What is Direct Contact Water Heating?

Many people opt for direct-contact water heaters over traditional boilers because direct-contact water heaters are generally cheaper and safer, and they often have a smaller footprint. Direct-contact water heaters excel in a large variety of applications, and they do not require additional boiler insurance or boiler operators. But what is direct-contact water heating, and what makes a direct-contact water heater different from a traditional water heater such as a boiler?

Two primary differences include the unique heat transfer method utilized by direct-contact water heaters and the distinctive heat transfer zone where water heating takes place. QuikWater direct-contact water heaters include both of these features.






QuikWater Firing Chamber

QuikWater’s 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 Vertical Chamber

QuikWater’s Distinct Heat Transfer Zone

In a direct-contact water heater such as a QuikWater Flagship, MultiTower, or MegaHeater, the heat transfer between the combustion gases and the water takes place inside a hollow vertical tower, which is above the end of the combustion chamber. This firing chamber promotes complete combustion and consequently avoids water impinging directly on the flame (which can lead to contaminated water). The water is sprayed into the top of the vertical tower, which is filled with stainless steel heat transfer media. This media provides a large surface area for heat transfer.

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.”

A burner is mounted on the end of the firing chamber, below the vertical tower housing the heat transfer zone, which provides the energy used to heat the water. The burner is a forced draft design, which increases heating efficiency and provides the air pressure necessary to pass through the heat transfer zone and out of the building. It is usually fired on natural gas, propane, or fuel oil.


If you are looking for a non-pressurized industrial water heater that can quickly produce hot water on demand at temperatures up to 200º F, look no further. Contact a member of the OGI Sales Team today or request a quote.