Water heaters are an important part of your home, and are often taken for granted. However, sometimes the heater will begin to make a variety of concerning noises. An unusual noise may be the first sign of a serious issue and should be addressed soon to avoid damage to the heater.
Common Issues in All Heater Types
There are some problems which occur in most or all heater types, creating a variety noises. These issues may be solved in almost identical manners between heater types.
Chattering in Modern Heaters
Modern water heaters incorporate a check valve at the hot water output. Inside the valve are balls which resemble marbles. These will create a chattering noise if they have residue buildup or if a well-based water supply has low pressure. The problem may be solved by removing the rubber nipple and cleaning the balls, or by increasing the water pressure.
Water heaters are sensitive to water pressure. A high pressure in the tank can cause high-pitched noises if the pressure relief valve isn’t functioning properly. You should have the valve replaced as soon as possible. Prolonged exposure to high pressure can cause cracks, leaks, or even a burst heater.
Pinging, banging, and knocking sounds are most commonly caused by sediment buildup. As water is heated, solids such as calcium separate and sink to the bottom of the tank. This sediment causes extra heat zones and lowers the efficiency of your heater. The sediment will absorb heat, which makes the water warm slower and shortens the tank’s lifespan.
Alleviating a sediment buildup is usually easy to do. In rare cases where the sediment has solidified, the heater will need to be replaced. Otherwise, follow these steps to flush the tank on any type of water heater:
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- Electric Heaters: Locate your circuit breaker/fuse box and shut off power to the heater.
- Fuel-Powered Heater: Note the temperature setting, and then turn the thermostat setting to “pilot”.
- If you choose, you may leave the heater turned off overnight so the water inside has a chance to cool. This makes for safer drainage, but may be difficult in a busy household.
- Turn off the cold water supply. The valve should be located either at or near the cold water inlet at the top of your tank. Ball valves turn 90 degrees, while gate valves may take several turns. Some gate valves have a stop feature which occurs while opening or closing. Make sure to turn past the stop to ensure your water supply has been cut off completely.
- Turn on a hot water tap to prevent a vacuum from forming in the pipelines.
- At the bottom of the tank is a drain valve or cock. In some cases, it will be behind a removable cover panel. Attach a garden hose to this tap and place the other end into your cellar drain or sump. A bucket may also be used, if you are careful not to let it overflow. Try not to use cheap materials, as the hot water may soften the plastic and cause leaks.
- Place a rag over the drain valve to prevent any accidental spraying.
- If you are running the water directly to a drain or sump, you may choose to open the pressure relief valve for faster drainage. The valve is usually located near the top and flips upward to open. Do not open the valve if you’re using a bucket, as the hot water will quickly overflow and create a safety hazard.
- Open the drain valve. Some older tanks have plastic drain cocks which may be difficult to open. Do not try to force them or they may break.
- After draining for a few minutes, fill a bucket and let it sit for a few minutes. If the water is clear and there is no visible sediment on the bottom, you may stop flushing. However, if the water is cloudy or there are grains at the bottom, continue draining the tank for a few more minutes and repeat this step.
- Once the water is free of sediment, close the drain valve, then the pressure relief valve (if opened). Turn off the hot water tap.
- Open the cold water valve and allow the tank to fill and the pressure to equalize.
- Once full, open the pressure relief valve again to bleed off any excess air in the tank to avoid further pinging sounds. Once the air is drained, close the valve again and turn on a hot water tap. Turn off the tap once water is flowing properly from the tap.
- Finally, turn the breaker or thermostat back on. After 20 minutes, test a hot water tap to make sure water’s heating properly.
Specific Heater Types
Depending upon the type of water heater you own, the cause of a sound may differ. The following issues tend to be related to specific heater types.
A common sound complaint with electric water heaters is a muffled boiling sound when active. However, this is a normal sound for this type of heater and not a sign of trouble.
High Efficiency Gas/Propane
These water heaters use a fan and PVC pipe for their exhaust. Bad bearings in the fan may cause a screeching noise, indicating the fan must be replaced. Thumping sounds may also occur if a rodent or other pest crawls into the exhaust pipe and is killed by the fan. Removal of the pest’s body will solve this sound issue, but you may also wish to check the fan for damage.
A roaring or popping sound occurs when the burner nozzle needs to be replaced. Unlike other types of water heaters, you should always contact a certified professional to fix an oil heater, as they use a high-voltage transformer which will cost between $10,000 and $20,000 to replace if damaged. The spark produced by this transformer must also be tuned precisely to avoid efficiency problems.
Propane and Natural Gas
Scale buildup on the burner can cause a roaring sound. Simply cleaning the burner will solve this problem.