How to Convert Forced Hot Air to Hydronics

Evaluate the Project

• 1

  Evaluate the existing HVAC system in the home. In order to convert forced hot air HVAC system to hydronics, you will need access to the underside of the floors throughout the home. If you are retrofitting an existing home, you will have installation problems if the main floor of the home is over a finished basement, or if you are converting a two-story home. In these cases, conversion isn't an option.

• 2

  Identify your budget. Before changing over the HVAC system, price out the materials and labor for the work. Balance this against how much you expect to save in HVAC costs. If you will not recoup the investment before you expect to sell your home, you may not want to go to the expense of converting.

• 3

  Find a qualified plumber or HVAC contractor who is experienced with hydronic heating systems. Invite him to look over your home, and discuss any unforeseen challenges involved in the process. An experienced installer may increase the cost of the job, but his expertise will save money and problems in the long run.

Demo the Existing HVAC System

• 4

  Remove the existing furnace and hot air ducts, assuming your home is a good candidate for conversion. Since they will not be used, all the hot air and cold air return ducts can be eliminated. You may consider leaving the ducts if there are any questions about the installation or you anticipate the possibility of switching back to a forced air HVAC system at some point in the future.

• 5

  Cover the warm air duct holes which are in the floors of your rooms. Covering any location that previously had a floor vent will prevent sound transmission from the rooms into the basement, and minimize the potential for heat loss through the holes that were once connected into the duct system.

• 6

  Plan your installation of the hydronic system. The on-demand heater and control circuit are installed at one end of your basement or in a central location. From the water heater, the hot water lines and return lines emanate outward and distribute heat throughout the building. Locate the on-demand heater and zone control systems in a location that maximizes the heating potential by minimizing the distance between the water heater and the rooms.

• 7

  Plan your heating zones. A hydronic system gives you the ability to heat different rooms to different temperatures. Some rooms are heated all the time, while others are heated only when occupied. This is one of the energy saving features of a hydronic system.

Installing the Hydronic System

• 8

  Install the on-demand water heater and the primary water heater loop according to the manufacturer's instructions. The primary loop controls the amount of water which cycles through the heater and ensures that the right volume of water is heated regardless of how much water is used throughout the home.

• 9

  Install the water lines and the radiant heat exchangers throughout the building. The heat exchanging devices fasten directly to the floor, in between the floor joists. The heat exchangers are then plumbed back to the control area, and individual zones and zone controls are installed to manage the temperature in each room.

• 10

  Install a thermostat in the center of each zone, and then connect the thermostat to the zone water valves in the basement via thermostat wire. Each thermostat controls the temperature in its zone. As the temperature drops, the thermostat opens the zone control valve, and allows hot water to flow through the radiant heat devices.

• 11

  Connect the system to the cold water supply in the home. The hydronic water supply should be separate from the potable water system in the home, since this water recirculates continuously through the system.