Energy Source - Gas
All burning fossil fuels have certain common elements.
1. All require adequate airflow into the "firebox" to provide enough oxygen for complete burning of the fuel.
2. All require adequate airflow out of the "firebox" (through the vent and/or flue system).
3. All produce combustion byproducts containing toxic gasses to some extent--more if badly adjusted or improperly ventilated.
These combustion byproducts are designed to be contained in the heat exchanger and venting system to prevent these toxic substances from contaminating the household air. CRACKS OR HOLES IN HEAT EXCHANGERS CAN ALLOW THIS LIFE THREATENING SITUATION TO OCCURE. HEAT EXCHANGER FAILURE USUALLY REQUIRES REPLACEMENT OF THE FURNACE--REPAIRS ARE RARELY POSSIBLE COST EFFECTIVELY. REGULAR MAINTENANCE BY QUALIFIED PERSONNEL MAY POSTPONE OR PROVIDE EARLY DETECTION OF THESE CONDITIONS. Newer and/or high efficiency units frequently have sealed blower compartments, jet-style burners, fan-assisted drafts, and other closed areas, which may not be visually inspectable at all.
•Gas (by far the most common fuel in our area) should burn with a clear blue flame for most complete combustion. While flickering orange may not be a concern (this can be burning dust particles), a yellow flame can indicate incomplete combustion (producing carbon monoxide instead of the normal carbon dioxide). Carbon monoxide (please see our page on carbon monoxide) is a colorless, odorless gas that can result from a faulty fuel burning furnace, range, water heater, space heater or wood stove. Proper maintenance of these appliances is the best way to reduce the risk of carbon monoxide poisoning. For more information contact the Consumer Product Safety Commission at 1-800-638-2772 for further guidance. It would be wise to install carbon monoxide detectors within the home.
Ignition should be clean--any loud pops when lighting or extinguishing, flames "whooshing" out the front of the chamber or rapid on/off cycles indicate a need for proper service. Note: Gas furnaces produce heat and water vapor (one of the combustion byproducts) inside a metal "firebox". This is a perfect recipe for rust. While proper maintenance, cleaning and adjustment can prolong life, eventually rust out and thermal stress may well cause heat exchanger failure.
An ounce of prevention is worth more than a pound of cure--proper maintenance of these machines by you and regular service by qualified personnel familiar with your make and model every year or two can yield big dividends in better operation and longer life!
Forced Air Heat
FURNACES GENERALLY HAVE LIFE EXPECTANCIES OF APPROXIMATELY 20 YEARS. PROPER UNDERSTANDING AND MAINTENANCE CAN PLAY A LARGE ROLD IN MAXIMIZING LIFE, BUT THERE ARE NO GUARANTEES. FAILURE CAN OCCUR AT ANY TIME.
How it works-- Air returning from the rooms of the house through the return duct system is drawn to the unit by a blower fan inside the main housing. After passing through a filter of some type to remove dust and other particles the air is forced around a heat exchanger ( a steel box enclosing the actual heat source). The air is warmed by heat conducted through the walls of the heat exchanger and is then forced out of the furnace through the plenum into the main truck ducts and out into branch ducts servicing the rooms through registers.
Air Delivery--Most thermostats have similar controls. A switch with "auto" and "on" settings usually controls the blower, which regulates airflow. In "auto" the blower only operates when actively heating or cooling. In "on" it will circulate air constantly (frequently contributing to more even temperature distribution and better air filtration). There is usually a second switch with "heat-off-cool" setting which, combined with the control to set the desired temperature, tells the unit what to do. NOTE: Since we don't want the blower starting to circulate cool air there is frequently a delay between the thermostat igniting the burners and the blower starting to circulate air to allow it to warm up first. Opening or closing the louvers on the registers into the rooms can adjust the airflow, and sometimes duct dampers are found on the ducts near the furnace, which allow air to be diverted to the upper or lower portions of the system. (Frequently, warm air is directed to the lower areas in the winter and cool air is directed to the upper areas in the summer to take advantage of the natural convection that causes warm air to rise and cool air to fall.
