Home Plumbing: How To Install A Point Of Use Water Heater

Installing a point-of-use water heater should always be done by a certified, licensed plumber who should follow the instructions.

Installation of point-of-use water heaters must be in accordance with the manufactures instructions, local codes, utility company requirements and the National Fuel Gas Code. After thoroughly covering all the codes, installation can begin. A certified licensed plumber should do all installations of point-of-use water heaters.

Location of the water heater is the first step of installation. The location has to carefully be examined. Do not install gas water heater where liquids are stored or used that emit flammable vapors. These liquids include gasoline, propane, paints, adhesives, thinners, solvent and removers. Remember, it takes very little air movement to carry flammable vapors quite a ways. The water heater has a pilot with an open flame and this can ignite the vapors causing an explosion or fire. For these reasons, garages are not a good place to install these water heaters. Not only is the garage an undesirable location, so is bathroom and outdoor unprotected areas. If the garage is the only location available, install the water heater so that the open flamed pilot and main burner are at least 40 inches above the garage floor to reduce the possibility of igniting any spilled flammable liquid. Another location requirement is that the water heater is located close to the gas vent or chimney and insulating long hot water lines will conserve water and energy. Protect the water heater and the lines from freezing temperatures.

Clearances are important when installing a point-of-use water heater. There must be a minimum clearance of combustible material 6 inches at the sides, 2 inches at the rear and 16 inches above the top of the draft hood outlet. A 24-inch minimum is required from the front for adequate inspection and servicing. Do not install the water heater where a water leak will harm the area adjacent to the water heater or the floors below it. If the water heater must be installed in a location such as this, a suitable catch pan is required.

For the water heater to operate properly there must be air available for combustion and ventilation. Consideration of these requirements is important when installing the water heater. If installation of the water heater is in an unconfined space, infiltration air will usually be enough for proper combustion and ventilation. If the space must be confined, there should be 2 permanent openings. These openings should begin at least 12 inches on top and 12 inches on bottom. Each opening should have a total free area according to the type of installation with the air for combustion coming from either inside the building or outdoors. When air for combustion comes from inside the building, each opening must have a minimum free area of 1 square inch per 1,000 BTU per hour of the total input rating of all gas utilization equipment in the confined space, but not less than 100 square inches. When the air from combustion comes from outdoors, ducts are used. These ducts are either vertical or horizontal. With horizontal ducts, the openings must have a minimum free area of 1 square inch per 2000 BTU per hour of total input rating of all equipment in the enclosure.

Do not install a water heater near an air supply that contains halogenated hydrocarbons found in areas such as beauty shops, dry cleaners, photo-processing labs and storage areas for liquid and powdered bleaches or swimming pool chemicals.

Always inspect the heater for possible damage before any installation. Double check the marking of the rating plate to ensure the type of gas furnished corresponds to what the water heater is equipped to use. After the inspection, attach the bracket on the water heater to a wooden post or wall, using wood screw. Do not use nails.



Now check the water supply. The water supply to the water heater must provide enough pressure for proper operations of the water actuated control valve. There should be enough total water pressure at the inlet to operate the water heater at full capacity. Install a shutoff valve close to the water inlet of the water heater for servicing and draining the water heater.

Connections made between the water heater and the areas where the hot water goes should be as short and direct as possible and a uniform pipe big enough to carry the full capacity of the water heater must be used.

Connect the water inlet, and install the water filter into it. Now connect the hot water outlet on the water heater as shown in the manufacture's instructions. If these connections are reversed, the water heater will not function. Install a new combination pressure and temperature relief valve that complies with the codes.

The gas supply connection should now take place. Gas supply lines must be gas-tight, should be the correct size, and installed so that the supply of gas provided meets the maximum demand of the water heater without loss of pressure. The piping must be ANSI approved steel or wrought iron and a metal-to-metal union and shutoff valve must be installed between the water heater and the gas supply pipe. Use a pipe joint compound that is resistant to the liquefied petroleum gas on the threaded joints. Also, include a drip leg close to the water heater.

After connecting the water heater to the gas supply, check all connections for leaks using soapy water, bubble solution or other acceptable means before using the water heater. Do not use matches, lighters, candles or other sources of ignition for checking these connections.

Close the manual shutoff valve located on the water heater to pressure test the gas supply piping system at test pressure that are either equal or less than ½ psig.

Connect the water heater to a gas venting system. This system should be built to that the flue gases can be removed to the outside atmosphere. Attach the vent connectors to the draft hood outlet so the water heater is connected to the gas vent or chimney. The vent connectors must be the same size in diameter as the draft hood outlet or larger, but never smaller. Extend the terminal of the flue pipe at least 2 feet above the highest point. This point is where it passes through a roof of the building and is at least 2 feet higher than any portion of a building within a horizontal distance of 10 feet. Pitch the horizontal vent connectors upward to the chimney at least ¼" per foot of length. Position single wall vent connector at least 6" from adjacent unprotected combustible surface. Securely fasten the joint of vent connectors with sheet metal screws or other approved methods. Protect any pipe that passes through a wall with a noncombustible material and provide enough clearance from the pipe. Support all parts of the pipe for the design and weight of the materials being used. The cap or roof assembly must have a venting that is not less than the venting of the pipe that it is attached to. Do not install the flue outlet in a wind pressure drift area. Design and construct a venting system so an adequate, positive flow of air removes flue gases to the outside atmosphere.

Be careful when installing the water heater. There are prohibited installation locations which include small, poorly ventilated rooms, airtight rooms with air-conditioning, near heating and cooling vents, where chemicals are used, in bathrooms, bedrooms or any occupied room that the door is kept closed,. In an area prone to freezing temperatures, in an area prone to vibrations, in recreation vehicles, mobile homes, boats or other watercrafts, or in corrosive, dusty and greasy environments are also prohibited locations for installing water heaters.

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