My first of this pump (103260LF) lasted 10 years recirculating hot water in my residence before it started making lots of noise. I replaced it with an identical model, which lasted 3 years and now is making noise. Both were on a thermostat so didn't run continuously. Are these repairable? Is there a decent flanged replacement which may last longer?

Hi Bruce
No its not normal it shud b isolated by lagging the noise travels through the timber lagging between pipes will help also how old is the pump shud only b a hum if pump ok any more and u need to replace , also u mite like to check speed of pump mite b on max turn down so long ur flow is ok or ur system mite get to hot

Unplug and replace.
Pumps get old and slow, and when they slow up they get hot, which damages pump more, so they get hotter until they stop working.
Copy following link for tips to make next pump last longer such as air valve, periodic cleaning with white vinegar.
http://waterheatertimer.org/Water-heater-recirculation-system.html
Gene
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10-30-12
Cost calculations for recirculation system vary widely.
These systems cost more, and they cause higher operation cost of water heater.

1) When pump is OFF, then hot water is no longer leaving the tank.
Most recirculation systems have choice of timer for setting specific times of operation, or thermostatic operation that activates pump when sensor detects temperature less than 90 degrees
BUT...

2) Condition of plumbing is suspect here because you are not receiving fully 90 degree hot water from the recirculation system.?.

Bad single-handle faucet cartridge, or bad recirculation check valve, are causes of crossover. Clean recirculation check valve with white vinegar. Replace worn faucet cartridge.
Test for crossover.
http://waterheatertimer.org/Crossover.html

3) There are other suspects, such as water leak.
Drips, broken pipe, bad TP valve.
Turn off all taps and put ear against pipe to listen for running water.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#listen

4) High costs: Lifting single-handle faucet in middle will immediately cause cold water to enter tank. Even if no hot arrives at tap, because the cartridge is drawing both hot and cold in equal amounts when handle is lifted in middle.
Today it is more efficient to install dual-handle faucets so tank is not receiving constant dose of cold water when single-handle faucet is not used correctly or tediously.
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Pump can be bad or clogged with debris loosened when pipes were moved.
Check installation, and check if crossover valve is installed correctly
Check if single-handled faucets are good
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/Crossover.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Question not 100% clear.

1) The pump is not working? Does the pump make a noise? if pump is not working full-time, it can cause delay in arrival.
If pump motor is suspect, and outlet has power, then check override switch located on timer. Set override to Timer, move some of the trippers outward, then manually rotate timer dial until pump turns ON.
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg
If no noise is detected, or noise stops and starts, or seems strained, or if pump is hot, then pump motor may have burned out.

2) If pump is working, and makes noise like a humming sound, and pump motor is not hot, but hot water is not circulating, then unplug pump so it will not overheat and burn up.
Disassemble the pump and cross-over piece. Clean piping with white vinegar or CLR. Do not soak in CLR or it will damage seals. Rinse parts thoroughly. Reassemble and see if problem is resolved.
If pump is vibrating, then suspects include sediment and/or air inside line, and this can be resolved by cleaning as described. Also install air vent to increase life of pump.

3) Other causes for hot water delay at faucet are crossover.
Crossover can be caused by bad single-handled faucet cartridge, and/or by clogged-or-failed check valve on cross-over piece on grundfos.
This type of problem lets cold water enter hot line, and causes delay in arrival of hot water. Clean-or-replace the grundfos cross-over piece, and replace bad faucet cartridge.
Open following link for testing instructions:
http://waterheatertimer.org/Crossover.html

Resources:
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/pdf/Troubleshoot-recirculation.pdf

Add a comment for more help.

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Question not 100% clear.

1) The pump is not working? Does the pump make a noise? if pump is not working full-time, it can cause delay in arrival.
If pump motor is suspect, and outlet has power, then check override switch located on timer. Set override to Timer, move some of the trippers outward, then manually rotate timer dial until pump turns ON.
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg
If no noise is detected, or noise stops and starts, or seems strained, or if pump is hot, then pump motor may have burned out.

2) If pump is working, and makes noise like a humming sound, and pump motor is not hot, but hot water is not circulating, then unplug pump so it will not overheat and burn up.
Disassemble the pump and cross-over piece. Clean piping with white vinegar or CLR. Do not soak in CLR or it will damage seals. Rinse parts thoroughly. Reassemble and see if problem is resolved.
If pump is vibrating, then suspects include sediment and/or air inside line, and this can be resolved by cleaning as described. Also install air vent to increase life of pump.

3) Other causes for hot water delay at faucet are crossover.
Crossover can be caused by bad single-handled faucet cartridge, and/or by clogged-or-failed check valve on cross-over piece on grundfos.
This type of problem lets cold water enter hot line, and causes delay in arrival of hot water. Clean-or-replace the grundfos cross-over piece, and replace bad faucet cartridge.
Open following link for testing instructions:
http://waterheatertimer.org/Crossover.html

Resources:
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/pdf/Troubleshoot-recirculation.pdf

Add a comment for more help.

Take a moment and rate answer for accuracy:
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Question posted under Grundfos recirculation system.
If pump is making noise, then air or sediment is probably trapped at the impeller.
Remove pump, and connection between hot-and-cold pipes and clean with white vinegar.
Or use CLR but do not soak parts in CLR or it can cause damage.
Additional Resources:
http://waterheatertimer.org/Water-heater-recirculation-system.html

Take a moment and rate answer:
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Do you have the auto-circ recirculation pump with timer?
If so, here is manual for that specific product:
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http://waterheatertimer.org/Auto-circ-manual.pdf
Manual gives instructions for a different timer dial than timer than shows on unit, so they must come with different dials.

Instructions say pegs pulled out = timer on
Conversely, pegs pushed in = timer off
You might be able to hear the pump operating to see if these instructions are correct for your recirculation timer. The kids would love a listening assignment under the sink.

To see images showing how recirculation system operates:
http://waterheatertimer.org/Water-heater-recirculation-system.html

Setting times:
Try 1/2 hour ON in morning and 1/2 hour ON in evening. Warm water will stay in pipe for a while.

Recirculation system with timer costs $10-17 per year to operate, assuming timer runs 1 hour per day with electric prices at 10 cents per kilowatt hour. Operation cost is straight line ... so if timer runs 2 hours per day, cost is $20-34 per year at 10 cents per Kwh.

Water saved might equal 5 gallons per day, or 1825 gallons per year depending on usage. Average water wasted waiting for hot water is 1/2- 2/3 gallon depending on length of pipe. Set a bucket under spigot to test your home when circulation system is not ON.

Cost of water depends on local billing rate. The municipality saves purifying water, pumping water to your home, and finally pumping and processing sewage drainwater.

If you are on a water well, the pump electricity from saving 2000 gallons a year is a dollar or two per year since water well generally consumes less than 1Kwh per day for ordinary house.

Check your particles with a magnet. If they stick your tank is rusting out and it may still have some warranty left, 5 -to 10 years is about right for a warranty issue. Any why check the particles with a magnet. Any way it is time to replace the heater. Sorry.

that's a faucet problem, nothing to do with the tank
either replace the faucet washer (The one that's noisy)
or get a diffeent style faucet