Outdoor Boiler heat exchangers

One of the most remarkable discoveries in nature is that, in the history of the world, no scientist has ever been able to invent a fluid that transfers heat more efficiently than just regular water!

So for example, when a heating fuel is burned, and the heat needs to be distributed throughout one or more buildings, this can be accomplished with a boiler. The advantage of a boiler is that the fuel is burned in just one location and the resulting heat can be transferred to a variety of OTHER locations very easily and efficiently. The fuel burned in a boiler heats water. That water is then circulated through hidden pipes to every section of your home and other buildings to provide comfortable warmth without losing any efficiency. Cool right?!

(The only small issue is when the boiler is made of steel, it must be protected with a corrosion inhibitor. But we have completely solved that problem with our Liquid Armor Water Treatment. Click HERE for more information on how to protect your boiler investment.)

To complete this efficient process, a “Heat Exchanger” is required to transfer the warmth from the circulating water into the space to be heated. These heat exchangers come in different forms depending upon their purpose, but the TOP 3 heat exchangers are as follows:

Water-to-Air Heat Exchanger

As its name sounds, a water-to-air heat exchanger transfers heat from water to air. Many people think these look like a radiator for a car. The hot water passes through small copper tubes that have metal fins attached. The circulating hot water from the boiler heats the tubes and fins. When warmth is needed, a blower fan turns on and blows air through the fins and tubes and voila – warm air!

Water-to-air heat exchangers are most commonly used in forced air ducts. See drawing below. These heat exchangers are often installed in the forced air furnace plenum which is located above the furnace. These come in several sizes, and are often installed by simply attaching “L-Brackets” to the inside of the plenum that the heat exchanger lays on in a “flat” orientation.

Detailed installation instructions are included with every water-to-air heat exchanger purchased at OutdoorBoiler.com.

Water-to-air heat exchangers come in different sizes, some as small as 12”x12” for a small room up to 24”x24” and larger for bigger spaces to be heated.

Water to Air Heat Exchanger Heat Output and Dimensions
Water-to-Water Plate Heat Exchanger

These heat exchangers transfer heat from one circulating liquid (usually water from the boiler) to a different liquid, WITHOUT mixing the liquids!

These water-to-water plate heat exchangers accomplish this by allowing the hot water (from your boiler) to pass over alternating plates, thus warming them up. The water to be heated is passed through the empty space between those alternating hot plates, which transfers the heat from the boiler water to the other liquid.

For example, to heat your domestic hot water with your outhoor boiler, you will install a “Domestic Hot Water Kit”, which includes a plate heat exchanger so that your outhoor boiler water never mixes with your hot water used in cooking or bathing.

Plate heat exchangers are also used to transfer heat from boiler water to in-floor heating systems, to boiler systems that use baseboard radiant heaters, and to industrial hot water systems such as dairies.

Plate heat exchangers come in different sizes based on the application, but typically range from 20 plates to 100 plates.

Plate Heat Exchanger Capacity Chart
NUMBER OF PLATES BTU CAPACITY GPM PORT SIZE DIMENSIONS PRESSURE DROP
20 PLATE 80,000 BTU 3.5 1” 5”X12”X2” 3.5
30 PLATE 120,000 BTU 10.5 1” 5”X12”X3” 1.7
40 PLATE 160,000 BTU 14 1” 5”X12”X4” 1.02
50 PLATE 200,000 BTU 17.5 1” 5”X12”X5” .7
60 PLATE 240,000 BTU 21 1 1/4” 5”X12”X6” .56
80 PLATE 320,000 BTU 28 1 1/4” 5”X12”X8” .36
100 PLATE 400,000 BTU 35 11/4” 5”X12”X10” .24
  • Plate material: stainless steel AISI 304L
  • Brazing material: Copper
  • Max pressure: 652 lbs. per sq. in
  • Test pressure: 971 lbs. per sq. in
  • Plate material: 0.05
  • Exchange area sq. ft.: 417 per plate
  • Max Temperature: 437F
Unit Heaters:

The easiest way to heat a workshop or similar spaces is with a “Unit Heater”. This is a self-contained heating system in a small box that includes a water-to-air heat exchanger and a built-in blower fan that turns on and off to keep the room at your desired temperature, according to the setting on your thermostat (thermostat sold separately).

What Size Unit Heater is Needed for My Building?

For a simple formula on how to select the proper size unit heater, click HERE to read our article “How to Calculate the Proper Size Unit Heater”.


Heat Exchanger Products

Water Treatment Products

20 products

20 products

Frequently Asked Questions

What does water to air heat exchanger do?

Water to air heat exchangers transfer heat from a fluid (typically water) to the air, or vice versa. A car radiator is a type of water to air heat exchanger, because its purpose is to get the heat out of the car engine. Home heating systems will use these heat exchangers to transfer heat from a boiler to make the air nice and warm.

How does an air heat exchanger work?

As its name sounds, a water-to-air heat exchanger transfers heat from water to air. Many people think these look like a radiator for a car. The hot water passes through small copper tubes that have metal fins attached. The circulating hot water from the boiler heats the tubes and fins. When warmth is needed, a blower fan turns on and blows air through the fins and tubes and voila – warm air!

What are the symptoms of a bad heat exchanger?

A heat exchanger that is bad may be failing from two potential problems: The fluid could be leaking, or it could be plugged thus preventing proper flow.

How much does it cost to replace a heat exchanger?

See our collection of great products here. There is a labor cost to replacing a heat exchanger too, but many homeowners can replace a heat exchanger by themselves.

What is a heat exchanger in a boiler?

The heat exchanger in a boiler has two components – a heat exchanger to transfer boiler fuel energy into water, and then a heat exchanger to transfer that heat from the water into the space to be heated. Check out our heat exchanger products here, and contact our technical support team for any guidance that you may need.

Can a boiler heat exchanger be repaired?

A boiler heat exchanger can usually be repaired. We have a technical support team that will walk you through the repair process step by step. Just contact us!