Deciding when to purchase a new system
First of all, if your heating system is less than 20 years old, it should still have some life left in it. You can expect as many as 20 to 25 years of service from properly installed and maintained heating equipment. To help make this long service life a reality, it is a good idea to have your heating system inspected and adjusted on an annual basis. If your system is over 10 years old, then you should definitely place it on an annual maintenance program. Good preventive maintenance will ensure that your system runs safely and efficiently for a long time.

Eventually, however, an older system may need to be replaced. You should replace your heating system when it is no longer cost effective to keep it in good working order. Your heating system has reached this point if one of the following statements is true:

1. The heating equipment has an unsafe condition which can't be repaired
2. Your old system is so inefficient that a replacement would pay for itself in energy savings.

An unsafe condition can sometimes develop in an older furnace. This occurs when cracks or leaks develop in the heat exchanger. The purpose of the heat exchanger is to keep the hot exhaust gases separate from the warm air which circulates through the ductwork and house. When there is a leak in the heat exchanger, poisonous gases and carbon monoxide can accumulate in the house.

Although boilers are less likely to fail than furnaces, they can also develop unsafe conditions. For example, in a boiler a low water level can result when any one of several different components either malfunctions or fails. Most boilers have a safety device called a low water fuel cut-off, which is designed to shut down the boiler when this occurs. If the low water fuel cut-off is faulty or missing, then the boiler will overheat and will be permanently damaged.

It will not be as obvious when your heating system has become obsolete due to its poor efficiency. Efficiency can be measured, however, and you should have your system tested when an annual inspection is performed. If your heating system is operating below 70% then new equipment is available with substantially higher efficiency. For example, a new 90% efficient furnace will save 22% of the fuel use of a 70% efficient furnace. The amount of money you will save depends on how much you presently spend on energy for heating your house. This can be estimated by one of the following methods:

1. Review your natural gas, propane, or oil bills.

To elaborate on method number 2, there is a simple analysis that you can do to estimate your heating energy use from your fuel bills. If you heat with one of these fuels then compare your usage in the winter to your usage in the summer. Your summer use, if any, is for cooking, water heating, and clothes drying. These are pretty constant uses throughout the year. If you average your summer use and then multiply by 12, you have an estimate of your annual non-heating fuel use. Subtract this amount from your total fuel use to estimate how much fuel you buy per year to heat your home. Multiply this amount by the winter fuel rate to obtain your annual heating bill.

Before You Buy
Before you buy a new heating or cooling system there are several decisions you should make. If you don't or aren't able to make an informed decision then someone else will decide for you. That someone will probably be the heating and cooling contractor, who doesn't necessarily have your best interests in mind.

Choosing a fuel type
The table below lists all of the heating fuel types commonly used in homes in the United States. This data varies regionally; however, the order of precedence is consistent across regions with one exception. In the Northeast, fuel oil heat is more prevalent than electric heat; it is the main heating fuel in about 36% of homes.

Most likely, you will want to stay with the same heating fuel that your present system uses, but there are cases in which you should consider switching. If you live in a cold climate and have electric heat you can benefit by switching electric resistance heating controls from individual thermostats to central low voltage or electronic thermostats. Another option is to replace baseboard resistance heating units with a high efficiency heat pump that will provides winter heating as well as summer air conditioning. There has also been a tendency to switch from fuel oil or LPG to natural gas as pipelines are extended into new neighborhoods. Prices for these fuels fluctuate, so it is difficult to predict which would be less expensive. Some people switch to natural gas for the convenience of not having a storage tank and not having to schedule fuel deliveries.

Choosing a system type
The table below shows the prevalence of all of the common types of heating systems found in the United States. Nationwide, the warm-air furnace is by far the most popular type of heating system. The distribution of system types varies regionally, but the overall popularity trends are constant with a couple of exceptions. In the Northeast, steam or hot-water systems are slightly more prevalent than furnaces, and in the South, heat pumps are the second most popular system behind furnaces.

