Indirect circulator bad?

[pete c]

I have a vaughn indirect water heater and an armstrong astro 50 circulator pump.

Last week I was in the basement diagnosing a bad air vent. Anyway, after reinstalling the vent and purging everything, I shut the boiler feed off....and forgot to turn it back on.

A few days later my wife says "what's that noise coming from the basement. I went down and saw that the circulator was making a racket. I then noticed the boiler feed shut off.

Whoops.

Turned it back on, purged the system and crossed my fingers, hoping I didn't ruin the circulator by running it dry. All seemed well, other than the circulator now being a little louder.

A few days later....no hot water. Went down, looked it over. Unscrewed the cap out of the end of the circulator motor and it was spinning and water leaked out. Not sure if this is normal or a sign of a bad seal. I took the pump off, dangled it in a bucket of water and turned it on. Good strong flow. So, I put it back together, purged it all again and the water heater came back. Hot water for a few days. Now we are back to square one. The pump is spinning, but, awfully quiet and no apparent flow.

One thing that seems odd is when I shut off the boiler return and open the valve just upstream from this faucet, the circulator seems to slow down as if all of a sudden, it has something to pump. But after awhile it speeds up again. Is it possible that there is a seal leak that is causing the circulator pump to draw air causing it to lose it's prime? I can't hear it. I held a just put out match under it and watched the smoke looking for a sign of airflow, but there is none.

I fear I may have to spring for a new pump. Is this model armstrong pump rebuildable? It is the astro 50.

Thanks

Pete

[pete c]

I dug a little deeper into the pump and believe I have found the problem.

I removed the winding, then grabbed hold of the metal housing inside of it, expecting I could unscrew it.

It didn't unscrew, but, did fall off in my hand. And on the end was a plastic impeller hanging off it crooked. It seems the impeller pulled loose from the knurled shaft it spins on.

I just mixed up some 5 minute epoxy. I coated the inside of the impeller with it and stuck it back on the shaft. Gonna let it sit awhile. Infact, I think I'll just let it cure over night, then fire it up in the morning. Hopefully all will be well then.

[pete c]

Well, the epoxied impeller is working like a charm. The pump is nice and quiet, all the hot water i can use. Is this likely to hold up indefinitely or at least until i get stupid and let the pump run dry again? I hope it will, but am not sure if the hot boiler water will cause the epoxy to break down over time.

[Redwood]

Let it roll and see what happens...

You may want to locate the replacement parts as insurance. If you have a replacement on hand it will never break...