It pays to do homework on HVAC maintenance in your Twin Cities home

Ah, fall. Brisk walks, leaf peeping, hot cider. Coming home to a chilly house. Ack!

Realizing your home's heating system is on the fritz can quickly put a damper on the season. Repairs are often pricey. Replacing your home's heating or cooling equipment costs thousands of dollars.

Twin Cities Consumers' Checkbook's evaluations of area heating and air-conditioning services for quality and price will help you find a competent contractor. Through Dec. 5, you can access the ratings, which also include pricing, free of charge at Checkbook.org/StarTribune/HVAC.

In Checkbook's surveys, several companies were rated "superior" for "overall quality" by 90% or more of surveyed customers. But others scored much lower, receiving such favorable ratings from only 60 % or fewer of their surveyed customers.

Checkbook also found big price differences. For example, to replace the control board for a Rheem gas furnace, Checkbook's undercover shoppers were quoted prices ranging from $263 to $870. To replace the dual-run capacitor for a Carrier central air conditioner, prices ranged from $135 to $459.

Comparing prices for repair work is difficult, because you will first probably need to have a company out to diagnose the problem. Because most companies charge hefty minimum fees just to show up, you will likely have to pay something to find out the price of the repairs.

Before scheduling a repair, ask companies for details on their minimum fees and for their hourly labor rates. You can use this information to get an idea which companies are likely to be least expensive.

Once a company has diagnosed your problem, it should provide you a written fixed price to fix it. If the repair estimate is no more than a few hundred dollars, you may as well have the company go ahead with it immediately. If the estimate exceeds $500 or so, consider getting additional written proposals from other companies.

Obtaining multiple bids for new equipment will save most consumers thousands of dollars, but most don't bother to do so. Differences in designs can affect how quickly and uniformly your system heats and cools your house, how much energy it consumes, how much noise it makes and multiple other issues.

Be skeptical about claims of cost savings from a more energy-efficient system. There may be substantial savings but some companies exaggerate to sell new, or more expensive, systems. You can calculate your own savings estimates by using the U.S. Department of Energy's Home Energy Saver tool at hes.lbl.gov.

Here are some tips for exploring new HVAC systems or repairs:

• For furnaces, it usually makes sense to pay extra for a more efficient model. The resulting energy savings usually quickly "pay off" extra purchase costs.

• Because all new central air conditioners are required to be fairly energy efficient, it usually does not make financial sense to pay more for a highly efficient model.

• If you are replacing both your furnace and air conditioner, consider buying a hybrid system that uses an air-source heat pump backed by an efficient (90+ AFUE) gas furnace. Such systems offer low energy costs, but because they cost a lot more up front than standard furnace-A/C combos, it takes longer for their energy savings to offset those extra costs.

• Ground-source heat pumps provide the lowest annual heating and cooling bills, but these systems are extremely expensive. So for this choice, you need to consider how long you will be in your house.

• Look for features such as variable-speed blowers and two-stage burners.

• Ductless systems allow you to control temperatures in a specific space and are highly efficient. This might be a choice if you are planning an addition or seeking to improve conditions for one room or an upper floor.

• Check your home's insulation, and use a programmable thermostat.

• Heating and air-conditioning services are likely to push for annual professional maintenance visits, and many will offer a maintenance contract. Such frequent professional service may not be needed if you are diligent about the most important maintenance task: replacing air filters whenever they get dirty.

Whether you need repairs or a new unit, pay with a credit card. If you are dissatisfied with the work, you can dispute the charge with your credit card company.

Twin Cities Consumers' Checkbook magazine and Checkbook.org is a nonprofit organization with a mission to help consumers get the best service and lowest prices. We are supported by consumers and take no money from the service providers we evaluate.