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I Married Up
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I'm not a fan.

I've replaced/removed several that were not very old. The pumps do not hold up well and start making crazy noises when they kick on.

In addition to that, they are stupidly inefficient as a retrofit option. Converting uninsulated pipe into a circ system is just a needless waste of energy. Even though running water until it gets hot is a waste also, it pales in comparison to an uninsulated heating loop that has to maintain its temperature level 24/7/365.
 

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I actually like those. I install them to be used at certain times(6am-8am, 6pm-10pm etc) and not to run 24/7. Or I'll install them on a switch that can be flipped on when the home owner wants hot water.
 

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Ridgid tool user
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Discussion Starter · #11 ·
I actually like those. I install them to be used at certain times(6am-8am, 6pm-10pm etc) and not to run 24/7. Or I'll install them on a switch that can be flipped on when the home owner wants hot water.
where do you put the switch? Any difference between the grundfos or the watts? They look the exact same to me, just a big difference in price
 

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The Old (antique) Master
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TX Plumber
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That's good to know, Bill. I, too like and have installed, without a problem, the Grundfos Comfort pump w/ timer and it works well.

The only issue I had once was with the check valve in the bypass valve. It would hammer back and forth when the lav faucet was shut off. This occurred when the pump was off. I called Grundfos and they sent me a newer and a little stronger check valve and problem was solved.

I try to avoid putting them on galv systems due to it speeding up the corrosion. I always recommend against running them 24/7. On Pex or CPVC systems it can run 24/7 but I agree with Biz that its a waste of energy. The timer or switch is best IMO. You're not wasting water either way.

The main issue I have with 24/7 circulation is pin hole leaks in copper. So little new construction done with copper pipes in Houston from 80 to the 2000s in residential was reamed at the cuts. Clearly I am going to see mostly improperly done copper being I do service, but this fact along with bad water and the extensive use of cheap type M copper is why 24/7 hot water circ pumps cause pin hole leaks so rapidly.

I have seen at a one year old hotel in between floors a 2" copper pipe that had a pin hole 3" away from a 2" X 3/4" copper tee. I went to shut the boilers down and found a 3/4" 90° in the boiler room that was on a hot water return also leaking but it was leaking on the fitting itself. When I cut out the fittings I could see that the pipe had not been reamed and was cut sloppy and fast.

On the tee they had shoved the 3/4" pipe way past the hub to the point of half way into the 2" part of the tee.

The 3/4" 90° on the return for the circ pump had a pin hole in the center of the top or outer edge. Both original pipe cuts on the 90° were also not reamed.

All the pipe was on the hot side and type M. It was in an incorporated city and was inspected. I went back with all pro press fittings and I did ream all my cuts.
 

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