High-efficiency gas furnaces feel cooler
High-efficiency gas furnaces discharge cooler air into living spaces compared to older furnaces. You’ll get used to the cooler temperature, and the energy savings of up to 40 percent should help “temper” your feelings toward the new fu rnace. Because your new furnace is more efficient, you may wish to raise the temperature setting a few degrees, allowing more comfort at little additional cost.
The discharge temperature is lower because the furnace uses almost all of the available energy in the gas it burns. This lowers the temperature that’s required to transfer heat from the products of combustion into the air circulated in your home.
You may feel a draft as this cooler air discharges at a greater speed from the supply duct grills. If this draft is a major problem, consider installing a plastic air deflector to redirect the air discharge. If air is not directed toward your skin, you will not feel a draft.
Another possibility: ask your heating contractor to check that the furnace and the fan speed were set up properly. If you notice a draft at one particular register, the contractor can lower the flow to that register.
Some top-of-the-line furnaces also have variable-speed fans and variable heating rates to adjust for this “draft” problem. Have the contractor make sure that all the settings are correct.
Heating and cooling adjustments-forced air furnace
Warm air rises; cooler air sinks. Keep this principle in mind, and you’ll realize why opening the correct air returns in winter and summer will provide better air distribution-which, in turn, allows more even temperatures in your home.
When you use a forced air furnace for summer cooling, you should open the high returns. This allows the furnace to take warmer air from the top of the room back to the air conditioning cooling coil in the furnace. In the winter, open the low returns to collect cold air at the floor.
For a two-story home, you may also need to adjust the supply air for winter and summer. In the winter, warm air rises to the second floor, so less heating is required there.
In the summer, warm air still rises, and a hot attic adds even more heat, so you need greater cooling (air flow) to the second floor than to the first floor.
The best way to control air flow is to adjust the small dampers in the heating/cooling duct system in the basement. Often, these dampers are found where round supply duct runs connect t o the main (rectangular) ducts. Look for small (¼-inch) threaded rods and wing nuts. You can adjust the damper by turning the screwdriver slot on the small rod. When the slot is parallel to the duct, the damper is fully open. You don’t need to adjust the wing nut, which simply locks the rod into place.
Heating ducts vary. Some systems have levers indicating the direction of the damper. Some rectangular ducts have dampers and levers.
To adjust air flow for summer cooling, start by fully opening all second floor dampers. Next, partially close dampers to first floor rooms that are getting lots of cold air. You will find that closing the damper to 50% or turning the shaft to 45 degrees will only partially slow the air flow. Often, even if you fully close the damper, there will still be air flow because the dampers fit very loosely in the ducts.
Closing first floor dampers will direct air to the second floor. rk your damper settings for summer and winter once you have found the correct balance.
Remember to clean the furnace filter, too, because a plugged f ilter can also restrict air flow.
Older homes were not built for cooling-the supply and return ducts to the second floor may not be adequate-so adjustments may not solve the problem. A quick fix may be to run the fan furnace continuosly.
Furnace air filters and maintenance
How often should you change the filter on the furnace? Whenever it’s dirty. And although it sounds a little silly, better filters get dirty more quickly and need to be changed more often.
A standard cheap (about $1) fiberglass air filter should be checked once a month and changed when it shows visible dirt. You also need to check the filter when running the central air conditioner, because air circulates through the furnace and the filter.
I suggest you replace the cheap fiberglass filter with a pleated paper filter. You will find them in any hardware or building supply store next to the standard filters. Read the labels-some are more efficient than others. Price will vary from about $3 to $15. These filters will trap much more dirt and smaller particles of dirt. They need to be changed more often because they do a better job of trapping dirt.
The next level up from standard throw-away filters are washable filters and electrostatic washable filters. Washable foam filters work quite well if coated with a special sticky spray like Filter Coat. Electrostatic filters are relatively expensive (about $100), but they do trap dirt well.
A better filter is the 6-inch-thick pleated paper filter. Air is forced through a long accordion of filter paper. Fine holes in the paper trap small particles of dirt. The large surface area limits pressure loss in the heating system. A special frame needs to be installed in the duct work, and the filter costs about $25, but it will last one or two years.
The top of the line is an electronic filter that charges metal plates in the air stream and attracts dust. This is the only type of filter that actually removes smoke particles from the air. This filter costs about $700 installed. Filter plates must be washed monthly in the dishwasher or by hand with soapy water.
I consider the pleated paper filters a good investment. The more expensive electronic filters are great for people with allergies or sensitivity to dust.
Service requirements for older furnaces
If your warm air furnace is old (say, 20 years or older), I suggest you have a professional heating contractor servi ce it every year. This is your best protection against carbon monoxide dangers and heating problems. Routine service will also ensure peak efficiency to save you operating costs.
A good service and inspection costs about $80 and should include a complete cleaning, safety check, and tuning.
The service contractor should:
- clean the burner and heat exchanger, and inspect for cracks.
- remove the burners, clean them, and tune for proper combustion.
- perform a carbon monoxide test in the heat exchanger.
- check the vent pipe and draft diverter.
- inspect the chimney for obstructions and draft.
- check vent pipes for proper clearance and materials.
- test fan controls and safety controls.
- check the thermostat.
- run the furnace through a complete cycle.
- check flame roll-out.
- check gas pressure (if appropriate for your furnace).
- clean and adjust the pilot light assembly.
- inspect gas fittings and repair any leaks.
- lubricate the fan and motor.
- check belt condition and tension.
- service the filter.
- clean the fan and housing if excessive dirt has accumulated.
Replacing parts or cleaning extensively will cost extra.
You should have a basic understanding of how the system works, so ask the service contractor to explain the basics. You should routinely service the filter and lubricate the fan and motor a second time during the heating season. You should also inspect the flue connection to the chimney.
Noises from the heating/cooling system
You may have noticed unexplained noises from your central heating/cooling system. What causes them, and what can you do about them?
A typical problem: when the air conditioning starts, there is often a loud “pop” from the ductwork. This may not occur when the furnace switches on.
When the central air conditioning runs, the furnace fan must move more air through the system than when the unit is used for heating. Often the fan will automatically run at a higher speed for greater volume and pressure.
Because of this increased pressure, the duct work is more likely to pop outward slightly. You can locate the problem area by listening for the sound and watching the ductwork when the air conditioner starts up. You’ll probably notice movement and sound in the large, flat pieces of sheet metal near the furnace.
When you find the duct that is moving or popping, reinforce it with a small brace-screw a l ightweight angle iron into the sheet metal over the part that is moving.
Now, how about noises you hear from your forced-air furnace? When the heating system starts and runs for a few minutes, there is often clicking and slight pounding of the ductwork in the basement.
This problem occurs as the metal ductwork heats up. The expanding metal needs room to move. The ductwork is trapped between the framing members of the house. Watch and listen for the problem area(s) as the furnace runs. You may need to loosen mounting brackets or adjust ductwork that is forced against wood framing.
Central air conditioner: to cover or not to cover?
Your central air conditioning unit consists of a compressor and condensing unit placed outdoors in a metal housing. These units, built to resist the weather, generally do not need a cover. In fact, covers can cause problems because they trap moisture and create an inviting winter home for small animals.
Professionals who service the units tell me that most of the damage they see in spring was caused by rodents living in the units and chewing on wiring.
If your air conditioner is subject to falling ice or other debris, you could cover its top with a piece of plywood, plastic or metal held in place by a weight.