You will probably want to replace your existing system with a new one of the same type. This is usually the most sensible option, because fewer parts of the system have to be replaced. For example, switching from a warm-air furnace or heat pump to a hot-water system would require installation of a new hot-water distribution system. Air systems use ductwork and water systems use piping. Some of the system types, such as built-in electric units and floor, wall, or pipeless furnaces; do not have any form of distribution. These are called unitary systems. Switching to a central furnace or hot-water system would require installation of a duct or pipe distribution system.

Some homeowners will choose to switch from a unitary to a central heating system. For example, if you are switching from electric baseboard heat to a more efficient heat pump; the new system will also have the added benefit of providing air conditioning in the summer. Another option is to switch from electric baseboard to a central gas or oil furnace. This change requires a chimney or power ventilator to exhaust combustion gasses, it also provides the opportunity to add central air conditioning to a home. In the Northeast, homeowners often switch heating systems to forced hot water. This is an economic choice—it is usually easier and less expensive to install the water distribution system than ductwork in an existing home.

The common theme in the examples mentioned in the previous paragraph is a tendency to get away from unitary heating systems. These systems can be the most expensive to operate.The only benefit to this type of system is that you have individual room control so that you heat only the rooms that you occupy. In practice, this is not a realistic strategy for many homeowners.

Looking at fuels other than electricity, it makes sense to switch from a unitary system to a central system. Notwithstanding the benefit of individual room control, when talking about fossil fuel fired equipment, a large central system tends to be more efficient than several small unitary systems. Going from a unitary to a central system also makes it easier to add central air conditioning and humidity control, both of which make occupants more comfortable and add value to the home.

Choosing a contractor
Once you have a pretty good idea what type of system you want to install, it is probably time to talk to a contractor. Replacing a heating system is not a do-it-yourself project for most people. When choosing a contractor, you should keep in mind that contractors often have relationships with specific manufacturers. We discuss manufacturers in the "Choosing a model" section, but you may want to research the models available from various manufacturers first. Then make sure the contractors you talk to are willing to provide you with something very similar to the brand and model you want. If you follow our advice on choosing a model, you should have a few options in mind.

Choosing a contractor can be a frustrating process, but it is worth the effort in the long run. It is a good idea to get several quotes for any large project since prices can vary widely for the same job. Usually three quotes will be sufficient to determine a reasonable price. If possible, you should try and get quotes from equally qualified firms. The trick is determining which firms to approach. Here are some tips that will be helpful.

• One of the best ways to select contractors is to get referrals from friends or family who have had work done on their homes.
• Check each contractor's licensing for applicability to the job and length of time held.
• Ask if licensed technicians will be performing the work.
• Ask about the contractor's warranty. Workmanship should be covered as well as all materials installed by the contractor.
• Take advantage of a contractor listing service, which prescreens contractors, and can place you in touch with qualified firms.

Choosing a model
This is a tough one. Choosing a furnace or boiler is not like choosing a new television or computer. The public at large tends to be less familiar with the features and performance points that are important to a heating system than those of an entertainment system. The issues that should come to mind when choosing a model are price, performance, reliability, and features.

Price versus Efficiency
The price is important, but should not be the only consideration. Buying the least expensive heating equipment is usually not the best investment. It is a better idea to consider the operating cost of the equipment as well as the first cost. Because heating systems last for many years, the operating cost will greatly exceed the first cost of the equipment over its lifetime. If you buy a more efficient system, then over time the lower operating cost will more than pay for the higher first cost. Not only that, high efficiency heating equipment improves comfort and air quality throughout the home, and helps reduce air pollution.

Identifying High Efficiency Equipment
One easy way for consumers to differentiate high efficiency equipment is to look for the ENERGY STAR® Label. Heating and cooling products with the ENERGY STAR Label are produced by most major manufacturers and have the same features as standard products but also incorporate energy saving technology. Lists of ENERGY STAR labeled equipment are available on the Environmental Protection Agency's web page.

