Boiler Pipework Question

Installing a replacement boiler. I now have a wall mounted unit with flow and return pipes upwards from the top of the boiler.
The flow continues upwards from the boiler, but the return from the floor level must now go up vertical alongside the boiler and then an inverted U to the boiler return pipe.
I feel that I need a vent at the top of the U to release any trapped air, logically I cant see a problem - or is there?
TIA
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On Mon, 24 Nov 2003 13:08:27 +0000, robf wrote:

Once the bulk of the air is out the pump should move smaller bubbles around to they find a radiator.
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Ed Sirett - Property maintainer and registered gas fitter.
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This appears to be an odd arrangement to me. Normally, the flow and return pipes run together in parallel, rather like the live and neutral of an electrical circuit. Do you have an old single pipe radiator circuit? On the other hand, sometimes the flow goes off to the cupboard to get valved, whilst the returns all meet up somewhere else.
Christian.
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