SERIES 35-60, 35-61 Installation Instructions 24 VAC Microprocessor Based DSI Control DESCRIPTION The Series 35-60 and 35-61 are Direct Spark ignition Controls designed for use in all types of heating applications. They utilize a microprocessor to continually and safely analyze and control the proper operation of the gas boomer. Value added features such as LED diagnostics, automatic one hour reset, and flame current test pins highlight the controls benefits.