Manufacturer's product literature is a good source of efficiency information. Most residential heating systems are rated by Annual Fuel Utilization Efficiency (AFUE). The efficiency of heat pumps is described by its Heating Season Performance Factor (HSPF). However, it is common to see listed an equivalent AFUE for Heat Pumps. This information can be found in the product brochures and used as means to compare options.

Reliability
The heating system you choose today will probably still be around 25 years from now. To avoid frequent service calls and a lifetime of aggravation, you want to get reliable equipment. You should compare warranties offered on various makes and models and consider a good warranty from a reputable manufacturer to be an indication of a reliable product. At a minimum, you will be offered a 1-year limited warranty on your new heating equipment. Some manufacturers offer longer warranties, up to 5 years on the overall system and 20 years on heat exchangers. Others offer extended warranties at additional cost. On heat pumps, you should look for a minimum 5-year warranty on the compressor. Just remember that there are options, don't settle for a minimum 1-year warranty if you don't have to.

Another element of reliability is quality service and preventive maintenance. Be sure that there is a service company nearby that is qualified on the type of system you are purchasing. The best case would be to have factory-trained service technicians do all repairs and preventive maintenance on your system. Modern, high efficiency equipment is complicated, much like newer automobiles, and it takes a great deal of training in order to troubleshoot problems effectively and keep heating equipment in good working order.

Features and Specifications
When buying a new car, some people are interested in the horsepower and torque ratings, engine block materials, gear ratios, ignition controls, and traction control. Others pay attention to heated seats, cup holders, remote control door locks, and sound systems. The first group is wisely concentrating on the performance specifications, while the second is looking at features, which are important as well. A wise heating system shopper will compare the specifications as well as the features on a few models before choosing a system. You have to look at product brochures in order to learn about specifications and find out what features are available on which models. These brochures can be obtained from the manufacturers' web sites or from local heating and cooling contractors that sell the brands you are considering. The following list covers many of the specifications and features that differentiate one manufacturer's product from another.

• Efficiency—AFUE or HSPF
• Controls—burner controls, ignition controls, safety shutoffs, and thermostats
• Ignition system
• Burner type and number of heating stages
• Heat exchanger construction and material
• Venting requirements— power vented, gravity vent
• Air filter type—efficiency, how often changed, cost to replace
• Noise levels
• Blower motor type and speeds
• Warranty

What should be included in the work order or contract
Here is a list of things that you want to have addressed in your written agreement with a heating and cooling contractor. Not all of these items will apply to all projects and you may decide to do some of these things yourself. It is a good idea to make the contractor responsible for obtaining building permits and meeting building code requirements. Keep in mind that if it isn't in writing, the contractor is not obligated to do it. If it is put in writing, but ambiguously so, the contractor will do it the way he wants.

• Completion schedule
• Specifications on equipment and materials including brand names and model numbers
• Warranties on workmanship and products
• Contractor will hand over all equipment installation and maintenance manuals
• Names of any subcontractors who will be used—check references on these firms as well
• Contractor must obtain all required permits
• Contractor must contact Dig-Safe before outdoor excavating is performed.
• Contractor must remove the old heating system and all other construction debris and dispose of in accordance with federal, state, and local regulations.
• Details of what the contractor will do, including:
  • providing a system in good working order;
  • testing and balancing the distribution system;
  • replacing worn piping and ductwork as needed;
  • replacing thermostats, valves, dampers, registers, etc.;
  • cutting and patching ceilings, walls (interior and exterior), and floors, as needed;
  • providing a concrete pad for outdoor equipment;
  • refinishing surfaces to match original conditions;
  • waterproof sealing or caulking of any exterior wall penetrations;
  • flashing roof penetrations; and
  • anything else you expect the contractor to do.
• Perform all work in accordance with state and local building codes.

Other Thoughts
Your heating system actually may be a heating and cooling system. If you have a warm-air furnace and central air conditioning, it is likely that both use the same distribution ductwork. Furthermore, the same blower distributes warm air in the winter and cold air in the summer. Therefore, when you replace the furnace, you are replacing part of the air conditioning system. If you do this, you should give strong consideration to replacing the other part of the air conditioning system—the outdoor condensing unit. You will then benefit from a completely compatible integrated system which will provide better performance and reliability than can be expected from a mixture of old and new components.

