The overflow was fitted with a herbie style drain to keep the noise down.
The OM4 connected to a dart was installed beneath the tank, first major mistake! Having drawn out the plan on the floor in the early stages a 24" wide wall looked way too thick so it was decided to go down to an 18" wall. Problem turned out that it was extremely difficult to fit the OM4 and the plumbing in with such a narrow wall. With much scheming and far too many 90 degree bends I finally got it all in.....
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