Furnace, Boiler or Heat Pump?
So, you’re building or renovating a house or building, and you’re at the point where you have to consider what kind of heating system to use. Your builder or renovator will be an invaluable guide, and knowing a bit about the different types of heating systems, where they work best, and how you’ll be using the spaces, will go a long way in aiding your decision-making.
Some of the resources you’ll want to consult include master plumbers, if you’re going with a water or radiator-based system, or a heating engineer / experienced HVAC expert if you’re going with forced heat. These experts can be consulted during planning and installation phases, or brought on periodically through all phases to advise on plans, installation and trouble-shooting, or they can work as your heating system contractor, planning, sourcing and overseeing the installation of your system. No matter what, be sure they have worked on many projects similar in size and complexity to your project. Experience is priceless in this field.
So, now that you have your expert, here are some of the things you need to think about:
- How will you use the space?
- How much heat do you need and when throughout the day?
- What kind of system will work well for the way you live and the space you’re heating?
- Any quirky or energy-use-related issues about the building?
- Any budgetary restraints?
Do the hard thinking before you plan and install. It will serve you well down the road.
Types of Heating Systems
Let’s take a quick look at the most popular types of heating systems and what they’re best-suited for.
The majority of households in the greater Edmonton area depend on a central furnace for heat. Most of these are powered by natural gas, which is relatively cheap and plentiful, and has an acceptable environmental footprint. This type of system is also easy to install.
Furnaces work by blowing heated air through ducts to rooms throughout the home or building. Inside the guts of the furnace, gas is burned, and the resulting flames warm a metal heat exchanger which transfers that heat to air that is then blown by a fan through the ducts. Combustion products are vented through a flue pipe, and less than 10% of energy is lost through this process.
Some furnaces go the extra mile to reduce wastage. Condensing furnaces take exhaust gases, cool them so the exhaust vapour condenses to water, and that water is then discharged via a plastic pipe.
Note that furnaces and boilers work in a very similar way, but one heats and circulates air and the other heats and circulates water.
Boilers are special-purpose water heaters, and they circulate heated water, which gives off its heat through radiators or other devices throughout a house or building. Cooled water then returns to the boiler to be reheated. Residential boilers typically use natural gas for fuel. Commercial boilers can be steam boilers, distributing steam instead of heated water, which then condenses to water in radiators. Fuels often used are natural gas and rarely, in Alberta, anyway, oil.
As with furnaces, condensing gas-fired boilers are relatively common and significantly more efficient than typical non-condensing boilers.
Radiant Floor Heating—A Special Kind of Boiler
Radiant floor heat generally refers to systems that circulate warm water (or other fluids) in tubes under the floor. This warms the floor, which in turn warms a room. It’s a more subtle and ambient system than a furnace and is considered highly efficient depending on the energy sources used. It can be expensive to install and tricky to fix if installation is not done perfectly. It also requires a very experienced system designer and installer and limits your choice of floor finishes.
Heat pumps are essentially two-way systems that use the temperature difference between a building or house and the ground to swap conditions as desired. Depending on the climate, air-source heat pumps use the outside air as the heat source in winter and a heat sink in summer. Ground-source (also called geothermal, GeoExchange, or GX) heat pumps get their heat from underground, where temperatures are more constant year-round. Air-source heat pumps are far more common than ground-source heat pumps because they are more affordable and easier to install. Ground-source heat pumps, however, are much more efficient, and are frequently chosen by consumers who plan to remain in the same house for a long time, or have a strong desire to live more sustainably.
The efficiency of a fossil-fuel furnace or boiler is a measure of the amount of useful heat produced per unit of input energy (fuel). Combustion efficiency is the simplest measure; it is just the system’s efficiency while it is running. Combustion efficiency is like the miles per kilometre your car gets cruising along on the highway. You’ll want to know and understand these figures when you’re making your decision on the type of system and the fuel sources you choose for that system.
Every system has its pros and cons, so look at initial costs—what it will cost to buy the parts of the system, prep the building to accept the system, and then to install it. The best-planned system is only cost-effective if it’s installed perfectly so it can work at peak efficiency.
Don’t forget running costs. If you have a pump that works off electricity, map out those costs while figuring in a steady annual rise in rates. If your system runs off natural gas, keep in mind it’s a market commodity subject to price volatility. Budget high just in case.
Finally, there are projected maintenance costs. A furnace needs annual maintenance and an inspection but typically requires little outlay over the first 10 years. An in-floor heating system could operate problem-free for years and then suddenly spring a leak. Budget for the worst case scenario and you’ll be OK.
Read more about furnaces.
Learn more about boilers.