Dan. The system is being "filled" with fresh water, despite the filling loop being disconnected. This cannot possibly happen in the primary heat exchanger. It can happen in a leaking secondary heat exchanger, or in a leaking diverter valve. Any view on the "return group"?
A customer's system pressure continually rises. I have disconnected the filling loop to rule out a leaking fill valve. I suspect the diverter or, unlikely, the secondary heat exchanger. My question is, is there any route that water could leak from the mains into the heating system in the "return...