Residential Water Heater Training www.university.hotwater.
Introduction The purpose of this manual is to provide training for employees, associates and consumers in the basic concepts of residential electric and gas storage type water heaters. This manual is organized into the following sections: Electric Water Heater Parts Photographs, illustrations and a brief description of the parts of an electric water heater. Electric Water Heater Operation How standard electric water heaters transfer heat into water.
Index Section Index Introduction ................................................................ Standard Electric Water Heater Illustration ................ Electric Water Heater Parts ......................................... Energy Smart II Water Heater Illustration .................. Energy Smart II Heater Parts ...................................... Electric Water Heater Operation ................................. Standard Gas Water Heater Illustration ......................
Standard Electric Water Heater This section provides an overview of electric water heaters. The first part of this section has illustrations, photographs and a brief description of each part. The second part of this section describes the operation of standard electric water heaters. When this section is completed, the reader should have a basic understanding of how an electric water heater transfers heat into water.
Electric Water Heater Parts Outer Jacket - The outer jacket of an electric water heater consists of three pieces: the jacket top, jacket skirt and jacket bottom. The jacket provides a space for insulation around the tank, preventing the consumer from coming into contact with hot surfaces and to reduce energy loss. Connections extend from the tank through the outer jacket to provide plumbing connections for the cold water inlet and the hot water outlet.
Standard Electric Water Heater Parts Control Circuit - The standard single-phase control circuit consists of a high limit control switch with a reset button, upper thermostat, lower thermostat, two heating elements and wires. The upper thermostat first sends electrical energy to the upper element until the water temperature in the upper third of the tank reaches the thermostat setting. Power is then transferred to the lower element until the remaining water reaches the lower thermostat setting.
Energy Smart II Electric Water Heater Nipple Heat Trap Heat Trap Nipple Smart Grid Anode Rod Dip Tube Electronic Thermostat (ET) Element Energy Smart Module (ESM) T&P Valve Thermistor Sensor Element Copyright© by AOS 2015. All rights reserved.
Energy Smart Water Heater Parts Energy Smart® Electric Operation - The Energy Smart® electric water heater includes an Energy Smart Module (ESM) user interface which allows homeowners to easily adjust the temperature, operating mode, and view diagnostic information without requiring any tools or removal of water heater components. The ESM is connected to an Electronic Thermostat (ET) above the upper element.
Electric Water Heater Operation Standard Electric The standard residential electric water heater control circuit consists of a manual reset high limit switch, an upper thermostat, lower thermostat, two heating elements and wires. When the upper third of the tank is heated to the temperature set on the upper thermostat, power is switched to the lower heating element. The lower element continues to heat until the water temperature in the lower portion of the tank is heated to the lower thermostat setting.
Electric Water Heater Operation When installing a new electric water heater or following draining the tank for maintenance purposes, the tank should be completely re-filled before applying power to the elements. Energizing a heating element that is not fully submerged in water is referred to as "dry firing," and will cause the element to immediately burn out.
Notes Copyright© by AOS 2015. All rights reserved.
Standard Gas Water Heater This section provides an overview of gas water heaters. The first part of this section has illustrations, photographs and a brief description of each part. The second part of this section describes the operation of standard gas water heaters and Flame Guard® gas water heaters. When this section is completed, the reader should have a basic understanding of how a gas water heater transfers heat into water.
Flame Guard® Water Heater Cold Water Outlet (Not Shown) Draft Hood Hot Water Inlet (Not shown) T&P Valve (Outside not shown) Outer Jacket Non-CFC Foam Insulation Glass Lined Tank Flu Baffle Baffle Dip Tube Anode Rod Piezo Igniter Gas Valve Drain Valve Burner Thermal Sensor Thermocouple Pilot Flame Trap Copyright© by AOS 2015. All rights reserved.
Flame Guard® Water Heater Series 100 Heat Trap Heat Trap T&P Valve Dip Tube Gas Valve Flue Baffle Anode Rod Copyright© by AOS 2015. All rights reserved.
Gas Water Heater Parts Outer Jacket - The outer jacket of a gas water heater consists of three pieces: the jacket top, jacket skirt and jacket base assembly. The jacket provides a space for insulation around the tank. The jacket base assembly is where combustion takes place, and it is designed to shield the floor from excessive temperatures. Tank and Flue - In addition to the top head, bottom head and shell, the gas water heater also has a flue running through the center.
Gas Water Heater Parts Honeywell Gas Valve Gas Valve– the gas valve has 2 functions. The first function is to regulate the gas pressure down to a usable level for a controlled and safe burn. The second function is to regulate the water temperature based on the set point. Venting - The combustion process creates by-product gasses such as carbon dioxide, carbon monoxide and nitrogen oxide. These gasses are harmful to breathe and need to be vented outside of the home.
Notes Copyright© by AOS 2015. All rights reserved.
