Weil-McLain BCP-8X Boiler User Manual


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The BCP-8S has multiple operating modes that satisfy most steam systems. It can sequence stages to achieve an adjustable Set Point.
Moreover, when used with the 420MOD Interface (389-900-226) it can accept a 4-20mA signal as a set point. The 420MOD must be
purchased separately. This gives the BCP-8S the capability of being controlled remotely.
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heat, by either closing the TSTAT input or opening the SHUTDOWN input, and when the outdoor temperature is below the Outdoor
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period, the BCP-8S will start calculating the Reaction Period. If after a full Reaction Time the control logic foresees additional stages are
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When the BCP-8S PID logic foresees that the system will overshoot, regardless of the current system and target values, it will make sure
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from short cycling.
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setting, as a mean to calculate the number of stages the BCP-8S shall have on at any point. For every Throttle Range below the set point
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55 Psi -1 ---- None A None
50 Psi 0 ---- None ---- A
45 Psi 1 A A B A
41 - 44 Psi 1 ---- A ---- A + B
40 Psi 2 B A + B C A + B
35 Psi 3 C A + B +C D A + B +C
30 Psi 4 D A + B +C + D E A + B +C + D
25 Psi 5 E A + B +C + D + E F A + B +C + D + E
20 Psi 6 F A + B +C + D + E + F ---- A + B +C + D + E + F
15 Psi 7 ---- A + B +C + D + E + F ---- A + B +C + D + E + F
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