ASME Immersion Thermostat:
Refers to standard duty commercial electric water heater built
to A.S.M.E. code construction specifications and where temperature sensor is inside integral storage tank.
AST (Aero) (AKA Storage tank):
Hot water storage tank used in conjunction with a boiler or fuel fired water heater.
Boiler:
Gas or oil fueled appliance without storage tank that heats water via heat exchanger for whole house or building space heating.
Booster:
Refers to under-counter style or point of use water heater used in commercial dishwashing applications.
Center Flue:
Refers to Flue configuration in center of oil-powered water heater (Aero Series)
Combination Heating:
Refers to products designed to heat both water and living space.
Defender:
BWC name for FVIR compliant combustion chamber (Defender Safety System).
Direct Vent:
Refers to water heaters that utilize dual pipe venting system for combustion air and exhaust.
Double Wall:
Refers to the internal heat exchange coil in an indirect water heater as two layers of glass-lined steel.
Electric-powered:
Refers to Products that use electricity as fuel.
Energy Saver:
residential and commercial water heater classification.
Energy Saver – Electronic Ignition:
Standard duty commercial gas water heater with electronic ignition.
Energy Saver – Millivolt:
Standard duty commercial gas water heater with millivolt controls.
Gas-powered:
Refers to Products that use either natural or propane gas as fuel.
High Input Direct Vent:
Refers to water heaters that utilize a dual pipe venting system for
combustion air and exhaust and recover more hot water faster than standard models.
Hydronic Heating:
Refers to the use of heated water to heat living space (i.e. baseboard, in-floor radiant applications).
Immersion Thermostat:
Refers to standard duty commercial electric water heater where temperature sensor is inside integral storage tank.
Indirect-powered:
Refers to products used in conjunction with a boiler or other hot water
source to heat water in a storage tank via an internal heat exchange coil.
Large Volume Jacketed:
Refers to storage tank that is insulated and has outer sheet metal shell.
Used with water heater in standard commercial applications.
Large Volume Unjacketed:
Refers to storage tank that is un-insulated (bare) and has no outer shell.
Used with water heater in standard commercial applications.
LD DV:
Refers to water heaters that utilize dual pipe venting system for
combustion air and exhaust for use in smaller commercial applications.
LD Jacketed:
Refers to storage tank that is insulated and has outer sheet metal shell.
Used with water heater in smaller commercial applications.
LD Lowboy:
Style of electric water heater for use in smaller commercial applications
with cylindrical shape and reduced height for low ceiling/confined spaces.
LD PDV:Refers to water heaters with power blower that utilizes a dual pipe venting system for combustion air and exhaust
for smaller commercial applications.
LD TTW:
Refers to water heater that uses a powered blower to vent combustion
gases through outside wall or roof in smaller commercial applications.
LD Upright:
Traditional style of electric water heater with cylindrical shape for use in smaller commercial applications.
LD Utility:
Style of electric water heater with varying storage capacity for smaller, point of use, commercial applications.
LD Wall Hung:
Style of electric water heater designed for wall mounting with bottom
inlet and outlet connections for use in smaller commercial applications.
Light Duty (LD) Energy Saver:
Refers to conventional vent water heater for smaller commercial applications.
Lowboy:
Style of electric water heater with cylindrical shape and reduced height for low ceiling/confined spaces.
Manufactured Home – Atmospheric Combustion:
Refers to water heaters for use in mobile homes that utilize conventional combustion and venting.
Manufactured Home – Closed Combustion/Direct Vent:
Refers to water heaters for use in mobile homes that utilize a single
vent configuration that provides both intake air and exhaust venting.
MD 3-Element:
Medium duty electric water heater with three heating elements for use in large residential or smaller commercial applications.
Multi-Flue:
Refers to multiple Flue configuration for enhanced heat transfer in commercial oil-powered water heater.
Oil Burners:
Combustion apparatus utilizing fuel oil to generate heat/hot water (Aero Series).
Oil-powered:
Refers to products that use oil for fuel.
PDV with Independent Venting:
Standard duty commercial gas water heater with powered direct venting
that utilizes external combustion air and exhaust through outside wall via separate vent and intake pipes.
Point of use:
tankless, instant hot water heater.
Pool Heater:
Heater designed to heat water in a residential swimming pool.
Power Burners:
High input combustion apparatus utilizing natural gas to generate heat/hot water in power burner water heaters.
Power Burner Water Heaters:
Large volume commercial gas water heaters with gallon capacities up to 1,500 gallons. For use in hotels, hospitals, stadiums, etc.
Powerful Compact (PC):
Point of use electric water heater featuring 2 gallon storage capacity.
Power Direct Vent (PDV):
Refers to water heaters with power blower that utilizes dual pipe venting system for combustion air and exhaust.
Rear Flue:
Refers to Flue configuration at rear of oil-powered water heater (Aero Series)
Residential:
Refers to products with output sufficient for in-home/consumer use.
Side Connects:
Refers to water heaters with tappings or holes in side of storage tank for use in hydronic heating applications.
Single Wall:
Refers to the internal heat exchange coil in an indirect water heater as one layer of glass-lined steel.
Solar Saver:
Water heater used in conjunction with solar heating equipment. Includes electric element back up.
Space Heating:
Refers to products designed to heat living space.
Storage:
Refers to water heaters with integral tank to hold heated water.
Surface Mount Thermostat:
Refers to standard duty commercial electric water heater where temperature sensor is mounted on outside of integral storage tank.
Tabletop:
Style of electric water heater for use in kitchen with integral countertop.
