FAQ

What is the importance of HVAC system design?
Why should you care about load calculations?
What can I do to maintain my existing system?
How often should I change filters?
What does an air cleaner do?
What can I do to maximize comfort and efficiency?

What is the importance of HVAC system design?

Most of us don't think about "design" when we think of heating and cooling, but it's just as important as a solid architectural design. A professional HVAC contractor won't simply replace what you have now with new equipment. It's possible that your existing system wasn't sized properly to begin with!

To make sure your new HVAC system meets your needs for comfort and energy efficiency, a quality contractor performs a series of calculations that take into account the overall climate where you live; how your home is sited (for example, if it faces south or north); the amount and quality of insulation in walls, basement or crawl space, and attic; how many windows the home has and how efficient they are; other sources of ambient heat, such as kitchen appliances and lights; even landscaping near the house.

These are called "load calculations." The formulas, which are included in ACCA's Manual J©, were developed by HVAC experts at ACCA and are the industry standard, often incorporated into local building codes.

Why should you care about load calculations?

It's simple: an under-sized system can reduce the comfort of your home, use more energy, and not last as long as a properly sized system. An over-sized system will cost more than you need to spend and may contribute to moisture-related problems down the line.

Any contractor who tells you a load calculation isn't important is not a professional. The professional understands that your year-round comfort is the ultimate goal. In the summer, your air conditioning system not only cools your home's air (sensible cooling), it removes moisture (latent cooling). In the winter, your heating system must keep you comfortable without causing high utility bills.

Insist that the contractor uses the Manual J residential load calculation procedure. He or she will produce a computerized analysis that indicates just how much heating and cooling capacity your new system should provide. After the installation of your new system is completed, you will receive a copy of the load calculation for your records.

The load calculation also enables the contractor to select the right kind of system. Heating and air conditioning equipment comes in many capacities, configurations, and efficiencies. It's important that your contractor selects the equipment that will be compatible with your home's heating and cooling needs.

Keeping your heating and cooling systems in good working order means your utility bills will be lower, your home will be more comfortable, and you'll need to call for repairs less often.

What can I do to maintain my existing system?

Schedule a maintenance service call before the heating season starts. If there are any problems with your system, it's better to find out before it's freezing outside! Do the same for your cooling system before sweltering season begins. Our maintenance customers always receive priority service during peak heating and cooling seasons.

DIY System Checks

• If you have a forced air heating system check your furnace's blower compartment and blower coils. Vacuum them if you see dirt and dust there. You should also check fan belt tension, and lubricate fan and motor bearings.
• If you have a steam system, check the shut-off valve for leaks.
• Bleed hot water system radiators at least once a year.
• Don't keep clutter near your furnace. It's a fire hazard, and may keep your system from operating efficiently.
• To make sure you're getting the most out of your heating system, keep the heating registers and vents throughout the house free of dust, dirt, and pet hair by vacuuming them at least once a year.
• Listen for odd sounds when your heating or cooling system kicks in. If you hear anything unusual, get in touch with your service professional so you can head off problems before they become serious.
• In winter months, set your ceiling fan at its slowest speed and reverse it in order to gently push warm air down from the ceiling without generating a breeze.

How often should I change filters?

A dirty filter can decrease the efficiency of your system by as much as 30%! A dirty filter also puts strain on the system and can cause premature failures. If your filter is dirty, imagine what the inside of your system looks like. That can lead to expensive maintenance. 1" disposable filters should be replaced once a month. Media filters should be replaced once every 6 months.

What does an air cleaner do?

At its most basic level, an air cleaner filters out the particles that cause irritation, such as pollen, spores, dust, and other contaminates. In order for any air cleaner to work correctly, the particles need to pass through it. Hence, if the particles are not in the air stream (for example, they're dust on furniture), an air cleaner won't remove them. However, a good air cleaner will:

• Remove allergy-causing particles that pass through it.
• Perform well consistently.
• Be economical to maintain.
• Handle a large volume of air efficiently.

