Fairway Farms Swim Club

Pool Boiler Temperature Controller: Difference between revisions

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== Overview ==
== Overview ==


The boiler temperature controller provides [[Low Operator]] and <b>High Operator</b> interlocks for the pool boiler.  The role of each interlock in boiler operation is described in detail [[Pool_Boiler#Operation|here]].
The boiler temperature controller ensures that the [[Pool Boiler|pool boiler]] internally operates at an optimal temperature.  It does so by providing [[#Low Operator|Low Operator]] and [[#High Operator|High Operator]] interlocks.


The system described from hereon was created to enhance control and monitoring over the Johnson Controls C450CCN-3, which was in service prior to 2022.  During the 2021 season, there were multiple observed instances of the boiler operating at a sub-optimal temperature.  To prevent condensation, the boiler should operate at about 120 degrees or higher.  This is achieved by mixing inlet water (ideally at 80 degrees or warmer) with water recirculated from the boiler outlet.  This circulation pump is shown in the <b>Boiler Loop</b> section on page 2 of the [[Process Flow Diagram]].
This controller does not manage the pool temperature.  That functionality is handled by the [[Pool Temperature Controller]].


The occurrence of low temperature was likely due to air trapped in the pump; a condition that is possible after air is introduced into the system when the [[Cleaning the Strainer Basket|strainer basket is cleaned]] or the [[Backwashing|filters are backwashed]].  The controller cannot prevent this condition, but it can detect it and alert the operator to minimize the impact of condensation.
In the system, a circulation pump (shown in the <b>Boiler Loop</b> section on page 2 of the [[Process Flow Diagram]]) force-returns some amount of hot water from the boiler outlet to the inlet.  This helps to maintain an elevated operating temperature (i.e.. 120 &deg;F or greater), reducing the risk of condensation forming on the heat exchanger that can cause damage over time.  Unfortunately, various factors may prevent the circulation pump from maintaining the proper temperature such as improper valve settings, trapped air, or pump failure.  Air may be regularly introduced into the system while [[Cleaning the Strainer Basket|cleaning the strainer basket]] or [[Backwashing|backwashing the filters]] may cause the pump to operate improperly.  The boiler temperature controller in place prior to 2022, a Johnson Controls C450CCN-3, did not detect low-temperature operation.


The key features of the new controller are as follows:
The controller cannot resolve fault conditions.  Instead, it notifies the operator of a fault condition, which usually requires manual intervention.


* Provides feedback of the boiler temperature via LCD display and via Modbus (RS-485) to the automation system.
The design has the following key principles:


Like in the [[Pool Temperature Controller]], the following principles are used in its design:
* The controller functionality shall help improve boiler function and longevity without adding unnecessary complexity.
* The core function (temperature control) shall be performed by a proven, durable controller.  In this case, a Euroterm 3508 was chosen due to its enhanced logic control capabilities.
* The [[Pool_Systems_Automation|automation system]] shall not be required for operation.  Failure of other components should have minimal impact upon its operation.


* The core function (temperature control) shall be performed by a proven, durable controller.  In this case, a Euroterm 3504 was chosen due to its enhanced logic control capabilities.
While the automation system is not required, it will have a communication link to the controller for monitoring purposes.
* The automation system shall not be required for operation.  Failure of other components should have minimal impact upon its operation.


== User's Guide ==
== User's Guide ==


The temperature of the boiler's manifold is shown as the largest value on the display, in degrees Fahrenheit.  A graphical bar below the measured shows the value relative to the typical minimum and maximum operating thresholds.
=== LCD Display ===
 
An LCD display on the front of the controller indicates the measured temperature of the boiler manifold (top-most value).  A graphical bar shows the value relative to the typical minimum and maximum operating bounds.  Temperature thresholds for a [[#Low Temperature Fault|Low Temperature Fault]], [[#Stage 2|Stage 2]] operation, and a [[#High Temperature Fault|High Temperature Fault]] are displayed on the subsequent lines.  All temperatures are displayed in degrees Fahrenheit.
 
The <tt>OP1</tt> and <tt>OP2</tt> indicators (beacons) indicate that [[#Stage 1|Stage 1]] and/or [[#Stage 2|Stage 2]] operation is active, respectively.  An <tt>ALM</tt> indicator is associated with a fault condition; user intervention may be required to restore boiler operation.  Blinking <tt>H</tt> and/or <tt>J</tt> indicators indicate communication port activity.
 
=== Stage Monitoring ===
 
At this time, no feedback is provided to the temperature controller to verify which stages are active; external conditions/faults may prevent firing stages.  See [[Pool_Boiler#Operation|Pool Boiler Operation]] for further details on how the controller contributes to the boiler interlocks.


=== Operating States ===
=== Operating States ===
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==== Normal Operation ====
==== Normal Operation ====


During normal operation, no user intervention is required.
During normal operation, no user intervention is required. Both [[#Stage 1|Stage 1]] and [[#Stage 2|Stage 2]] heating is enabled.
 
The <tt>OP1</tt> and <tt>OP2</tt> beacons at the top of the display indicate that both [[#Stage 1| Stage 1]] and [[#Stage 2| Stage 2]] heating are enabled.  At this time, no feedback is provided to the temperature controller to identify if either stage is active; external conditions/faults may prevent firing stages.


==== No Stage 2 ====
==== No Stage 2 ====


The boiler temperature is greater than the [[#Stage 2| Stage 2]] threshold, and [[#Stage 2| Stage 2]] is disabled as a result.
The boiler temperature is greater than the [[#Stage 2|Stage 2]] threshold, and [[#Stage 2| Stage 2]] is disabled as a result.  This is not a fault condition, though it may indicate sub-optimal operation.  Only [[#Stage 1|Stage 1]] heating is enabled.


