Grundfos RCP-96 Recirculation Pump for Tankless Water Heaters Logo
Posted on Oct 30, 2009
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I have a Grund fos circulating pump on my water heater and no instruction booklet. There are little blue teeth all around the timer. Should the time you want the pump to recirculate the hot water show the teeth pointing out or should they be pointing into the center. I would appreciate you help. Thank you

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Rod Davies

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  • Expert 150 Answers
  • Posted on Nov 01, 2009
Rod Davies
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Try putting a few teeth either in or out and turn the timer until the arrow points to that setting. You will then know which is which

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0helpful
1answer

Laing model 330 Pump not working-delay in hot water delivery.In the past,a vibration occurred when cold water running above the pump.Can this be repaired.Power operating to pump. Thanks, mel ross

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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0helpful
1answer

Pump not working-delay in hot water delivery.In the past,a vibration occurred when cold water running above the pump.Can this be repaired.Power operating to pump. Thanks, mel ross

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.
0helpful
1answer

Recirculation pump goes on even when not timed by timer i.e, it's one during times not set by the timer. My thermostat on my hot water heater is set to "warm" not "hot". So the pump...

Open following link for Re-circulation information and resources:
http://waterheatertimer.org/Water-heater-recirculation-system.html

On a new Autocirc, you can choose between 'Timed' operation or 'Thermostatic' operation using the slide switch located below timer dial.
For Thermostat operation, slide switch to ON.
For Timed operation slide switch to Timer.

This solution assumes system is functional, and the check valve and internal wiring are working. Autocirc is a quality product.

Add a comment with outcome so others with same problem will benefit.

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For a price, expert works with you while you work on autocirc or any do-it-yourself project.
Fixya is always less expensive than a service call.
1helpful
1answer

I have a Lang Autocirc with timer for 11 years. The past few months water not getting hot I timed how long hot water takes in faucet before \unit by 6' and faucet just after unit and times the same over 2...

Autocirc can be uninstalled and the pipe cleaned out with CLR (calcium lime and rust), otherwise there are no repair parts.
Once the motor begins to slow, it overheats and burns out.
11 years is a good run, so you must have good water or are careful about your water softener.

http://waterheatertimer.org/Water-heater-recirculation-system.html
Using the timer and running Autocirc 1 hour a day costs between $11 and $17 per year to operate.
2 hours a day is $22-34 per year.
This includes pump operation and additional time that water heater operates.

Add a comment for more free help.
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For a price, expert speaks with you over phone while you work on circulation system or any do-it-yourself project.
Fixya is always less expensive than a service call.
0helpful
1answer

Grundfos recirculating system. Never has produced semi instant hot water at sink it is installed on. Could the original comfort valve be defective

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

The circulation system should draw hot water directly from the water heater as shown on illustrations on link above.

The Grundfos pump works on a thermostat, and some work on a timer.
Can you hear the pump working?
There should be a humming sound.
Check the timer -or- thermostat setting.

It is possible the lines are clogged with sediment if you have hard water.

If I was going to fix the problem:
1) check thermostat or timer
2) listen for pump sound
3) check electricity going to unit
4) take apart the pipes and inspect for clogging
If there is a clog, I would flush the line or soak the part in CLR (calcium lime rust remover)

The circulation pumps are sealed and there is no way to take apart the motor, timer, or thermostat for repairs.

add a comment if you need more assistance.
0helpful
1answer

Pump runs 5 minutes and stops

Move the slide switch to ON.
Open following link for recirculation system resources.
http://waterheatertimer.org/Water-heater-recirculation-system.html

The recirculation can work on either the timer or the thermostat using slide switch located next to the timer dial.
First of all, look to see if dial is rotating as time passes.
Next look at position of slide switch. If switch is moved to 'timer,' then the timer controls the on-off function for pump.
Move the pins located on timer dial to control on-off times.
If the switch is moved to ON, then the thermostat controls the pump, and turns on until temperature in pipe reaches 94 or 100 degrees F approximately. I forget exact cutoff temp.

Upvote the help.
And take advantage of fixya expert assistance live.
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0helpful
2answers

Which circulating pumps works on tankless water heaters

Laing UCT-909-TANKLESS UltraCirc Tankless Water Recirculating Pump

This is designed to maintain the proper flow to fire the heater. Please be sure the pressure in the house is at least 5 psi over the minimum required for your unit.
0helpful
1answer

Gron d fos pump hot to touch.no hot water in

Your circ pump is burnt out which is causing your hot water to not flow adequately to your fixtures.
0helpful
2answers

Need to wire a zone control for a closed system with a circulator

thats because the rinnai does not have a set up for a circulating pump it would make the unit run all the time,, they are not designed to work that way,, you will have to just wait for the hot water to get to the faucet just like before,,don't let any one tell you there is a way once the water flows it turn on the tankless so it would never shut off, you could get on that goes on a timer on say the farthest fauset away from the unit and set the timer to come on like 2 min before you are ready to use the water in that bathroom in the morning or at night other then that there is nothing else you can do
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