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- 28 Jan 2017
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Ever since my CH system was installed over a decade ago the pump has seemingly pulled air back in through the vent pipe once the water got hot, if set anything higher than the lowest speed. I have had a plumber out once to revise the pipework (pump repositioned vertically rather than horizontal) but this didn't solve the issue. The layout looks okay (see photo below - cold feed on the far right, expansion on the far left and the vent pipe definitely extends more than 450mm above the F&E tank in the loft), but I have always wondered about the bores. I'm sure I've seen examples where the feed is 22mm and the vent 15mm, and this makes sense. However, both are 22mm in my setup - does this really matter?