Each kind of air cleaner has its pros and cons, which may differ depending on your air-cleaning requirements. Take a look at what your needs are based on your dwelling and allergies and talk to your professional HVACR contractor about the best kind for you.

What can I do to maximize comfort and efficiency?

Are you getting the most for your comfort dollar? Or are you paying to heat and cool the neighborhood?

Whether your comfort system is old or new, in a new or old home, in an apartment or a single-family home, there are many little things you can do to optimize its efficiency and minimize your utility bills. They're definitely worth the small amount of time and expense they take, because in the long run, they'll save you money.

Outside

Whatever the season, you want to keep your comfortable air inside the house. That means caulking and weather stripping doors and windows, around chimneys and flues, and anywhere else inside air can escape. Be sure to check for cracked or broken shingles, crumbling grout, and worn or torn vapor barriers, too.

Inspect the exterior of your home once or twice a year. A good way to remember is to do it when you have your regular, professional HVAC check-up because heating and cooling will be on your mind anyway.

If you're building a new home or replacing windows, invest in vinyl-or wood-clad insulated (thermopane) windows and storm windows and doors. Then keep them closed whenever the heat or air conditioning is on!

Keep vegetation and debris well away from the outdoor unit of your system. They can block air flow, which forces the system to work harder to produce the same level of comfort. You'll spend more now...and in a few years, when the equipment fails prematurely and you have to replace it. However, use vegetation to keep your home cooler in summer and warmer in winter. For example, plant a row of trees on the side of your home the wind usually comes from. They'll act as wind blocks. Because deciduous trees lose their leaves in the winter, they'll let in the sun's light and warmth in winter; in the summer, they provide cooling shade. Do, however, be careful about how close you plant anything to the house, and take into account that trees and shrubs grow. They can block light, and in some areas of the country become highways for such pests as carpenter ants. A local landscape architect, reputable garden center, or the state or county extension agency can help with plant selection and placement.

Inside

Set the thermostat at the highest comfortable level in the summer and the lowest comfortable level in the winter. A change in one degree changes energy consumption by about 4%. Humidifiers and dehumidifiers can make a huge difference in how the temperature feels.

Install a programmable thermostat. It will automatically adjust the temperature at night or when you're not going to be home for a long period of time.

Lights are a source of indoor heat, a problem in the summer. Wherever possible, replace incandescent bulbs and fixtures with compact fluorescents. They use a lot less energy, produce less heat, and last longer. Today's fluorescents aren't like those of only a few years ago – you can choose a warm, yellow light similar to incandescent light. You can use them in table lamps, ceiling fixtures (including ceiling fan fixtures), torchieres, and for indoor and outdoor lighting. Some can be used with dimmer switches, too. Avoid halogen lamps. The light is clear and bright, but they create a lot of heat.

In the summer, keep drapes and blinds closed on the sunny side of the house during the day. In the winter, open them to take advantage of solar heat but close them at night to help block cold air (even if you have insulated windows).

Insulate attics, crawl spaces, basements, and walls to the R value recommended for your area. Your HVAC contractor can tell you how much you need. Don't forget to insulate duct work in un-conditioned space.

Use a gas fireplace or put glass doors on a wood-burning fireplace. (Be sure to check with the manufacturer first – some small fireboxes with zero-clearance flues cannot be outfitted with glass doors.) Keep the damper closed whenever you're not using the fireplace.

In the summer, do household chores during the coolest part of the day if you can. Cooking, laundry, washing dishes, and heavier work such as vacuuming are examples. Check to see if your electric utility offers time-of-day pricing. That could save you even more money.

HVAC System

Check filters regularly and clean or replace them when needed. Your HVAC technician will tell you how often that's likely to be based on the manufacturer's recommendations and local air quality conditions.

Make sure room vents are working properly. Close them at least part-way in rooms you're not using. Never block them with furniture, pictures, or window coverings. Consider a zoned system if your home has two or more stories or is very large. A programmable thermostat in each zone can save energy and money.

Then sit back, relax, and enjoy year-round comfort!

© Air Conditioning Contractors of America Association, Inc., www.acca.org. Reprinted with permission.