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Gas Heat Terms
Terms in this set (69)
Automatic Combination Gas Valve
For gas furnaces incorporates a manual control, gas supply for the pilot, adjustment and safety features for the pilot, pressure regulator, and the controls for the main valves.
Bimetallic Safety Device
The pilot heats the bimetal strip, which closes electrical contacts wired to the gas safety valve. As long as the pilot flame heats the bimetal, the gas safety valve remains energized and gas will flow when called for.
A device used to prepare and burn fuel.
A by product of natural gas combustion that is not harmful.
A poisonous, colorless, odorless, tasteless gas generated by incomplete combustion.
A reaction called rapid oxidation or burning produced with the right combination of a fuel, oxygen, and heat.
Condensing Gas Furnace
A furnace with a condensing heat exchanger that condenses moisture from the flue gases, resulting in greater efficiency.
A electronic ignition modular controller that will try to relight the pilot after the shutoff period. Once in the shutoff period, there will not be any bleeding of pilot gas.
The exact temperature at which moisture begins to form.
Diaphragm Gas Valve
A diaphragm valve that uses gas pressure on one side of the diaphragm to open and close the valve.
Is excess air after combustion and usually enters at the end of the heat exchanger.
Direct Spark Ignition
A system that provides direct ignition to the main burner. No pilot is used in this system. This system goes into a "safety lockout" if the flame is not established within the "trial for ignition" period.
A venting system for a gas furnace, which pulls the outside air in for combustion, and vents the flue gases to the outside.
Sometimes called a counter flow furnace. The air intake is at the top, and the discharge air is at the bottom.
Dual In Line Pair switch (DIP)
A very low amperage, single pole, double throw switch used in electronic circuits to set up the program in the circuit.
Dual Rod (remote) Sensing
Uses a separate ignitor and flame-sensing rod or electrode. The sparking is accomplished with one rod and the sensing is done with the other.
To ensure complete combustion of the fuel used, combustion chambers are supplied with this. It increases the amount of oxygen and the probability of combustion of all fuel. It mixes with raw gas in the burner before a flame is established.
Automatically turns the blower on and off. It can be temperature controlled or time delayed.
When the flame strikes the cooler metal of the chamber, the temperature of that part of the flame is lowered below the ignition temperature. This results in poor combustion and produces carbon monoxide and soot
Flame Proving Device
A device in a gas furnace to ensure there is flame so that excess fuel will not be released, causing an explosion in a gas furnace.
In a gas furnace, the flame changes the normal current to direct current. the electronic components in the system will only energize and open the gas valve with a direct current.
Uses a fan or a blower to move air over the coil?, A mechanical draft produced by a device upstream from the combustion zone of an appliance.
Gas Furnace Burner
A device that uses gas to create heat and light.
Drops the pressure to the proper level (in. WC) and maintains this constant pressure at the outlet where the gas is fed to the gas valve.
Gas Type Solenoid Valve
Is an normally closed valve.The plunger is attached to the valve or is in the valve. When an electric current is applied to the coil. This opens the valve. The plunger is spring loaded so that when the current is turned off the spring forces the plunger to it's NC position, shutting off the gas.
A device that automatically reignites a pilot light if it goes out.
Is a time period built into the module that allows for a certain time to light or relight the pilot or main burner. If the time period is exceeded, the module will go into a lockout or shutdown.
A material or system that exchanges heat from one system or material to another. A device that efficiently transfers heat from one substance to another.
Heat Motor Controlled Valve
An electric heating element or resistance wire is wound around a rod attached to the valve. When the thermostat calls for heat, this heating coil or wire is energized and produces heat, which expands, or elongates, the rod.
High-Efficiency Gas Furnace
Hot Surface Ignition
This system uses a special product called silicon carbide that offers a high resistance to electrical current flow but is very tough and will not burn up, like a glow coil
Heated air flows horizontally as it leaves the furnace. Return air enters horizontally at one end of the furnace, and supply air exits horizontally at the other end. (used where headroom is limited ie: attics)
Flame or Ignition Velocity
The rate at which the flame travels through the gas and air mixture. Is determined by the type of gas and the air-to-gas ratio.
Usually used with induced draft systems; pull or suck combustion gases through the heat exchanger. A single port burner made of aluminized steel that has crossover porting for good flame retention, proper flame carryover to each main burner.