The [[#Stage 2| Stage 2]] threshold is the temperature value to the right of the <tt>Stg2</tt> identifier on the display, and should typically be set to TBD.
The [[#Stage 2| Stage 2]] threshold is the temperature value to the right of the <tt>Stg2</tt> identifier on the display, and should typically be set to <span style="background:yellow">TBD</span>.  To adjust this threshold, see the [[#Threshold Adjustment|Threshold Adjustment]] section below.


If this state is active, it may be desirable to adjust the recirculation valve positions.  Since operating only in [[#Stage 1| Stage 1]] produces less heat, the ability to heat the pool is reduced.  This is primarily an issue where the amount of heat loss in the pool exceeds the capability of [[#Stage 1| Stage 1]] heating (i.e. the pool cools faster than it can be heated).  Consult with [[Board_Building_and_Grounds Building and Grounds]] if needed to properly adjust the valve positions.
If this state is active, [[Pool_Boiler#Recirculation_Valve|adjustment of the recirculation valve position]] should be considered.  Since operating only in [[#Stage 1| Stage 1]] produces less heat, the ability to heat the pool is reduced.  This is primarily an issue where the amount of heat loss in the pool exceeds the capability of [[#Stage 1| Stage 1]] heating (i.e. the pool cools faster than it can be heated).


==== Boiler Fault ====
==== Boiler Fault ====
The boiler has not fired [[#Stage 1|Stage 1]] is response to a <b>Call for Heat</b>.  This is an informational fault only; it does not disable either stage.  This fault is only applicable if the <b>Call for Heat</b> signal is wired to the controller.


==== Low Temperature Fault ====
==== Low Temperature Fault ====


The boiler temperature is less than the low-temperature threshold and both stages are disabled as a result.  The low-temperature threshold should typically be set to TBD, though it may be necessary to reduce this temperature during early season operation.
The boiler temperature is less than the low temperature threshold and both stages are disabled as a result.  The low-temperature threshold should typically be set to <span style="background:yellow">TBD</span>.  This is a latching fault and must be cleared via the front panel before the boiler will operate.


This is a latching fault and must be cleared via the front panel before the boiler will operate.
Before attempting to clear the fault, the source of the fault should be cleared.  See the [[Pool_Boiler#Low_Temperature_Fault|Pool Boiler Low Temperature Fault]] section for further information ([[Pool_Boiler#Recirculation_Valve|recirculation valve adjustment]] may be needed).


==== High Temperature Fault ====
==== High Temperature Fault ====


The boiler temperature is greater than the high-temperature threshold and both stages are disabled as a result.
The boiler temperature is greater than the high-temperature threshold and both stages are disabled as a result.  The high temperature threshold should typically be set to <span style="background:yellow">TBD</span>.  This is a latching fault and must be cleared via the front panel before the boiler will operate.


This is a latching fault and must be cleared via the front panel before the boiler will operate.
=== Threshold Adjustment ===


=== Changing Thresholds ===
Threshold adjustment is typically not necessary or recommended.  Instead, it is recommended that the system be evaluated for deficiencies.
 
If a parameter must be adjusted, press the scroll button (left of the down arrow) to move the up/down cursor to the desired parameter.  Press the up/down keys to adjust the temperature.  Internal bounds limit how high or low a parameter may be adjusted.  Use extreme caution in adjusting each parameter, as each could have significant impacts upon boiler operation.


=== Other Buttons ===
=== Other Buttons ===
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=== Low Operator ===
=== Low Operator ===


The low operator is activated when the following conditions are true:
The low operator is activated (the relay contact is closed) when the following conditions are true:


* A call for heat is present.
* The RTD is producing valid feedback (not shorted or open-circuit).
* The RTD is producing valid feedback (not shorted or open-circuit).
* The boiler temperature is below the over-temperature shutdown threshold (timing rules apply).
* The boiler temperature is below the high temperature fault threshold (timing rules apply).


The low operator may be released when any of the prior conditions are no longer met.  In addition, it may be released when:
The low operator may be released when any of the prior conditions are no longer met.  In addition, it may be released when:
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=== High Operator ===
=== High Operator ===


The high operator is activated when the following conditions are true:
The high operator is activated (the relay contact is closed) when the following conditions are true:


* All conditions for the low operator are met.
* All conditions for the [[#Low Operator|low operator]] are met.
* The main valve (MV) is active.
* The boiler temperature is below the second stage threshold (timing rules apply).
* The boiler temperature is below the second stage threshold (timing rules apply).


== Controller Hardware ==
== Controller Hardware ==


=== As Shipped Configuration ===
=== As-Shipped Configuration ===
 
When shipped from the factory, a long configuration code is printed on the side of the controller to identify the configuration.  The code on the installed controller is decoded below:


{| class="wikitable"
{| class="wikitable"
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|LO
|LO
|Isolated Single Logic Output
|Isolated Single Logic Output
|
|May not be used.
|-
|-
!IO Slot 2
!IO Slot 2
|D4
|D4
|DC Control
|DC Control
|Will not be used.
|Will not be used; see modifications below.
|-
|-
!IO Slot 3
!IO Slot 3
|TK
|TK
|Triple Contact Input
|Triple Contact Input
|
|May not be used.
|-
|-
!H Comms Slot
!H Comms Slot
|PD
|PD
|Profibus with D-type Connector
|Profibus with D-type Connector
|Module is an AH026222U002.
|Module is an AH026222U002 (visually identified).
|-
|-
!J Comms Slot
!J Comms Slot
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