Introduction
The fall chill will shortly be upon us and it will soon be time to think about turning up the heat. With the existence of so many heating and cooling systems it is hard to know which one is right for you. Below is a brief description of several of the most common ways to heat your home and the features that differentiate one system from another.
Forced Air
A forced-air HVAC system consists of a gas-fired furnace, cooling coils, a condensing unit, and ductwork throughout the house. Forced-air systems can be very efficient if high-efficiency equipment (condenser and furnace) is selected. However, if the ductwork is leaky and/or poorly insulated, a significant amount of energy can be lost. It is recommended that all indoor equipment and ductwork be installed within the conditioned space. That is, ideally, no equipment or ductwork would be placed in an uninsulated basement or vented attic.
Central Hydro-Air
Air systems combine elements of central forced-air systems with central hydronic systems. A gas-fired boiler acts as the central heating plant for the house, generating heat for space heating as well as domestic hot water. The boiler generates hot water which is circulated to an air handler. One air handler would be required for each separate duct distribution system. The hot water circulates through a fan coil in the air handler, heating the air as the blower passes it though. The hot air is then distributed throughout the house via ductwork. The air handlers can also be fitted with a cooling coil for air conditioning. The cooling coil, connected to a condenser outside, absorbs heat from the air as the blower passes it through.
Radiant Heat
A radiant floor heating system consists of a gas-fired hot water boiler, distributive PEX Tubing, supply and return piping headers, and circulators. While it can be installed under any type of floor but slab, tile, and masonry floors are best due to their thermal storage properties. Hardwood floors also work well with a radiant floor heating system. Carpet should be avoided as it insulates the floor, preventing heat from entering the room.
Baseboard
Baseboard heating, either electric or hot water, uses radiators along the floor to distribute heat around the house. Electric heating is not recommended due to its inefficiency and high operating expenses in a heating dominated climate. Hot water baseboard heating consists of a gas-fired hot 
water boiler, distributive piping (either copper or PEX), and fin-tube radiators.
Split Ductless
Split-ductless heat pumps are a good solution for the additional rooms that need only periodic conditioning or that are difficult to reach with the heating/cooling system of choice. Operating similarly to a forced air system, split-ductless heat pumps use hot and cold air to heat the room. The system is comprised of an outdoor and indoor unit, connected by refrigeration pipes, without any ductwork. The connection is made through a 3" hole in an exterior wall, which can be easily sealed. The indoor unit is mounted on a wall and has a low profile so as to be aesthetically pleasing. The exterior condensing unit is much smaller than a typical condensing unit for a central air-conditioning system.
Ductless Convention Heater
Ductless convection heaters work exceptionally well to satisfy the heating demands of room additions, apartment suites, and the like. They operate very similarly to a furnace but do not require any ductwork to be installed. The natural gas heater is a stand-alone unit, directly vented to the outdoors.
Individual Room Hydro-Air
Much like spilt-ductless heat pumps, individual hydro-air units are small, scalable forced-air systems that do not require ductwork. Small fan units are installed within a wall for each heated room. Hot water is delivered to the hydronic coil within the fan, which heats the air as it passes through. The hot water is produced by a boiler or domestic hot water tank. The same piping and coil can be used to deliver water chilled by an outdoor air-conditioning unit, which can provide cooling to the same rooms using the same fan units.
Summary Table
|
|
Pro |
Con |
Good For: |
|
Forced Air |
· Easily integrates with ventilation system to maintain healthy IAQ
· Heating and cooling in one infrastructure |
· IAQ might be compromised if air filters and ducts are not replaced and cleaned, respectively
· System equipment and infrastructure not easily scaled |
· Central HVAC system for base home design |
|
Central Hydro-Air |
· Same benefits as forced-air
· Lower operating costs than forced-air/DHW tank combo |
· Same drawbacks as forced-air
· Much higher installation costs than forced air system |
· Central HVAC system for base home design |
|
Radiant Heat |
· Efficient method of heating
· Provides high occupant comfort
· Minimal indoor contaminant introduction |
· Requires separate cooling and ventilation system
· System equipment not easily scaled |
· Adding luxury feature such as heated bathroom floors
· Heating optional rooms |
|
Baseboard |
· Easy, inexpensive installation
· Minimal indoor contaminant introduction |
· Requires separate cooling and ventilation system
· System equipment not easily scaled |
· Heating optional rooms |
|
Split Ductless |
· Energy efficient
· Scalable for building additions |
· Heat pump units might need supplemental heating |
· Heating/cooling optional rooms |
|
Ductless Convection Heater |
· Energy efficient
· Scalable for building additions |
· No cooling capacity |
· Heating optional rooms |
|
Individual Room Hydro-Air |
· Scalable for building additions
· Easy to install |
· May not provide cooling to rooms |
· Heating optional rooms |
|
Porch Infrared |
· Luxurious
· Allows outdoor spaces to be used 3 seasons |
· Extremely inefficient since the heat quickly dissipates to the atmosphere |
· Luxury outdoor heating feature |
Conclusion
This overview of the most commonly installed systems should help bring some clarity to the complex topic of heating your home. Keep this for reference if you are considering updating your heating system, or building a new home. We hope that when it comes time to turn up that thermostat, you enjoy a better understanding of the common household heating systems and their features.
The DHCD grant requires that at least 70% of the funds awarded be used towards renewable energy systems (photovoltaics, hydropower, and wind) and the remaining 30% be used towards other "green" improvements, such as those that improve energy efficiency.
