STA-RITE SR200NA Service Manual page 81

SECTION SIX – Glossary
Glossary
AGA - American Gas Association. The certifying body for gas-fired
appliances.
Air Flow Switch - The switch that senses the pressure drop across
the air orifice. It will prevent or stop combustion by causing the gas
valve to stay closed or close if air flow is insufficient for combustion.
Air Gas Mixing Tube (Air Gas Mixer) - The tube on the inlet side of
the combustion blower where the air and gas are mixed together.
Air Orifice - The metering hole in the plate inside the blower inlet
endcap. It meters the correct amount of air for combustion.
ANSI - American National Standards Institute. Develops industry wide
voluntary standards for safety, signage, measurements, etc.
Automatic Gas Shutoff Switch (AGS) - The switch that senses the
outlet water temperature and causes the gas valve to close if the
water temperature exceeds 150° F (65.5° C).
British Thermal Unit (BTU) - The amount of heat required to raise
the temperature of 1 pound of water 1° Fahrenheit.
Bonding Lug - An electrical connector mounted on the exterior of the
heater to which the bonding conductor for the pool system is
connected.
Burner Control Module - See Ignition Control.
Check Valve - A valve that allows for the flow of water in only one
direction.
Combustion Chamber - The entire sealed portion of the appliance
within which combustion occurs. It contains the heat exchanger.
Condensate - The liquid which separates from a gas (including flue
gases) due to a reduction in temperature.
Control Board - The electronic circuit board that works in conjunction
with the thermistor as the heater thermostat. It also contains the
remote communications circuitry.
Combination Gas Control Valve - The regulator to a) maintain gas
outlet pressure and b) turn the gas off and on to the heater. It has
dual shutoff valves.
Combustion Air Blower (Mixing Blower) - The motor-driven blower
that supplies the correct air/gas mixture to the gas burner/flameholder.
Draft - The flow of gases or air through chimney, flue, or equipment
caused by pressure differences.
Draft Hood - A device built into the heater or made a part of the vent
connector to: a) provide for the ready escape of flue gases in the
event of no draft, backdraft or stoppage beyond the draft hood; b) pre-
vent a back draft from entering the heater; and c) neutralize the effect
of stack action of the chimney or gas vent upon the operation of the
appliance. The Sta-Rite pool heater has a pressurized burner and
does not use a draft hood.
Excess Air - Air supplied for combustion beyond that which is
required for perfect combustion.
Fireman's Switch - A switch external to the heater that keeps the
pool pump running for 15 minutes after the heater shuts off.
Flameholder - A cylindrical perforated can that supports the combus-
tion of the air/gas mixture. Combustion takes place just off the
flameholder's surface.
Flue Gases - The products of combustion (including the excess air)
which flow out the heater exhaust.
Gas Orifice - A disk with a hole in it located in a gas line union. It
meters the correct flow of gas for combustion. Kits are available to
convert heaters from Propane to Natural Gas and vice versa, and
also to correct combustion problems.
Heat Exchanger - The series of finned copper tubes that carry water
internally. It is contained in the combustion chamber and allows for
the transfer of heat from the combustion gases to the water.
Heating Value (High or Total) - The number of British thermal units
produced by the combustion, at constant pressure, of 1 cubic foot
(0.03m 3 ) of gas when the products of combustion are cooled to the
initial temperature of the gas and air, when the water vapor formed
during the combustion is condensed, and all corrections to standard
conditions have been made. This value for natural gas is approxi-
mately 1,000 BTU per cubic foot. For Liquefied Petroleum Gas
(Propane) it is about 2,500 BTU per cubic foot.
Heating Value (Low) - The same as the High or Total Heating Value
when the water vapor is not condensed, resulting in a lower value.
This value is approximately 900 BTU per cubic foot for natural gas
and 2,300 BTU per cubic foot for Liquefied Petroleum Gas (Propane).
High Limit Switch - The switch that senses the outlet water tempera-
ture and causes the gas valve to close if water temperature exceeds
135° F (57.2° C). The setting of this switch is lower than that of the
AGS.
Hot Surface Igniter - Ignition of the gas/air mixture caused by an
electrically heated element whose surface gets hot enough to ignite
the air/gas mixture, without any sparks or pilot lights.
Igniter - A device which uses electrical energy to ignite gas.
Inlet/Outlet Manifold - The manifold to which the inlet and outlet
water lines are connected. It contains an internal water bypass valve
to maintain correct water flow to the heater. It routes the water into
and out of the heat exchanger tubes and houses the High Limit
Switch, Automatic Gas Shutoff, and Thermistor. It also contains the
thermal governor, which minimizes condensation on the heat
exchanger.
Input Rating - The gas burning capacity of an appliance in BTUs per
hour.
Internal Bypass Valve - The valve in the inlet/outlet manifold that
automatically controls the water flow through the heat exchanger. It
causes the excess flow to bypass the heat exchanger, so that it mixes
with the heater water as the water leaves the heater.
Limit Switches or Limit Controls - Devices responsive to changes
in pressure, temperature, or liquid level for turning on, shutting off, or
throttling the gas supply to an appliance.
Manifold Adapter (obsolete) - A transition piece located between
the inlet/outlet manifold and the heat exchanger tubes. See inlet/outlet
manifold.
Membrane Pad - The control panel at the top of the heater where the
operating temperature and heating function selections are made.
NFPA - National Fire Protection Association. Publishers of National
Electrical Code (NEC) and National Fuel Gas Code (NFGC). For
more information, call 1-800-344-3555.
Orifice - The opening in a cap, spud, disk, or other device whereby
the flow of a gas is limited.
Pressure Relief Valve - A valve mounted on the manifold adapter
that will automatically open at a preset pressure. For the Sta-Rite
heater the rating is 50 psi (345 kPa). This must be an ASME valve
with a minimum BTU rating equal to that of the heater.
Pressure Switch - A switch that senses the inlet water pressure. It
causes the gas valve to close or prevents it from opening if the water
pressure is less than the switch set point.
Primary Air - The air introduced into a burner that mixes with the gas
before it reaches the port.
Safety Shutoff Device - A device that will shut off the gas supply to
the burner(s) in the event the source of ignition fails.
Secondary Air - Air externally supplied to the flame at the point of
combustion, generally only in a natural draft unit.
Thimble - A device used for the penetration of a wall through which
the vent piping is run.
Transformer - An electrical device that converts line voltage (120
VAC) to low voltage (24 VAC). It provides low voltage for the safety
switch circuits and for the control board.
Vent Body - The plastic elbow designed for the attachment of a vent
connector or the venting system.
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