forward task for a plumber, and is also very DIYable with a certain level of competence. 
It would make sense to replace the lockshield at the same time, and you can buy them in such pairs.
Fitting a 'magnetic filter' to your boiler return would also make sense since your system is drained, and this will help keep the system water clean. Corrosion inhibitor is added on the final refill.
Once all done, then the tedious and time-consuming task of 'balancing' your system begins! This is very DIYable, using a couple of clip-on thermometers, and you may wish to take this task on as you'll be otherwise paying for a couple of hours of pro plumber work.
Cost? A decent make is around £20-odd per rad? And, what?, a half-day's work for a plumber, or a full day or two DIY? Not really sure, but a plumber should be able to give you a good ballpark figure over the phone, I think.
Finally, if you are doing this, do consider going 'Smart', at least on some of the most often adjusted TRVs - Ie, ones you also need to turn on and off each day, such as bedrooms. These will be part of a Smart thermostat system, which you can control from a phone App. Eg:
Bed 1 - 18oC at 6am. 12oC at 7.30am. 18oC at 10.30pm. 14oC at 11.30pm.
Bed 2 - 19oC at 7.30am. 10oC at 8.30am... etc.
So, no more running around turning them on and off for wakie time or bedtime.
All tweakable as you want from your phone. 
Going out during the day? Touch-touch and heating lowered. On the way back home? T-t and heating turned back up from wherever you are.
Smart TRV heads can be had from around £40 each, tho' the valve bodies will be extra. 

Lorian

Cheap ones and expensive ones do the same thing. Expensive with gas actuators can operate a little quicker but in practical terms the won't save anything more. If you go for a reputable brand like danfoss or Honeywell you are more likely to be able to buy new heads in the future if any fail.

Given the age of your system it could impact some of the benefits of having TRVs as the boiler won't modulate down. What is the boiler make and model?

Grandad2b

Lorian said:

Cheap ones and expensive ones do the same thing. Expensive with gas actuators can operate a little quicker but in practical terms the won't save anything more. If you go for a reputable brand like danfoss or Honeywell you are more likely to be able to buy new heads in the future if any fail.

Given the age of your system it could impact some of the benefits of having TRVs as the boiler won't modulate down. What is the boiler make and model?

So, essentially unless all the TRVs need to look the same there's little point buying a more expensive brand?

The boiler was replaced last summer which is why I'm now looking at TRVs. The previous one's instruction manual was in Latin This one is much cleverer (though I do wish we'd gone for system rather than combi).

ThisIsWeird said:

Hi G'dad.
First check what type of CH plumbing system you have - do you know what a one-pipe system would look like? The two pipes that supply your radiator, is there also a pipe that joins them, running under the rad?
Differences between TRVs. Essentially it comes down to build quality. Also aesthetics - cheap ones can look cheap, and you'll certainly pay for 'designer'. Finally it's whether they are bi-directional, Ie can be fitted either end - they'll operate properly regardless of the water flow direction going through them.
Having said that, not all cheapies are bad, or costly ones good. And I suspect all modern TRVs will now be 'bi' (but, if you can, still fit them to the 'flow' end).
The principle behind a TRV is that is prevents the room from being over-heated, which would be a waste. 'Manually' adjusting a basic rad valve does not provide this control, at least not unless you sit beside the rad constantly adjusting it. 
Even with TRVs - a significant improvement over manual - they still need to be manually adjusted to obtain the actual room warmth you want, and to turn them on and off when required. They just provide a stable, chosen, temp once set, so should provide more comfort, and obvious energy savings too. 
A good example of where they hugely score over 'manual' valves will be in rooms prone to fluctuating temp swings, say from doors being opened a lot, or from solar gain through a south-facing window. With a manual valve set in one position to get the rad 'nicely warm', if the room cools down more than usual - doors being opened - the rad's output won't change to compensate. The TRV's will. Similarly if the sun blazes through your window midday, your stupid manual valve will still keep the rad chugging out.
To fit them will require your CH system to be drained down. Then it's usually a straight forward task for a plumber, and is also very DIYable with a certain level of competence. 
It would make sense to replace the lockshield at the same time, and you can buy them in such pairs.
Fitting a 'magnetic filter' to your boiler return would also make sense since your system is drained, and this will help keep the system water clean. Corrosion inhibitor is added on the final refill.
Once all done, then the tedious and time-consuming task of 'balancing' your system begins! This is very DIYable, using a couple of clip-on thermometers, and you may wish to take this task on as you'll be otherwise paying for a couple of hours of pro plumber work.
Cost? A decent make is around £20-odd per rad? And, what?, a half-day's work for a plumber, or a full day or two DIY? Not really sure, but a plumber should be able to give you a good ballpark figure over the phone, I think.
Finally, if you are doing this, do consider going 'Smart', at least on some of the most often adjusted TRVs - Ie, ones you also need to turn on and off each day, such as bedrooms. These will be part of a Smart thermostat system, which you can control from a phone App. Eg:
Bed 1 - 18oC at 6am. 12oC at 7.30am. 18oC at 10.30pm. 14oC at 11.30pm.
Bed 2 - 19oC at 7.30am. 10oC at 8.30am... etc.
So, no more running around turning them on and off for wakie time or bedtime.
All tweakable as you want from your phone. 
Going out during the day? Touch-touch and heating lowered. On the way back home? T-t and heating turned back up from wherever you are.
Smart TRV heads can be had from around £40 each, tho' the valve bodies will be extra. 

Ah, yes. If I shut off the flow at the first rad then none of the others would get hot. That would be unfortunate as well as counterproductive. :sulk: I honestly don't know but the rads do seem to be independent of each other. 
I have stayed in places with TRVs so understand the basic operation but the subtleties had passed me by. 
The new boiler already has the magnetic filter - I expect it will be pretty full at the first service but hope that's just decades of gunge which will be relatively quickly purged.
The reason I asked about upgrade paths was because of the possibility of retrofitting smart valves - are the bodies the same and just the head changes or do you have to replace the whole thing?

FreeBear

ThisIsWeird said: Having said that, not all cheapies are bad, or costly ones good. And I suspect all modern TRVs will now be 'bi' (but, if you can, still fit them to the 'flow' end).

I've got Drayton RT212 TRVs on all my radiators (came "free" with the radiators). They can be fitted to either end of the radiator, but you do need to watch the direction of flow - I put mine on the inlet so that the head is vertical.

One thing I have noticed is that when my boiler is running at a reduced flow temperature and a TRV operates, it reduces the load on the boiler - Whilst not a bad thing, if load drops below minimum output (nominally 3.2kW), the boiler starts to short cycle which kills the efficiency. Many boilers can not modulate down to 3.2kW (5-7kW appears to be typical, especially for the cheaper ones), so they end up short cycling even before any TRVs kick in.

If you are looking at reducing gas consumption, there are other strategies that have potential to cut your bill - A programmable thermostat that allows for different temperatures throughout the day/week could save up to 15% (in reality, more likely 5%). Turning down the flow temperature will improve boiler efficiency, and turning the thermostat down a degree or two will save even more.

If you have an old oil fired boiler, chances are it doesn't modulate (there are only a couple on the market that will). And if it isn't a condensing boiler (gas or oil), there is not much saving to be had from turning down the flow temperature. And I doubt that TRVs would save any noticeable amount. However, a programmable thermostat will, regardless of the boiler type or age - I fitted one to an old Baxi gas boiler, and saw a ~10% saving straight off.