Forced Hot air Heating System's

Gate City Sheet Metal Home

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Forced Hot Air Heating Systems

Is Your Furnace Obsolete ?

Until recently, gas furnaces have not been able to utilize an efficient proportion of the heat they produce. Many of the gas furnaces in operation today waste up to 40% of the heat they generate! This means high gas bills. All furnaces today are rated for their fuel efficiency through a standardized rating system known as the Annual Fuel Utilization Efficiency Rating or A.F.U.E. The efficiency of every furnace is measured by its ability to utilize the heat it produces.

A furnace with an A.F.U.E. of 80 means that 80% of the fuel used by the unit actually goes toward home heating. Twenty years ago, even the best furnaces were capable of achieving A.F.U.E.s of only 60% to 80%. Ten years ago 90%+ furnaces were the best on the market , Today high efficiency furnaces operate at A.F.U.E. levels up to 97%!

GAS FURNACE

A gas fired warm air furnace uses natural (city) gas or propane burned in an open or sealed chamber to heat an exchanger, and with the help of a blower or fan, move air across the exchanger into ductwork to heat the space. It’s basic components are: a gas valve, burner assembly, heat exchanger, blower, and cabinet.There are a number of unique combustion chamber and heat exchanger designs for gas furnaces, but they are copyrighted or patented by different manufactures and will not be described in detail. Efficiency of a gas furnace corresponds to the type of burner. Some open burners use a standing pilot or electronic ignition, and draft naturally through the heat exchanger into a hood and smoke pipe, and are usually 80% efficient or less. Other open burners use electronic ignition and a ventor motor to meter the exhaust gases through the heat exchanger and into a chimney, and are 80-90% efficient. Condensing gas furnaces use a sealed chamber, a condensing coil to extract as much heat from the exhaust gases as possible, and a ventor motor to meter the flow through the exchanger, then vent into PVC pipe. This furnace has an efficiency rating over 90%.Accessories that can be installed inside or outside the furnace are: a fan center to turn the blower on independent of the heat cycle, an air filter, electronic air cleaner, high performance media air filter, humidifier, and an evaporator coil for central air conditioning, Sometimes a condensate pump will be used to dispose of the water generated in the dehumidification process of the air conditioning, or the condensing of exhaust gases from a high efficiency furnace.A Zone control panel and motor actuated dampers will be attached to the furnace or ductwork if the system is zoned. Routine maintenance includes: monthly filter replacement or washing the electronic air cleaner grids when in constant use, and cleaning the humidifier if so equipped. A properly functioning gas burner will not need cleaning. Black soot is evidence of an incorrect air mixture or other malfunction, and should be checked by a qualified serviceman.

Basic trouble shooting:

1. Check that the thermostat is set higher than the actual room temperature. If you have a programmable thermostat, make sure it has fresh batteries.

2. If equipped with central air, or the system is zoned, Make sure the selector switch is on heat.

3. Check the emergency switch( usually a red switch plate at the top of the cellar stairs or on the side of the furnace) to see that it is on.

4. If you are familiar with the fuse or circuit breaker panel, see if the fuse is burned or the breaker tripped. Correct the problem once. If it repeats, call a serviceman.

5. On standing pilot furnaces, the burner will not light if the pilot has gone out. If you are not familiar with the function of the gas valve or lighting the pilot, call for service.

6. Furnaces with electronic ignition have a sequence of safety steps the burner takes to light. Information is usually attached to the inside of the burner or blower access door. Follow the procedure according to the manufacturers guidelines to avoid the risk of fire or explosion.

7. Do not disconnect any piping to check for gas supply. An instrument is used to check for pressure, and should be done by a qualified serviceman.

8. If the furnace is vented through PVC (white plastic pipe) out the side of the building, examine the ends of the pipe or pipes outside. Blockage of any kind will cause a shutdown.

