Navien boiler

[Plumber69]

What would happen if you never put a primary loop in. System has 2 zones each with a dedicated pump

 

[Fitter30]

Most of there models have a built in pump so you wouldn't want the two zone pumps with in series. Flows would be changing every time a zone pump would be running. On a ch model you can piped like page 25.
https://www.google.com/url?q=http:/...FjABegQIBBAB&usg=AOvVaw1gyH7qd9OFmKEY3yZcI43R

 

[Sponsor]

 

[automaton]

No hydraulic separation from the internal circulator, so possibly lots of stress on the internal pump and exchanger if the flows don't match (what your zones require and what the boiler can do). Additionally, the two zones may not get the same temperature water.

 

[Dana]

Low mass water tube boilers only have some much range between the minimum flow needed to avoid flash-boil and the maximum at which the flow will erode and wear the heat exchanger from the inside out. It may be possible to design the system and spec a pump that would meet both the radiation's flow requirements and the boilers under all operating conditions, but it might not be. A hacker design that pumps either too little or too much flow through the boiler would likely void the warranty.