Making the best with less than perfect

PaulVW

We will be replacing a boiler with 2 high efficiency boilers because of how the mechanical room is piped, we can't change the 9 zone pumps to pump away from the expansion tank. The pumps will be on the return to a 3" hydrolic separator. Normally I connect the expansion tank on or near the hydro-separator. I'm wondering if in this case it would be preferable to install it on the boiler side of the hydro-separator? All the pumps are fairly low head and the zone pipes are good sized so I don't anticipate any problems with cavitation or air removal as the existing system worked reasonably well for many years. Would like some ideas to make the best of a less than perfect situation.

Paul Pollets

How is it that the zone pumps or piping can't be changed or modified? Why install new boilers without upgrading any near-boiler piping that would decrease performance?

Steve Minnich

I agree with Paul. The near boiler piping is every bit as important, if not more, as the boiler itself.

SWEI

Starting with the near-kilowatt load of all those circulators...

hot_rod

What about changing the pumps to zone valves and then use an ECM system circ?

It is not recommended pumping into the return on a sep or primary secondary piping.

With multiple boilers and large piping, if the system requires a base mounted expansion tank, of example, you can connect the tank like this.