Gas Water Heater Operation The heat from the pilot flame creates an electrical current in the thermocouple circuit that operates a small spring-loaded electromagnet in the gas valve. The Electromagnet holds the main gas supply line interrupter open allowing gas to flow to the pilot and main burner. If the pilot goes out, the electromagnet will no longer receive a current and the spring loaded interrupter will shut off the gas supply.
Gas Water Heater Operation Air for combustion passes through the bottom of the water heater into the combustion chamber. Gas flows into the burner and is ignited by the pilot flame. As the heated water rises, cooler water sinks to the bottom of the tank. Copyright© by AOS 2015. All rights reserved. Heat from combustion rises and contacts the tank bottom head being transferred through the steel into the water.
Gas Water Heater Operation Flame Guard® Water Heaters Spills of gasoline or the presence of other flammable vapors near a standard gas water heater can be very dangerous. The American National Standards Institute (ANSI) now requires all residential water heaters to be flammable vapor ignition resistant (FVIR). All American Flame Guard® Water Heaters are fully compliant with ANSI FVIR standards. Flame Guard® water heaters have a sealed combustion chamber.
Gas Water Heater Operation The control circuit for a Flame Guard® water heater is similar to a standard gas water heater. The main difference is the addition of a resettable thermal cutoff switch to the thermocouple circuit. If flammable vapors are ignited they will trigger the thermal switch, cutting off the gas supply to the pilot and burner. This prevents the vapors from being reignited after they have self-extinguished. Copyright© by AOS 2015. All rights reserved.
Gas Water Heater Operation Series 100 Flame Guard® Water Heaters Spills of gasoline, or the presence of other flammable vapors, near a standard gas water heater can be very dangerous. The American National Standards Institute (ANSI) now requires all residential water heaters to be flammable vapor ignition resistant (FVIR). All American Flame Guard® Water Heaters are fully compliant with ANSI FVIR standards. Series 100 Flame Guard® water heaters have a sealed combustion chamber.
Gas Water Heater Operation In order for a Series 100 Flame Guard® water heater to operate, the pilot must be lit. The heat from the pilot flame creates an electrical current in the thermopile. The thermopile generates the power needed to operate the electronic gas control without requiring an external power source.
Gas and Electric Water Heater Parts Heat Traps In some models, a heat trap is installed at the hot water outlet and cold water inlet to reduce standby heat loss. The heat trap saves energy by preventing hot water in the tank from rising into the plumbing lines. Heat traps can be installed internally or externally.
Gas and Electric Water Heater Parts Anode Rod - The anode rod is a sacrificial part installed to reduce tank corrosion. A tank full of hot water acts very much like a battery with small electrical currents flowing between the different types of metals. The anode rod is made of aluminum or magnesium which is more conductive than the steel of the tank. The electrical currents corrode the anode rod rather than the tank. Dip Tube - The dip tube moves incoming cold water to the bottom of the tank.
Applications Selecting the right type of water heater depends on the application. The amount of electrical power available, the ability to run vent pipe, as well as the size and shape of the installation area should be considered when selecting a water heater. Electric Water Heaters For an electric water heater it is important to know the voltage available. This is usually 240 Volts or 120 Volts.
Applications Gas Water Heaters Failure to properly vent a gas water heater can cause an explosion, fire or carbon monoxide poisoning. All gas water heaters must be vented according to the National Fuel Gas Code. Venting decisions will depend on the location inside the house where the water heater is to be installed. If replacing an existing unit, the vent diameter of the new unit must not exceed the vent diameter of the old unit, or new venting must be installed.
Applications Direct vent water heaters also depend on the buoyancy of hot combustion gasses for proper venting but are generally used where vertical venting is not possible or desirable. Because they draw their combustion air from outside the structure, they do not waste conditioned air from inside. The most important consideration with direct venting is that the water heater must be located very close to an exterior wall.
Applications Power venting is used when the water heater has to be installed in an interior location of the structure and a long horizontal vent pipe must be used. The vent pipe can run from 40 feet to as much as 120 feet, depending upon the vent pipe diameter, Btu output of the water heater, and the number and type of bends in the vent pipe. Power vent water heaters have a motorized blower located at the top of the flue that forces combustion by-products to outside the home.
Water The two main sources of water are surface water and ground water. Surface water comes from lakes, streams and reservoirs. Ground water comes from wells. Water sources usually contain some impurities. Most are harmless to people, but some can damage a water heater over time. 0 Seconds Suspended Solids Surface water is more likely to contain suspended solids, such as sand, dirt, silt, clay, algae and decaying vegetation.
Water Hard Water Hard water contains dissolved calcium and magnesium and is harmful to all water heaters. Calcium and magnesium combine with other elements in the water and form salts which build up as scale. Scale is sometimes referred to as lime deposits. Hard water is most noticeable as a hard-to-remove soap scum on tubs and other bathroom fixtures or as very low sudsing when using detergents. When water is heated, it becomes less dense allowing scale to deposit at a higher rate.
