Failed recirculating pump question

I've got a Grundfos w/timer installed on my 75 gal. water heater. The pump is about six years old and the new heater was installed just a couple of months ago.

After having some additional outside plumbing work done one day last week , I discovered the pump had stopped functioning (same day) and, I suspect, burned up. I unplugged it immediately and one would have had 1st degree burns if the casing had been touched. I let it cool down for an hour+ and plugged it in and it rapidly heated, w/no pump movement, although the timer was functioning.

Can this failure be attributed to the plumber not deactivating the pump while the water was turned off during the time he was working outside? (about 3 1/2 hrs.) I'm not sure what the flow rate is on the pump but could this have caused the failure? I just cannot believe this is a coincidence.

Opinions appreciated...

Could very well be the case. The plumber should of shut that pump down to avod overheating from lack of continous flow. Follows the same logic of a submersible pump running without water; it eventually shortens the life of the pump. Some have built-in thermal switches but it's not worth the risk of expecting the pump to work consistently.

At six years though it might be worth taking that pump apart and see how much corrosion the internals have.

Your observation of "No pump movement" suggests that the pump may be jammed. That could occur if some junk was left in the line.

Overheating from no water flow could cause it to damage the impeller and jam so it would have "no pump movement".

Thanks, Rugged -- that's exactly what I was thinking. Although the pump is six years old, it really has only been operating about 3.5 - 4 years, since I spend about half of my life on the road and the pump is turned off when I'm away.

If he (plumber) still has the old pump I'll see about having a look at it. I'm awaiting a new one that he will be installing and I am going to (gently) bring up the subject of not de-powering the pump prior to shutting off the water.

Thank you!

Bob,

You and Rugged have confirmed my suspicions -- enough to approach the plumber when he arrives to install a new one. I didn't say anything to him at the time, but I think he should be absorbing the cost to replace it, particularly when he knew it was there.

Thank you.