Integrated Furnace Controller (IFC)
Controls the ignition sequence of operation of most modern gas furnaces.
Used when the furnace does not light or does not sense a flame. The heat exchanger must be purged of residual unburned gas or combustion byproducts from the previous unsuccessful ignition attempt.
A safety control that automatically shuts off a furnace if it gets too hot. Also controls blower cycles.
Liquid Filled Remote Bulb
Includes a diaphragm, a tube all filled with a liquid, usually mercury. The pilot flame heats the liquid, the liquid expands, causing the diaphragm to expand, which closes contacts wired to the gas valve.
Is liquified propane, butane, or a combination of propane and butane. When in the vapor state these gases may be burned as a mixture of one or both of these gases with air.
Is a time period built into the module that allows for a certain time to light or relight the pilot or main burner. If this time is exceeded, the module will go into either a soft or hard lockout.
A furnace that is approximately 4 ft high. It is used primarily in basements installations with low head room where the duct work is located under the first floor. Air intake and discharge are both at the top.
A device where multiple outlets or inlets can be controlled with valves or other devices. Our industry typically uses this with orifices for gas burning appliances.
Is much lower than 1 psi and is expressed in inches of water column (in.WC). One inch of water column pressure is the pressure required to push a column of water up 1 in. One psi of pressure will support a column of water 27.7 in. high or 1 psi = 27.7 in. WC Natural 3.5 in. WC: LP 11 in. WC
Natural gas composed of 90% to 95% methane, a combustible hydrocarbon.
Modulating Gas Furnace
Uses a modulating gas valve instead of a staged gas valve. Uses a variable-speed warm air blower to vary the speed and amount of warm air. Two stage combustion blower motors are standard on most modulating gas furnaces. An IFC is also used.
Multi-Poise (multipositional) Furnace
Can be installed in any position. They can be upflow, downflow, horizontal right, or horizontal air discharge.
fossil fuel formed from marine organisms that is often found in tilted or folded rock layers and is used for heating and cooking
Non 100% Shutoff
A system is non-100% shutoff when there is a failure in the flame-proving device system and the main gas valve shuts down but the pilot valve continues to bleed gas.
Is a precisely sized hole through which the gas flows from the manifold to the burners. Is located in the spud. The spud is screwed into the manifold. This allows the correct amount of gas into the burner.
Allows the combustion blower motor to operate for a certain time period after each heating cycle. This control strategy. along with a Pre-Purge, is double insurance that the heating cycle will start with only air in the heat exchanger, allowing a quick and safe light-off.
This control scheme allows the combustion blower motor to run for 30 second to clear or Pre-Purge the heat exchanger of any unwanted flue gases, household fumes, or dust that may have accumulated during the last heating cycle.
A sensitive pressure regulator located inside a combination gas valve that senses the outlet or working pressure of the gas valve.
Single-Rod (Local) Sensing
Single-rod, or local, sensing consists of an igniter and a sensor all in one rod. It is often referred to as a one-rod pilot, Single-rod flame rectification systems use a single-rod to accomplish both ignition and sensing.
Is a gas valve and an electronic control module in one package.The electronic module and gas valve are in one enclosure. This valve combines the features of an IP system and an HSI system in one.
Is a time period built into the module that allows for a certain time to light or relight the pilot or main burner. If this time period is exceeded the module will go into a semi-shutdown for a certain period of time, but will eventually keep trying to relight the system.
Spark to Pilot (Intermittant Pilot) Ignition
A spark from the electronic module ignites the pilot, which ignites the main gas burners. The pilot burns only when the thermostat calls for heat. This system is popular because fuel is not wasted with the pilot burning when not needed.
Pilot flame that remains burning continuously.
Consists of two dissimilar metals welded together at one end, called the "hot junction." When this junction is heated, it generates a small voltage across the two wires or metals at the other end.
Consists of several thermocouples wired in series to increase the voltage. If a __________ is used, it performs the same function as the thermocouple.
This furnace stands vertically and needs headroom. It is designed for the first floor installation with ductwork in the attic or for basement installation with the ductwork between or under the first floor joists.
Variable Output Thermostat
Venting Products of Combustion
Water Column (W.C.)
The pressure it takes to push a column of water up vertically. One inch of water column is the amount of pressure it would take to push a column of water in a tube up one each.
A device that uses a column of water to measure low pressure in air or gas system.
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