How Do Gas Pack Furnaces Work?

Internal Workings

• The heating and air conditioning components of a gas pack work on the same operating principles as conventional separate furnaces and air conditioning units. The difference is in how the components of an air conditioner and a gas hot-air furnace are arranged and combined into a compact all-in-one unit that provides complete four-season climate control. Gas packs require an outdoor concrete pad or rooftop mount, electric and fuel gas hookups and an airtight connection into your home’s supply and return duct work. Otherwise, the only component of the gas pack inside your home is the unit’s thermostat.

Professional Installation

• Installing a gas pack is a complex task not meant to be undertaken by homeowners. In most cases, gas pack manufacturers won’t provide warranty service on units unless they were installed by a licensed heating and air conditioning contractors. Gas pack prices vary widely from contractor to contractor and by brand. As of the date of publication, a low-end unit will average $3,500 installed, while a mid-range unit will average $5,000 and a super-efficient high-end unit can reach $7,500.

Gas Pack Drawbacks

• Gas pack units have two major drawbacks. If you want to upgrade either the furnace or the air conditioner, or if either component fails, you must also replace the other unit. You can't modify or replace just one part of a gas pack. Gas packs also don’t have the longevity of conventional split furnaces and central air units. Gas packs are constantly exposed to the elements and typically last seven to 12 years while conventional split units can last up to 20 years. Most manufacturer warranties are only for five years. Usually, the furnace part fails first because of corrosion of heat exchangers and burners.

Extending Life

• Diligent maintenance is essential to get maximum service life from a gas pack. Have your unit serviced annually by a heating/air conditioning technician. Annual maintenance involves cleaning dirt and debris from the coils and lines, lubricating moving parts, cleaning the furnace burners and heat exchanger, checking for refrigerant leaks and for signs of corrosion or excessive wear. The homeowner after each lawn mowing should rinse grass clippings and other debris from the gas pack, and clear away fallen leaves in autumn and excessive snow accumulations in the winter.