HVAC Buyer's Guide

HVAC stands for Heating, Ventilation, and Air Conditioning. A residential HVAC system is a complete home comfort system that can heat and cool a home, as well as provide improved indoor air quality and humidity control. There are many different types, and they can include individual components such as AC units, heat pumps, air handlers, furnaces, air cleaners, humidifiers, and dehumidifiers.

For broader project planning, explore WBC’s building materials resources.

Here’s the part most people get backwards. The brand on the equipment matters less than two things: matching the system type to the home, and sizing it right. A Manual J load calculation should always be required to determine size. Oversizing leads to poor humidity control and premature wear. Get those two right and a mid-tier system outperforms a premium one that’s wrong for the house.

For a Montana home, the central decision usually comes down to this: heat pump, furnace-and-AC split, or a dual-fuel pairing of the two. Cold winters drive that choice. More on that below.

System Types and How to Choose Between Them

Every HVAC setup falls into one of two camps. Each type falls into one of two categories: ducted or ductless. In a ducted system, the main unit pushes air through a series of air ducts. Ductless systems lack air ducts and use alternative methods to distribute treated air.

Split systems are the workhorse. Split systems are the most common types used in residential buildings. They consist of two separate components — one for heating and one for cooling — and use a traditional thermostat to control the temperature for the entire structure. In most buildings, the heating unit sits in a basement, utility closet, or other indoor storage space. The heater is gas-powered and pushes heat through the ductwork. The cooling system is located outside and connects through tubing, using compressors, coils, and refrigerant to create cool air.

Hybrid (dual-fuel) splits add flexibility. A hybrid split has the same structure and cooling unit as a split system but doesn’t rely solely on gas. Its heater can burn gas or switch to electric power. This gives owners more control over energy consumption and can help reduce costs in milder climates.

Packaged units consolidate everything. These are less common than split systems, but their smaller size makes them better suited for small buildings lacking extra storage space. The heating and cooling components are housed in a single unit, generally stored on a roof, in an attic, or near the foundation. The upside is maintenance. Both packaged options cost less to install than split systems and are easier to maintain.

Ductless mini-splits solve the no-ductwork problem. A ductless mini-split is an ideal solution for homes without ductwork. It delivers conditioned air directly to individual rooms, offering flexible comfort control. One compressor can connect to up to nine indoor air-handling units, and their flexible zoning lets users heat and cool occupied rooms only, preventing energy loss associated with ductwork. The catch for Montana: the heating components are less effective in below-freezing temperatures, so people living in colder climates often need to add a separate heating system.

Hydronic (radiant) heating is the boiler-and-water approach. Unlike air-based systems, hydronic heating uses liquid to radiate heat. A boiler heats water, then distributes it through pipes under the floors. Once the liquid reaches a radiator or baseboard heater, it distributes heat throughout the room.

System Type	Ducted?	Best Fit
Split system	Yes	Most common residential setup; gas furnace + outdoor AC
Hybrid / dual-fuel split	Yes	Cold climates needing gas backup for the worst days
Packaged unit	Yes	Small buildings short on storage space
Ductless mini-split	No	Homes/additions without ductwork; mild-climate heating
Hydronic / radiant	No	Uniform, quiet floor heat via boiler and water

Heat Pumps, Efficiency, and Sizing

The heat pump is where modern HVAC buying gets interesting. A heat pump is a versatile HVAC system that heats and cools by transferring heat rather than burning fuel. It moves heat from one place to another using electricity and refrigerant — it does not generate heat, it transfers it. It reverses the refrigerant flow to flow in the opposite direction, making the indoor coil get hot and the outdoor unit get cold, so you can heat with electricity.

That transfer trick is why the efficiency math works. By transferring heat instead of generating it, heat pumps can deliver up to three times more heat energy than the electrical energy they consume.

People assume cold air has no heat to give. Wrong. The heat content of air at -18°C equates to 85% of the heat contained at 21°C. This allows the heat pump to provide a good deal of heating, even during colder weather.

Three main types to know. Air-source heat pumps transfer heat between indoor and outdoor air. They are the most common type for residential heating and cooling. Geothermal (ground-source) pumps transfer heat between the home and the ground; installation costs are higher, but they offer superior efficiency and lower operating costs due to consistent ground temperatures. Ductless mini-splits round out the list for homes without ducts.

