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Fitting a radiator (combi boiler system)
nick205 - 17/10/22 at 08:43 AM

Morning all,

I need to fit a radiator where I removed one a few years ago and capped the pipes that come out of the floor. It's in a 1st floor bedroom and the combi boiler is also in and airing cupboard on the 1st floor.

Not having done this before I'm guessing I need to:

1. Drain the central heating to release the pressure
2. Fir the radiator
3. Refill the central heating
4. Turn the central heating on
5. Bleed the radiators to ensure there's no trapped air

Is this the correct process?

If not can anyone advise please?

Thanks,
Nick

cliftyhanger - 17/10/22 at 08:52 AM

Yes, or if upstairs you can just drain enough so you can do the job.
If you wish, you can shut all the rad valves which greatly reduces the amount top drain/refill
Don't forget the inhibitor....

nick205 - 17/10/22 at 09:03 AM

quote:
Originally posted by cliftyhanger
Yes, or if upstairs you can just drain enough so you can do the job.
If you wish, you can shut all the rad valves which greatly reduces the amount top drain/refill
Don't forget the inhibitor....



Thank you.

1. Bathroom radiator (headted towel rail) has a working TRV
2. The other upstairs raditor rad valves are ancient and very very hard to turn - part of the job may be to replacing those with new TRVs.

3. The combi coiler itself is also on upstairs so I'm guessing I may have to drain enough to clear the upstairs?

4. If I drain the system completely I can replace the ancient rad valves with TRVs downstairs as well.

Bigger job, but will modernise the system a step and give us more control in the house.

SteveWalker - 17/10/22 at 10:14 AM

If you are fitting TRVs all round, you need to ensure that one radiator (often the towel rail is used) is not fitted with one or that a separate automatic bypass valve is fitted - to ensure that a path for water flow remains open at all times. Your boiler and pump will not take kindly to running while all the radiators are closed off by their TRVs.

nick205 - 17/10/22 at 10:25 AM

Thanks Steve - noted.

May avoid fitting TRVs to the 2 rads in downstairs WC and hall way in any case.

[Edited on 17/10/22 by nick205]

nick205 - 17/10/22 at 11:19 AM

Another consideration I have is small diameter pipes (microbore ?). Maybe when the houses in my street were built Copper was expensive and they were trying to save money, by using less of it. Not impossible to do, but just another consideration and I find the smaller stuff a bit more fiddly than Ø15mm.

Russell - 17/10/22 at 12:24 PM

quote:
Originally posted by nick205
Another consideration I have is small diameter pipes (microbore ?). Maybe when the houses in my street were built Copper was expensive and they were trying to save money, by using less of it. Not impossible to do, but just another consideration and I find the smaller stuff a bit more fiddly than Ø15mm.


Nothing wrong with 10mm microbore. If you find getting hold of TRVs with 10mm inlet a pain, get some of these from Screwfix: 15mm to 10mm reducer

nick205 - 17/10/22 at 12:30 PM

quote:
Originally posted by Russell
quote:
Originally posted by nick205
Another consideration I have is small diameter pipes (microbore ?). Maybe when the houses in my street were built Copper was expensive and they were trying to save money, by using less of it. Not impossible to do, but just another consideration and I find the smaller stuff a bit more fiddly than Ø15mm.


Nothing wrong with 10mm microbore. If you find getting hold of TRVs with 10mm inlet a pain, get some of these from Screwfix: 15mm to 10mm reducer



Agreed, nothing wrong with microbore (I just just find it more fiddly).

Reducer parts noted - used similar before.

The water pipes in our house are Ø15mm, it's just the central heating pipes are microbore.

cliftyhanger - 17/10/22 at 03:05 PM

I think microbore was used as it came in a roll, and just like plastic pushfit stuff today, made teh job much quicker.
If all ancient, I woukld drain, the fill with some quick acting cleanser, run the boiler etc then carry out a full drain. May as well while you are doing the job, no doownside except £15 and some extra time.
I would be tempted by a magnaclean too. And if happy to do so, pulll the HW heat exchanger and give that a good clean/descale.

nick205 - 17/10/22 at 03:44 PM

Noted and again, not a bad call to clean the system through.

I can see the speed advantage of working with the material in a roll. There's a few other "builder speed" things in the house where you can tell they were working to get the job done quick as. The roofing felt (under the tiles) isn't as overlapped as it ought to be. Less felt used per house and fewer spans of felt per roof.

number-1 - 17/10/22 at 03:58 PM

I have just fitted another rad in the living room.

I cheated and used JG Speedift fittings and pipe and was super easy to do.

I drained the entire system and refilled using some inhibitor. I found that just bleeding the rads the boiler was noisy/ whooshy.....and had to bleed the water pump too which was really easy to do and has been fine since.

I did fit TRV on the new rad but wound it all the way open as downstairs is always cold and they say not to have a TRV in the same room as the thermostat

nick205 - 18/10/22 at 10:23 AM

number-1

Good info on bleeding, thanks.

Also on not fitting a TRV to the rad in the room where the thermostat is. Our Thermostat is in our kitchen, where there's one rad. That one rad is behind a sofa (sofa is apparently for the dog and not people). That rad will most likely be left well alone in any work I carry out (can't be arsed to move the sofa and be faced with SWMBO + dog glaries).