Cast Iron or Bronze Circulation Pump?

[type@uwm.edu]

Hi--
I'm advising my plumber re pump model choice for water circulation in a closed-loop system for radiant floor heating using a masonry heater. We're looking at the Taco 007 series. One pump will used for the storage tank- heater loop (copper pipe, ~7gpm) and two pumps will be used for the upper and lower floor radiant heating loops. All are closed systems. My water has some iron content. The efficiency of the two pumps looks very similar. Is there an advantage with using a bronze or cast iron pump like longevity or ease of repair? Thanks for your suggestions! Rob

[hj]

Normally there is no reason to use a bronze pump in a closed heating system because a cast iron one is not subject to corrosion.

[type@uwm.edu]

Thanks for your expertise! Rob D.

[jadnashua]

A bronze pump would be required where potable water was involved. In a properly maintained closed heating system, fairly quickly all of the free oxygen is purged from the system so the cast iron pump is fine - no oxygen, no rust. If you have leaks and are constantly adding water, it can be a problem.

[Bill Arden]

floor radiant heating loops.

If you used non-barrier PEX then you would need the bronze pump.