Pool Boiler Temperature Controller: Difference between revisions
Pool Boiler Temperature Controller (view source)
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== Background == | |||
=== Pre-2022 Design === | |||
In the prior design (pre-2022), a xxx provided two-stage burner control and over-temperature shutdown. | |||
The new controller adds important features: | |||
* Shutdown of both stages if the boiler temperature does not reach a minimum temperature threshold after a warm-up period. This may occur if the recirculation pump fails, or is providing insufficient return water into the loop (due to air in the pump, improper valve position). Operating the boiler at low temperature for an extended period may result in condensation, which may reduce the life of the boiler. | |||
== Theory of Operation == | |||
=== Call for Heat === | |||
A call for heat is detected when the first input (terminal #13 - see wiring note) is energized. | |||
=== Low Operator === | |||
The low operator is activated when the following conditions are true: | |||
* A call for heat is present. | |||
* 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 above the minimum temperature threshold (timing rules apply). | |||
The low operator activates the first stage burner once the boiler interlock conditions and timing are satisfied. | |||
=== Main Valve Active === | |||
The main valve active input is energized via boiler terminal #30. This is the same signal that provides "Boiler ON" feedback to the [[Pool Temperature Controller]]. When the main valve is active, the first stage is presumed to be operating. If the main valve is not active some period of time after the low operator is activated, a boiler fault may be assumed. | |||
=== High Operator === | |||
The high operator is activated when the following conditions are true: | |||
* All conditions for the low operator are met. | |||
* The boiler temperature is below the second stage threshold (timing rules apply). | |||
== Eurotherm 3508 == | == Eurotherm 3508 == | ||