I have a Thornycoft 245 with a Bowman heat exchanger. The fresh water filling cap has a 2 inch copper overflow pipe which just vents into the bilge. When I do the weekly check on the coolant level I have no real idea if I'm loosing coolant and I'd want to know that ASAP! All I do is just top up but i dont know whether all i'm doing is overfilling each time, clearly on such a big unit there will be a largish amount of expansion. So I thought I'd add a simple expansion tank to the overflow pipe, is there any reason not to do this? Would it add pressure to the system? Does the expansion tank have to be above, level or below the heat exchanger?
Thanks for your advice.