I currently have a C plan installation. Zone valve is on the return from the cylinder, the pump is next to the boiler in the kitchen.
I want to upgrade to a fully pumped system, BUT lots of my pipework is under a newly fitted bathroom and kitchen. My initial plan was to go for a Y plan. I was going to fit a 3 port valve just after the pump down near the boiler, and then remove the original 2 port valve on the cylinder return. I figured that this would allow me to pump both circuits before they entered the valve and become sperated into HW and CH, adjusting wiring to suit.
However, I've since read that motorised valves cannot be installed BEFORE the cylinder vent - which my initial design would be. Where my cylinder feed Tees into the top of the cylinder, the pipe continues upwards to the loft to vent over the header tank.
So now I'm in a situation where I need to keep the original 2 port valve on the cylinder return becuase its after the vent, and I'm thinking of adding a second 2 port valve on the CH circuit after the pump, effectively making what I understand to be an S system.
The only problem I can see with this is that the water will always be pumped along the exising 28mm 'gravity' pipes, through the cylinder and stop at the 2 port valve even if the HW isn't called for, which means I'll always get hot water regardless..? Furthermore, if this is the case whats to stop the water being pumped out the vent pipe..!!? (should have also mentioned that I cant replace the existing 28mm gravity pipes for 22mm becuase they're under a newly fitted kitchen and bathroom - fitted just before we moved in).
Can someone offer any advice?
I want to upgrade to a fully pumped system, BUT lots of my pipework is under a newly fitted bathroom and kitchen. My initial plan was to go for a Y plan. I was going to fit a 3 port valve just after the pump down near the boiler, and then remove the original 2 port valve on the cylinder return. I figured that this would allow me to pump both circuits before they entered the valve and become sperated into HW and CH, adjusting wiring to suit.
However, I've since read that motorised valves cannot be installed BEFORE the cylinder vent - which my initial design would be. Where my cylinder feed Tees into the top of the cylinder, the pipe continues upwards to the loft to vent over the header tank.
So now I'm in a situation where I need to keep the original 2 port valve on the cylinder return becuase its after the vent, and I'm thinking of adding a second 2 port valve on the CH circuit after the pump, effectively making what I understand to be an S system.
The only problem I can see with this is that the water will always be pumped along the exising 28mm 'gravity' pipes, through the cylinder and stop at the 2 port valve even if the HW isn't called for, which means I'll always get hot water regardless..? Furthermore, if this is the case whats to stop the water being pumped out the vent pipe..!!? (should have also mentioned that I cant replace the existing 28mm gravity pipes for 22mm becuase they're under a newly fitted kitchen and bathroom - fitted just before we moved in).
Can someone offer any advice?
