Changing radiator valve on closed system.

[daverave7]

I'm replacing a radiator in my bathroom with a towel radiator, which will also need new radiator valves. I'm hoping to do this without draining the system. I have a system boiler (boiler and hot water tank) and a closed/ unvented heating circuit. Am I right that if the valve is removed, then the system should create a vacuum and water loss will be minimal? Should I also release the pressure in the red expansion vessel before removing each valve?

Other than a few buckets and being close to the bath, are there any other tips?

 

[cross thread]

Most cases, turn boiler off, drop pressure and should be ok,no need to touch expansion vessel

 

[daverave7]

Most cases, turn boiler off, drop pressure and should be ok,no need to touch expansion vessel

There's a valve underneath and attached to the expansion vessel... is this the valve to use to drop the pressure?

 

[Mottie]

I'm replacing a radiator in my bathroom with a towel radiator, which will also need new radiator valves. I'm hoping to do this without draining the system. I have a system boiler (boiler and hot water tank) and a closed/ unvented heating circuit. Am I right that if the valve is removed, then the system should create a vacuum and water loss will be minimal? Should I also release the pressure in the red expansion vessel before removing each valve?

Other than a few buckets and being close to the bath, are there any other tips?

I replaced my rad valves without draining down a little while ago. https://www.diynot.com/diy/threads/suggestions-of-how-to-stop-this-leak.590628/#post-5584996

 

[Madrab]

There's a valve underneath and attached to the expansion vessel... is this the valve to use to drop the pressure?

Nope, never use the pressure relief valve (under the EV) to release the system pressure. Only drain @ the rad in the bathroom. Turn off both valves, open up the rad bleed valve and release the pressure, crack one of the rad nuts open and drain the rad. Once that's drained and removed then crack open the rad valve slowly and run the system pressure down into a bucket till it stops, you shouldn't lose much more water over what pressure is in the system. Crack open the other valve and drain any water that may exit that side. Once done remove old valves and replace, with any luck the nuts and olives will be the same, just get a few turns of PFTE tape around the old olive if you're re-using.

 

[daverave7]

Another Q, relating to my towel radiator. The current piping is plastic i.e. 10mm flex pipe and I have bought speed fit couplers (10mm to 15mm) to connect to my new radiator valves. Will these work with compression fittings?

 

[BlueLoo]

Don't use ptfe tape at all on compression fittings good grief.
Especially on todays modern boilers with complex heat exchangers.

You shouldn't need it. Keeping it clean and simple should be ok.

Here's a huge thread about it:

Recommend a Jointing Compound (for Compression Fittings)

Hi all, I'll soon be replacing all our old radiators with new radiators, along with new TRVs.

forums.moneysavingexpert.com

If you absolutely can't get a seal, either redo the olives or use something better designed for the job. (Read the thread).

 

[daverave7]

Another Q, relating to my towel radiator. The current piping is plastic i.e. 10mm flex pipe and I have bought speed fit couplers (10mm to 15mm) to connect to my new radiator valves. Will these work with compression fittings?

Or perhaps I should use something like the below? Are these compatible with flexpipe?

Radiator Valve 15mm x 10mm Pushfit Chrome Speed Fit Reducing Straight Compression Stem (Pack of 2)

15mm x 10mm Pushfit Radiator Chrome Reducing Straight Stem Compression Valves (Pack of 2)Brand new, premium quality pack of 2 brass push fit straight stem valves in long lasting bright chrome plated finish, used to reduce 15mm thermostatic and manual radiator valves to 10mm...

spares-2-go.com

 

[Madrab]

Don't use ptfe tape at all on compression fittings good grief.

If something isn't used on re-used olives/fittings, then chances are they will weep. One turn around the olive ensures no return needed, with absolutely no risk to 'complex HEX's'.

New fittings shouldn't need anything but even then I now replace all brass olives with copper.

 

[Madrab]

I have bought speed fit couplers (10mm to 15mm) to connect to my new radiator valves. Will these work with compression fittings?

What couplers did you buy? is it these?

or these

If so yes they will work with the compression end on the valve

 

[daverave7]

What couplers did you buy? is it these?

View attachment 323735 or these View attachment 323736
If so yes they will work with the compression end on the valve

Yes, I have the one to the left! Good to know I can use these! Is there any need for an insert? I'm guessing not, as they're already quite rigid.

 

[BlueLoo]

If something isn't used on re-used olives/fittings, then chances are they will weep. One turn around the olive ensures no return needed, with absolutely no risk to 'complex HEX's'.

New fittings shouldn't need anything but even then I now replace all brass olives with copper.

There's much better things on the market than ptfe tape.
It's all but banned commercialy because it causes havoc when it inevitably loses itself in the systems. Pump glands, valves, exchangers, etc.

Dreadful stuff, inelastic and only ever for taper threads and even then, i think id rather see hemp and jointing compound.

 

[Madrab]

There's much better things on the market than ptfe tape.

Really, that's interesting, TBH not found anything more convenient and potable that a roll of gas tape in all the years and I'm sure I've tried them all but maybe not. Where/when there is a need to wrap a used olive for belt and braces, what would be a better product?

Certainly haven't heard anything about its use being banned, either commercially or anywhere else TBH. If it's used properly there's little or no risk at all that it will get into any system. The only products I've heard any concerns about are the Hawk - Loctite or similar products like fluids and threads as it seems to be more prone to break offs and/or clogging/contamination.

 

[BlueLoo]

Really, that's interesting, TBH not found anything more convenient and potable that a roll of gas tape in all the years and I'm sure I've tried them all but maybe not. Where/when there is a need to wrap a used olive for belt and braces, what would be a better product?

Certainly haven't heard anything about its use being banned, either commercially or anywhere else TBH. If it's used properly there's little or no risk at all that it will get into any system. The only products I've heard any concerns about are the Hawk - Loctite or similar products like fluids and threads as it seems to be more prone to break offs and/or clogging/contamination.

Of the top of my head, Ptfe cord is a better product for taper threads.


Loctite products are excellent.
They will also advise you on best product and practice if you give them a call on your particular configuration

However, you have to read and understand the pds.

I get the point that if it's a wrap of ptfe or a replumb, the easy route is tape but you'll be coming back to it again at some point. It's just not made for this situation.

 

[Madrab]

Of the top of my head, Ptfe cord is a better product for taper threads.


Loctite products are excellent.
They will also advise you on best product and practice if you give them a call on your particular configuration

However, you have to read and understand the pds.

I get the point that if it's a wrap of ptfe or a replumb, the easy route is tape but you'll be coming back to it again at some point. It's just not made for this situation.

OK, if that's what you believe then fair enough. I do have to say though It's certainly not any better, it's just a different solution, have used/tried most of them

If multiple pro's are asked about what they use then there will be multiple answers, some prefer thread, some prefer PTFE tape, some prefer liquids and jointing compounds. Some are potable some are not, they all work just as well as each other, it really is down to personal preference. That whole subject has been done to death many times on here.

I use Gas PTFE as I have multiple uses for it and it works perfectly well for all possible applications. Never ever had any issue with it ending up where it shouldn't, that only ever happens with poor workmanship.