Swapping to a TRV valve ....in this scenario?

ChasingtheWelshdream

Evenin' All. 

Are there any kind plumber folk willing to answer a TRV question and explain something to me please?

Quick version: Does it matter which radiator doesn't have a TRV? Can I choose a different rad to be the 'always on' one?

Long version: Following on from my previous threads (here, but not really relevant to this - just a timeline)

How to tidy these radiator pipes? — MoneySavingExpert Forum
How to tell a 'quality' radiator before purchase? — MoneySavingExpert Forum

I've come up with a different solution to our hallway - we are going to install 'panelling' and will channel the wall enough to hide the pipes behind, re-route as needed and come out the wall to connect to the radiator via corner valves. (I forgot to mention in one thread that the flooring is original Edwardian terrazzo so there's no possibility of coming up through the floor).  I've got me radiator, got me valves, marked everything out and am nearly good to go. :-)

The radiator in question is the one that doesn't have a TRV -  it's near the room thermostat so I understand why. But it's also been out of action and turned off at the valves for well over a year, so hasn't acted as a bypass at all.

Could I put a TRV on this radiator, and change to manual valves in another room instead - like the bathroom rad?

The reason I ask is I've seen some lovely traditional valves that would go much better with the style of the room and the column radiator, but the manual versions are twice the price of the TRV ones. Just a teeny step too far but I could stretch to a pretty TRV. Would it be a problem?

Very much a first world problem I know, whether a valve is pretty or not. 

Thanks!

nofoollikeold

1. The only reason for having an "always on" radiator is to dissipate heat if all the other radiators are off.  This is not required if the system has what is known as an automatic bypass valve (ABV) correctly fitted.  The ABV will open if it senses there is no where for the water to go (when all TRVs are closed for example) and send the hot water from the boiler directly back to the boiler.  There should be enough length of pipework between the ABV and the boiler for the water to lose its heat to the atmosphere, although some boilers do have an internal ABV.
2. If your system has an ABV then you can do whatever you want.
3. If it doesn't have an ABV and you don't want to fit one, then the room with the room thermostat should have a radiator without a TRV.  Otherwise the room thermostat and TRV "fight" each other.  You could get round this by setting the TRV to maximum, which means that room is controlled by the room thermostat.
4. You could also move the room thermostat.  Easy if its a wireless one, not so easy if it is wired.  If wired, you could change it for a wireless one.  

ChasingtheWelshdream

Thank you, that's really helpful and food for thought.

I have no idea if there is an ABV, but I've now googled pictures and will have a nosey around to see if I can see anything. The floorboards are all easy to lift along the pipe routes. The radiators/pipes are pretty ancient but the boiler is only 5 years old, so it would be interesting to see if there is one. I shall hunt for the manual that's been filed in a very, very safe place......

We've thought about changing the thermostat actually as it's not in a great location. A freezing (currently) unheated hallway not indicative of the rest of the house, and often hit by a blast of heat from the woodburner when we open the door - when sometimes it even reaches the giddy heights of 18 degrees! So really, we only use it to switch the heating on/off - it would make much more sense to be wireless in another room.

I've decided to crack on with the valves I've got for the time being just so I can get it back into service. I will be moving other radiators over the next few months, so I can take my time deciding whether to splurge on different ones when the system is drained again, if funds allow. I suspect that by that time I won't even notice them. But always worth exploring the options, and I like to find out more about how my house works,

grumbler

nofoollikeold said:

1. The only reason for having an "always on" radiator is to dissipate heat if all the other radiators are off. 

I don't think so. A boiler has a thermostat, so there is no need to dissipate heat.

The reason is not to overload the pump when all pipes are closed.

ChasingtheWelshdream

Assuming there is no ABV fitted, I'm guessing there hasn't been any damage caused by the radiator being closed for it's second winter, and therefore not being able to act as a bypass? 

Most of the TRVs are set to 3 as a minimum, with just the bathroom/wc set to 2. Downstairs are set to max and the kids rooms get turned up an hour before bed as a boost before we turn the heating off anyway. As I say, the thermostat is really just us clicking the boiler on/off as the temperature can't be relied on.

