Pipe run from boiler to UFH manifold is specified by UFH folks as 28mm
so 28mm fittings on manifold, but current run is in 22mm.

Were I to bother to replace the 8' run in 28mm, would there be
significant benefit as I'd have to replace 3 nicely radiused bends (both
f+R) with 28mm 90 degrees.
i.e. would solder 90's on 28mm still make for significantly greater flow
than radi'd 22 mm (both F + R)

(The run essentially round 3 sides of base of old chimney stack in
airing cuppoard.)

Persdonally I'm thinking towards just 28mm from Manifold to existing 22mm.

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