Humidifiers generally fit into three categories--those that spray water directly into the top of the furnace (atomizing), those that utilize a basin to hold water and use a rotating medium inside the basin to deliver water into the air stream (rotary medium) and those that drain water through an internal screen, blow air through the screen and drain the excess water out of the unit (flow-through). Be wary of any humidification introduced directly above the unit. Leaks can cause premature rustout and shortened life on all types of equipment. If you choose a central humidifier try to locate the humidifier on a trunk duct several feet away from the air handler. All humidifiers can incubate mold and mildew, which can cause odors and contribute to allergies. Consider using in line filters or water treatment chemicals containing algaecide and mildewcides along with regular maintenance to control this. Humidifiers tend to build up scale and mineral deposits quickly which can cause valves to clog, floats to stick and can prevent moving parts from turning freely. All humidifiers should be disassembled and cleaned with vinegar and water solutions on all sensitive areas every 2-3 months during the heating season. Be careful to disconnect power and to avoid getting the motor wet. Bypass style units seem to require less attention than most but all are vulnerable and should be watched.
Electronic Air Cleaners - Electronic filters can be very effective at cleaning dust, pollen, and other airborne particles from the air contributing to better health and greater comfort for the inhabitants, as well as better operation and longer life for your air conditioner.
AIR CONDITIONER LIFE EXPECTANCY IS GENERALLY 10-15 YEARS. IT IS USUALLY THE EXTERIOR UNIT (CONTAINING THE COMPRESSOR) WHICH FAILS. PROPER UNDERSTANDING AND MAINTENANCE CAN PLAY A LARGE ROLD IN MAXIMIZING LIFE.
How and Why It Works - air conditioners seem complex but the operate on a very simple principle. Here is an illustration:
1. We all know that spray deodorant is a liquid at room temperature while still pressurized in the can. When we spray it out however (dropping the pressure) it changes to a gas and it gets cold. WOW!
2. We also know that when we raise the pressure on a material, even if no heat is applied it gets warmer. WOW!
This relationship between pressure, liquid/gas state and temperature is the basic mechanism by which the air conditioner operates. Using special tubes to circulate a chemical between a coil inside the house and one outside the house and by increasing or decreasing the pressure in the proper places (and therefore altering the temperature), air conditioners perform the cool part of the cycle inside the house, and put the warm part outside to dispose of the heat.
GOOD AIRFLOW IS CRITICAL both for proper operation and to protect against massive system failure. Keep the exterior coil clear of any obstructions--shrubs, toys, garden tools and so on--for several feet in all directions. Keep the coils in good repair - dents, dings, bent fins and so on can impair proper air flow. If the coil gets dirty from dust, lint from the dryer vent, or other sources have it cleaned for the same reason.
The interior coil is usually in the plenum (between the furnace and the main trunk duct). Again, good air flow is critical. CHANGING THE FILTERS ONCE A MONTH IS THE SINGLE MOST IMPORTANT STEP CAN TAKE TO MAZIMIZE THE LIFE OF YOUR U NIT!! Dirt which evades a dirty, missing or improperly installed filter will collect on blower vanes and on the coil, reducing airflow and shortening the life of the unit. Keeping supply registers and return grills unobstructed also contributes to better operation. If airflow is weak, check for dirty filters, blocked return grill or blower failure. These can all be corrected. If the culprit is poor ducting however, corrections may be difficult to perform effectively. If the amount of temperature change is less than the design prescribes, refrigerant levels may be too low and must be checked by a technician. Be sure to use the overcurrent protections that match the manufacturer's data plate. Failure to do so can have implications for warranties and fire insurance. This is frequently not changed to match a new unit when it is installed.
If the air gets very cold, very quickly, check for dirt on the filters and the coil. Too much cooling can mean that the air is remaining in contact with the chilled coil too long which is a sign of reduced airflow and may lead to premature failure of the unit. If humidity in the house remains high or water is collecting in and around the bottom of the interior of the unit the condensation drain may be clogged and need cleaning.