Pool Boiler Temperature Controller: Difference between revisions
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!Block | !Block | ||
!Description/Comments | !Description/Comments | ||
|- | |||
|DigAlarm1 | |||
|Triggers a non-latching alarm if <b>Call for Heat</b> is active for an extended period without <b>Main Valve (MV) Active</b>. This alarm has no functional impact; it is used to alert the operator only. If the <b>Call for Heat</b> input is not connected, this alarm will never trigger. | |||
|- | |||
|DigAlarm2 | |||
|Triggers a manually-latched alarm per a rising edge on <b>Lgc2 1</b>. The alarm remains active until acknowledged. | |||
|- | |- | ||
|IO.PV | |IO.PV | ||
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|IO.LgcIO.LB | |IO.LgcIO.LB | ||
|The <b>Main Valve (MV)</b> input. | |The <b>Main Valve (MV) Active</b> input. | ||
|- | |||
|Lgc2 1 | |||
|Logically ORs the delayed-on <b>Main Valve (MV) Active</b> input signal and the result of the conditioned RTD measurement is less than the low-temperature threshold comparison. A rising edge on the output of this block indicates that the boiler temperature is below the threshold after the <b>Main Valve (MV)</b> (Stage 1) has been active for some period of time. | |||
|- | |||
|Lgc2 2 | |||
|Logically ORs the inverted output of <b>Lgc8 1</b> the non-inverted output of the control loop to produce a Stage 2 control signal. | |||
|- | |||
|Lgc2 4 | |||
|The output is active if the conditioned RTD measurement is less than the low-temperature threshold. | |||
|- | |||
|Loop 1 | |||
|Operates an on-off control loop with a setpoint (Stage 2, displayed on the controller as "Stg2") and feedback via the conditioned RTD measurement. | |||
|- | |||
|Timer1 | |||
|Provides a delayed-on <b>Main Valve (MV) Active</b> input signal. Used to act upon conditions that are only relevant some period of time after the gas has fired (i.e. boiler warm-up). | |||
|- | |||
|UsrVal 1 | |||
|The low-temperature threshold. Displayed on the controller as "LowT". | |||
|} | |} | ||
Notes: | |||
* Lgc2 3 is not used. | |||