FORCED WARM AIR

There are two basic ways of heating a home; radiant heat room by room, or a central heating system. Radiant in each room can be electric, wood stove, gas heater , kerosene, coal, a fireplace, etc. Central systems can be hydronic or forced warm air. A forced warm air system uses ductwork to distribute heated air from a source (furnace or air handler) to each room. The furnace can produce heat from any number of fuels; gas, oil, electricity, wood, or coal, or a combination of any fuels. An air handler will use a hot water coil to produce heat. Unless fresh air is piped in from outside of the home, the system will re-circulate 100% of the air it supplies. This means it must obtain air from the home by way of a return air duct or ducts. Properly installed, a warm air system becomes a loop by which air is drawn from the living space through return ducts to the furnace, heated, and sent back to the same space through supply ducts. The advantages to this type of heating system are numerous. The air can be heated, cleaned, sterilized, humidified, or cooled (central air conditioning). If return air ducts are strategically located, the will reduce heat loss by recycling the warmest air back in to the system that collects at upper areas of the house. Supply ducts located around the outside walls of the rooms will temper the cold air as it infiltrates the home and reduce any discomfort from the air flow to a minimum. The disadvantage is that ductwork takes up space. When installed by an experienced contractor, the ductwork will take up minimal or no extra space, and literally disappear into the framing of a house.

ELECTRIC FURNACE

An electric furnace uses resistance calrods to create heat directly in the air stream. Inside the jacket or cabinet will be controls, a blower, and the circuit breakers for the heating elements. Some furnaces have the breakers accessible from the outside of the cabinet. It’s basic components are; the cabinet or jacket, a blower, heating elements, and controls. Accessories can include: an air filter, electronic air cleaner, or high performance media filter; humidifier, or air conditioning evaporator coil. A system with central air might have a condensate pump to remove the water generated in the dehumidifying process of the air conditioning. A zone control panel and motor actuated dampers will be attached to the furnace or ductwork if the system is zoned. Routine maintenance includes monthly replacing the air filter or washing the electronic air cleaner grids during constant use, and cleaning the humidifier. Humidifiers can be of the steam generating type, which will be line voltage powered, and should be shut off before servicing. Deadly high voltage conditions exist inside the cabinet; leave control servicing to a qualified technician.

Basic troubleshooting:

1. The thermostat must be set higher than the actual room temperature. If the thermostat is programmable, be certain it has fresh batteries.

2. If there is central air, or the system is zoned, make sure the selector switch is on heat.

3. If you are familiar with the fuse or circuit breaker panel, check for blown fuses or tripped breakers. Correct the problem once. If it repeats, call a serviceman.

4. Do not attempt to service the controls inside the cabinet. Deadly high voltage conditions exist.

OIL FURNACE

An oil fired warm air furnace uses no.2 fuel oil burned in a sealed chamber to heat an exchanger. Then with the help of a blower or fan, forces air across the exchanger, into ductwork to warm the structure. It’s basic components are: the burner, heat exchanger, fire box, blower, and cabinet, sometimes known as the jacket. Accessories that can be installed inside or outside of the unit include: a fan center(usually a low voltage relay that can turn the blower on independent of the heat cycle), an air filter, electronic air cleaner, or high performance media filter, humidifier, and air conditioning evaporator coil . With central air, sometimes a condensate pump will be used to remove the water discharged in the dehumidification action of the air conditioning. A zone control panel and motor actuated dampers will be present on the furnace or ductwork if the system is zoned. Routine maintenance includes; monthly filter replacement or washing the electronic air cleaner grids when in constant use, cleaning the humidifier if so equipped, and an annual tune up of the burner. An oil burner tune up includes a nozzle and filter replacement, heat exchanger and smoke pipe cleaning, and a fuel to air mixture adjustment. Since the mixture adjustment requires the use of special instruments to meet federal standards, it is best left to a professional to obtain peak efficiency.

Basic Troubleshooting:

1. First check that the thermostat is set higher than the actual room temperature. If you have a programmable thermostat, check that it has fresh batteries.

2. If equipped with central air, or the system is zoned, make certain the selector switch is on heat.

3. Check that the emergency switch (usually a red switch plate at the top of the cellar stairs or on the side of the furnace) is on.

4. If you are familiar with the fuse or circuit breaker panel, see if the fuse is burned or the breaker is tripped. Correct the problem once; if the fuse blows or breaker trips again, call a serviceman.

5. If you can access the burner, check the red button on the protecto relay. Older furnaces will have a stack limit switch mounted on the smoke pipe that connects the furnace to the chimney. Push the button one time only. Repeated attempts to fire the burner without ignition can create an explosive condition. If the burner fails to fire and continue running on its own, call for service.