Pipe freeze spray kit

[jonnybegood]

Are these any good when changing a valve on a 15mm pipe, the bottle states up to 30min freeze time, So could you cap the end of the pipe before the 30mins expires.
If this is correct and possible what would be the best method for this, Don't want to drain the full system just to replace a rad valve.

It is a sealed combi system

Cheers

 

[megawatt]

They work fine ... Follow the instructions and don't forget to depressurise first.

 

[horhay]

if its a combi you are just as easy to drain the system plus you dont have to worry about the pipe un freezing and flooding your house

 

[jonnybegood]

They work fine ... Follow the instructions and don't forget to depressurise first.

Depressurise? What will that mean me doing.
The radiator is in the lounge downstairs, The way I was looking to approach it was to close the inline valve that allows water to flow downstairs through the system (This is in the old airing cupboard) Close both valves either side of the rad,remove rad and place bucket to catch any excess and leaks from the knackered lockshield, apply the freeze spray around 4 inches before the lockshield valve, remove the valve from the pipe.
Attach the new valve to the pipe within 30mins and then connect up the rad at my leisure.

Would draining system be any easier than that, Everyone you speak to says that draining combi systems is not straight forward, then others say go ahead its easy.

What are the steps in doing this with a combi.

 

[megawatt]

Sealed systems are pressurised to circa 1bar. Whilst DIY freezing kits will still maintain the integrity of the ice plug at this pressure I prefer to lose the pressure just to be on the safe side.

Foolproof way to lose the pressure is to vent from the bleed valve on the rad you will be removing until the pressure guage on the combi reads 0. Some use the combi's PRV (as its quicker) but you risk getting dirt in the valve by doing this and could end up with more problems than you started with.

Don't forget to restore the system pressure iaw the boiler manual and bleed the system once the work has been completed.

MW