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.

Water-to-water geothermal heat pump with source and load circulating pumps 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 system is large enough. Most hydronic piping systems are sized for the very high water temperatures of a fossil fuel boiler (typically between 140 and 160° F), meaning they have a relatively small amount of piping. 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 piping. If a geothermal hydronic heating system doesn't have enough piping, it will be unable to fully heat your home during the coldest parts of the heating season. To prevent this problem, you must significantly increase the amount of piping in a fossil fuel boiler system, before 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. Existing flooring can make pouring new Gypcrete floors 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 all these cases, it may be better to use a "high-temperature" water-to-water geothermal heat pump, which can heat water up to 145° F. Although these units are about 60 percent more expensive than regular water-to-water geothermal heat pumps, and are only made in a 34,000 BTUH size (which means you might have to add auxiliary heat, or buy two high temperature units), sometimes they will be less expensive than the cost of replacing your flooring material or installing hundreds of feet of extra piping.

Water-to-water geothermal heat pump systems also 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.

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.