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Condensing Boiler Applications

Highlighting a recent installation which houses a Patterson-Kelley SC1000 Sonic Condensing Boiler we will talk about why a condensing boiler should be used for Closed-Loop Water Source Heat Pump applications.


In this youtube video, Greg tells us about what causes the condensate in a hot water boiler.

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Before condensing boilers became popular, this application would require extra valves and pumps to protect the boiler from utter destruction from low incoming water temperatures within a short period of time.

Condensation in a boiler comes from cooling the flue gasses below the dewpoint. In low temperature applications, with less than 130F returning to the boiler, condensation is inevitable. It doesn’t matter if you install a “condensing” boiler or not.

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This school has a closed loop water source heat pump application. The supply water to the building doesn’t rise above 120F. Installing a condensing boiler designed to withstand the low-temp operating conditions will allow the client to enjoy lower energy costs. 


A boiler is operating at a higher efficiency when it is condensing because there is less heat going up the chimney and more heat entering the water. Lower water temperatures allow for a higher percentage of the combustion heat to enter the system water. This can be shown with the heat transfer equation: Q = 500 * Flowrate * Delta-T. T he higher the Delta-T the higher the rate of heat transfer.

The PK Sonic TM boiler uses two different types of stainless steel in two different heating zones to permit operating in condensing conditions without causing a corrosion issue. Ask us how we can increase your heating system efficiency.

Condensing Water Boilers

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The Evergreen® boiler extends comfort levels to every area of your property for the long run. The Evergreen is perfect for residential applications or light commercial. Quiet operation, aesthetically pleasing design, floor standing or wall mount options, environmental sustainability, heating comfort with lower utility bills and more.

Sizes available from 70 MBH to 399 MBH

Patterson-Kelley’s stainless steel boiler breaks through the limitations of all other stainless designs with our revolutionary DUET TM  technology. It’s the industry’s first heat exchanger comprised of two unique chambers built to optimize the turndown process. This unique design allows the P-K SONIC ® to operate at 97% efficiency with a 5:1 turndown and ultra-low emissions.

Sizes available from 650 MBH to 4000 MBH.

Fun Facts

Founded in 1880 as Benjamin F. Kelley & Company, Harsco Industrial Patterson-Kelley has evolved over the years, adapting to lead the marketplace. The company’s first product, feed water heaters, introduced pioneering technology with tube bundles. After World War II, the company’s focus shifted from storage water heaters to more complicated, custom engineered heat exchangers and other heat transfer products.

Following its 1974 acquisition by Harsco Corporation, Patterson-Kelley continued to lead the marketplace. In 1987, the company entered the gas fired commercial boiler industry, and innovation continues today with recent developments such as the NURO Touch Screen Control System that when used alongside the NURO Connect App, allows users to monitor and adjust their system settings from anywhere at any time.

136 years of excellence!

The PK NURO TM Touch-Screen Controller

The PK NURO TM Touch-Screen Controller

A massive U-Tube bundle made at PK in East Stroudsburg, PA

A massive U-Tube bundle made at PK in East Stroudsburg, PA

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