What is Direct Contact Water Heating?

Insulated QuikWaterMany people opt for direct-contact water heaters over traditional boilers because direct-contact water heaters are generally cheaper, safer, they often have a smaller footprint, and they do not require additional boiler insurance or boiler operators. But what makes a direct-contact water heater different?

A Unique Heat Transfer Method

Direct contact water heating involves a heat transfer method in which water is heated by coming in direct contact with hot combustion gases. There are no tubes isolating the combustion gases from the water being heated. These exhaust gases come into direct contact with the water in a non-pressurized environment that is open to standard atmosphere.

QuikWater Heat Transfer MediaThe heat transfer between the combustion gases and the water takes place inside a hollow vertical chamber. The water is sprayed into the top of the vertical chamber, which is filled with stainless steel heat transfer media. This media provides a large surface area for heat transfer.

The Heat Transfer Zone

The water falls through the media under atmospheric pressure. The exhaust gases are simultaneously forced up through the media by the burner blower. Most of the heat transfer in a direct-contact water heater occurs in this “heat transfer zone.”

In the same vertical column, below the heat transfer zone, a burner is mounted that provides the energy used to heat the water. The burner is forced draft, which increases heating efficiency, and it is usually fired on natural gas, propane, or fuel oil.