Water to Air Heat Exchangers for Hydronic Heating and HVAC
Water to air heat exchangers transfer heat from circulating hot water to moving air through a finned coil. Featuring copper tubes and aluminum fins, these coils connect hydronic heat sources with forced-air heating systems, HVAC air handlers, and ductwork without mixing the water and air circuits.
Common applications include outdoor wood boilers, hydronic furnaces, residential heating systems, workshops, garages, and greenhouses. Available coil sizes and heating capacities help accommodate different airflow requirements, water temperatures, and installation spaces.
When selecting a coil, consider the required BTU output, water flow rate, airflow (CFM), connection size, and available installation space to ensure compatibility with your system.
At Alfa Heating Supply, our water to air heat exchanger solutions are designed for reliable heat transfer, compact installation, and long-term durability in residential, commercial, and industrial heating applications.
Key Benefits of Water to Air Heat Exchangers:
- Efficient heat transfer between hot water and air for heating applications
- Compatible with hydronic heating systems, boilers, outdoor wood boilers, and HVAC air handlers
- Copper tube and aluminum fin construction for effective thermal performance
- Multiple BTU capacities available for different heating requirements
- Compact coil designs for installation in limited spaces
- Reliable operation under varying water temperatures and airflow conditions
Quick Selection Guide: How to Choose a Water to Air Heat Exchanger
Selecting the right water to air heat exchanger depends on your required heating capacity, water temperature, water flow, airflow, and available installation space. Check these key parameters before selecting a coil:
- Heating Capacity (BTU/hr): Match the required heat output to your heating load.
- Water Temperature & Flow: Check the available supply temperature and water flow rate (GPM).
- Airflow (CFM): Make sure the coil is suitable for the available blower or air handler airflow.
- Coil Size: Confirm the required width, height, depth, and connection configuration.
- Pressure Drop: Check the water-side and air-side pressure drop to ensure compatibility with your pump and blower.
For detailed sizing guidance, see our Water to Air Heat Exchanger Selection Guide
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Water to Air Heat Exchangers for Hydronic Heating Systems
Water to air heat exchangers allow hydronic heating systems to supply heat to forced-air distribution systems. In a typical installation, hot water from a boiler or other hydronic heat source circulates through the heat exchanger coil, while a separate fan or air handler moves air across the finned surface.
As heat passes from the hot water through the copper tubes and aluminum fins into the moving air, the heated air can be distributed through ductwork or delivered directly into the space, depending on the system configuration. The water and air remain in separate flow paths, so the two circuits transfer heat without mixing.
When integrating a water to air heat exchanger into a hydronic system, consider the required heating capacity, available water temperature and flow rate, airflow requirements, and allowable pressure drop. These factors help determine the appropriate coil size and configuration for the application.
Applications of Water to Air Heat Exchangers
Water to Air heat exchangers are widely used in hydronic heating and thermal transfer systems where efficient heat exchange between water and air is required. These systems are commonly installed in residential, commercial, and industrial environments to provide reliable and energy-efficient heating solutions.
- Outdoor wood boiler heating systems
- Hydronic forced air furnaces
- HVAC air handlers
- Residential heating systems
- Workshop and garage heating
- Greenhouses
- Commercial heating systems
- Industrial air heating systems
Typical applications include the following system categories:
How Water to Air Heat Exchangers Work
A water to air heat exchanger transfers heat from hot water to an air stream through a finned coil. Hot water flows through the copper tubes, while air passes across the aluminum fins, which increase the surface area available for heat transfer.
As the air moves across the heated coil, it absorbs heat and carries it into the space being heated. The water and air remain in separate flow paths, allowing a hydronic heating system to supply heat to a forced-air distribution system without mixing the two streams.
In a typical installation, a separate fan or air handler moves air across the coil. The amount of heat transferred depends on factors such as water temperature, water flow rate, entering air temperature, and airflow.
Water to Air Heat Exchangers for Outdoor Boilers
Water to air heat exchangers connect outdoor boilers and wood-fired hydronic heating systems with forced-air furnaces, air handlers, and ductwork. Hot water circulates through copper tubes while a fan or blower moves air across the aluminum fins, transferring heat without mixing the two circuits.
These coils can be installed in furnace cabinets, air handlers, or custom duct systems and are suitable for homes, workshops, garages, agricultural buildings, greenhouses, and commercial or industrial heating applications.
Available in multiple sizes and BTU capacities, our water to air heat exchanger coils can be selected based on heating capacity, water temperature and flow, airflow (CFM), coil dimensions, and pressure drop.
For systems connecting hydronic heat sources with furnaces and ductwork, see our Forced Air Heating System solutions.
FAQ
A water to air heat exchanger is used to transfer heat from hot water (or hydronic systems) into air for space heating applications such as wood boilers, furnaces, garages, workshops, greenhouses, and HVAC air handling systems.
Yes. Water to air heat exchangers are commonly used with outdoor wood boilers and hydronic heating systems to distribute heat into forced air systems, providing efficient whole-building heating.
The required size depends on BTU output, airflow (CFM), and application. Small garages may require 60,000–100,000 BTU, while residential or shop heating systems may require 120,000–240,000 BTU or more.
They can be installed in furnace ductwork, air handlers, garage heaters, greenhouse ventilation systems, and custom hydronic HVAC systems.
Hydronic coils are a type of water to air heat exchanger. They use copper tubes and aluminum fins to transfer heat from hot water into air streams in HVAC systems.
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