Rad valve replacement checklist

[Desi80]

I've got a rad that was leaking a decent amount of water, tried nipping things up but it didn't help. Yesterday I thought I'd quickly whip the nut off and repack the gland spindle and add a bit of PTFE when reattaching the nut.
I undid the top nut but there' s a black plastic/rubber inner that's risen up and it's stopping me reattaching the top nut. (see attachment)


So now I'm guessing it's time to replace the valve, there's another one I can do whilst I'm at it too.
I've got a pressurised combi system. My checklist is as follows:


• Make sure water feed and power to system is off
The water feed is the valve in the airing cupboard I use to top up pressure right?
• Drain system with a hose and jubilee clip, the drainage point is on the rad in question
• Replace valves
• Refill system, bleed, top up pressure, add inhibitor


I've got a couple of questions, can I get that bit of black plastic back in the valve and save me the headache of bleeding the whole system?
If I do end up replacing valves is there some kind of overflow system to stop me overfilling the system? Do you leave some bleed valves open to let the air out as it fills?
Any help would be good as I don't want to leave this too long, it's cold!

 

[Desi80]

 

[ShaunCorbs]

easier in the long run to just replace the valve (the plastic would be brittle so prob wont seal anyway)

yes

yes normally fill your system to a pressure of about 1.2bar then air a couple of rads and repeat until all rads are full

 

[Desi80]

Thanks Shaun, I'm currently looking into a pipe freezing kit from screwfix (can't post a link as I'm a new member)

 

[Riley]

Thanks Shaun, I'm currently looking into a pipe freezing kit from screwfix (can't post a link as I'm a new member)

drain it down mate. Easy to freeze microbore. Also easy to defrost microbore under pressure with water running out of the radiator

 

[dancinplumba]

Snatch it ;-)

 

[Best]

Would be really stupid to drain the system down! Why would you do that on a pressurised system? Take the pressure off the system somewhere like a draincock and then the system is dead, zero pressure. Just tighten by hand any auto vent screws to prevent air getting drawn in and after turning the other rad valve off, remove your faulty valve and replace.
Expect some water to glug out of rad - so stuff a little bit of rag temporarily in the tail while putting the new valve on.

 

[Desi80]

Thanks for the feedback everyone.

Yes, Best, I want to avoid draining down if possible, there's the hassle and the added cost of the inhibitor etc.

So if I slowly let some water out somewhere that kills the pressure in the system right? Then I can freeze up the pipe just in case and do a quick swap.

Hopefully that will be ok...

 

[ShaunCorbs]

Thanks for the feedback everyone.

Yes, Best, I want to avoid draining down if possible, there's the hassle and the added cost of the inhibitor etc.

So if I slowly let some water out somewhere that kills the pressure in the system right? Then I can freeze up the pipe just in case and do a quick swap.

Hopefully that will be ok...

it would be ok, but i wouldn't recommend it for a diyer as few things can go wrong, and draining down and putting fresh inh would help/ might be needed anyway

 

[stevetheplumber]

get a sraight swop valve shut one valve on each rad let some out of the drain off loosen both nuts on the valve then just do a quick swop