Safety As water is heated, it becomes more corrosive and expands. These two conditions can create safety issues, but modern water heaters are designed with features to insure safe operation. These concepts and other safety issues will be covered in this section. Galvanic Corrosion A water heater is very much like a large battery. Water is conductive allowing electrical current to pass through it. High concentrations of dissolved minerals and an acidic pH can increase water conductivity.
Safety Thermal Expansion Water expands as it is heated. For example, 30 gallons of water expands to 30 ½ gallons as it is heated from 40°F to 120°F. Water cannot be compressed, so it will cause pressure to build up in the tank if no expansion area is provided. In older water systems, expanding water flows from the heater back into the supply line preventing pressure build up. But due to new code restrictions, many areas now require a check valve between the residence and the incoming municipal water supply.
Safety Excessive Temperatures The T&P valve will also activate when the water temperature exceeds 210°F. Activation of the T&P valve for excessive temperatures will result in a large amount of water being discharged and could indicate a problem with the control circuit. This problem should be corrected at once in order to prevent scalding injuries. Gas water heaters are equipped with an energy cutoff (ECO) switch.
Safety Defining Hot Water Hot water can be defined in many ways. The most common way to define hot water is by the application. Water temperature that is considered hot for one application may be only warm in a different application and vice versa. The following chart shows common temperatures used for various applications.
Sizing and Performance Water heaters require routine maintenance to ensure they remain in efficient operating condition. The following components should be periodically checked, and any noted maintenance issues should be immediately addressed. T&P Valve The T&P valve should be manually operated at least once a year to insure that it is working properly. Stand clear of the outlet and slowly lift and release the lever handle. Allow the valve to operate freely and return to its closed position.
Sizing and Performance Determining Efficiency To determine how much hot water the heater can produce and how fast it can produce it, recovery capacity, recovery efficiency, tank draw efficiency and standby efficiency will have to be considered. Recovery Capacity Recovery capacity is the number of gallons of incoming cold water per hour the water heater can heat to a specific temperature. The difference between the incoming cold water temperature and the hot water produced is called the temperature rise.
Sizing and Performance An improperly sized water heater can result in cold bath water, a cold shower or a dishwasher full of dirty dishes. An improperly sized water heater can force users to alter their lifestyles to accommodate it, such as by spacing shower times farther apart. In order to make sure that the water heater selected is the correct one, it is important to know how much hot water will be needed and how fast the water heater can produce it.
Specifications Recovery Efficiency Recovery efficiency, also called thermal efficiency, is a measure of the total amount of heat produced that gets transferred into the water. Standby Efficiency Standby efficiency is a measure of how much heat is lost from the stored water while the water heater is not heating water . Electric water heaters have a recovery efficiency of about 98%.
Testing and Standards In addition to high internal quality standards, both gas and electric water heater models are subject to safety and efficiency standards set by consumer and government agencies. Quality Quality auditors randomly pull finished water heaters from the assembly line for examination. The auditor has a checklist of 88 possible defects which range from minor to critical.
Testing and Standards First Hour Rating Model Estimated Annual Operating Cost Estimated Yearly Energy Use National Average Cost Per KWH Copyright© by AOS 2015. All rights reserved.
Definitions American National Standards Institute (ANSI) - Agency that set standards for safety of gas water heaters. Anode - Material that current flows from inside a battery. Anode Rod - Sacrificial part made of aluminum, magnesium or other compounds that is corroded by electrical currents in order to protect the inside of the tank. Back Draft - The back flow of air into the flue. Usually caused by negative air pressure in the home or improper vent termination.
Definitions Energy Guide Label - Yellow label displayed on every water heater that compares that model’s energy use to similar models. Expansion Tank - A tank installed on the incoming water line that absorbs expanding water and prevents pressure buildup inside the tank. First Hour Rating - A measure of the amount of usable stored water that is available combined with the quantity of water that can be heated in one hour.
Definitions Pilot Light - A small flame that stays lit all the time and ignites the burner flame. Potable Water - Water that is suitable for drinking because it contains nothing harmful. Radiant Hydronic Heating - Home heating system that circulates hot water through tubes in the floor or through baseboard heaters. Recovery Capacity - The number of gallons of incoming cold water per hour the water heater can heat to a specific temperature.
Top Index American National Standards Institute (ANSI) - 22, 40, 42 Anode Rod - 4, 7, 12, 13, 14, 25, 30, 32, 36, 39, 40,42 Atmospheric Venting - 27 Back Draft - 16, 42 Burner - 12, 13, 15-16, 18, 20-26, 34, 36, 39, 40, 42 Calcium - 21, 43 Canadian Standards Association (CSA) - 40 Cathode - 32, 42, 43 Cathodic Protection - 42 Closed Water System - 33, 42 Condensation - 25, 42 Demand - 2, 8, 38 Department of Energy (DOE) - 40, 42 Dielectric Water Connections - 32 Dip Tube - 4, 7, 9, 12-14, 25, 42 Direct Vent
