BOILER WATER AS THE ENERGY SOURCE
Electronically operated control valves use a solid state temperature sensor which is wired to an electronic control module. The electronic control module has an adjustable set point. The control module compares the set point with the sensed temperature and sends an electric signal to a magnetic linear actuator on the control valve. The magnetic linear actuator modulates the control valve and regulates the amount of boiler water through the valve to maintain the set point of the controller. When the set point is achieved, the controller sends a signal to the valve actuator and the valve closes. In the event of high temperature or loss of building power, the limit control closes the electric power to the controller which closes the valve.
A two way valve modulates from fully closed to fully open varying the amount of hot water circulated through the coil to maintain the desired output temperature. When closed the two way valve may cause a change in the heating water loop pressure.
A three way valve modulates from directing all heating water through the coil to directing no heating water through the coil, varying the amount of hot water circulated through the coil to maintain the desired output temperature. The pressure drop in the heating system will be relatively constant with a three way valve.
An optional safety system, which will deactivate the main control valve as described in solenoid safety system, will also activate a second solenoid valve to drain excessively heated water from the heater. The controller is designed to permit different set points for the valve closure and draining.
Double wall brazed plate or plate and frame heat exchangers have inner and outer plates with a vented leak path. If either the inner or outer plate fails, no cross contamination of potable water is possible and a visible indication of the leak will show.