Buying a Furnace

Many people buy their first furnace without even realizing it. They buy a house with their furnace already installed. Many people buy their second furnace with the same amount of thought -- they open their phone book and call the first HVAC (Heating, Ventilation and Air Conditioning) contractor on the list. This strategy is likely to net you a furnace that will keep your house warm. But you are also likely to spend hundreds, if not thousands of dollars more than necessary.

How do you choose the most appropriate furnace?

Savvy furnace shoppers generally consider several criteria:

1. Is your furnace correctly sized?
2. Are you buying an appropriately efficient furnace?
3. Are you getting the best price for your furnace?

Is your furnace correctly sized?

Is it customary for HVAC contractors to charge for a load calculation? If your furnace develops problems after installation, can you contact the furnace manufacturer for redress of the issues?

An oversized furnace (one whose capacity is too large) costs substantially more to operate than a correctly sized furnace. This is because oversized furnaces typically cycle on and off more often than correctly sized furnaces, and cycling on and off is more expensive than running at steady state.

The only way to know if your furnace is correctly sized is for your HVAC contractor to do a load calculation. A load calculation takes into account the size of your house, the insulation value of your windows, the amount of insulation in your walls and roof, and a host of other criteria to determine the appropriate furnace capacity.

Ask your HVAC contractor if s/he performed a load calculation before you accept the furnace that they recommend. If you are replacing an old furnace (as opposed to buying a furnace for a new home you are constructing) they may argue that they chose a furnace as big as your last furnace. But your old furnace might be too large for your house. Request that they perform a load calculation, and find another contractor if they refuse.

Is the efficiency of your furnace appropriate for your house?

High efficiency furnaces typically cost more than average and low- efficiency furnaces. However, they tend to cost less to operate on a month to month basis as they use less fuel to generate the same amount of heat. Therefore, after a given payoff period, high efficiency furnaces tend to cost less than low efficiency furnaces.

However, high efficiency furnaces may not always be the most appropriate choice. (Your 90% efficient furnace will cost you more than your 80% efficient furnace if you move to a new house within the payoff period. And depending on which furnace you choose, the payoff period may be surprising long!) You need to consider a number of factors such as your climate, and how long you plan to own your home.

Are you paying the best price for your furnace?

There are several ways to reduce the cost of purchasing and installing a new furnace.

Encourage several HVAC contractors to compete for your business. However, keep in mind that you rarely want to make your decision based on up-front price alone. Choosing a reputable HVAC contractor is as important in determining your overall satisfaction and cost as choosing an appropriate furnace.