Thank you so much for the very helpful replies.
As I stated, it was a hyperthetical question and have taken on board your replies.
And because of your replies I managed to find a direct replacement :^O - Drayton LP241 and will probably stick the Horstmann on the bay.
As for the zone valve...
Hi all
This is just a hyperthetical question at the moment...
My heating system at home consists of a standard boiler with cylinder and cylinder stat, pumped with one 2 port zone valve (think it's 2 port), no room stat, TRV's on all rads and a Danfoss Set3M programmer
I have been given a...