Draining Heating System Question
Discussion
Stupid question but I'm looking for some reassurance.
I need to drain down my central heating system in order to change a radiator valve (the lockshield valve side is leaking from the olive to the copper pipe). I've tried a PTFE bodge and it still weeps...
To avoid having to rebleed every radiator (its a large house so lots of radiators!) can I isolate each one (screw down the lockshield, turn the TRV to 0) to just leave the ones I need to play with?
Logically I think I can but I may be missing something.
I need to drain down my central heating system in order to change a radiator valve (the lockshield valve side is leaking from the olive to the copper pipe). I've tried a PTFE bodge and it still weeps...
To avoid having to rebleed every radiator (its a large house so lots of radiators!) can I isolate each one (screw down the lockshield, turn the TRV to 0) to just leave the ones I need to play with?
Logically I think I can but I may be missing something.
Mr_J said:
I'm not a plumber but surely you'd have to rebalance the system or somehow remember how open each lock shield was. Bleeding them would be far less hassle. I'm pretty certain my plumber also adds inhibitor to each radiator at the same time.
They need rebalancing anyway so I'm not too worried about thatActual said:
If it is the compression joint leaking then have you tried to nip it up tight with a spanner?
Yeah sadly that didn't work. I think it's been bashed about a bit and just isn't sitting properly now. I've managed to stop it from weeping by cranking it up tight but I don't trust it and any movement (eg. Opening the lockshield) is likely to set it off againLennyM1984 said:
Actual said:
If it is the compression joint leaking then have you tried to nip it up tight with a spanner?
Yeah sadly that didn't work. I think it's been bashed about a bit and just isn't sitting properly now. I've managed to stop it from weeping by cranking it up tight but I don't trust it and any movement (eg. Opening the lockshield) is likely to set it off againNot for the faint hearted but it is possible to remove and replace radiator valves without draining down. If the system is pressurised then release pressure by venting a radiator and then closing the vent. If the system is gravity fed then get in the loft and put a bung in the expansion tank outlet. The theory is that once an airlock is established the radiator valve can be removed without too much water escaping due to the airlock. Have a catch bucket and towel ready of course. And good luck with that
You'll need to re-bleed all the rads anyway, because the pipework in between the rads will drain down and fill with air, which will then collect at the top of all the rads when you open the isolating valves and run the system.
The advantage of doing what you suggest, though, is it won't take as much water when refilling and hence you won't need to use as much anti-corrosion additive (assuming the system already has it).
The advantage of doing what you suggest, though, is it won't take as much water when refilling and hence you won't need to use as much anti-corrosion additive (assuming the system already has it).
Personally I think there's a lot to be said for regularly draining down and refilling your heating system, as (much like the coolant system on your car), its a good opportunity to remove some of the crud, rust and dirt built up in the system and refill with fresh inhibitor. I'd use this as a good excuse to do it.
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