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About half of the homes in Washington Grove rely on heat pumps to heat and cool their homes. Other homeowners are considering switching their heating systems from oil or propane furnaces, or boiler/radiator systems to heat pumps. The Sustainability Committee enthusiastically encourages making this switch.

To help people who are examining this investment, we have prepared Q&A’s about switching to heat pumps. This month, we focus on switching from a ducted forced air system that currently depends on fuel oil or propane as the heat source. In upcoming months, we will address switching from boiler/radiator systems and also geothermal systems.

A heat pump works the same way as an air conditioner or refrigerator for cooling, but in reverse for heating as well.  By condensing and evaporating a refrigerant gas within the system, a heat pump actually “moves” heat to or from the living space as needed. Overall, the system is 2 to 3 times more efficient than an oil furnace, though the efficiency decreases as outside temperatures become more extreme.

The Committee does not make specific recommendations for Washington Grove homes as every home has unique conditions, but we can help get you started by addressing some questions you may have.

How will the new system work?

A central forced air furnace with AC is the easiest system to replace. You already have the ductwork distributing to every room (which may need some improvements as discussed in 4 below); the controls are similar (central thermostat); the changes are relatively invisible; and humidity control and air filtration are also central and similar. It’s called a “box swap” because in many cases the new system’s “boxes” replace the old ones or are easily configurable to fit.

How will the switch benefit me?

In Maryland, with 95% of oil furnace and 99% of propane furnaces, it is cost effective to swap the system with an efficient heat pump at the time the AC needs to be replaced.  The increased cost over merely replacing the AC is often paid back in only one to two years.  Annual savings range from $350 for standard heat pumps to almost $1,000 for “cold-climate” heat pumps.  The difference in savings is due mainly to whether there is backup heat for the coldest days of the year, the type of backup, and how much it is used. The most efficient heat pumps do not need backup heat at all. Over its lifetime, the heat pump system will at minimum pay for the cost of the conversion or return up to $10,000 in life cycle savings. It will also create a cleaner, safer house in the process. Two added benefits of a high-efficiency heat pump are more efficient cooling, which will be increasingly important as climate change raises temperatures in our already hot, humid climate, and more stable electric prices as the potential for future fossil fuel cost increases.

How will the switch benefit the environment?

A heat pump that relies on electricity from a standard energy mix on our grid will emit only one-sixth of the greenhouse gases that come from an oil or propane furnace—an enormous improvement.  Better yet, if you have a renewable electric source, such as community solar, the emissions drop almost to nil. Overall, the more fossil fuels we leave in the ground the more manageable will be the changes we must make to avoid climate collapse.  An additional benefit both inside the home and to the community is elimination of the secondary combustion particulates and gases spread into the air around us.

What physical changes will happen in and out of my house?

A new compressor or “outside unit” will replace the AC “outside unit” and a heat pump/air handler will replace the furnace/air handler that is usually located in the basement. If there is sufficient height, it can be a one-for-one swap. If not, some additional reconfiguration of either the “box” or your ductwork will usually get it to fit.

In many cases no changes need to be done to the distribution ductwork, but attention must be paid to the ductwork itself that was sized to serve the bursts of hotter, higher velocity air coming out of the fuel oil/propane furnace. The heat pump uses lower temperature, lower velocity air distributed more continuously throughout the day and thus may deliver the heat more slowly thru the ducts to the rooms.  The size of the heat pump should correlate with the transfer capacity of the ductwork. In some cases, supplemental heat pumps may need to be added to more distant areas or increases to either the return ducts or both supply and return ducting could be required. Often, sealing and insulating the old ductwork will suffice without ductwork changes.

Conducting an energy audit of your house will help you get the properly sized heat pump. Following the insulation and air-sealing advice will result in a smaller unit and a more comfortable house.  Usually, part of the installation contract is removal of the old oil or propane tank, piping, and any residual fuel left inside, and, if needed, an increase in the electrical circuit to 220v.

What is the likely cost range for a new system?

With the simplest “box swap”, you will be presented with a choice of a standard, a high-efficiency, or a “cold-climate” heat pump. Though the standard ones are cheaper initially, they will not produce the highest savings mentioned above as they cycle on and off frequently and require backup heating for most cold winter days.  High-efficiency heat pumps have built-in modulating capacity that generally makes them much more efficient and capable of handling colder winter days.  With these systems, the use of a backup fuel source is minimized.  With the “cold-climate” units, there is no backup needed as they can function efficiently at much lower temperatures than we see in Maryland. The simplest backup is an electric resistance coil built into the unit, but it can also be a propane furnace or even your old oil furnace. Whatever you choose, it will need to be integrated into the controls.

Generally, the standard “box swap” is $3,000 to $5,000, a high efficiency swap is around $10,000, and a cold-climate swap can be closer to $15,000. If ductwork modifications are needed, add the cost of those changes, and plan on about $1,000 for the tank removal.

How long does it take to install a new system?

The “box swap” can be done in one day. If the ductwork needs adjustment, it can take several days. It is best to plan ahead so that you are not left in the middle of the winter with a possibly broken oil system, forcing you to make rushed decisions in cold weather.

What maintenance will the new system require?

Very little. The filters need to be changed and any humidification system serviced, but unless there is refrigerant leakage, there are no real adjustments or burned-out elements to replace. And because there is no combustion, there is no clean-up of soot.

How long do heat pumps last?

Like air conditioners, they last 15-20 years. This is similar to current gas furnaces, but many of us in town have ancient oil furnaces that have lasted decades. Unfortunately, these old furnaces are very inefficient both in the amount of oil they consume, how much of the heat value gets to the house, and how much of it goes up into the atmosphere.  The Energy Star Homes program recommends replacing any system every 10 years to take advantage of the ever-increasing efficiencies. Energy Star also records the efficiencies of all units submitted and raises the standards every couple of years.

How do I get started in making the change to a heat pump?

The best first step is to conduct an energy audit of your house and a load calculation to determine the correct size of the unit you need and to ensure that you purchase a right-sized unit.  An audit will also help to ensure the comfort of your home once the changes are completed. Next steps should be discussions with two or more contractors with experience in high-efficiency systems, a site visit, load calculation, and cost estimates for various options.

Are there people in town who can talk to me about this?

We are planning on getting small groups of interested residents together to share our experiences and discuss the more detailed aspects of each type of conversion.  If you are interested, please let Bob Booher know, and we can meet with other Sustainability Committee members or residents who have useful experience.

Can you recommend any websites that will tell me more about this technology?

Yes, here are a few that may be helpful:

Can I get any rebates, tax credits, or loans to help pay for a heat pump?

There are a variety of financial support offers but they change often. It’s best to research this question at the time you purchase a heat pump.  Meanwhile, here are a few examples:


Federal Tax Credits

  • Tax credits have currently expired.  Legislation to extend is pending. Watch for updates.

Loans (Maryland)

  • Clean Energy Advantage Loan Pilot Program for “high efficiency equipment.”
  • BeSMART Energy Efficiency Loan for Homeowners, including ENERGY STAR heating and cooling systems.


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