Radiator flow return connections

30 Dec 2009
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United Kingdom
Currently re-plumbing house and wish to know if there is any preference for a fully pumped system to have flow entering at the bottom or top of a radiator with the return from the top or bottom respectively.

My preference was for flow at bottom with return at top through bi-directional thermostatic valve (connections to radiator are fixed at top of one end and bottom of other end).
Pipes are in but I am at the stage of making final connections and could swap flow/return quite easily if there was a good reason for doing so.

Can anyone offer their thoughts/opinions on this simple question or does it simply not matter?

Many thanks.
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Hi there,

On older gravity systems it was deemed better to have flow top return bottom..

More recently convention seems to be flow & return at bottom.

Some systems still have flow coming int at top with a trv fitted, just to make it easier for the elderly to control the temp.

Go with whichever you prefer as long as they are on opposite sides.

Hi Rico,
Thanks for fast response. The TRV is at the top and the tappings are top and bottom on opposite ends so I think I will continue with my original preference.
Had a feeling that it wasn't going to be overly important.
This whole project is an upgrade from the previous single pipe pumped system - the new system is dual zones, heat store, some underfloor heating and eventually a solar panel but with the old boiler. Just hope it works correctly.
Once again many thanks.

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