I have a pressurised (and sealed) central heating system.

I need to remove a radiator upstairs, and this will require draining
the entire system upstairs. (Drain valve above boilder in kitchen
will be used)

However, when the job is finished I do not really want to use just
mains water to top it up as surely this will rust the system? So I
guess I need to introduce some rust-inhibitor to the system.

I have no manual (or skills/knowledge) - so was wondering:-

- What product to use
- how much to use
- How to introduce it!

I had a new tank installed by a *cough* professional last year who did
the similar drain, but didn't introduce anything (so down 50% on
anything that was there anyway).

House is typical new small 3-bed semi

Many thanks indeed!