Chemtrol Pool Controller: Difference between revisions

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== Instrumentation ==
The Chemtrol Pool Controller is a model PC2100 unit (often referred to as the "Chemtrol unit" in the Wiki).  It was manufactured by [https://sbcontrol.com/ Santa Barbara Control Systems].
 
In the configuration used at Fairway Farms, it samples ORP (oxidizing properties of a sanitizer, such as chlorine), pH and total dissolved solids (TDS).  It adds calcium hypochlorite (via the "chlorinator") and/or hydrochloric (muriatic) acid (via the "acid pump") to the pool as part of a closed-loop system.
 
== Operation ==


=== Chemical Probes ===
=== Alarms ===


The ORP and pH probes are said to be rated for a year of use.  In reality, they will probably last longer.  Probes should be replaced when readings do not align with those from the chemical test kit (and cannot be corrected for via calibration).
An alarm has been configured to sound when a measurement parameter (pH, ORP, TDS, or flow rate) is far out of normal operating bounds.


The [http://www.sbcontrol.com Chemtrol] branded probes are quite expensiveWe have had good success with probes (installed in the 2020 season) from [https://sensorex.com/ Sensorex].  The cost is about 75% less than those from Chemtrol.
The parameter that is responsible for the alarm will flash on the Chemtrol LCD displayNote that it is normal and expected for the unit to alarm when the main pump is stopped.


* pH5000 Polycarbonate Swimming Pool pH Sensor ($56 as of May 2020)
=== Bypass Line Flow ===
* ORP1000 Polycarbonate Laboratory ORP Sensor ($86 as of May 2020)


=== Flow Meter ===
Due to the large diameter of the water piping in the system, direct measurement is not possible.  Therefore, a "bypass line" (a 1/2" plastic pipe tapped off of the post-filter pipe) supplies water to the sensor probes.  An inline flow meter identifies the rate of flow to the probes.  If insufficient flow is present, the sampled water may not have the same properties of that in the main piping.  This is potentially a dangerous situation - as excessive chemical dosing could occur (with no feedback).  To prevent this, the Chemtrol halts all chemical dosing when the flow is below a certain threshold.


The flow meter is a [https://www.gemssensors.com/search-products/product-details/rfo-type-electronic-flow-sensor-155481 Gems RFO-Type 155481], as installed during a service call by Aquatic Source in August 2016.
When there is insufficient flow, the message "Bypass Line" is shown at the bottom of the display. This also triggers an alarm (if configured).


There is a slight discrepancy to work out with this flow meter - the 1/2" model has a standard flow range of 4 to 20 GPM, per the catalog pageThe Chemtrol typically shows about 1 GPM during operation with this sensor.
According to the manual, the flow should be about 2-3 GPM.  This can be adjusted by turning the "out" knob (leave the "in" knob fully open).  In our system, up to 5-6 GPM seems to be a better target (when the system flow is optimal), allowing some marginIt is critical that there is enough flow to fully submerge the probe tips at all times to avoid damage and ensure proper measurement.


== Procedures ==
== Procedures ==
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# Press the left arrow twice to return to the main screen.
# Press the left arrow twice to return to the main screen.


On the main screen, an "A" to right of the ORP reading indicates that the chlorinator is enabled (automatic control), "X" indicates it is disabled.
On the main screen, an "A" to the right of the ORP reading indicates that the chlorinator is enabled (automatic control), "X" indicates it is disabled.


=== Enabling or Disabling the Acid Pump ===
=== Enabling or Disabling the Acid Pump ===
Line 41: Line 44:


On the main screen, an "A" to the right of the pH reading indicates that the acid pump is enabled (automatic control), "X" indicates it is disabled.
On the main screen, an "A" to the right of the pH reading indicates that the acid pump is enabled (automatic control), "X" indicates it is disabled.
== Instrumentation ==
[[File:Pool Controller Instrumentation.jpg|thumbnail|Instrumentation for the pool controller.]]
=== Chemical Probes ===
The ORP and pH probes are said to be rated for a year of use.  Recent experience suggests that they are useful for about two swim seasons.  Probes must be replaced when readings do not reliably align with those from the chemical test kit (and cannot be corrected via calibration).
The "original" [http://www.sbcontrol.com Chemtrol] branded probes are expensive.  We have had good results with probes from [https://sensorex.com/ Sensorex] (purchased in 2020 and 2022).  The cost is about 75% less than those from Chemtrol.
* pH5000 Polycarbonate Swimming Pool pH Sensor ($62 as of May 2022)
* ORP1000 Polycarbonate Laboratory ORP Sensor ($97 as of May 2022)
NOTE: In the future, the pH1000 may be a better buy (only $54 versus $62, as of 2022).  The only difference is the cable length (confirm that it will reach).
=== Flow Meter ===
The flow meter validates the presence of fresh sampled water in the "bypass line" for monitoring by the Chemtrol unit.  The flow meter is a [https://www.gemssensors.com/search-products/product-details/rfo-type-electronic-flow-sensor-155481 Gems RFO-Type 155481].  This particular model is what was installed during a service call by Aquatic Source in August 2016.  It was subsequently replaced with an identical model in April 2021.  The failure seems very premature; the unit no longer produces pulses on its output.  An initial tear-down/diagnosis shows no obvious root cause.
The flow meter is an absolute necessity for automated chemical control.  Due to the large main re-circulation lines in the system (larger than 2 inches), a bypass line is used to provide an alternate path to the pH and ORP sensors.  The flow meter verifies that sufficient flow is present in this bypass line (such that the measurements reflect the chemical levels in the main re-circulation line and pool). 
The flowmeter for the bypass line can be disabled under certain circumstances.  However, this must be used with extreme caution, as operating a chemical feed without sufficient monitoring could cause dangerous/damaging chemical reactions.
Upon installing the newest unit (April 2021), the bypass flow rate read-out was adjusted.  Per the datasheet for the 155481, the unit produces 225 Hz (pulses/second) for a 20 GPM flow rate.  The Chemtrol requires a value in "pulses per unit volume".  In this case, 225 Hz / 20 GPM = 11.25 Hz/GPM, or 11.25.  Prior to April 2021, a default value of 1 was used, resulting in a typical (incorrect) readout of 0 to 1 GPM.
The wiring for the flow meter is shown in the "PC2100 Auxiliary" (page 43), as part of the [[Pool_Systems_Automation#Auxiliary|Pool Systems Automation Drawings - Auxiliary]] package.
== Drawings ==
Connections to the Chemtrol Pool Controller (PC2100) are shown in the drawing below.
[[File:FFSC-003 Pg 1 - PC2100 Wiring.png|300px]]


== Technical Information ==
== Technical Information ==


* The left-hand connectors (on the generation of controller that we own) for TDS/Temp, PWFS (paddle wheel flow sensor), Flow and PPM are Conxall/Switchcraft 4-position Mini-Con-X male pin connectors.  The mating connectors are Conxall/Switchcraft 6282-4SG-311 and as of January 2021, they are stocked by multiple distributors (Digi-Key, etc).
* The left-hand connectors (on the generation of controller that we own) for TDS/Temp, PWFS (paddlewheel flow sensor), Flow and PPM are Conxall/Switchcraft 4-position Mini-Con-X male pin connectors.  The mating connectors are Conxall/Switchcraft 6282-4SG-311 and as of January 2021, they are stocked by multiple distributors (Digi-Key, etc).
* The display is a Newhaven Display NHD-160128WG-BTMI-VZ#-1.  If replacing, make note of the required backlight resistor modification.  Hawk Electronics of Buffalo Grove, IL stocks this part for $63.30 (as of January 2021).  Replacement (at your own risk!) is fairly straightforward for an experienced technician; it requires simply the de-soldering of a header.
* The display is a Newhaven Display NHD-160128WG-BTMI-VZ#-1.  If replacing, make note of the required backlight resistor modification.  Hawk Electronics of Buffalo Grove, IL stocks this part for $63.30 (as of January 2021).  Replacement (at your own risk!) is fairly straightforward for an experienced technician; it requires simply the de-soldering of a header.

Latest revision as of 12:26, 13 August 2022

The Chemtrol Pool Controller is a model PC2100 unit (often referred to as the "Chemtrol unit" in the Wiki). It was manufactured by Santa Barbara Control Systems.

In the configuration used at Fairway Farms, it samples ORP (oxidizing properties of a sanitizer, such as chlorine), pH and total dissolved solids (TDS). It adds calcium hypochlorite (via the "chlorinator") and/or hydrochloric (muriatic) acid (via the "acid pump") to the pool as part of a closed-loop system.

Operation

Alarms

An alarm has been configured to sound when a measurement parameter (pH, ORP, TDS, or flow rate) is far out of normal operating bounds.

The parameter that is responsible for the alarm will flash on the Chemtrol LCD display. Note that it is normal and expected for the unit to alarm when the main pump is stopped.

Bypass Line Flow

Due to the large diameter of the water piping in the system, direct measurement is not possible. Therefore, a "bypass line" (a 1/2" plastic pipe tapped off of the post-filter pipe) supplies water to the sensor probes. An inline flow meter identifies the rate of flow to the probes. If insufficient flow is present, the sampled water may not have the same properties of that in the main piping. This is potentially a dangerous situation - as excessive chemical dosing could occur (with no feedback). To prevent this, the Chemtrol halts all chemical dosing when the flow is below a certain threshold.

When there is insufficient flow, the message "Bypass Line" is shown at the bottom of the display. This also triggers an alarm (if configured).

