feed and vent pipes

[mike]

Hi The system is fully pumped H/W & Heating.

I need to move the H/W tank and to alter the pipe runs, is it alright for the cold feed and vent pipes to be connected to the return pipe and not to the feed pipe as it is now.

thanks

Mike

[John Stumbles]

Possibly, unless the relative pressures in the system due to the pump may cause some parts of the system to be at negative pressure (wrt atmospheric) which is Not Good. I'd consider converting to a sealed system (see sealed system FAQ, google...)

[Christian McArdle]

The vent pipe should be on the boiler flow. Some boilers might not require this, but speak to their technical help line first. The boiler will almost certainly require an overheat shutdown (i.e. be suitable for sealed+pressurised operation), but this might not be enough.

Christian.