Managing Your Home's Systems - Heating and Cooling

Heating and Cooling Systems

FORCED AIR SYSTEMS
The duct system that circulates the air in a home is carefully designed to deliver the exact amount of air at the right temperature into the right sized space. There is a match between the heating and cooling loads and the air delivery. Because these loads will change with the seasons, there is a need to adjust the air delivery system seasonally.

During the winter season more air is directed to the lower levels and in the warmer months more air is delivered to the upper levels. This is accomplished by manipulating “duct damper” levers on the trunk lines and adjusting the register grill dampers.

Uniform air delivery along an entire ducted system is maintained by varying size ducts. The central trunk lines decrease in size as run-outs tap them to take air to various registers ensuring that the right amount of air is delivered. Existing ducted systems are difficult to modify or expand because changes will almost always mean additional taps or taps in newplaces which will lessen the pressure both at site and downstream from the new run-outs. This is why it is rarely advisable to finish a basement and try to heat and cool it with the existing duct system.

HEATING AND COOLING SYSTEMS
The U.S. Consumer Product Safety Commission (CPSC) and the National Propane Gas Association (NPGA) suggest the following safety tips for proper care of propane tanks in severe snowstorms:

• Use a broom instead of a shovel when clearing snow off the tank or around the exposed piping, regulator, gauges, or tubing.
• When clearing the roof, avoid shoveling snow onto exposed piping around the propane regulator near the building or onto the propane tank and piping, as well as any meters or other piping that may be in use.
• Check regulator vents on the propane system to be sure they are free of snow, ice or water that could freeze. (A two-stage system has a regulator on the tank and at the entrance of the propane piping to the building; a single regulator is on the tank.) If a regulator vent is clogged with ice or snow, contact your propane supplier immediately.
• Check all gas appliance exhaust and combustion air vents, such as dryer or furnace vents, to be sure they are kept clear of snow and ice.
  

• In areas where heavy snows are expected, cover the regulator, relief valves, and fill valves with a protective cap or "dome." This dome will keep out snow, ice, or rain which might clog the regulator if it freezes. In systems using more than one regulator, or where the cover is not in place, make certain the exposed regulator vent is in the downward position to keep out moisture.
• Prior to heavy snow storms, mark the location of the propane tank and other equipmentwith snow stakes which should extend well above the maximum anticipated snow depth. Consumers whose tanks and piping are not presently marked should mark them now.
  
  

NATURAL AND LP GAS
The most common gas heating equipment in residential use is natural gas. It is piped underground from a central system. Natural gas is very clean burning and needs very little service. An annual check-up of the system is recommended. There are some small but important clues to malfunction that could easily be overlooked. Be wise. If you notice such things as a yellowish flame (out of adjustment), condensation from chimneys (very cold climates), or dripping water from attached air conditioning equipment (during humid weather), call for service.

FUEL OIL
Fuel oil burners work by forcing oil through a tiny opening to atomize it and mix it with fan driven air to form a combustible mixture. The oil/air mixture gets out of adjustment as theopening wears. Poorly adjusted burners will quickly waste a lot of fuel, and under severe conditions can become dangerous. Adjustments and cleaning are definite necessities and require professional equipment. It is highly recommended that oil-burning equipment be kept under professional maintenance care. Your oil company may offer a maintenance contract. If not, mark your calendar to ensure regular service. It is a good idea to keep fuel oil tanks full during the off season. High relative humidity in summer air can condense inside cold earth temperature tanks and sink to the bottom. This is how burners shut off in the winter (since a line full of water will not sustain burning), and how tanks rust out on the bottom.

If you should find that your oil burner will not respond to the thermostat, first check your circuit panel to be sure there is electrical power flowing through the circuit breaker and that the emergency shutoff switch is set to the on position. If you are sure power is available check the burner on the furnace or boiler itself. Find the red “reset” button and push it. Call for professional service if the burner does not start running.

ELECTRIC HEATING
Thin wires will heat up as electricity flows through them. An example of this is the metal burners on the top of cooking equipment. Forced air systems use a series of resistance elements to heat air within ducting. The furnace wiring and controls should be checked yearly in such systems. These systems are especially vulnerable to dripping condensed water from air conditioning equipment. Electric baseboard units tend to collect dust from air circulating through them and should be cleaned every six months. These units can get very hot, so drapery and furnishings must be kept at least twelve inches away from them. Electric radiant units do not heat the air. They heat objects.

Electricity is not an efficient heat producer when used to energize resistance elements, although it is quite efficient when turning a motor. This is why electricity is used primarily for motorized systems, rather than as the basic heat producer for large areas, and why heat pumps are so efficient!

HEAT PUMP
If your home contains a heat pump system, you should be aware of the performance characteristics unique to these systems. As with any system, read the manufacturer’s literature and follow all instructions for efficient operation and maintenance of your system. Clean or replace filters once a month. Provide professional service for your system at least once every two years.

Keep the outside unit clear of any materials that would interfere with air circulation. Snow, ice, landscaping materials, trash, leaves, and other accumulating items can cause inefficiency or damage the unit.

A heat pump system operates differently from a gas forced-air furnace. The same system provides both heat and air conditioning. This is possible because a refrigerant flows back and forth in the coils of the heat pump,controlled by a reversing valve. In the heating mode, the heat pump removes heat from the outside air and transfers it to the inside air. In the cooling mode, it does just the opposite, removing heat from the inside air and discharging it outside of the home. The thermostat inside your home controls this heating or cooling activity.

Do not expect dramatic temperature differences in the air coming from the vents as is common with other kinds of systems. The coils used in a heat pump system operate at lower temperatures than those common in a gas forced-air system. As a result, for example, in the heat mode, air from the supply vents will typically range from 85 to 90 degrees F. The vents will not feel hot, though the air discharged is warmer than the air in the room by as much as 20 degrees.

At lower outside temperatures, less heat is available for the heat pump to draw from the exterior air. Therefore, from time to time the auxiliary heat system will come on to maintain the temperature you set at the thermostat. The auxiliary system will also come on whenever the temperature at the thermostat is moved 1.5 degrees or more at one time. If the light stays on when the outside temperature is more than 30 degrees F, contact a service person.

When the heat pump is operating in the heat mode, the coils outside may reach below freezing temperatures. Moisture in the air will condense into frost and accumulate on the coils under these circumstances. From time to time, the system will go into defrost mode to clear accumulated frost from the coils. This is a normal part of the operation of the system and will occur automatically. During the defrost cycle, the outside fan will stop temporarily. The temperature of air flow into the home will be a bit lower during the defrost cycle. The defrost cycle can only occur once every 90 minutes and lasts no longer than 10 minutes.

Unless you have a night setback thermostat designed to work with a heat pump system, do not turn the thermostat down in the evenings. Adjust the temperature a fraction of a degree at a time until a comfortable, permanent setting is found.

Registers will require adjustment from time to time to maximize your family’s comfort. Do not completely close off more than one supply register at a time. This can restrict the air flow too much and reduce the efficiency of the system. A good technique is to completely open all the vents, then gradually move the temperature setting up until the coolest room is comfortable. Once the coolest room is comfortable, gradually close the vents in the warmer rooms until all rooms are comfortable as well. Reverse the process for air conditioning.

As with any heating system, return air vents must be clear so the air flows through the ducts unimpeded. Avoid placing furniture where it blocks the return air vents.