The products listed here are water-to-air heat exchangers for connecting a hot-water heat source with forced-air ductwork; they are not complete forced-air wood furnaces. The 30-by-30-inch model is best for buyers assessing a larger exchanger, while the 12-by-12-inch and 12-by-15-inch models suit smaller installation openings. The 20-by-20-inch and 18-by-18-inch options offer intermediate dimensions. Check the furnace or boiler requirements, airflow, duct opening, and water connections before choosing.
| Product | Listed size | Best suited for |
|---|---|---|
| AB Store 30-by-30 | 30 by 30 inches; 1 1/4-inch ports | Buyers comparing a larger exchanger and larger listed ports |
| 12-by-12 exchanger | 12 by 12 inches; 1-inch ports | Installations requiring a compact exchanger |
| AB Store 20-by-20 | 20 by 20 inches; 1-inch ports | Buyers seeking a middle-size option with stated capacity |
| Furnace Supply 18-by-18 | 18 by 18 inches; 1-inch connections | Buyers whose opening matches this size |
| AB Store 12-by-15 | 12 by 15 inches; 1-inch ports | Smaller installations with a stated 67,500-Btu capacity |
AB Store 30-by-30 Water-to-Air Heat Exchanger
Best for: Buyers whose installation calls for a 30-by-30-inch exchanger and 1 1/4-inch copper ports. The listed size and larger port diameter distinguish this option from the other products in this selection.
The manufacturer lists a 285,000-Btu capacity and says output can reach up to 360,000 Btu per hour depending on the application. Its construction includes 12 aluminum fins and three rows of 3/8-inch seamless copper tubes per inch. A steel shell supports the exchanger, and the fins have an epoxy coating, according to the product details.
This model is selected for its large listed dimensions, larger connections, and detailed construction information. The manufacturer also describes it as usable with different hot-water sources, including boilers and solar panels. Confirm the actual heating capacity for the system design rather than treating the maximum stated output as guaranteed.
Limitation: The 30-by-30-inch dimensions and 1 1/4-inch ports may not fit existing ductwork or plumbing sized for a smaller exchanger.
12-by-12 Water-to-Air Heat Exchanger
Best for: Buyers looking for a compact 12-by-12-inch exchanger with 1-inch copper ports. The supplied product name identifies it for outdoor wood furnace, residential heating and cooling, and forced-air heating applications.
The listed information does not provide capacity, fin count, tube arrangement, or construction details for this specific item. Its main comparison point is its compact stated size and 1-inch connection specification. Match both dimensions to the available duct opening and verify port size against the water circuit before purchase.
This option is selected for installations where a smaller exchanger footprint is the priority. It may be a better fit than the 20-by-20- or 30-by-30-inch models when the cabinet or duct space is limited, provided its rated output meets the system’s heating needs.
Limitation: The supplied product details do not state a Btu capacity, so buyers cannot compare its stated output with the other listed models from this information alone.
AB Store 20-by-20 Water-to-Air Heat Exchanger
Best for: Buyers who need a 20-by-20-inch exchanger with 1-inch copper ports and want a product listing with stated capacity and construction details.
The listing gives a capacity of 160,000 Btu and says output can reach up to 360,000 Btu per hour depending on the application. It describes 12 aluminum fins and three rows of 3/8-inch seamless copper tubes per inch. Other listed features include a steel shell, brazed edges and contact points, and epoxy-coated fins.
This model is selected as a middle-size option with more performance information than the compact 12-by-12 listing. The manufacturer describes the exchanger as suitable for heat transfer from sources such as boilers and solar panels. Choose it if the dimensions and 1-inch ports suit the installation and the system designer confirms its capacity is appropriate.
Limitation: The stated maximum output is application-dependent; it should not be assumed to represent guaranteed performance in every furnace or duct system.
Furnace Supply 18-by-18 Hot-Water Coil
Best for: Buyers whose planned installation requires an 18-by-18-inch water-to-air coil with 1-inch copper connections.
The supplied product details identify the product as an 18-by-18 water-to-air heat exchanger for an outdoor wood furnace and specify 1-inch copper connections. No capacity, fin configuration, material description, or other performance information is included in the provided listing details.
This product is selected because its listed dimensions provide a distinct middle-size alternative to the 12-by-12, 12-by-15, and 20-by-20 options. Buyers should compare the coil’s actual face dimensions with the available cabinet or duct opening and ask the seller or installer to verify capacity for the intended system.
Limitation: The supplied feature information is brief and does not state a Btu rating, making output comparisons difficult.
AB Store 12-by-15 Water-to-Air Heat Exchanger
Best for: Buyers who need a smaller 12-by-15-inch exchanger with 1-inch copper ports and a stated capacity.
