Pipes higher than feeder tank

Horlock

OK so here's my silly question for today:

Obviously, you can't run a hot water pipe to a tap which runs higher than the cold water tank. Since the water wont flow up hill.

But the question is can you run a central heating pipe to a radiator higher than the central heating over flow tank? I think the answer is no. I think it is no because the pressurised water would prefer to overfill the overflow tank than work its way around the system. But I could be wrong. I'm not really sure of the mechanics of how a central heating overflow tank works - ie why when you pump water around in the system it doesn't want to go up to the tank - unless my guess above is totally correct - in which case it might just about make sense.

rich13348

If you have a pressurised system it doesn't have an overflow tank as that would be an open system so no pressure can build uup. So you must have an open system with a header tank that fills the boiler.
Either way I don't think it will be an issue the "overflow tank" or header tank fills the boiler then the pump pumps it around the radiators as that radiator would be furthest from the boiler you would just open its locksheild valve the most so it gets the most flow.

anotherbaldrick

Horlock wrote: »

OK so here's my silly question for today:

Obviously, you can't run a hot water pipe to a tap which runs higher than the cold water tank. Since the water wont flow up hill.

But the question is can you run a central heating pipe to a radiator higher than the central heating over flow tank? I think the answer is no. I think it is no because the pressurised water would prefer to overfill the overflow tank than work its way around the system. But I could be wrong. I'm not really sure of the mechanics of how a central heating overflow tank works - ie why when you pump water around in the system it doesn't want to go up to the tank - unless my guess above is totally correct - in which case it might just about make sense.

The reason is that a pump has a positive pressure zone at it's outlet and a negative pressure zone at the inlet or suction side. A knowledgable installer will therefore always connect the cold feed to the system close to the pump inlet negative pressure side. As reason would suggest there will exist a zero pressure zone halfway round the system

southcoastrgi

no you can't is the simple answer, the rads are filled by gravity from the header tank so if you put a rad higher than the tank you will never get any water in it