How to Drain a Water Heater
A water heater serves to warm water for various purposes like cooking, cleaning, bathing, and heating spaces. In North America, they're often referred to as hot water tanks. There are several types available: conventional storage heaters, tankless heaters, heat pump heaters, solar heaters, and indirect heaters.
Conventional storage heaters focus on maximizing water capacity and swiftly providing hot water. Household tanks typically hold 75 to 400 liters (20 to 100 U.S. gallons). These heaters can operate on various energy sources like electricity, natural gas, propane, solar, or heating oil. Electric ones use resistance elements to warm water in storage. Natural gas heaters are prevalent in the United States and Europe. Maintenance involves removing sediment and mineral scale biannually to prolong their lifespan.
Tankless or demand-type heaters heat water directly without a storage tank by swiftly warming water-filled coils.
Heat pump heaters move heat from one area to another instead of generating heat directly, utilizing ground and air heat to warm water, minimizing electricity usage.
Solar heaters harness the sun's energy through panels, transferring it to a closed-loop system that warms the water in the tank.
Tankless coil and indirect heaters leverage a home's space heating system to supplement water heating.
Electric Water Heater Theory of Operation
Your electric water heater is quite like a large electric kettle. It has two heating elements, an upper and a lower, which work together to ensure you always have hot water. When your water heater senses that the water is cold, it first powers up the upper heating element. This part heats about a quarter of the water in the tank, starting from the top. Once the water at the top reaches the desired temperature, the upper element switches off, and the lower element takes over to heat the remaining water. This process ensures the entire tank is evenly heated. After you start using hot water, cold water enters the tank from the bottom. This cold water triggers the lower element to turn on again, maintaining a consistent supply of hot water for your needs.
Gas Water Heater Theory of Operation
Gas water heaters work similarly to electric ones in terms of water filling and usage, but the heating process is different. When the tank is full of cold water, you initiate the heating process by turning on the gas supply and lighting the burner, as instructed in your heater's manual. The heart of a gas water heater is the burner, which heats the water from the bottom of the tank. A special component, the thermocouple, ensures the gas supply is safely managed during this process. As the burner heats the water, a thermostat inside the tank monitors the temperature. Once the water reaches the preset temperature, the thermostat signals to stop the gas flow, thus preventing overheating. Similar to an electric heater, as hot water is used, cold water refills the tank and the heating cycle continues, ensuring a constant supply of hot water.
Safety First! Before you begin any repair, remember that safety is paramount. Always disconnect your Water Heater from the power source before attempting any repairs or diagnostics. This precaution is crucial to prevent electric shock or damage to your appliance as well as personal injury. These precautions should also be followed:
- Before checking the water heater, turn off the electricity.
- Before servicing the water heater, turn off the gas supply.
- Never restore the electricity to the water heater if the tank is empty; do so only after it is full of water.
- Never turn on the gas to the water heater if the tank is empty; do so only after it is full of water.
- Never remove the heating elements with the tank full of water.
- At least once a year perform maintenance on the water heater according to the manufacturer’s recommendations.
- If a water heater needs to be replaced, it is strongly recommended that all electrical, plumbing, gas, and placement of the tank be done by qualified personnel. Observe all local codes and ordinances for electrical, plumbing, and installation procedures.
Keeping your water heater in good shape is essential for ensuring it works efficiently and lasts a long time. Here are some easy steps you can follow:
Regular Inspections for Leaks: Every now and then, take a moment to look over your water heater tank. You're checking for any signs of water leaks. Pay special attention to:
- Pipe Connections: Examine where pipes connect to the tank. If you notice any corrosion or signs of wear, it's important to get these fixed promptly to avoid water damage.
- Temperature/Pressure-Relief Valve: This is a safety feature on your tank. Check if there's any leakage here.
- Internal Components: Safety first - turn off the electricity to your water heater. Then, remove the access panels to inspect the wiring, heating elements, and insulation. Look for any signs of water. If you find a leak, it's crucial to either repair it or consider replacing the unit.
