A: Good question. The wrong furnace installation could cost you hundreds of dollars a year — thousands over its lifetime — and affect the comfort and quiet in your home, maybe even your safety. And you probably would just live with it. At a cost of $3,000 to $8,000 and lasting 15 to 20 years, a new furnace isn't an easy do-over.

The first step is to educate yourself. Don't just rely on a contractor or utility to make the decision for you.

You're basically buying two items: a furnace and its installation. Usually it's a package deal, but you have to make sure that it works for you. The best furnace poorly installed will not deliver what it should; even the best installation won't make a furnace perform better than it can.

LOOKING AT FURNACES:

—Know your abbreviations. AFUE (Annual Fuel Utilization Efficiency) is how well the furnace uses gas. Generally, the bigger the number, the better. AFUEs of more than 95 percent are required for natural gas and propane appliances; fuel oil is 90 percent. (It's 90 percent for boilers.)

—Buy efficient. The furnace will need to be efficient to qualify for the tax break. But the real reason is that these furnaces will save you money over the years. It's been calculated that there can be a $300 difference yearly between mid-efficiency and high-efficiency furnaces, or $6,000 over a 20-year lifespan.

—Buy sealed combustion. The furnace's burner is sealed from household air, protecting you from carbon monoxide.

—Ask for the variable-speed fan. Some furnaces have poor fan quality or design, needlessly wasting electricity (your money), creating uneven heating and noisy ducts. A variable-speed fan help prevent these. The contractor should verify that it's compatible with your ductwork.

—Compare. Often a contractor or utility will offer just one or two models. If they aren't what you want, tell them. (Energy Star furnaces and boilers are listed at www.energy star.gov.)

SELECTING CONTRACTORS:

Selecting the right furnace is just half the equation; you also need to have it installed well.

—Get bids from several contractors. One can be your utility, of course. (Utilities selling furnaces are just like any other contractor.) Be sure contractors spell out what they are going to do so you can compare bids. Price is important, but cheapest isn't always best. If they can't get you the type of furnace your want, keep looking.

—Ask if NATE-certified technicians will do the work. They train and recertify technicians so skills are current.

—Ask if ACCA Standards for Quality Installation are used. The standards require that certain quality steps are followed and documented. For example: furnace of correct size; compatible components; sealed combustion; operation controls testing; proper operation, and maintenance shown to the consumer.

—Don't forget. In addition to a federal tax incentive, check with your utility for a rebate.

This column includes information from Minnesota Office of Energy Security.