The Mini-MOD-CNC is has the capability to lead-lag two different groups of boilers: condensing and non-condensing. The controller provides two means of selecting the lead group switching, either using a specific system or outdoor set point with an adjustable switching delay. If using the outdoor temperature as the switching mechanism, and it is above the set point, the Mini-MOD-CNC will use the condensing boiler group as the lead group, switching to the non-condensing group after the outdoor temperature drops below the outdoor switching set point. When using the system temperature set point as the switching mechanism, and it is below the set point, the Mini-MOD-CNC will use the condensing boiler group as the lead group, switching to the non-condensing group after the system temperature rises above the system switching set point. For the modulating group of boilers, an advanced PID logic has been used to provide modulation that can fit most applications, whether the boilers are to sequence normally, one after the other, or in parallel. — Heat-Timer Corp., Fairfield, N.J.
Simultaneously control condensing and non-condensing boilers
| By Chemical Engineering