Water-to-air coils offer efficient heat transfer for outdoor wood furnaces and hydronic heating systems. This guide highlights five well-rounded options, noting who each is best for and why. Read on to compare fit, installation, and energy considerations.
| Product | Best For | |
|---|---|---|
| AB Water to Air Heat Exchanger 20×20 (20×20, 1″ Copper Ports) | Mid to large systems seeking robust performance | Excellent heat transfer surface and easy plenum installation |
| AB Water to Air Heat Exchanger 12×15 (12×15, 1″ Copper Ports) | Smaller setups needing compact footprint | Solid performance with durable steel shell |
| GPOAS 20×20 Heat Exchanger (20×20, 1″ Copper Ports) | New installations prioritizing space efficiency | Space-saving design with strong construction |
| GPOAS 16×18 Heat Exchanger (16×18, 1″ Copper Ports) | Moderate layouts prioritizing install ease | Compact yet sturdy with easy plenum slide-in |
| Outdoor Furnace Supply 8×8 Coil (8×8, 1″ Copper Ports) | Very small or retrofit projects | Simple 1″ copper connections for quick setup |
Note: The table summarizes general traits. For each product, verify compatibility with your furnace and plenum size before purchase.
AB Water to Air Heat Exchanger 18×18 1″ Copper Ports
Best For: Households needing a robust 18×18 coil with 1″ copper ports for outdoor wood-furnace setups. This model emphasizes high heat transfer with 12 aluminum fins per inch and three rows of 3/8″ copper tubes. It is suited for systems that can accommodate a larger exchanger in the plenum. Limitation: installation may require adequate plenum clearance due to its size.
GPOAS 20×20 Heat Exchanger With 1″ Ports
Best For: Residential heating systems that need a balance of space efficiency and heat capacity. It uses a sturdy 306 steel case with base brazed joints, offering strong performance with 12 fins per inch and 3 rows of 3/8″ copper tubes. Caution: ensure plenum depth supports the unit’s footprint and weight.
AB Water to Air Heat Exchanger 12×15
Best For: Small to mid-sized spaces where a 12×15 coil can provide reliable heating and cooling. The unit combines wavy fins with seamless copper tubes for improved heat transfer. It relies on a durable steel shell and epoxy-coated fins for longevity. Limitation: slightly smaller surface area may reduce peak capacity in very large spaces.
AB Water to Air Heat Exchanger 20×20 (20×20)
Best For: Medium-to-large heating installations where higher flow and heat transfer are needed. The design features 12 fins per inch with 3 rows of 3/8″ copper tubes, delivering strong performance for renewable-energy integrations. Choose this if space allows and you want strong compatibility with boilers or solar assist. Caution: ensure adequate ventilation around the unit in outdoor placements.
Outdoor Furnace Supply 8×8 Coil
Best For: Retrofit projects or very compact installations where a tiny coil suffices. The unit provides 1″ copper connections for straightforward plumbing. Limitation: limited surface area may constrain heat output in larger spaces or high-demand scenarios.
Buying Guide
What size coil do I need?
Size should align with your furnace output, space in the plenum, and desired heating capacity. Larger coils deliver more surface area and potentially higher heat transfer but require more installation space.
What material considerations matter?
Common coils use copper tubes with aluminum fins or steel shells. Copper and aluminum provide good conductivity, while steel shells add durability and pressure resistance. Some fins are epoxy-coated for resistance to wear.
How easy is installation?
Coils designed to slide into a plenum with MNPT ports usually require minimal tools. Verify port size (1″ ports are common) and ensure clearance around the unit for maintenance and airflow.
Energy and compatibility considerations
Water-to-air coils support diverse heat sources, including boilers and solar panels. They are designed to transfer heat without relying on electricity to operate the coil itself, though the overall system may include pumps and controls that require electricity.
Maintenance expectations
Look for corrosion-resistant materials and epoxy-coated fins for longevity. Regular inspection of connections and fins helps sustain efficiency, especially in outdoor or high-temperature environments.
What about safety and installation limits?
Adhere to manufacturer guidelines for pressure and temperature limits. Ensure that the coil’s weight, size, and mounting method are compatible with the existing furnace plenum and that venting or clearance around the unit meets code requirements.
FAQ
- What is a water-to-air coil used for? It transfers heat from water to air to heat or cool a space via a forced-air system.
- Do these coils require electricity? The coil itself does not require electricity, but auxiliary components like pumps and controls may.
- Can I install a coil in a small plenum? Yes, but verify that the unit fits and does not impede airflow or maintenance access.
- Which coil is best for renewable energy integration? Coils designed for external heat sources and energy-efficient operation are suitable; check compatibility with boilers or solar collectors.
- Is copper port size important? Yes, 1″ ports are common and compatible with many fittings; ensure your piping matches.
- What should I avoid? Avoid selecting a coil that is too large for the available plenum or one with weight/clearance that cannot be safely supported.
