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RESIDENTIAL GAS, NON POWER VENTED, WATER HEATER
SERVICE HANDBOOK
State Water Heater Technical Training Department
© 2004 Ashland city, TN
27
TECHNICAL BULLETIN - 14
ALUMINUM HYDROXIDE
SYMPTOMS
“Crackling”, “gurgling”, or “popping” noises from new water heaters (installed less than
six months).
CAUSE
In a few isolated parts of the United States where the water supply has a relatively high pH (8+),
water conditions will react with the aluminum anode to form excessive amounts of aluminum
hydroxide on the anode and in the bottom of the tank. Aluminum hydroxide looks like “jelly
beads” or a green, blue or gray gel like substance in the heater drain or at faucet aerators
.
THE FIX
This procedure should only be performed by someone with abilities equal to a licensed
tradesman. Aluminum hydroxide can be removed by using one of the methods outlined.
If tank is new with no lime build-up to any degree:
1 Turn off the heater.
2 Remove the anode.
3 Flush the tank thoroughly with water.
4 Replace the aluminum anode (identifiable by smooth surface on plug) with magnesium
anode (identifiable by weld bead on plug).
If the tank is new with lime build-up to any degree:
1 Turn off the heater.
2 Drain the heater.
3 Remove the anode.
4 Add UN-LIME to the tank.
20-40 gallon models (use 3 gallons of UN-LIME)
41-65 gallon models (use 5 gallons of UN-LIME)
66-100 gallon models (use 7 gallons of UN-LIME)
(On electric models, be certain the lower element is immersed in solution.)
5
Heat the UN-LIME to a temperature between 140F to 160F.
GAS - Heat for 7 to 10 minutes.
6 Shut off the water heater.
7 Allow the heated UN-LIME to stand for up to 12 minutes.
8 Drain and flush the tank. Caution: UN-LIME will still be hot.
9 Replace the original aluminum anode with a magnesium anode.
10 Fill the system with water.
11 Turn heater fuel “ON”.
NOTE
Since aluminum hydroxide is a product of a chemical reaction dependent on the water condition,
any treatment is not considered warranty related.