What exactly is a heat pump?
A heat pump is similar to an air conditioner, except the outdoor unit has the ability to move energy from the outdoors to the indoor side. With an air conditioner, the outdoor unit only has one route at which it can go through the refrigeration cycle, making the cold air for the home with the evaporator coil on the indoor side. Using a heat pump, the outdoor unit can supply both cooling OR heating to the indoor side.
It’s crucial to understand when talking about heat pumps that people understand there isn’t anything in the world of physics that means “cold.” All things HVAC will run back to the laws of thermodynamics to work appropriately. Cold is a relative term that humans have created to describe when they notice there is a lack of energy in the air around them (and temperature describes the amount of energy in the air – Kelvin is the absolute scale, so even when we are in -5F that does not mean that there is negative energy, there is still actually a lot of energy left). But a mechanical device doesn’t have feelings, nor does physics, so that unit will find the available energy outside, warm up the refrigerant, deliver it to the indoor coil, and then supply heat to the indoor side using your blower motor and ductwork. The process happens reversely when the unit is set to cooling mode. We agree it’s counterintuitive thinking and confusing, but rest assured, we understand the science, so you don’t have to
A heat pump is a unit that has the ability to complete the refrigeration cycle in both forward and reverse depending on the conditioning requirements on the indoor side of the home.
What efficiency values are available?
(Please review the air conditioning before reading)
We go into great detail on air conditioners, what the SEER value means, and some of the shortcomings of SEER values. SEER is only used to describe how efficient an outdoor unit is at creating the cooling load for the home. But, when we are focused on heat pumps, we need to use a different marker of how efficient the outdoor unit is at creating the heating load for the home – so we use Heating Seasonal Performance Factor (HSPF). A heat pump is described by its SEER and HSPF value since it can do heating and cooling.
All the ideas that are spoken about during our description of traditional air conditioners still hold proper here; your home’s construction could be the reason your savings for investing in higher efficient equipment could be the reason savings are actualized (or not); we are currently moving everything to SEER2 and HSPF2 because of new government regulations, and yes – these outdoor units have gone up considerably in price because of the forced overhaul of the efficiency rating system and the constraints that were put on the manufacturing industry.
The shortcomings of a traditional heat pump system
Now you know that even when it’s cold outside, there is still energy in that bitter-cold air. A standard heat pump – those that are going to operate with either a single-stage or two-stage compressor – are going to struggle to be able to produce enough heat for the home when the temperatures start to approach 40 degrees Fahrenheit; that is why most customers have to have a form of auxiliary heat installed with their heat pump system. The more common setup would be in homes where they are all electric, with no natural gas fuel source available. For these customers, you will have heat strips inside the air handler – sometimes called an electric furnace. All homeowners should do all they can to limit the time their heat strips are running as they are very costly to run, consuming a lot of electricity. They are glorified toaster oven coils inside the electric furnace that get glowing red hot, and then the air goes over them to supply hot air to the living spaces.
It’s also important to mention that heat pump heat is a different kind of heat. A heat pump/heat strip system will not produce the same air temperature from the registers that a natural gas furnace would produce. Also, the air coming out won’t be quite as dry as a furnace would be – which could be considered a good thing, but let’s not forget high temperatures are also very good at being a cleaning agent for burning off any kind of dirt and debris that might be clung to the evaporator coil. Once again, it’s a delicate science to get it right and ensure that we, as contractors, have managed your expectations and can hit all the goals you know of for your project.
A dual-fuel setup is what we recommend for homeowners who like the idea of having a heat pump installed but have natural gas available to them. Our glass ball of being able to see into the future is broken at the moment, but history tells us utilities are going to go up. Which will go up faster between electricity and natural gas, though – we have zero answers there. But, with a heat pump installed with a gas furnace, you now are in a position where if we were to experience a massive natural gas price increase, you would still have a different heat source to rely on, which would be more cost-effective. Being in a dual-fuel setup, you can have the best of both worlds if utilities climb to new heights. Opening the box that is dual fuel would lead us down an entirely new rabbit hole, and we only recommend heat pumps that are more advanced for this type of setup.
Advancements in Heat Pump Technology – Variable Capacity Heat Pumps
We cover in “All Things Air Conditioners” the different compressor types – which are also all available in when discussing all the different heat pumps you have available to you. But, when speaking of heat pumps, we typically only spend most of our time discussing single-stage compressors and variable capacity compressors (two-stage just isn’t going to be as applicable in heat pumps – if we are only focused on the heating functionalities).
Heat pump manufacturers are getting smarter with their technology, and there are now units on the market that are designed to work below the traditional threshold of 40F, or the point where a conventional heat pump struggles to be able to create any kind of heat for the home. The usage of heat strips considerably increases. We currently have access to several of these units, and the situation will determine which brand we will propose as a solution but rest assured they are all solid units.
However, there are some things to consider to ensure this will be the best option for your home. Even though an advanced heat pump can create heat using its functions, don’t forget to think about the physics at play. On a really cold day, your home may require more BTUs than the outdoor unit is rated for. For example, if you have a 3 Ton (or 36K BTU) home, your heating requirements will typically exceed 36K BTUs. The heat pumps ability to create energy is finite, meaning if we get to really cold temperatures and now the house requires 60-70K BTUs of heat, well, you’re still going to need some form of auxiliary heat in the form of a gas furnace or a heat strips to “keep up” with massive temperature swings.
And I know what you’re thinking, “what is the point in investing in this kind of technology if I am still going to have to use my dreaded electric heat strips?” Once the temperature is achieved at its set point, the house will not require as many BTUs to HOLD temperatures inside so that you will use your auxiliary heat less, hopefully much less (but we do get crazy temperature swings here in the Midwest). Also, these are variable capacity units! They can modulate the energy they produce, ramping up and down as the house requires it. In cooling mode, this technology makes for considerable changes to the comfort of a home. Still, the variable capacity mechanisms in heating are how the unit can operate at exceptionally very low temperatures.
Other things to consider when purchasing a heat pump
Truth be told, many of the topics we covered in air conditioners also apply in this case. It’s essential to ensure the unit is appropriately sized for the home, indoor air quality can be affected by your choice of heat pump system (plus any accessories that can enhance effectiveness), but the rebates and tax credits on heat pumps systems are going to be different – and even enhanced for purchasing AHRI matched systems.
With heat pumps, here in Kansas City, the local electric company, Evergy, offers enhanced rebates for those that install qualifying heat pump systems. These rebates are going to be larger than those that are offered to homeowners that are only looking to install an air conditioning system. In the case of dual fuel, where a gas furnace is installed, you still have the ability to “double dip,” meaning you can maximize your Evergy rebate but also be eligible to receive Spire rebates, given the system hits all the necessary criteria.
Finally, your tax credits. These are shaping to be some of the largest we have seen in a long while. A tax credit initiative exists for those purchasing a qualifying heat pump system to receive up to $2000 toward their tax bill. Although we know enough to answer some of the basic questions, we are in no way claiming to be tax professionals, so we ask all of our customers to consult with their tax professionals to ensure that this tax credit will be of maximum value to your financial situation. As always, we will ensure the system can achieve all the minimum efficiency requirements that the CEE sets forth.