Noisy Grundfos Recirculating Hot Water Pump

Hello,
I went on vacation and turned off the water supply to the house. I forgot to turn off the recirculating pump.

When I came back 7 days later, my Grundfos pump was extremely seriously hot, and seemed to be frozen.

I let it cool down, then it was has hard to start. After a few tries, it reluctantly started, but it now makes a pretty loud noise.

Attached is a link where you can hear the noise (the pump does have a cover -- I removed it to give the capacitor a bang). It is a mechanical, rattling, pulsating noise. It also sounds like it is getting ready to freeze at any moment.

Prior to this, it just gave off a slight hum/whirring sound.

Pump is a UP 15-18 SU. It has union fittings. I read that this pump is the same as the UP 15-29 SU.

Is it shot? Is there any reason not to buy a new one? Did I damage it when I turned off the house water and left it running? I can't see how this would hurt anything, but what do I know?

I am a good do-it-your-selfer, and I would like to replace it myself, but this is new territory.

Thank You!

VIDEO OF NOISY PUMP:
https://youtu.be/fo9SzWi26y8

Replace pump it is burnt up

The pump is water lubricated. Sorry to say it will need to be replaced.

trashed,,,,,,,,,

Lesson learned for next time, I hope!

Thanks for the quick answers. Can someone help me understand how this happened?

I shut off the water right at the entrance to the house. I didn't throw any other valves, and I can't see how shutting off the main water valve would disrupt the flow to the pump.

I understand that the pump is cooled by circulating water. However, I did not break that flow. I didn't let any water out of the system. As far as I could tell, that loop was still able to circulate water. When I got back home, there was no air in the lines.

So, did I do it, or was it just bad timing? Inquiring mind needs to know.

Thanks

When you turn off the water a simple leaking toilet can cause a pressure drop and the pump will start to cavitate. That is enough to burn a pump the pumps can not move air

Thanks once again to all. I guess I will start shopping for a pump.

look on the old pump for a model number, get the same thing

http://www.supplyhouse.com/Pumps-Flanges-288000 good prices

Frodo, I don't believe they make the pump model I have any more. I have a UP 15-18 SU. However, I did find a cartridge kit for it.

However, it might be better to replace the whole thing, since it got awfully hot.

Thanks for all the help. I received my new pump (from Supply House) on Friday. I am waiting until Monday to start the replacement, since I think it's a bad idea for me to do "plumbing" jobs on the weekend.

There is a check valve (with a bleed screw) on the water heater side of the line (see pic). There is a ball valve on the house side of the line, which of course I will shut off.

1) Will the presence of the check valve mean that I will not have to drain the tank (because the valve will prevent water flowing from the heater back toward the pump)?

2) I am assuming the bleed screw on the check valve is to help bleed any excess air out of the pump after the water is re-supplied to the pump. Would this be correct?

Thanks!

Check valve may hold but would not count on it. small nut on side of check valve it not a bleed port. it is holding the hinge pin for the swing gate in the valve.

make sure you orientate the motor as per instruction when you replace it

If you install pump wrong it will burn up also I would replace check valve faulty valve will give you cold water back feeding into circle line

Mr_David said:

Check valve may hold but would not count on it. small nut on side of check valve it not a bleed port. it is holding the hinge pin for the swing gate in the valve.

Click to expand...

I very much appreciated this tidbit about the "bleed screw."

Got up at the crack of dawn to replace the pump. I was psyched up for a nightmare, but it actually took only about 20 minutes! The check valve DID hold, so it was not necessary to drain the tank.

The new Grundfos pump is virtually silent compared to the old one (at least before I burned it up.)

Attached is pic of new pump, I have not yet removed the temporary handle I made so I wouldn't drop it while messing with it. Also, the sign I made to help keep this from happening again...

Thanks to all for the help.
David

You will have issues with the galvanized tee at heater

journeyman said:

You will have issues with the galvanized tee at heater

Click to expand...

I saw that as well but decided to leave it be. I've seen old homes with galvanized pipe systems still working. Some parts replaced with copper.
That tee and nipple will probably out live the water heater.

I agree that it is better to have used brass nipples and tee and loose the dielectric union.
I like to install a brass nipple and a threaded ball valve there. Then the tee.
if the nipple gets choked off, then just jab a screw through the valve to un-choke it without having to drain the heater.

plumb_idiot said:

Thanks to all for the help.
David

Click to expand...

good job. I like the tag