Pumps in series (simplest pressurized layout)

[MrEd]

I am using a modified version of the "simplest pressurized system" that nofossil prepared.

One trait of this system is having two circs running in series.

Whenever my tarm is running, and a zone is calling for heat, both the tarm circ and the load circ will be running. As soon as the zones are no longer calling for heat, the load circ will shut-off and the single tarm circ will continue to run and heat up storage.

My question is, when two pumps are running in series, what is the equivalent single circ size that I would need to replace the two smaller ones? I am thinking for example of using two grundfos 15-58 3 speed pumps for this purpose. When they are both running (and lets assume they are both on the high setting), what is the equivalent size pump that I would need to match that? What does the pump curve look like when you use two?

I like the idea of using the 2 smaller, cheaper pumps to replace a single larger one...but is there any downside to this approach?

 

[Nofossil]

I am using a modified version of the "simplest pressurized system" that nofossil prepared.

One trait of this system is having two circs running in series.

Whenever my tarm is running, and a zone is calling for heat, both the tarm circ and the load circ will be running. As soon as the zones are no longer calling for heat, the load circ will shut-off and the single tarm circ will continue to run and heat up storage.

My question is, when two pumps are running in series, what is the equivalent single circ size that I would need to replace the two smaller ones? I am thinking for example of using two grundfos 15-58 3 speed pumps for this purpose. When they are both running (and lets assume they are both on the high setting), what is the equivalent size pump that I would need to match that? What does the pump curve look like when you use two?

I like the idea of using the 2 smaller, cheaper pumps to replace a single larger one...but is there any downside to this approach?

In the sticky design, the wood and load circs both run together. The load circ should be matched to the loads, presumably the same size as the wood circ or slightly smaller.