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Heat Pump Systems: What You Need To Know
By Mike Holmes
Monday, August 9th, 2021 @ 3:11pm
What Is A Heat Pump?
A residential heat pump is an HVAC system that uses refrigeration and electricity to provide heating and cooling to a home. A heat pump is fully reversible. This means it can heat AND cool your home. The biggest advantage benefit of using an air-source heat pump is the high efficiency it can provide in heating compared to other systems like furnaces, boilers and electric baseboards. There are two main components to a heat pump:
- A condenser, that typically is on the exterior of the building
- An air handler unit located in the interior of the home.
The two units are connected by a refrigeration line that passes hot or cool air into the home – because the condenser and air handler are separate this system is typically called a “mini-split”.
A multi-split unit has multiple indoor units located in the home and is served by a single outdoor unit.
Major Benefits Of a Heat Pump System
Heat Pump’s Efficiency
Heat pumps move heat rather than generate heat. This makes them very energy efficient. In fact, a heat pump can reduce your electricity consumption by 50% compared to electric resistance heating such as furnaces or baseboard heaters (according to US Department of Energy).
Energy Savings Advantage Of A Heat Pump
Because heat pumps are so energy-efficient, you will enjoy energy savings as a result as well. When purchasing a heat pump, you should also look into rebates offered in your area.
I highly recommend looking into sources of heat loss in your home first. Check windows and doors for air leakage to start. Address these issues first before buying a heat pump. You may end up needing a smaller heat pump size!
Ducted Heat Pumps VS Ductless Heat Pumps
Heat pumps also provide heating and cooling in two ways – ducted and ductless.
Ducted Air-Source Heat Pumps
Ducted is when the indoor coil of the heat pump is located in a duct and air is heated and cooled before going through the house.
Ductless Air-Source Heat Pumps
Ductless is when the heat pump is located in an indoor unit, and is generally located on the floor or wall of a room or space it is heating or cooling. We installed the Climate 5000 Ductless System by Bosch on an upcoming project. It doesn’t require any ductwork.
It’s also perfect for smaller homes with tighter spaces. This system is also one of the quietest on the market with sound levels as low as 20 dBA.
And here is the best part. The multi-part filter in the Bosch Mini-Split constantly works to clean the circulating air. This means reducing the number of potential allergens and bacteria entering your home. You are improving your indoor air quality and creating a healthier environment for your family.
Geothermal Heat Pumps (Ground Source or Water Source Heat Pumps)
Geothermal heat pumps are used for space heating and cooling, as well as for heating water. The geothermal heat pump transfers heat stored in the earth or in groundwater into your house in the winter. In the summer, it takes heat out of your house and puts it back in the ground. You will need ductwork to distribute warm or cool air throughout your house.
Heat Pump VS Furnace
The major difference is that furnaces burn fuel (oil, gas or propane) to generate heat, while heat pumps move heat by using electricity.
If you live in an area where electricity is affordable, you should consider a heat pump. They are an alternative to furnaces and air conditioners, as they can also supply cool air for a central air conditioning system during hot weather.
High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months. With recent advancements, they can now be used in sub-zero temperature regions.
How does A Heat Pump Work?
The easiest way to describe this is to look at a refrigerator or freezer. It moves heat from inside the box to the outside. A thermostat inside the box maintains a set temperature, so when the box gets warm, it starts pumping heat out of the box. When the box is cooled and reaches it’s set temperature, the pumping stops until it warms up again.
The two most popular sources of thermal energy (to create a source and a sink) are air-source and ground-source heat pumps.
Air-Source Heat Pumps
The Heating Cycle of Air-Source Heat Pump Systems
In the winter months, heat is taken from outdoor air and “pumped” indoors. The unit operates like an air conditioner in reverse. The refrigerant extracts heat from the air outside and uses it to warm your house. The refrigerant line carries this heat to the indoor unit, which then transfers the heat to the air inside your home via a fan inside the interior unit.
If you live in an area where electricity is affordable, you should consider a heat pump.
The Cooling Cycle of Air- Source Heat Pump Systems
In the summer months, your heat pump in cooling mode uses a refrigerant to extract warm air from inside your home and releases it into the air outside. When you remove energy from a source, the temperature of the source goes down. Now think of your home as the “source”. Removing energy means cooling down the house. It is the same principle used by air conditioners and refrigerators.
Ground Source Heat Pumps
Ground-source units are not as popular as air-source. These units use the earth, groundwater, or both as the source of heat in the winter. In the summer months, those same sources are used as a reservoir to reject the heat that is removed from the home. The biggest advantage is that the ground is a constant temperature source. You are not subjecting the unit to fluctuations in temperature, which means a more efficient type of heat pump.