The listing gives a capacity of 67,500 Btu and says the product can produce up to 360,000 Btu per hour depending on the application. It describes 12 aluminum fins and three rows of 3/8-inch seamless copper tubes per inch. The product also has a steel shell and epoxy-coated fins, according to the supplied features.
This option is selected for buyers who want a compact footprint but need more performance information than the 12-by-12 listing provides. Its stated capacity is lower than the 20-by-20 and 30-by-30 products’ listed capacities, but actual suitability depends on the installation and system design.
Limitation: Its 67,500-Btu listed capacity may not meet a larger heating demand; have the required output checked before choosing based on dimensions alone.
Buying Guide: Choosing A Heat Exchanger For Forced-Air Wood Heating
Forced-air wood furnace searches can refer to complete furnaces or to components that transfer heat into a forced-air duct system. The products in this selection are water-to-air heat exchangers, not complete combustion appliances. A heat exchanger needs a compatible hot-water source and an air-moving system to deliver heat. Confirm what equipment you are buying before comparing products.
What size exchanger fits the installation?
Start with the opening or cabinet dimensions, not the largest model. The listed options range from 12-by-12 inches through 30-by-30 inches. Confirm whether the stated size refers to the exchanger’s face, the required opening, or another measurement by checking the full product specifications. Also allow for any installation clearances specified by the manufacturer or installer.
A larger exchanger is not automatically the right choice. It must fit the air-handler or duct arrangement, and its airflow resistance and water-side requirements must suit the system. If replacing an existing coil, record its dimensions and connection positions before selecting a replacement.
How should Btu capacity affect the choice?
Compare a product’s stated capacity with the heating load and operating conditions of the home. In the supplied listings, the 12-by-15 model states 67,500 Btu, the 20-by-20 model states 160,000 Btu, and the 30-by-30 model states 285,000 Btu. The 12-by-12 and 18-by-18 product details provided here do not state capacity.
These figures are product-listing claims, not a substitute for a heat-load calculation. The 30-by-30 and 20-by-20 listings also mention possible output up to 360,000 Btu per hour depending on application. Treat that as a conditional maximum, not a guaranteed result. Ask an HVAC professional to evaluate the heat source, water temperature and flow, airflow, and building demand.
Which port size should you check?
Four products identify 1-inch copper ports or connections; the 30-by-30 model lists 1 1/4-inch ports. Port diameter must match the planned piping and the requirements of the water circuit. A mismatch can require additional fittings or changes to the design, so verify connection size and orientation before ordering.
What construction details matter?
The 20-by-20 and 30-by-30 listings describe copper tubes, aluminum fins, steel shells, and epoxy-coated fins. The 12-by-15 listing also describes copper tubes, aluminum fins, a steel shell, and an epoxy coating. The 12-by-12 and 18-by-18 details provided here do not include comparable construction information.
These details can help compare listings, but they do not establish expected service life or prove suitability for a particular water chemistry or operating pressure. Review the complete manufacturer specifications and follow installation and maintenance instructions.
Will it work with a wood furnace or another heat source?
A water-to-air exchanger transfers heat from circulating hot water to air passing through the coil. The 30-by-30 and 20-by-20 listings describe use with sources such as boilers and solar panels, as well as forced-air heating applications. Check that the heat source can supply the water temperature and flow the exchanger requires. Do not assume that a heat exchanger includes a furnace, pump, controls, ductwork, or other system components.
What should be checked before purchase?
- Measure the available installation opening and confirm the product’s actual dimensions.
- Match the listed connection diameter to the planned plumbing.
- Verify capacity with a qualified installer based on the building’s heating load and system conditions.
- Check whether the listing provides complete specifications for pressure, flow, temperature, and installation orientation.
- Confirm which additional components are required; the listed products are heat exchangers, not complete furnace systems.
Frequently Asked Questions
Are these products complete forced-air wood furnaces?
No. They are water-to-air heat exchangers or coils. They transfer heat from hot water to air and must be part of a compatible heating system.
Which listed product has the largest stated capacity?
The AB Store 30-by-30 listing gives a capacity of 285,000 Btu. It also mentions output up to 360,000 Btu per hour depending on the application, which is not a guaranteed output for every installation.
Which exchanger has 1 1/4-inch ports?
The AB Store 30-by-30 model lists 1 1/4-inch copper ports. The other products with stated port sizes list 1-inch connections.
Can I choose an exchanger by matching its size to my duct opening?
Size is important, but it is not the only requirement. Check capacity, port diameter, airflow, water flow, and installation specifications as well as the opening dimensions.
Which product has the least performance information in the supplied details?
The 12-by-12 and Furnace Supply 18-by-18 listings do not include a Btu capacity in the supplied product features. Confirm their ratings and full specifications before comparing them with models that state capacity.