The efficiency alphabet soup. For all of these ratings, the higher the number, the more efficient the unit.

Rating	What It Measures
AFUE	Gas furnace or boiler efficiency — a percentage; a 97% AFUE means 97% of the fuel burned goes directly to heating the home
HSPF2	Heat pump heating efficiency during colder months
SEER2	Average cooling efficiency over a range of temperatures from 65–104°F
EER2	Cooling efficiency at a specific 95°F; can matter more than SEER2 in a hot climate
BTU	A measurement of heat energy; a higher BTU number is needed to heat or cool a larger space

On sizing — don’t skip this. In general, a larger space needs a higher BTU unit, but you work with an HVAC professional to determine proper sizing for the home. Bigger is not better. Oversizing causes the humidity and wear problems flagged at the top. And before sizing anything in a heating-dominated climate, tighten the house first. It’s recommended that heat losses from the home be minimized from areas such as air leakage through cracks and holes, and poorly insulated walls, ceilings, windows, and doors. Tackling these issues first can allow you to use a smaller heat pump size, reducing equipment costs and allowing the system to operate more efficiently.

Cold-Climate Performance and Installation

Modern heat pumps have moved past their mild-climate reputation. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates. Modern cold climate heat pumps can operate efficiently even in freezing temperatures — some models down to -22°F.

For Montana winters, the dual-fuel pairing is the sweet spot. In regions with extreme cold, a heat pump can be paired with a gas furnace. This dual fuel system maximizes efficiency by using the heat pump for mild days and the furnace for the coldest days.

Installation is where good equipment lives or dies. Installation requires a licensed contractor to ensure AHRI-matched components, properly sealed refrigerant lines, and balanced airflow. Ductwork condition is non-negotiable — leaky or undersized ducts reduce efficiency regardless of equipment quality. Improperly sized or improperly installed ductwork can result in problems, as can leaky ductwork.

Permits aren’t optional either. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings.

One safety note on anything that burns fuel. The use of furnaces, space heaters, and boilers can result in incomplete combustion and the emission of carbon monoxide — a tasteless and odorless gas with serious adverse health effects. Incomplete combustion occurs when there is insufficient oxygen.

A note on humidity, relevant to Montana’s dry air: humidifiers increase humidity in dry air during the winter or year-round in dry, arid climates.

For supplemental and portable heating needs — garage shops, job sites, drafty corners — Western Building Center carries a range of options including ceiling-mount and 240V electric garage heaters, oil-filled radiant units, ceramic tower and oscillating heaters from Best Comfort, the Vornado vortex heater, PowerZone portable and milkhouse heaters, and Mr. Heater propane equipment. These cover spot heating, not whole-home comfort, but they earn their keep through a Montana winter.

Frequently Asked Questions

What’s the difference between a heat pump and a furnace? A furnace creates heat by burning fuel. Where air-source heat pumps use electricity to heat and cool, furnaces create heat by burning a fuel source like natural gas or propane, then distribute that heat throughout the home. A heat pump moves existing heat instead. It does not generate heat; it transfers it, which makes it highly energy-efficient compared to traditional furnaces.

Does a heat pump work in winter? Yes. In winter, a heat pump extracts heat energy from the cold outdoor air and transfers it inside. Even cold air contains heat energy that the system can capture. In extreme cold, pairing it with a gas furnace in a dual-fuel setup covers the coldest days.

Why does proper sizing matter so much? An oversized system short-cycles. Oversizing leads to poor humidity control and premature wear. The fix is a load calculation done up front. Always require a Manual J load calculation to determine size.

Are ductless mini-splits a good choice for a cold climate? They shine in homes without ductwork, but heating is the limitation. The heating components are less effective in below-freezing temperatures, so people living in colder climates often need to add a separate heating system.

Do heat pumps use a lot of electricity? They run on electricity but use it efficiently. While they run on electricity, heat pumps are highly efficient. By transferring heat instead of generating it, they can deliver up to three times more heat energy than the electrical energy they consume.

What’s the advantage of a packaged unit over a split system? Space and maintenance. Their smaller size makes them better suited for small buildings lacking extra storage space. Both packaged options cost less to install than split systems and are easier to maintain.