According to the manual, the flow should be about 2-3 GPM. This can be adjusted by turning the "out" knob (leave the "in" knob fully open). In our system, up to 5-6 GPM seems to be a better target (when the system flow is optimal), allowing some margin. It is critical that there is enough flow to fully submerge the probe tips at all times to avoid damage and ensure proper measurement.

Procedures

Enabling or Disabling the Chlorinator

The chlorinator is controlled by the Chemtrol unit. The instructions below assume that the Chemtrol unit is operating, and that the main screen is visible.

  1. Press the up or down arrow until the ORP readout is highlighted.
  2. Select the ORP sub-menu by pressing the right arrow.
  3. The first item in the ORP sub-menu selects the feed mode. Press the right arrow to change the mode.
  4. Press the up arrow until the ORP feed mode is AUTO to enable or OFF to disable.
  5. Press the left arrow twice to return to the main screen.

On the main screen, an "A" to the right of the ORP reading indicates that the chlorinator is enabled (automatic control), "X" indicates it is disabled.

Enabling or Disabling the Acid Pump

The acid pump is controlled by the Chemtrol unit. The instructions below assume that the Chemtrol unit is operating, and that the main screen is visible.

  1. Press the up or down arrow until the pH readout is highlighted.
  2. Select the pH sub-menu by pressing the right arrow.
  3. The first item in the pH sub-menu selects the feed mode. Press the right arrow to change the mode.
  4. Press the up arrow until the pH feed mode is AUTO to enable or OFF to disable.
  5. Press the left arrow twice to return to the main screen.

On the main screen, an "A" to the right of the pH reading indicates that the acid pump is enabled (automatic control), "X" indicates it is disabled.

Instrumentation

Instrumentation for the pool controller.

Chemical Probes

The ORP and pH probes are said to be rated for a year of use. Recent experience suggests that they are useful for about two swim seasons. Probes must be replaced when readings do not reliably align with those from the chemical test kit (and cannot be corrected via calibration).

The "original" Chemtrol branded probes are expensive. We have had good results with probes from Sensorex (purchased in 2020 and 2022). The cost is about 75% less than those from Chemtrol.

  • pH5000 Polycarbonate Swimming Pool pH Sensor ($62 as of May 2022)
  • ORP1000 Polycarbonate Laboratory ORP Sensor ($97 as of May 2022)

NOTE: In the future, the pH1000 may be a better buy (only $54 versus $62, as of 2022). The only difference is the cable length (confirm that it will reach).

Flow Meter

The flow meter validates the presence of fresh sampled water in the "bypass line" for monitoring by the Chemtrol unit. The flow meter is a Gems RFO-Type 155481. This particular model is what was installed during a service call by Aquatic Source in August 2016. It was subsequently replaced with an identical model in April 2021. The failure seems very premature; the unit no longer produces pulses on its output. An initial tear-down/diagnosis shows no obvious root cause.

The flow meter is an absolute necessity for automated chemical control. Due to the large main re-circulation lines in the system (larger than 2 inches), a bypass line is used to provide an alternate path to the pH and ORP sensors. The flow meter verifies that sufficient flow is present in this bypass line (such that the measurements reflect the chemical levels in the main re-circulation line and pool).

The flowmeter for the bypass line can be disabled under certain circumstances. However, this must be used with extreme caution, as operating a chemical feed without sufficient monitoring could cause dangerous/damaging chemical reactions.

Upon installing the newest unit (April 2021), the bypass flow rate read-out was adjusted. Per the datasheet for the 155481, the unit produces 225 Hz (pulses/second) for a 20 GPM flow rate. The Chemtrol requires a value in "pulses per unit volume". In this case, 225 Hz / 20 GPM = 11.25 Hz/GPM, or 11.25. Prior to April 2021, a default value of 1 was used, resulting in a typical (incorrect) readout of 0 to 1 GPM.

The wiring for the flow meter is shown in the "PC2100 Auxiliary" (page 43), as part of the Pool Systems Automation Drawings - Auxiliary package.

Drawings

Connections to the Chemtrol Pool Controller (PC2100) are shown in the drawing below.

Technical Information

  • The left-hand connectors (on the generation of controller that we own) for TDS/Temp, PWFS (paddlewheel flow sensor), Flow and PPM are Conxall/Switchcraft 4-position Mini-Con-X male pin connectors. The mating connectors are Conxall/Switchcraft 6282-4SG-311 and as of January 2021, they are stocked by multiple distributors (Digi-Key, etc).
  • The display is a Newhaven Display NHD-160128WG-BTMI-VZ#-1. If replacing, make note of the required backlight resistor modification. Hawk Electronics of Buffalo Grove, IL stocks this part for $63.30 (as of January 2021). Replacement (at your own risk!) is fairly straightforward for an experienced technician; it requires simply the de-soldering of a header.