Rattling noise at pump - Taco 007-F5 Outdoor Wood Furnace Circulator Pump

Sound like "air" is in the system. That will be your cheapest fix before changing parts.
All the Best.

Sounds kinda lame, but check every nut, bolt and screw on the heater and where it fastens to the wall. something may simply be loose!

Sounds like ITS kettleing this means its nearing boiling point potentially very dangerous, u need to check out pump, also over heat thermostat i wouldnt use till its safe

New water heater?
http://waterheatertimer.org/New-water-heater-making-noise.html
http://waterheatertimer.org/Repair-water-heater-valve.html
Water does not compress. So each faucet has air chamber located behind wall. Air chamber is usually just a vertical piece of pipe about 18" long with a cap so it never fills with water. When water flows... all the water back to the main supply begins to move toward the faucet. The weight of this water can be considerable. When faucet is turned off, the whole column of water suddenly stops, but weight of water is still pushing forward.
Without air chambers to cushion the sudden stop of water weight, the pipes bang and rattle. With air chambers, the weight of the water pushes up into the air chamber causing the air to compress, which silently cushions the weight of water, but also causes a push-back when water stops moving forward. The push back can then move water backwards where it compresses air inside another air chamber. So the water can slosh back and forth.
IF you have factory-installed heat traps on your water heater, these things have rubber baffles. The baffles hum and rattle and whistle and clog and cause strange sounds that carry through the pipes and water heater and wood joists etc. The water sloshing back and forth can move the baffles and cause noise.
Or maybe you have a check valve that has gotten loose.
Post question on pro water heater forum:
http://www.thetankatwaterheaterrescue.com/forums/forum3/
Add a comment and say what you discover

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1) Turn up thermostat temperature:
http://waterheatertimer.org/How-to-adjust-temperature-on-water-heater.html
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

2) Electric water heater noise
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#bang

3) Add comment Dec 2012 and say what you find.

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

first check for loose pipes the you might want to add a damper on the pipe to absorb the hammering just t in a piece of pipe and make it go higher than the pipe with the noise and put a cap on topp of that

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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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 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.

try by draining tank. it may have sediment build up in it. heres how. go to www.ehow.com/how_5544402_drain-hot-water-tank.html this site will explain it better. have a good day! Sediment can drift into recirculation lines, jam open check valves, and cause the recirc pump to stick until it burns out. it causes noise, sometimes enough noise to annoy, or even frighten, people if the tank is inside a dwelling. The noise is caused by small amounts of water under the sediment layer turning to steam bubbles, which then collapse violently.

Thermostat may be heating element hotter than normal causing a change in temperature causing the noise. You could try adjusting temp down a little on thermostat. It sounds like it's getting the water very hot and thermostat may not be working correctly.