Every heating system requires an energy source. Furnaces and boilers usually burn natural gas that’s piped in from the street. In areas without city gas, propane gas is stored in a tank outside the house, located where it can be easily refilled by a local fuel dealer. In the Northeast, furnaces and boilers are likely to burn fuel oil that’s delivered by truck and stored in a tank on-site. Electricity can directly power resistance heaters, which work like larger versions of the coils in your kitchen toaster. Electricity can also run heat pumps, which work like air conditioners in reverse. Electricity can come from the grid, but today it’s becoming popular to generate electricity on-site using photo-voltaic (PV) panels. PV’s environmental advantages have led some municipalities to forbid new fuel-burning heating systems with the idea that PV (in combination with grid-supplied electricity) will provide the power needed.
Consider Programmable Thermostats
No matter what kind of whole-house heating system you have, its use will be governed by a thermostat. In its simplest form, a thermostat tells the heating system when to turn on and off, based on a temperature setting that you can adjust. But these days, many homeowners rely on programmable thermostats that store different temperature settings to promote both comfort and improved energy efficiency. With a programmable thermostat, you don’t have to manually turn down the heat before going to bed at night; instead, you can program your thermostat to make this setting change automatically.
Efficiency Is Important
Efficiency is getting the most heat out of whatever fuel you use. More efficient equipment typically costs more upfront but uses less fuel over time. Standard gas or oil equipment’s efficiency runs in the 80% range, meaning that you get about 80% of the potential energy of the fuel. High-efficiency furnaces and boilers can operate at 90% and more.
Home Heating Systems Comparison
Forced Air Heat
The most common heating system is forced air, where air is warmed at a furnace or heat pump. In furnaces, fuel is burned and the hot exhaust gases are channeled through a heat exchanger. This warms the air that is then blown by air handlers (large, squirrel-cage blowers) throughout the house via a ductwork system. The same ductwork can also be used for air conditioning. Ideally, all ductwork should run inside the insulated part of the house, but it’s common for some ducts to run in attics. Any ductwork in the attic must be insulated, and all joints in any ductwork must be sealed with either mastic or special tape to prevent air leaks. In new houses, there will be at least one supply and one return duct in most rooms. The return ducts lead back to the air handler. To ensure even heating and cooling, the supplies and the returns must be balanced so the flow of air through them is equal. The heating contractor should do this (a process called commissioning) by adjusting dampers with the system running.
Radiant Heat
Far more common in northern climates where air conditioning is less important, radiant heat works by warming radiators along the outside walls or the floors below your feet. The heat can come from electric-resistance coils in radiators (inexpensive to install, but often quite expensive to run) or by hydronics. Hydronic heating works by pumping water heated in a boiler through pipes to radiators along outside walls or through plastic PEX tubing laid in the subfloor. The chief advantage of installing radiant floor heat is that it doesn’t blow air around, creating a more consistent warmth. The main disadvantage is that there are no ducts, so you’ll need a parallel system if you want cooling as well.
Heat Pumps
One type of heat whose popularity has grown by leaps and bounds is the heat pump. A heat pump is essentially an air conditioner run in reverse. Air conditioners take heat from inside the house and dump that heat outside. Heat pumps take heat from outside (believe it or not, there is still heat in even very cold air) and dump it inside. Most heat pumps take heat from the air, but some, called ground-source heat pumps, get it from coils placed in drilled wells or buried in trenches. Air-source heat pumps are far cheaper to install. Today’s heat pumps deliver warmth even when the air outside is well below zero. The best heat pumps deliver in the neighborhood of 2.5 watts of heat for each watt of electricity used to run the system. And, heat pumps are reversible to work as air conditioners. Heat pumps can replace the furnace and heat exchanger in a conventional forced-air system or they can be installed as mini-splits. Mini-splits use wall-mounted heads with their own fans to circulate air. Many homeowners install mini-splits to retrofit air conditioning and end up using them for winter heat as well because they’re cheaper to run than existing gas or oil heat systems. In cooling mode, heat pumps use the same Seasonal Energy Efficiency Rating (SEER) as air conditioners. The minimum code-allowed SEER is now about 15, and better units approach SEERs of 27. In heat mode, the Heating Season Performance Factor (HSPF) is used. The code-minimum is 7.7, and you can get units with HSPFs as high as 12.5.
Maintenance Requirements Vary Across Heating Systems
Maintenance is important to make sure your heating system is working properly. Any forced-air system will require dirty air filters to be replaced with new air filters at least twice a year. A dirty filter inhibits air flow in the system, preventing it from functioning efficiently. The good news is that inspecting and replacing air filters are easy tasks that any homeowner can handle. Gas-fired furnaces and boilers won’t need much maintenance—a visit every few years is usually enough. Oil-fired equipment should be serviced annually. Get trained technicians to do this work. They know what problems can develop as a heating system ages, and they can do the servicing work to optimize system performance and longevity.
