Be a massive job, but have you thought of lagging those couple of miles of PMR piping?
I use Keith Appleton's method....be warned it gives your fingers RSI after awhile!
I could, but I like the brass. I could’ve saved about $750 dollars U.S., by using copper pipework like Keith Appleton, but I elected for
Brass pipes. PMR charged an arm and a leg for the pieces especially speciality pieces, and it adds up FAST!