Schedule your Home Energy Audit Today!
Hydronic Forced Air
Quick Facts
- A single gas fired water heater can provide hot water as well as warm air (easily replacing a traditional forced air furnace) in a combined hydronic design.
- Air handler component is equipped with a fan and a filter to distribute warm clean air to the house through a duct system
- Fresh, outside air can be used with minimal energy loss when the system is combined with an integrated or external heat or energy recovery ventilator
- Can be used in conjunction with hydronic radiant heat (instead of forced air) and with solar thermal hot water heating
- Can be used in conjunction with an air conditioner to provide centralized cooling
- Ideally should be installed after the building envelope is sealed and insulated
Energy Efficiency, Comfort, and Health
Hydronic forced air delivers more even, comfortable heat while typically using less energy than even a highly efficient gas furnace. When it is combined with a home’s water heater, total system efficiency and total home energy usage decreases since it saves energy by reusing the heat of the hot water. This means a more comfortable home environment while using less energy. Less energy means less CO2 emissions. In addition, the clean closed combustion system used in high efficiency hydronic water heaters, along with the use of a recovery ventilator, means that the air entering the home will be fresher and cleaner.
Function and Optimal Operation
A hydronic forced air and water heating system is a single system which provides centrally controlled heating, cooling, and ventilation along with hot water to a home. Since it uses the forced air duct system present in most homes, it can be a simple and effective way to increase system efficiency without making substantial structural and system-wide changes to a home. It can also be easily configured to integrate renewable technologies such as solar thermal water heating. Highest efficiency levels will be attained when used in conjunction with a well insulated, correctly sized and leak free duct system. As with any temperature regulation system, a programmable thermostat or in conjunction with a zoned duct system to assure that a hydronic forced air system is as efficient and as effective as possible.
Components
Water Heater | Air Handler | Recovery Ventilator | Thermostats and Controls | Duct System | Air Cleaner
These systems can be bought as complete systems or pieced together by selecting each component separately in order to maximize performance and efficiency. Each component plays an important role in the functioning of the system and can have a significant impact on system efficiency.
Water Heater
This is the most integral part of the system; it provides the heat and hot water to make the home comfortable. It should be a high efficiency gas water heater or boiler used alone or in conjunction with a solar thermal hot water system. Hot water is supplied from the water heater to the home for domestic hot water uses such as showers and sinks, as well as to the air handler. [+] MORE
Air Handler
The air handler (replaces the typical furnace) is an important component of any forced air heating (or cooling) system. It contains a powerful motor operated fan which blows air over a heating coil (through which hot water flows) sending warm air through the duct system to the house. Warm air circulates through the house and returns to the air handler through a filter to repeat the process. Alternatively, fresh air can be integrated into the air supply loop by the optional addition of a recovery ventilator in the cold air return side of the system. If the home’s thermostat permits the fan to be turned on independently of the heating coil, the air handler can be a component of a whole house ventilation and air cleaning system. Variable Speed or Electronically Commutated Motors (ECM) are especially valuable in these applications due their dramatic efficiency gains over standard Split Capacitor Motors during fan only operation.
Examples include:
Recovery Ventilator
When a home is thoroughly sealed to prevent losses of conditioned air and infiltration of pollutants, it becomes doubly important to supply the home with fresh outside air and to expel any occurring moisture or stale air. An energy ventilator permits the exchange of fresh outdoor air for stale interior air in a heating (or cooling) system without sacrificing efficiency by first bringing the outside air to the temperature of indoor air. In climates where indoor humidity is similar to exterior humidity, a heat recovery ventilator (HRV) is used, if humidity is a concern, an energy recovery ventilator (ERV) should be used. Recovery ventilators are very efficient because they use thermodynamics instead of mechanics to recover heat (or cool) from outgoing stale interior air and transfer it to incoming fresh air. This technology can also be part of a whole house ventilation and air cleaning system.
Thermostats and Controls
This is the main point of interaction an occupant has with the systems which regulate the temperature and air quality of the living spaces. Whether the heat is delivered through a forced air or radiant heating system, thermostats and more sophisticated controls can allow the occupant to interact with the air regulation systems to tailor and automate temperature as well as humidity and ventilation. Options for increased comfort and energy efficiency include zoned heating and cooling. However, the energy efficiency and comfort levels attainable with a programmable or zoned thermostat are limited by the efficiency of the forced air or radiant heating system it controls, as well as the building envelope of the home in which it operates. [+] MORE
Duct System
The duct system is a network of components which work together to supply warm or cool air to the living space and to return stale air to the furnace or hydronic air handler to be filtered. Due diligence is often not followed when installing a duct system and installation tends to be very error prone. Care and building science concepts must be applied to the design of repair of an effective long-lasting system. Such design and repair is among the most cost effective of all home performance retrofits. [+] MORE
Air Cleaner
Air cleaning is an integral part of maintaining healthy indoor air quality. The most efficient forced air systems can include an integrated air cleaner which can run continuously, using either filtration or electric charge to remove particles from the air. [+] MORE.