optional cost-saving Integrated Bypass technology that diverts water flow away from the heater when there is no call for heat. FEATURES Heat When You Want. Save When You Don’t. - The heater is typically only used 3.5% of average annual pump runtime, the other 96.5% of the time the heat exchanger can be bypassed Save Even More with VersaFlo Integrated Bypass - Variable-speed pumps can be run at a lower speed when bypassing the heater, saving up to $350 per year in electricity costs