In air-source heat pumps, there is a unit (heat exchanger) that is installed on the building’s exterior. In ground-source systems, the heat pump unit is installed inside the home.
The Heating Cycle of Ground Source Heat Pumps
An antifreeze solution is cooled by the heat pump’s refrigeration system to several degrees colder than the outside soil. The refrigerant circulates through the underground piping system and absorbs heat from the soil. This is then brought back to the heat pump unit inside the house. In groundwater or antifreeze mixture systems, it then passes through the refrigerant-filled primary heat exchanger. The heat is transferred to the refrigerant, which boils to become a low-temperature vapor.
The Cooling Cycle of Ground Source Heat Pumps
The cooling cycle is basically the reverse of the heating cycle. The direction of the refrigerant flow is changed and it picks up heat from the inside air and transfers it directly to the ground water. The heat is then expelled outside, into a body of water or return well or into the underground piping (in a closed-loop system).
Air-to-Air Heat Pumps
This is one of the most common and efficient electric HVAC devices designed for home heating and cooling. The energy cost of the air-source heat pumps is lower than gas, oil heating systems or geothermal.
Which Brand of Heat Pumps Is Best?
Recently I came across the Bosch IDS Family of Inverter Heat Pumps and they are quite impressive. Bosch brings homeowners the most energy-efficient and environmentally responsible products, and that’s why we install them on our shows.
Bosch Inverter Ducted Split Air Source Heat Pump System
- One of the quietest air-to-air heat pumps on the market
- You get consistent room temperature
- Bosch IDS heat pumps self-adjust, keeping your indoors at a comfortable temperature and provide humidity control
- It’s highly efficient and you only consume the energy you need
The Bosch Inverter Ducted Split Family adjusts the compressor capacity rather than a simple on/off control like other manufacturers. This means reduced operating costs. It also features enhanced humidity control and higher efficiency. The system works together with the thermostat to automatically adjust according to your preferences. It also includes integrated sound dampening features, which keeps the units quiet.
How Do You Choose a Heat Pump System?
Most manufacturers of air-source heat pumps have a minimum operating temperature, which means the unit can’t function below a certain temperature. Usually in newer models, this can range from -15°C to -25°C.
Check The Warranty
Going with a leading brand for HVAC solutions is important. Look into the warranty offered by the manufacturer as well as the maintenance recommended. Most manufacturers will provide a one-year warranty on labor and parts. For the compressor (parts only), typically the warranty is 5 years. Warranties do vary between manufacturers, so check the fine print. Bosch offers replacement parts protection for up to 10 years. This standard offering covers all components incorporated into the heat pump system at the time of manufacture.
Certification, Standards, and Rating Scales for Heat Pumps
The cooling efficiency for air-source and ductless-split systems is measured by SEER (Seasonal Energy Efficiency Ratio). The heating efficiency of air-source and ductless-split systems is measured by HSPF (Heating Seasonal Performance Factor). There are federal minimums for the SEER and HSPF ratings, so do your research!
Sizing Considerations when Choosing A Heat Pump
If a heat pump is undersized or oversized, it will not heat or cool your home effectively. This can also lead to higher energy bills. If you go with a bigger unit than needed, you are paying a bigger price upfront and the unit will cycle on and off unnecessarily. This means a shortened life span. Always consult with an HVAC specialist.
The IDS (Inverter Ducted System) family is available in 4 sizes, ranging from 2-5 ton capacity, which means 3 different systems:
- the IDS Light
- the IDS Plus
- And the IDS Premium.
The IDS family comes with a 10-year residential limited warranty. And that means peace of mind.
Do You Need a Dual Fuel Backup For Your Heat Pump?
For colder climates, a dual fuel backup may be required. This depends on where you live and the design and efficiency of your home. There are many high-efficiency heat pump systems that come with an integrated electric resistance heating system that act as a backup at colder temperatures.
Mini-split heat pumps without ductwork, electric baseboards or high-quality electric fireplaces are a viable back-up option.
Natural gas heating systems can be used as backup systems for central heat pumps as well, but require special modifications to work the homes heating system. In many rural areas, wood heating is used to supplement a heat pump on the coldest days.
Heat Pump Installation
Before purchasing a heat pump, I recommend upgrading your insulation and fixing sources of air leaks. You want your building envelope to be as efficient as possible.
I recommend bringing in a professional contractor to install your heat pump. This is not a DIY job, especially because you are likely dealing with an indoor and outdoor unit. Your HVAC specialist will determine where each unit will go and explain what will be necessary to connect the units and how to connect the heat pump to your home’s existing systems.
The same goes for maintenance tasks. You should hire a qualified contractor to do the maintenance on your unit.
For more information on HVAC systems check out: HEAT & ENERGY RECOVERY VENTILATORS – HRV VS ERV