There are other aspects to the heating system which have not been discussed. There are controls, such as thermostats, humidistats, aquastats, dampers, and control valves. There are other components such as air filters, humidifiers, and condensate pumps which are not part of the furnace or boiler but are important parts of the system. There is distribution ductwork or piping for central systems, and a chimney or flue for gas or oil systems. All parts of the system should be put in good working order when a new system is purchased. Definitely consider upgrading controls as they will have a lot of impact on how comfortable you are and how much energy you use.

Don't buy an oversized heating system. First of all, you should take care of all your weatherization improvements before buying a new heating system. This means adding attic insulation, sealing air leaks, and caulking and weather-stripping windows and doors. Then make sure that the contractor performs a heating load calculation on the house. The new system may not need to be the same size as the old one. When you make your home more weatherproof, one of the benefits is that your heating system doesn't need to be as big.

After You Buy
After you have selected a contractor and signed a work order or other agreement your responsibility turns to one of oversight. You should be focused on ensuring that the contractor fulfills all of his obligations.

Overseeing the construction process
It is not necessary to stand over the contractor's shoulder constantly while the work is being done. It is necessary to observe all aspects of the work and to be available to answer questions if the contractor runs into unexpected situations. When you are observing the work, think about the items in the contract. If the contractor seems to be deviating from the plan, don't be afraid to question it. Often, the contractor will have to improvise to make a new system fit into an old house. The contractor is usually the best person to decide how to make the new system work. On the other hand, if there is to be a serious deviation from the original plan (for example, the exact placement of the furnace, or where a hole will be cut in the exterior wall for the flue) you should be involved in the decision-making process. This is why one of the most important aspects of construction oversight is communication with the contractor.

Make sure that the contractor knows how to reach you and knows that you want to be informed immediately of any problems. Both you and your contractor have the same goal; to get the job done right the first time.

Starting up the system
System start-up includes turning on the heating equipment for the first time, testing the equipment, and balancing the entire system. You should be present for system start-up because this is when a lot of important activities take place which can not be seen after the fact. You also want the contractor to familiarize you with how the system is supposed to operate and what you should do if there is a problem. The contractor tests the system during start-up. This means that the heating equipment is run through its full cycle and the contractor takes various measurements to ensure it is functioning properly. You should expect the contractor to test all parts of the system including items that were not changed to ensure that the system as a whole will work properly.

The other important part of start-up is balancing. Balancing ensures that all of the rooms in the house will receive the right amount of heat. In water systems valves are used for balancing and in air systems dampers are used. You can pretty much assume that if your heating equipment is old enough to need replacing, your distribution system needs to be rebalanced. Rebalancing means adjusting dampers or valves until all of the terminal devices (registers and radiators) receive the amount of air or water that they are supposed to receive. If balancing isn't done correctly then you will have uneven heating throughout your house.

Warranty Period
Once you are happily through the construction and start-up process, you should enjoy many years of trouble free service from your new heating system. If however, problems arise, you want to identify them and get them corrected during the warranty period if possible.

You should try to be very aware of the performance of your new system during the first couple of heating seasons. If the furnace or boiler cycles (turns on and off) frequently for short durations then you should consider this a problem and call the installing contractor or the service contractor who is honoring the installation warranty. If you have cold or hot spots in the house, this is probably a balancing problem and you should also get the contractor back out there to correct it. If you are replacing a very old system with a new, highly efficient system, you can also expect to see a reduction in your energy bills. The exact amount of the reduction can't be predicted because there are so many variables such as how you set your thermostat, how cold it is outside, and what types of problems you were having with the old system. The best measure is how comfortable you are in your home. You can expect that, with your new energy efficient heating system, you will be buying more comfort for each dollar you spend on energy. If you are not more comfortable and spending the same amount on energy, there may be a problem with your new heating system.