freezing pipes to replace a radiator

[900se]

Hi,

I'm replacing a radiator - mounting the new one in a new position.

The new pipework is in place - ready to connect. I was going to drain the sealed combi-boiler system but there's no drain cock and most of the pipe is under the floorboards so finding a lowest point is going to be awkward.

So instead, I'm going to freeze the pipes (having closed the rad valves), cut and attach to the two new pipes to the new rad.

However, should I freeze each pipe in two places and cut between them or should I freeze each pipe in just one place and cut on the valve side of that point?

Thanks.

 

[Softus]

You're wasting your time - drain down now and install a drain off cock so that you can deal with future maintenance.

For example, what you going to do the next time a radiator springs a leak and one of its rad valves doesn't hold up? You won't be wanting to freeze pipes and keep them frozen at the rate of about 50p per minute.

 

[ChrisR]

Systems with no drain cocks often have rusty radiators!
It's important to flush the system when new and add corrosion inhibitor. Instead, your system will probably be full of soldering flux, and consequently radiators rusting from inside out.

Drain it, refill it, with something like Fernox HD restorer, run for a week, drain and refill, with something like Sentinel X100.
And of course, add full flow drain off points to flow and return.