Hot water circulating system mystery


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Old 07-25-16, 01:24 PM
T
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Hot water circulating system mystery

My home was built with two 50-gal water heaters plumbed in series, with a circulating system using a Grundfos 59896115 pump. The water heater with the fresh water feed (and expansion tank) sprung a leak. I had it replaced with a new water heater but now the circulating system isn't working.
The pump runs but no instant hot water inside the house.
I isolated and removed the pump. The impeller spins and i got water flow when I opened the gate valve on the return line.
It's a mystery.
Anybody have any ideas?

Thanks.
 
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Old 07-25-16, 03:59 PM
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We would need a few pictures of your setup there to comment. http://www.doityourself.com/forum/el...-pictures.html
 
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Old 07-25-16, 05:22 PM
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Re: Pix

Thanks Pete. Will have them up tomorrow.

Tom
 
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Old 07-26-16, 12:00 PM
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Pix of this project

Name:  Both Tanks.jpg
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Size:  29.5 KBName:  New tank and circ pump.jpg
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This is what the set-up looks like. Fresh water feeds the new tank which feeds the second tank.

The recirc return feeds back into the new tank.

The Grundfos pump works but no water circulates through the system.

If I turn the system on, the Grundfos pump gets too hot to touch in about 10-minutes.

I'm baffled...

Tom
 
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Old 07-26-16, 12:40 PM
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Are both valves open before and after the pump? Gate valves often break and when they do its usually in the closed position... Do any of the handles just keep turning and turning?

It appears you have a return on the hot water line from say a master bath?

There should be a check valve somewhere also.. If these stick open then cold water feeds back through the recirc line and youll have no instant HW... Ifact you may have minimal HW everywhere...
 
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Old 07-26-16, 01:23 PM
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Update

Name:  Check Valve.jpg
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Size:  40.3 KBName:  Check Valve-2.jpg
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New discovery! The check-valve in attached to the water heater. And, the water flows from the bottom of the tank up through the Grundfos into the house. I thought the water returned through the Grundfos into the bottom of the tank.

Either that or, the check valve is installed upside down...

As you can see, the Grundfos got so hot it melted the insulation to the pipes.

Is this any help?
 
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Old 07-26-16, 01:38 PM
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Update Part Deux

I confirmed the flow arrow on the pump; the check valve is upside down.

Problem solved.

Thank you for your help. Without it I wouldn't have discovered the problem and the logical solution.

Best to you,

Tom
 

Last edited by TCaruthers; 07-26-16 at 01:39 PM. Reason: spelling
  #8  
Old 07-26-16, 02:36 PM
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Wow!!! It was that easy???? LOL...

Yes the pump flow is toward the heater.

Hmmm... who installed check valve upside down?


Im glad that may be your issue and post back your final results please... It will help others immensely im sure...
 
 

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