Using Hydronic Radiant Floor Heating with a Water-to-Water Geothermal Heat Pump


Water-to-water geothermal heat pumps work great with correctly designed hydronic radiant floor systems. The temperature of the air in the home will be warmer at the floor, and cooler as you rise toward the ceiling, which is unmatched for heating comfort. This also reduces the heat loss through the ceiling and upper walls. Because of this lower heat loss, and because a water-to-water geothermal heat pump has lower operating temperatures, these systems have the highest efficiencies and energy savings of any active heating system. The only drawback to these systems is their higher cost of installation.

Hydronic Radiant Geothermal Mechanicals Many people ask us if they can replace their fossil fuel-fired boiler with a water-to-water geothermal heat pump. This can be done, but only if the existing piping or radiator system is designed for it. Most hydronic systems are sized for the very high water temperatures of a fossil fuel boiler (typically between 140 and 180° F), meaning they have a relatively small amount of surface area in the piping or radiators. A water-to-water geothermal heat pump operates at much lower temperatures (between 90 to 120° F). This makes it more efficient (COPs are often over 5), but requires more heat transfer surface area. If a geothermal hydronic heating system is not designed right, it will be unable to fully heat your home during the coldest parts of the heating season. To prevent this problem, your boiler system must be evaluated correctly to determine if it can be used with a water-to-water geothermal heat pump.

Adding enough hydronic piping to your home can sometimes be very difficult and expensive. Pouring new Gypcrete floors is usually cost-prohibitive. Heavy carpet and some types of wood flooring will slow the heat transfer from underfloor pipes. And baseboard radiators are typically designed to use water temperatures no less than 145° F. In some of these cases, it may be better to use a "high-temperature" water-to-water geothermal heat pump, which can heat water up to 140° F. In other cases, you can combine a water-to-water geothemal heat pump with a forced-air hydronic air handler, to get the extra BTUHs needed in your home during the coldest parts of the year.

Water-to-water geothermal heat pump systems need other components that are typically lacking in fossil fuel-fired boiler systems. Buffer tanks, certain types of controls, and air handlers might need to be added, for proper operation with a water-to-water geothermal heat pump. If you install an air handler with your water-to-water heat pump, you can also cool your home in the summer months, using the same geothermal heat pump.

We can correctly design every part of a hydronic radiant system for any application, whether you are upgrading an existing system, adding a system, or designing a system for your new home. Most new heating-only radiant designs with up to four zones will cost $2400, and heating and cooling radiant designs with four zones of heating and two zones of cooling will cost $4200. Let us know what you'd like to build and we'll confirm your quote!