Jeepers_Creepers

A 5-year old boiler will almost certainly have an auto-by-pass inside it, and also be a modulating type - ie it'll adjust its output to suit demand, so as your house warms up and the rads dissipate less heat to the rooms (ie as the return water temp goes up), the boiler will reduce it's power output, probably right down to around 5kW to keep things ticking over. If even this is too much - as it will be many times - it's just shut down. The auto-by-pass takes care of any momentary flow restriction. 

Your other issue was TRVs and where to use them (you want a TRV on this new rad 'cos it's a lot cheaper?) Basically fit them anywhere/everywhere. In the room you fit your wall thermostat, just open them to max as nflo says - your house would have to be on fire before they close (a slight exaggeration...)

Yes, move the wall 'stat somewhere sensible, and that is the 'main' room you want to keep at a steady temp. That's yer sitting room or other living area. Simplest way as said before is to go 'wireless', and the simplest way to go wireless is to fit the receiver where the current wall stat is - it should be an easy wiring job, provided the old stat has a neutral wire too. Failing that, fit the receiver wherever the boiler's wiring centre is.

If you find out that the new 'wall stat' room heats up too quickly for the rest of the house, so turns the boiler off while the rest of the house is too chilly, then you don't turn down the TRVs there (keep them on 'max', remember?) but instead you tweak closed the lockshield valves a teeny bit at a time - a quarter-turn at most - to 'slow' your rads down. 

ChasingtheWelshdream

Thank you all much appreciated!

I'm slowly learning much more about our house as we gradually - very gradually - start moving away from a liveable wreck. I may take many, many times longer than most and spend far too many hours reading up on things, but I do get there in the end. And the more I prove I can do, the less excuses DH has for saying 'its too much work'   

FreeBear

ChasingtheWelshdream said: I've come up with a different solution to our hallway - we are going to install 'panelling' and will channel the wall enough to hide the pipes behind, re-route as needed and come out the wall to connect to the radiator via corner valves.

If you are chasing slots in your walls to hide the pipes, a couple of points..

Vertical chases should not be deeper than 1/3 of the thickness of the wall. Horizontal chases, maximum of 1/6.

Copper pipes must be protected from cement, plaster, and lime - 15mm copper slides very nicely through 20mm plastic conduit. And avoid having any joints buried in the wall.

Clean off any flux residue and wipe down with a bicarb of soda solution - Being mildly alkali, it will neutralise the acidic flux.

Ideally, you want to insulate pipes, but this isn't always possible.. Some steel capping over the pipes should stop anyone from drilling in to the pipes or whacking a nail through.

Jeepers_Creepers

For supplying a single rad, chicken out like I did and use 10mm plastic piping...

ChasingtheWelshdream

Thanks both, it’s 10mm so I don’t need to chase deeply and I have conduit salvaged from elsewhere already.  

The vertical drop from the ceiling will be chased, conduit, plastered properly.

I’ve cunningly planned the panelling to hide the rest of the pipes, so I’m only needing to chase out just enough to recess them, but they’ll then be covered behind wood. With a sneaky access panel where I’ve planned the joints.

Should work...(she says/hopes ....  )

My thinking is, If it all goes belly up, we’re no worse off heat-wise than we were before and I can just keep plugging away at it until it works. There’s no hurry.

That’s how I sorted my downstairs loo when DH and my own super practical father told me it was too complicated to do and just live with it. (Repositioning the loo). Lots of trips to the friendly plumbing shop armed with photos and websites, and never afraid to sound stupid. Yes it took me a very long time, but I got there in the end.

Hence why I ask what may appear to be stupid questions but really appreciate each and every comment. 🙂

Jeepers_Creepers

You clearly have it in hand
The trickiest part with pipes coming through the wall is the short length of pipe on show, and that it needs to be pretty accurately aligned with the valves. Fortunately, with decorative pipe collars around the exiting pipes, you should have wiggle room.
And then a 15mm pipe sleeves to cover any visible 10mm pipe.