steam system circulators

Kevin Huther

we just had a cast iron circulator installed on our new burnham steam boiler system, which has a 45 gallon superstor hot H2O tank, and is power vented out the side of the house. my question is will the cast iron circulator corrode within 12 months because the steam PH levels will eat away at it or is it fine as is? is a smarter option a bronze circulator which will not corrode and will last forever no matter the amount of steam in the circulator or high PH levels? thanks.

Brad White

Bronze is better

Not just the pH issues but the amount of O2 present in the water plus any CO2 dissolving and forming carbonic acids. Basically, a steam system is an open system. The intermittent operation gives time between cycles for stuff to collect. For this reason, I do not like water-lubricated circulators in that application. Coupled circulators would be my choice although many use water-lubricated circulators without problems for years. Many variables, particulates or lack of them being one.

I would definitely install a fine-mesh strainer and blow-down valve upstream of my circulator to catch loose material and mud that may be drawn in. Raise the circulator so that it is not at the very low point can help.

An iron circulator? I would give it a year or less as you suggest. If you are not willing to change it out, at least buy the bronze circulator and if you do not have one yet, a bronze strainer, ready to go in. Prepare for a shut-down in either case, of your DHW.