The Best Size Pipe to Make a Fireplace Heat Exchanger

Exchanger Tubes

• Heat exchanger tubes are components that carry air from one area to another within the fireplace, typically around the back of the fireplace and out the other side so the air can become heated more easily. There is no strict guideline for the type or number of exchanger tubes you can use. Many use at least several tubes to maximize efficiency, but some use only one or two, depending on setup. The average size of most tubes is either 3/4 inch or 1 inch in diameter.

Heater Sizes

• The overall size of your tubing array will depend on the size of your fireplace, so measure your insert or firebox carefully. Do not assume a general size. For a rough idea, many fireplace exchangers are around 14 inches wide and 18 inches high. Blower units will take up extra space. For larger fireplace units, both height and width can be extended markedly from these average sizes.

Unit Considerations

• While 3/4-inch or 1-inch diameters are common sizes, you may find many different sizes of heat exchanger pipes, from 3/8 inch to 1 1/4 inch. The best size will take advantage of your fireplace size and fuel. Smaller tubes may be useful for low exchanger surface area needs. You can also control exchanger surface by reducing or increasing the number of tubes, rather than the actual size.

Reclaimers

• Reclaimers are heat exchanger units that sit up high on your fireplace exhaust tubing and process the exhaust, to extract any remaining heat. These heat exchangers are separate systems. They are designed to fit around the size of a typical wood or pellet stove exhaust pipe, often 6 inches in diameter. These reclaimers do not need other tubing to work properly, but this single measurement is key to proper reclaimer performance.