BigWallop wrote:

So, in summary, although I disagree with the suggestions you've made on the type
and construction materials of the pump required in the situation that the OP
(Harry) has

I think you've misunderstood the reasoning. In a CH system, the only
reason the iron/steel components (pump, rads, boiler water jacket etc.)
last more than a few months is that it's a closed system.

You start off with a set amount of water. In the first few weeks, all of
the oxygen in this water gets reacted out. The water by then has zero
dissolved oxygen, and is limited in the amount of corrosion it can cause.

But if you had a constant supply of fresh water the corrosion would
carry on at the same rate. Within a few months there weill be very
little iron left.


--
Grunff