Heat Pumps Reduce Overall Costs While Adding Comfort
Heat pumps can be an energy-efficient alternative to furnaces and air conditioners in moderate climates. Because they move heat rather than create it, they can provide up to four times the output of heating and cooling relative to the energy saved over other options.
Heat Pump Types and Traits
Air-source heat pumps are one common type. They transfer heat between your house and the outdoors. If you heat with electricity, a heat pump can reduce the amount of electricity you use. High-efficiency heat pumps also do a great job dehumidifying your air, reducing energy use except in most low-temperature regions.
When a home has no ducts, air-source heat pumps are available in a ductless version called a mini-split heat pump. In addition, a special type of air-source heat pump, called a “reverse cycle chiller,” generates hot and cold water rather than air, allowing it to be used with radiant floor heating systems in heating mode.
Geothermal (ground-source or water-source) heat pumps, also called GeoExchange, transfer heat between your house and the ground, or a nearby water source, are another option. Installation is expensive, but these are less costly over time because they rely on the earth’s thermal energy for heating and cooling. They can provide heating, cooling and even hot water. Installation costs depend on the size of your lot, the subsoil, and landscape. Ground-source or water-source heat pumps are preferable in extreme climates, and customer satisfaction with these systems is very high.
Shopping for a GeoExchange system, keep the following in mind:
- Look for equipment that is certified by the Air-Conditioning and Refrigeration Institute (ARI). Certified equipment carries the ARI seal
- Look for a performance guarantee on your installed system
- Work with a contractor who can estimate the ideal capacity rated unit needed for your GeoExchange system
- Look for an experienced contractor to make sure the system will work in conjunction with the system(s) you already have
A new type of heat pump for residential systems is the absorption heat pump, or a gas-fired heat pump. Absorption heat pumps use heat as their energy source, and can be driven with a wide variety of heat sources.
Ecological impact of heat pumps
Heat pumps are energy-efficient and safe for the environment. In conditions where heat pumps can meet the space heating, hot water heating, and cooling needs in homes and industrial settings, they are poised to introduce a positive worldwide impact.
Of the global CO2 emissions that amounted to 22 billion tonnes in 1997, heating in buildings caused 30%, and industrial activities caused 35%. The potential CO2 emissions reduction with heat pumps is calculated (by what authoritative organization?) as follows:
- 6.6 billion tonnes CO2 come from heating buildings (30% of total emissions).
- billion tonnes can be saved by residential and commercial heat pumps, assuming that they can provide 30% of the heating for buildings, with an emission reduction of 50%.
- A minimum of 0.2 billion tonnes can be saved by industrial heat pumps (estimation based on a study by Annex 21 (clarify the source).
- The total CO2 reduction potential of 1.2 billion tonnes is about 6% of the global emissions, which means this is one of the best options.
Renewable energy incentives
Given the various benefits of renewable energy, incentives are becoming common to encourage the use of efficient energy systems. Consider the example below that illustrates this point:
Financial incentives offered by Tri-State Generation and Transmission and United Power, (based where?) combined with the many advantages of geo-exchange comfort systems, are motivating home and business owners along Colorado’s Front Range to consider geo-exchange comfort systems over other forms of heating and cooling.
Monte Schmidt of Valley Heating and Air Conditioning of Brighton, Colo., said, “Tri-State and United Power’s proactive support of geo-exchange heating and cooling technology, and their consumer education programs, have produced a groundswell of interest in the geo-exchange alternative.
“By choosing geo-exchange, not only does the customer benefit from lowered operating costs, improved comfort and safety, the power industry, Tri-State and United Power, benefits from lowered power consumption and more evenly loaded power demand. As the number of geoexchange customers increases throughout the Front Range, so will the cumulative economic benefits to the power industry and, ultimately, to all power consumers.
“Last autumn we were selected by Valley Bank and Trust of Brighton to replace their fossil fuel system with a WaterFurnace geoexchange system,” Schmidt explained.
