thanks. I have both circulators on same return line. see pics 11,12 & 13 above or below. I would like to use the new ifc ones if possible. However, given their current configuration, I'm thinking water would need to able to move through them because they are hooked up in series? Or doesn't that matter? The water is what lubricates them. Maybe my system requires water to be able to pass through circulators given their current configuation. pexsupply says, that's why they sell both - some systems require water to be able to pass through the circulators even when they are off. they also recommend consulting with a licensed hvac technician who would be able to tell if i could use the new ifc ones or not. just want to make sure each zone will circulate heat. I don't want to burn up 2 new hundred dollar pumps. thanks.
Ayuh,... I see 2 pumps for 2 zones,...
Both pumps run independent of each other, they're
NOT in series...
Only the boiler water is common, 'tween the 2 zones...
If ya use the pumps, w/ check-valves, there won't be any ghost flows through the pump that's not callin' for heat...
In picture #11,...
If the pump furthest from the boiler is runnin',..
There'll be ghost flows through the pump closest the boiler, due to the siphon effect...
By usin' the check-valves, Only the zone callin' for heat(pump runnin') will see hot water...