Hello, I am fairly convinced I have a manifold flow direction issue. I thank JohnMo and ProDave for there contributions in my introduce yourself post.   I have a fifteen year old ashp-UFH, manifold system that I can not believe has been plumbed in REVERSE and thus has been costing my old parents a fortune all this time. Also confused how a Mitsubishi accredited engineer could comission it as fit, but that is not the issue.   I know a manifold can be plumbed into the left side