Tankless:
Refers to products with no storage capacity that utilize a heat
exchanger or burner system to heat water as it passes through tubular heat exchanger.
TTW1(Through-the-Wall):
First generation product that uses a powered blower to vent combustion gases through outside wall or roof.
TTW2 (Through-the-Wall):
Second generation product with higher BTU inputs that uses a powered blower to vent combustion gases through outside wall or roof.
Upright:
Traditional style of water heater with cylindrical shape.
Upright HE:
Refers to electric water heater with higher efficiency ratings than standard upright electric models.
Utility:
Style of electric water heater with varying storage capacity for point of use applications.
Water Heating:
Refers to products designed to heat water.
Wall Hung:
Style of electric water heater designed for wall mounting with bottom inlet and outlet connections.
XR:
Extra Recovery - Refers to gas-powered models that recover more hot water faster than standard models.
| 
Gas Water Heater
Lower the thermostat to 120 degrees Fahrenheit. Lower temperatures minimize tank damage from overheating and reduce energy
consumption. Once a year, test the pressure-relief valve. Lift up on the lever and let it snap back. The valve should let out a burst
of water into the drain pipe. If it doesn't, install a new valve. Once a year, flush the water heater by draining several gallons of
water from the tank. This annual flushing removes the sediment that can cause corrosion and reduce efficiency.
Replace old water heater. When you buy a new water heater, remember that pressure-relief valves usually have to be bought separately.
Make sure you buy a valve that matches the working pressure rating of the tank you buy.
Shut off the gas by turning the handle of the in-line valve until it's perpendicular to the gas line. Wait 10 minutes for the gas to
dissipate. Shut off the water supply at the shutoff valves. Disconnect the gas line at the union fitting or at the flare fitting
below the shutoff valve, using pipe wrenches. Disassemble the pipes and fittings and set them aside to use later.
Open the hose bib on the side of the tank to empty the tank. Drain the water into buckets or attach a hose and run it to a floor drain.
Disconnect the hot and cold water pipes above the water heater. If the pipes are soldered copper, use a hacksaw or tubing cutter to
cut through them, just below the shutoff valves. It's important to make straight cuts so the fittings will be watertight when you
connect the new water heater. Disconnect the exhaust duct by removing the sheet metal screws.
Remove the old water heater with an appliance dolly.
Use the appliance dolly to put the new water heater in place, positioning it so the control box is close to the gas line.
Keep 6" or more clearance around the unit for ventilation, and make sure the access panel for the burner chamber isn't obstructed.
Check the side of the tank with a level. If you need to, place wood shims under the legs to level the unit.
Position the flue hat so its legs fit into the slots on the water heater, then slip the exhaust duct onto
the flue hat. Using a level, check the horizontal duct for the proper slope - it should slope upward ¼" per foot to keep fumes from
backing up into the house. Attach the flue hat to the exhaust duct, driving #4 gauge 3/8" sheet metal screws every 4" around the duct.
Wrap the threads of a new pressure-relief valve with Teflon tape. Use a pipe wrench to screw the valve into the tank opening.
Measure the distance between the pressure-relief valve and the floor. Cut a length of copper or CPVC drain pipe that will reach to
within 3" of the floor. Attach the pipe to the pressure-relief valve, using a threaded male adapter. Solder a threaded male
adapter to each of the water supply pipes. Let the pipes cool, then wrap Teflon tape around the threads of the adapters.
Wrap Teflon tape around the threads of two heat-saver nipples. If you look closely, the nipples are color coded and have directional
arrows to help you install them correctly. Attach the blue-coded nipple fitting to the cold water inlet and the red-coded fitting to
the hot water outlet, using a pipe wrench. Install the cold water nipple with the water direction arrow facing down; install the hot
water nipple with the arrow facing up. Connect the water supply pipes to the heat-saver nipples with flexible water connectors.
Tighten the fittings, using an adjustable wrench or channel-type pliers. 
Gather the gas pipes and fittings that you removed from the old water heater, and test-fit them for the new unit. You might need one
or two new black-iron nipples if the new water heater is taller or shorter than the old one. The capped nipple, called a drip leg,
protects the gas burner by catching dirt particles. Always use black iron, not galvanized iron, for gas lines. Clean the pipe threads
with a small wire brush, then coat them with pipe joint compound. Assemble the gas line fittings in the following order: 1) control
box nipple, 2) T-fitting, 3) vertical nipple, 4) union fitting, 5) vertical nipple, 6) cap. Black iron is fitted with the same methods
used for galvanized iron. If the gas line is made of flexible copper, use a flare fitting to connect the gas line to the water heater.
Remember to use the right techniques for flare fittings.
To restore the water supply, open the hot water taps at faucets throughout the house, then open the water heater inlet and outlet
shutoff valves. When the water runs steadily from all the faucets, close them. Open the in-line valve on the gas line. To test for
leaks, dab soapy water on each joint. If the fittings leak, the water will bubble noticeably. Use a pipe wrench to tighten any
leaking joints. Turn the gas cock on top of the control box to the PILOT position. Set the temperature control on the front of the
box to the desired temperature, between 120 degrees and 125 degrees Fahrenheit.
Remove the outer and inner access panels covering the burner chamber. Light a match, and hold the flame next to the end of the pilot
gas tube inside the burner chamber. While holding the match next to the end of the pilot gas tube, press the reset button on top of
the control box. When the pilot flame lights, continue to hold the reset button for one minute.
Turn the gas cock to the ON position, and reattach the inner and outer access panels.
