• Energy efficient with 95% to 97% Thermal Efficiency
• Stainless Steel Heat Exchanger
• CSD-1 Standard on 500 to 850 MBH Boilers
• Integrated Cascade
• Multiple pump control and thermostat inputs
• 5 to 1 Turndown
• 75 psi Pressure Relief Valve on Keystone Boilers
• Indirect water heater priority
• Outdoor reset
• Outdoor air temperature sensor

Triangle Tube is best known for two things: feats of hydronic innovation and incredibly efficient products. If you are looking for those qualities in your hot water boiler, the Keystone certainly fits the bill. The Keystone is a high-efficiency, condensing boiler for large spaces. The condensing technology behind the Keystone will capture and reuse gaseous heat that escapes traditional boilers. Stainless steel construction of the heat exchanger and an internal condensate trap will protect the KS 399 from corrosion. The Keystone's modulating burner scales heat production based on your needs and reduces unnecessary energy consumption. All told, the Keystone is an incredibly reliable and efficient water heating solution.

Triangle Tube Boiler Installation & Warranty Information

We recommend that the installation of all Triangle Tube Boilers and Water heaters be done by a licensed, trained and qualified technician with the proper knowledge and background.

Should you experience an issue during the installation or the initial startup of the unit, please do not contact the manufacturer. You should have the technician that installed the unit contact either us or the manufacturer. Triangle Tube cannot accept any service or warranty calls from anybody but a licensed technician.

Neither we or Triangle Tube can be held liable for improper installation and operation of any Triangle Tube boiler product purchased from our company. Should a warranty issue arise where parts will need to be replaced, an installation receipt will be required along with your sales receipt. Failure to provide a receipt or invoice may result in the warranty not being honored.