In a press release from Valley Heating and Air Conditioning, Donna J. O’Dell Petrocco, Valley Bank and Trust president and chief operating officer, said, “Our new system will provide a clean, safe, and comfortable environment for our staff and customers while conserving our precious energy resources and protecting our environment.” (Note: It’s often good policy when using a testimonial from a new user to follow up to ensure that their subsequent experience has been positive. If not, don’t use the testimonial.)
Dual Fuel Heat Pumps
Dual-source heat pump technology means an extra measure of energy efficiency and performance certainty are available to consumers. The term “dual source” refers to the use of both air and geothermal sources for the condensing process.
Dual-source heat pump (DSHP) technology is currently available only from one manufacturer: Global Energy & Environmental Research, Inc. (GEER) of Lutz Florida. GEER manufactures a line of residential units and retrofit packages for larger commercial-sized systems. Residential sizes range from 2 1/2 -ton to 5-ton nominal cooling capacities with a 20+ SEER under rated conditions. GEER also makes the dual-source technology available as a retrofit package for commercial HVAC systems in the 5- to 30-ton range. In the retrofit application, the existing compressor(s) are replaced with downsized high-efficiency compressor(s) and the dual-source geothermal technology. The compressors can be downsized because the dual-source technology makes up the difference in capacity.
The DSHP systems can also be designed with a dual compressor to provide additional heating capacity at colder temperatures. Annual maintenance requirements for the DSHP technology are similar to those of comparably sized air-source heat pumps. Standard preventive maintenance includes periodic filter replacement and coil cleaning.
Dual Fuel Overview
A dual-fuel heat pump is an electric air-source heat pump that uses an alternative natural fuel source such as natural gas, LPG, or oil, as an auxiliary or backup heating option, instead of more costly, less efficient electric resistance coils. A functional system can be achieved within a single integrated unit, or pieced together by combining a standard air-source heat pump with a furnace via a controller. The controller determines which unit operates, based on situation requirements and variables including outside temperature, efficiencies, and relative cost of fuels.
- Electric heat air-source
- Automatic fossil-fueled heat source other than wood
- Radio Control
- Dual Fuel meter
- Water heater
Operating Traits for Heating
- Can run through the same Dual Fuel control and rate
- Operates at a separate, Off-Peak schedule
Operating Traits for Air conditioning
- Can run through the same Dual Fuel control and rate
- Operates at a separate, “Cycled Air” schedule
Chief Benefit: Reduces operating costs compared to single fossil fuel heating systems
- Additional expense of installing 2 separate heat sources
- Increased maintenance costs because of more moving parts
- Ductless (mini-split) heat pumps
Split systems combine the flexibility of room air conditioners with the whole house cooling of central systems. It is challenging to install central air conditioning in a building that does not have forced air ducts. Mini-split heat pumps do not require ductwork for central air conditioning. Ductless mini-split heat pumps are one way to gain the benefits of central air conditioning without requiring ductwork. Instead, their smaller refrigerant lines take up little room compared to large ducts, and therefore are easier to install.
Ductless mini-split systems combine the flexibility of room air conditioners with the benefits of whole house cooling of central systems. Although some systems provide heating and cooling, ductless mini-split heat pumps are usually installed primarily for cooling.
While distribution energy losses in conventional systems have been estimated as high as 30 percent, similar losses for ductless systems are about 1 percent to 5 percent. Without ductwork, which can leak and lose energy, mini-split heat pumps are even more highly enhanced by zone control.
The cost of ductless heat pumps has gone down. Operation costs vary. Installation is relatively easy.
Ductless, mini-split-system heat pumps (mini splits) make good retrofit add-ons to homes without ducts. This includes hydronic (hot water heat), radiant panels, and space heaters (wood, kerosene, propane). They are also good for room additions.
Generally, mini splits have two parts: an outdoor compressor/condenser, and an indoor air-handling unit. A conduit, which houses the power cable, refrigerant tubing, suction tubing, and a condensate drain, links the outdoor and indoor units.
Advantages of mini splits are their zoning options, small size, interior design options, easy installation, safety, cost per cooling capacity, and their reduced energy loss compared with ducted systems.