Unless you've got a nearly-mains-pressure pump, you still have a problem once you open the tap, as the moment you do, the pressure in the supply pipe drops. When this happens your combi 4043 will still have to hold back (mains pressure (minus) pump pressure).
as previous posted Who or what the f*** did that drawing?
we install both thermal stores and unvented cylinders for solar preheat systems vented will not work (correct me if you know a way it does)
cold main supplys cylinder
cylinder heats from boiler/ solar via coil/s
hot water leaves cylinder
pipe stat or cylinder stat to switch on temperature
hot water pipe divides
pipe 1 ........................pipe 2
zone valve..................zone valve
direct pipe...................indirect pipe via combi
single check valve........single check valve
supply to taps
the valves change when temp drops/rises at determined temp around 50 degrees is where we set them
have not experienced the pressure problem described earlier as 1 valve is always open
use the valve that fails open on pipe 1
It's not going live. It was just me speculating on how something might work. You guys say it won't work and you say why. That's the sort of feedback I wanted. Thanks. I live and learn and shall not speculate anymore as throwing a few ideas around seems not be the thing to do.