ECM pump for near continuous running???
 

Would any of the hi efficiency ECM pumps used in hydronic heating system that cycle with controls be the same or different for using in near continuous running? Do they need to be built different to sustain near constant use. I want a pump that I can run near constantly to redistribute solar gain from my front portion of high mass hydronic floor(exposed to direct gain passive solar) to the rear(no solar exposure) when it is available as well as moving injected heated water into single zone loops when needed. Will near continuous use shorten a pumps life?

This question is very open ended, and brings up more questions about your particular rig to be answered properly. The main questions hover around the amount of heat you plan on moving versus the zones to be heated. The ideal pump will be sized so it can deliver a little bit more than average flow rate necessary. Sometimes it will lag in peak capacity, but that's ok. If longevity is your main concern, that may or may not be at odds with overall efficiency. Depends on your budget.

My main question is a pump for continuous running different than a pump that cycles on/off with demand. or will any ECM pump that does one be OK for the other? This is for in a simple single zone heating loop.

Pretty much all ECM pumps are designed to be variable speed.

All commercial grade pumps are rated for duty, power, rpm, load, and temperature range. Duty is the S rating. Check out this page:

https://www.engineeringtoolbox.com/a...les-d_739.html