Fitting TRV's

[TinyofCarlisle]

Hi All,

I have recently moved to a new house and want to fit TRV's but thought I'd better ask a few questions first. I will also be replacing the bathroom rad with a towel rail.

My boiler is a Baxi Bermuda Inset 2 50/4. 8 rads in 6 rooms 4 upstairs 4 down.

I have a room stat in the dining room and have trouble controlling the heating upstairs without turning off the rads.

Firstly, will TRV's resolve this? (Naive I know but better to ask)

If yes, What brand would you recommend? (and for that matter which should I avoid?)

Do I need replace the lockshields at the same time as new TRV's?

Should I be attempting the job at all or is it best left to the experts?

Any advice would be appreciated!

Thanks.

 

[mikej2005]

Firstly, will TRV's resolve this? (Naive I know but better to ask)

You'll certainly have more control over the heating if the rooms are getting too hot and should allow you to select a lower temperature in each room. They're unlikely to make rooms any hotter, unless your current valves are stuck down in some way and restricting the flow.

Do I need replace the lockshields at the same time as new TRV's?

It would make sense to replace them, especially if they're old and/or weeping and you're going to go to the trouble of draining the whole system anyway. They're not expensive.

Should I be attempting the job at all or is it best left to the experts?

If you're handy with a couple of spanners, then it's certainly possible for the average DIYer to tackle a job like this but don't underestiumate the length of time the job will take. I'd be doing it in summer, personally.
You'll need to know how to drain and refill your system too, so check that out first.

You'll also have the issue of whether to re-use existing olives/nuts or not with both your lockshields ands your TRVs, as removing olives isn't trivial and if you cut them off, you'll shorten the length of pipe you have to play with.

 

[TinyofCarlisle]

Cheers,

The rad's upstairs are too hot, its like walking into a sauna climbing our stairs.

I'm a mechanical enginner so I dont forsee any physical problems with replacing the valves.

As for draining the system, I will have to have a closer look. I am assuming that it can be drained at the downstairs radiators as I can't find a drain point (any lower in the system any ways). There is a small cold water tank in the loft which i assume is the header tank, we have a seperate cold water tank in the airing cupboard which supplys the rest of the house.

Any advice on where not to place a TRV? Ive read a few posts that say not to have one on a single radiator presumably in the room with the room stat.

Thanks Again

 

[mark.neale]

There should be a draining point either on one of the downstairs rads, or on the pipes under the boiler if its downstairs. Otherwise you will have to take the slower (& messier) route of draining from a rad valve.

Its best not to have a TRV on the rad which is in the same room as the stat, otherwise they could work against each other.

The small tank in the loft is the header/feed and expansion tank for the heating circuit pipes that go to all the rads. Before draining the system, you will need to isolate the water supply to this tank, either by a valve on the pipe that feeds the float valve, or tying the float arm up.

Only replace lockshields if they are old, otherwise leave alone.

 

[mikej2005]

If you don't currently have a convenient drain-off point for your CH, then you might want to consider replacing a standard lockshield with one with a built-in drain-off point for future use.

In the meantime, check the boiler for drain-off points - this will allow you to empty most of the system, although any lower lying rads and pipes will have to be drained individually if necessary.

You'll have to isolate the cold supply to your header tank before you start and open all the radiator air vents cautiously, once the system is partially drained.

Current Part L recommendations are not to have a TRV in the same room as the main thermostat.

Edit - sorry Mark - was typing as you posted

 

[Bon]

You might want to think about flushing your system out prior to dumping it too.

 

[mark.neale]

No worries mikej2005.

Great minds............

 

[TinyofCarlisle]

Thanks all for the advice, very useful.

What a great forum!

 

[bengasman]

Indeed no trv with roomstat.
Any major brand will do, as most of the “house” brands of major plumbers merchants, stay away from the very cheap ones and diy chains own
With a bermuda, flushing first would be a good idea.
I always stick the trvs on the flow side, even the bidirectional ones