Combi Boilers

Only that if you let out too much water, you may lose a little pressure and need to top up afterwards. See the sealed system FAQ if you need details on how to do that:

Any leaks when you loosen it will be more substantial than with a tank fed system, but in principle it should work. Make sure you have the system drain valve connected to hose, with someone standing by to open it if the leaks are too severe and can't be nipped back up successfully with the spanner.

Christian.

Surely if you've shut off the radiator valves first it doesn't matter if you've a sealed or tank fed system?

Rob

The sealed system will be at a higher pressure, so any leaks caused by rotating the radiator will be more severe. Leaks can appear between the rad and the valve, or between the valve and the pipework, although the former is much more likely.

Christian.