Pool Boiler Temperature Controller: Difference between revisions

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== Overview ==
== Overview ==


The boiler temperature controller provides [[#Low Operator|Low Operator]] and [[#High Operator|High Operator]] interlocks for the pool boiler.
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.
* Provides feedback of the boiler temperature via LCD display and via Modbus (RS-485) to the automation system.

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