Overview: A practical means for delivering radiant heating and cooling is with a heat pump. Modern heat pumps use 66-75% less energy than an electric resistance heating and cooling appliance. A heat pump is a mechanism that is used to extract heat from a source with lower temperature and transfer it into a source with a higher temperature. Heat pumps can be an important component of Net Zero Energy Radiant homes.
Air to Air Heat Pumps:Side by Side Mini Split air to air heat pumps are very popular, efficient and relatively inexpensive for spot cooling in living areas with significant cooling loads that are used independently of the radiant floor heating system. These heat pumps typically utilize wall-mounted consoles without ducting.
Hydronic Heat Pumps: Hydronic (water based) heat pumps are either ground source or air sourced designs that delivery warm water to the RadiantBoard, heat the domestic hot water and generate chilled water for fan coils or radiant ceiling cooling. Radiant Cooling. Either type of hydronic heat pump operates most effectively delivering the low water temperature that matches so well with the heat transfer efficiency of RadiantBoard. A perfect match!! RadiantBoard Performance
Ground Source Heat Pumps: Geothermal ground source heat pumps use the ground as a heat exchanger to efficiently produce warm and cool water. While these systems can be very effective, they are typically expensive and complex hydronic mechanical systems that should be fully engineered. http://www.montereyenergygroup.com/
Geothermal heat pumps are normally more popular, efficient and cost-effective in eastern North America due to ground conditions and utility rebates.
How they work.. A geothermal system consists of a circuit of polyethylene tubes that are laid underground. A mix of water and refrigerant is then used as a method of heat transfer. The heat pump cools down the liquid that is flowing underground to the degree that is below the earth temperature. Once underground, heat from the earth is absorbed into the liquid, and the heat is extracted once the water reaches the heat pump on its way back. This is a closed loop system, therefore once the heat is extracted, the water is cooled again and the cycle is repeated for as long as the heat pump remains turned on. The size of the piping loop should be correlated to the size of the property that needs to be heated. Depending on various factors, such as property size or soil texture, the loops can be either horizontal or vertical. In the horizontal installation, 4 to 7 feet trenches are dug and the pipe is laid down. In vertical loop installation, which is more costly, a 100 to 500 feet hole is drilled and piping is inserted into it.
Air to Water Hydronic Heat Pumps: A new generation of small air to water hot water heat pumps are now on the market. They are basically a normal, super-efficient modern variable speed heat pump with a refrigerant to water heat exchanger that produces warm and cool water (https://www.chiltrix.com/small-chiller-home.html). They also can be matched with an indirect water heater to produce domestic hot water. The warm water circulates through the RadiantBoard while the cooling can be accomplished with mini fan coils or with radiant ceiling cooling. Since these heat pumps use ambient air, they do not need all the expensive ground heat exchangers that make ground source heat pumps so expensive.
Heat Pump Water Heating: Electric resistance water heaters are expensive to operate, as are electric boilers, in most of North America and are thus rarely used if natural gas or propane is available. However, electric heat pump water heaters are typically twice as efficient and half the cost to operate as a standard electric resistance water heater.
Stand Alone Heat Pump Water Heater: For small load radiant heating applications, a large heat pump water heater can be a dedicated source of warm water for radiant. Proper sizing is critical.
Combined Hydronic Heat Pump Water Heater: For very low heat load projects, consider using a large volume, well-insulated heat pump water heater to meet both the domestic hot water load and heating load for the project. Example: Install an 80-gallon heat pump water heater and employ an external heat exchanger to create a closed-loop system for your radiant system. A great package that addresses this need is made by Taco http://www.tacocomfort.com/products/systems/radiant_systems/x-pump_block_xpb/index.html
The Ultimate Green Solution:
Whole House Ventilation: In many climates, a home does not require refrigerant cooling so much as a whole house ventilation system that circulates air from the north side of the building and employs nighttime cooling strategies combined with a very tight building envelope.