4th rusted circulator

tpowls84

Need advice an a hot water system. I have a cast iron boiler with 3 hot water zones and 2 radiant zones. All heating loops and one radiant zone is piped with Wirbo Hepex and other radiant zone is piped with Onix by watts radiant. All zones are controlled by cast iron taco circulators. System is about 9 years old and have had to replaced 4 circulators within the last 3 years. Circulators are clogged with rust build up. Once replaced and system purged I noticed water to be extremely rusty. I know fresh water and oxygen will cause this problem. Where can oxygen be introduced into this system if all piping has oxygen barrier? No radiant is under a slab where there could be a possible leak. Would water treatment solve this problem?

SWEI

Is there an automatic water feeder on the system? Has the expansion tank been tested?

The Onix could be either a cause or a victim depending.

kcopp

From My experience its the Watts EPDM rubber tubing that is less than great. It says barrier tubing but its not or its very poor.
Drain the system. Then flush it out w/ straight water. Pump in a good cleaner. Either Fernox, Sentinel or Rhomar. Then drain flush and clean out all the crap in the lines. When you have it all out then add in a good inhibitor.
I have done it a number of times.

http://www.fernox.us/products/water+treatment+chemicals/cleaners/cleaner+f5+express

4Johnpipe

Not sure if it has been determined if it is the Onix tubing or the connections. I have seen situations where it was used for baseboard with 180 degree water running through it and it was deteriorating from the inside out. Clumps of rubber found in the rusted circs...If it is accessible my recommendation would be to replace it with the Upnor HePex.

Alan (California Radiant) Forbes

Next time your pump goes bad, install one that's non-ferrous.

Robert O'Connor_12

4 circulators in 3 years is excessive. Hopefully if you have a low water cut off, and it works. Try turning off the water feeding the boiler and see if the pressure drops. If it does, you have a leak. My suspicion tells me it could be the hose. All good answers above.