Annual Cleaning: Once a year, give your water heater a thorough clean-out. This means draining and flushing the tank to get rid of any sediment build-up. Here's how to do it:
- Preparation: Start by turning off the electricity to your water heater. Then, shut off the water supply.
- Draining the Tank: Attach a garden hose to the draincock (the tap at the bottom of your tank) and open it up. To help the tank drain faster, open a hot water faucet somewhere in your house.
- Refilling the Tank: After draining, close the draincock and turn the water supply back on. Keep a hot water faucet open while the tank refills. This allows any trapped air to escape. You'll know the tank is full when water flows normally from the open faucet.
- Final Steps: Once the tank is full and there's no more air coming out, you can close the faucet. Don't forget to go around and open other hot water faucets briefly to clear any air from those lines too. Finally, you can turn the electricity back on to your water heater.
Following these simple maintenance steps will help keep your water heater running smoothly and might even extend its lifespan.
|Description and Function
|Signs of Failure
|Combination Control Valve
|Consists of a gas pressure regulator valve, thermostat, and ignitor, with a gas cutoff device to shut off gas supply in case of thermostat failure.
|Burner not igniting, inability to control water temperature, slow hot water recovery, sooting, failure to shut off gas.
|Inefficient heating, potential safety hazards due to gas leakage or overheating.
|Integral part of the heating system; involves gas delivery and flame management.
|No gas to burner, yellow-lazy flame, flames lifting off burner ports, burner not igniting, high temperatures, poor maintenance.
|Inefficient heating, potential for unsafe operation, increased risk of fire or gas leakage, need for regular cleaning and maintenance.
|A sensor for measuring temperature, consisting of two dissimilar metals that produce a voltage when heated, used to control the gas flow to the pilot flame.
|Burner not igniting, pilot light not remaining lit.
|Inability to maintain pilot flame, leading to failure in heating system startup or operation.
|Piezoelectric device used in gas water heaters, generates a spark at the burner when activated.
|Burner not lighting or remaining lit.
|Inability to initiate the heating process, resulting in no hot water supply.
|Mechanical device controlling current flow to the water heater, senses heat from the tank wall. Attached to the high-limit thermostat.
|No hot water, burned wires, water heater runs continuously, fuse blows or circuit breaker trips.
|Risk of overheating, potential electrical hazards, continuous energy consumption, interruption of hot water supply.
|Monitors and controls the water temperature in the lower section of the tank, manages the lower heating element.
|Similar signs as the upper thermostat, including failure to cycle on and off.
|Inefficient heating, potential overheating, risk of electrical issues, interrupted hot water supply.
|Nichrome filament encased in magnesium oxide powder and immersion-type casing, heats the water in the tank.
|No hot water, burned wires, fuse blows or circuit breaker trips.
|Loss of hot water supply, possible electrical hazards, need for component replacement.
Formulas and Facts
- 1 gallon of water weighs 8.33 lbs
- 1 gallon of water has a volume of 231 cubic inches
- 1 cubic foot of water weighs 62.38 lbs and contains 7.48 gallons of water
- 100 feet of 3⁄4-inch copper pipe contains 2.5 gallons of water; 1-inch pipe contains 4.3 gallons 8.33 BTU will raise 1 gallon of water 1°F at 100 percent efficiency (electricity)
- 11 BTUs are required to raise 1 gallon of water 1°F at 75 percent efficiency (gas)
- 3412 BTU equals 1 kilowatt hour (Kwhr)
- 1 Kwhr will raise 410 gallons of water 1°F at 100 percent efficiency
- 1 BTU × 0.293 = watts
- 1 KW = 1000 watts
- 2.42 watts are required to raise 1 gallon of water 1°F
- 1 Kwhr will raise 10.25 gallons of water 40°F at 100 percent efficiency
- 1 Kwhr will raise 6.8 gallons of water 60°F at 100 percent efficiency
- 1 Kwhr will raise 5.1 gallons of water 80°F at 100 percent efficiency
- 1 Kwhr will raise 4.1 gallons of water 100°F at 100 percent efficiency