Sorry to complicate things but....

If a combi is used with a vented cylinder, then 2 zone valves are required, one for the heating and one for the hot water, BUT what if I want to split the downstairs heating from the upstairs heating....

Can this be done, the only problem is the heating in the house is existing on a semi gravity system.

Is it best to use the honeywell cm67 wireless package!!!!!!

cheers guys