Furnace VS. Boiler VS. Heat Pump

Heating and cooling uses more energy that any other system in the house. You can save A LOT of money by selecting the right heating equipment. So the question is, what IS the right heating equipment? As you can imagine, the answer is complicated, but here's a breakdown of the three most common energy sources for today's home.

Furnace VS Boiler VS Heat Pump @MeldrumDesign

Furnace

A furnace takes natural gas, electricity, propane, or oil and turns it into hot air. The hot air is circulated through the house in air-ducts.

Pros

  • Ductwork can be used for the heating AND cooling systems.

  • Least expensive initial cost.

  • No possibility of frozen pipes or flood-causing leaks.

Cons

  • Heats by air movement. Air movement is nice in warm months but feels "drafty" in cool months.

  • Air movement spreads dust and allergens. It also creates a dry environment.

  • Air filters must be cleaned/replaced up to twelve times a year.

  • If you don't want to rely on Passive Design to cool your space, you'll need an Air Conditioning system too.

If you're going to buy one:

  1. Check out the Energy Star Guide.

  2. Ensure supply & exhaust air is coming and going safely.


Boiler

A boiler takes oil, natural gas, electricity, or alternative fuel and turns it into hot water or steam. The hot water/steam is then circulated using radiators or radiant floor systems.

Pros

  • Modern boilers can provide heating AND hot water.

  • Steady, consistent, comfortable heat with no air drafts.

  • Better air quality, no spreading of allergens or dust.

  • Very minimal maintenance.

  • Quieter than hot air systems.

  • More efficient than hot air systems. Water holds heat better than air. This means much lower energy costs.

Cons

  • The heating and cooling systems are distributed separately. You'll need radiators for heating AND ductwork for cooling.

  • Initial cost is very high compared to other heat sources.

  • Slower to react to thermostat commands.

  • Possibility of frozen pipes if the house gets too cold.

  • Leaks can cause floods and significant damage to your home.

  • If you don't want to rely on Passive Design to cool your space, you'll need an Air Conditioning system too.

If you're going to buy one:

  1. Steam boilers operate at a higher temperature and are inherently less efficient than water boilers.

  2. Check out the Energy Star Guide.

  3. Ensure supply & exhaust air is coming and going safely.


Heat Pump

A heat pump pulls heat from air, water, or the ground and transfers it into or out of your home by way of air (more similar to a furnace than a boiler). These systems are called air-to-air, water source, or geothermal heat pumps.

During cold months, the pump pulls heat from outside and pushes it inside. During warm months, the pump pulls heat from inside and pushes it outside. For this reason, heat pumps work best in moderate climates.

Pros

  • It collects rather than produces heat making it MUCH more efficient that other systems.

  • No need for Air Conditioning. Heat pumps can heat AND cool. They're also amazing dehumidifiers.

  • There are ducted AND ductless systems.*

  • Many new heat pumps have a desuperheater (<hilarious word) which recovers waste heat and uses it to heat water. Desuperheaters are significantly more efficient than traditional water heaters.

Cons

  • If you're in a very cold climate, you should probably install backup burners for those days when the heat pump can't pull much warmth from the frigid air outside. Many manufacturers provide backup burners in the same system as the heat pump.

  • Air source heat pumps require an outdoor compressor/condensor and an indoor air-handling unit.

  • Can have problems with low airflow, leaky ducts, and incorrect refrigerant charge.

  • As with a furnace, filters, coils, and fans must be cleaned/changed up to 12 times a year.

If you're going to buy one:

  1. Look for two-speed heat pumps. They're better able to adjust to the heating/cooling need at that moment.

  2. Look for dual-speed or variable-speed motors. They keep air moving at a comfortable velocity.

  3. Look for Reverse Cycle Chillers.

  4. Check out the Energy Star Guide.


*Ductless Mini-Split

Mini-splits are the ductless version of an air-source heat pump. They have been widely used in Europe for many years and are finally making the jump to America. In general, they are my favorite system for a moderate climate such as Southern California.

Pros

  • Fantastic for zoned systems. Put one mini-split in each zone and turn it on only when you need to use that space.

  • No ducting! That means much less mechanical space required in floor and wall assemblies. It also means no heat lost as air moves through ducts. This can improve efficiency by up to 30%.

  • Only one small hole in walls to connect outdoor compressor and indoor air handler. The handler can be up to 50' away from the compressor.

  • Can use one compressor for several air handlers.

  • The air handlers also have thermostats making the zones that much easier to control.

  • Relatively easy install.

  • Excellent for additions or renovations to an existing home.

Cons

  • The air handlers are white boxes mounted high on the wall or in/on the ceiling. (You've probably seen them before.) They're not horrible but they're not exactly inconspicuous.

  • Install can be expensive because many American HVAC professionals are not yet comfortable with the technology.

  • Initial cost is higher than other options. Usually, this cost is recovered in energy savings over the life of the equipment.

  • Must be sized properly. Too large a system is more expensive to buy and operate.


Other Tips:

  • Before replacing your heat source, improve the efficiency of other elements. For example, you can insulate ductwork or piping, switch to a programmable thermostat, beef-up your wall insulation, and add zone-control.

  • Place your heat source in a conditioned space so it doesn't have to work so hard to heat the water or air. For example, a hall closet is better than the garage.

Conclusion:

If you're in a moderate climate and plan to use your system regularly, a heat pump would be a great option for you. If you won't use your system very often, perhaps a furnace is the better choice.

If you're in a more seasonal climate, a new boiler with baseboard or radiant floor heating could be your most efficient option. That being said, it's worth looking into a heat pump. Heat pump technology is improving rapidly and there are many new options for seasonal climate homeowners.

In my opinion, heat pumps are the way of the future. They are MUCH more efficient and create a more comfortable environment. And as technology gets better, cost and ease of installation will only improve.


In case you can't get enough of this nerd-talk, here's an infographic to delight your eyes. (Thank you government!)

Furnace VS Boiler VS Heat Pump @MeldrumDesign

Sources not linked in text:

https://energy.gov/energysaver/furnaces-and-boilers

https://energy.gov/energysaver/home-heating-systems

https://energy.gov/energysaver/heat-pump-systems

https://energy.gov/energysaver/ductless-mini-split-heat-pumps

http://www.slantfin.com/difference-between-boiler-furnace/

https://www.kompareit.com/homeandgarden/hvac-compare-boiler-vs-furnace.html