Modulating pool or spa heater systems and associated methods

A method for controlling a pool or spa modulating heater, comprising the steps of:

• determining a current mode of operation for the pool or spa heater with a controller communicatively coupled to the pool or spa heater, the pool or spa heater being capable of variably modulating energy output thereof to heat water of a pool or spa in fluidic communication with the heater;
• establishing a temperature overshoot setpoint for the current mode of operation and a target water temperature setpoint for the pool or spa water for the current mode of operation;
• determining a current water temperature of the pool or spa water;
• determining an optimized modulation rate for the pool or spa heater for the current mode of operation based on one or more of a determination of a current load on the pool or spa heater, a determination of whether a water flow rate through the pool or spa heater is sufficient, and baseline modulation parameters for the current mode of operation;
• determining a maximum modulation rate for the pool or spa heater for the current mode of operation based on one or more of a maximum output of the pool or spa heater and a determination of whether the water flow rate through the pool or spa heater is sufficient;
• and
• controlling the pool or spa heater to operate at one of the optimized modulation rate and the maximum modulation rate based on the temperature overshoot setpoint for the current mode of operation, the target water temperature setpoint for the current mode of operation, and the current water temperature.

A method of controlling a pool or spa modulating heater and variable speed pump, comprising:

• receiving, at a controller of the modulating heater, an instruction to operate according to a heating mode of operation;
• instructing, with the controller, the variable speed pump to operate at a starting speed;
• instructing, with the controller, the modulating heater to operate at a starting modulation rate, the modulating heater being capable of variably modulating energy output thereof to heat water of a pool or spa in fluidic communication with the heater;
• instructing, with the controller, the modulating heater to increase modulation rate to a maximum allowed modulation rate and the variable speed pump to decrease speed to a minimum allowable operating level;
• determining a current heater outlet water temperature of the water at an outlet of the modulating heater;
• comparing the current heater outlet water temperature to a heater outlet water temperature setpoint;
• instructing, with the controller, the variable speed pump to increase speed to a maximum allowable operating level when the current heater outlet water temperature is greater than the outlet water temperature setpoint;
• and
• adjusting, with the controller, the modulation rate of the heater while the variable pump speed is operating at the maximum allowable operating level to cause a current water temperature to gradually approach a target temperature setpoint for the pool or spa water and minimize overshoot.

A modulating heater system for a pool or spa, comprising:

• a pool or spa heater in fluidic communication with water of a pool or spa, the heater capable of variably modulating energy output thereof to heat the water of the pool or spa;
• and
• a controller communicatively coupled to the pool or spa heater, the controller configured to:
• receive an instruction for the heater to operate according to a heating mode of operation;
• instruct a variable speed pump to operate at a starting speed;
• instruct the heater to operate at a starting modulation rate;
• instruct the heater to increase modulation rate to a maximum allowed modulation rate and the variable speed pump to decrease speed to a minimum allowable operating level;
• determine a current heater outlet water temperature of the water at an outlet of the heater;
• compare the current heater outlet water temperature to an outlet water temperature setpoint;
• instruct the variable speed pump to increase speed to a maximum allowable operating level when the current heater outlet water temperature is greater than the outlet water temperature setpoint;
• and
• adjust the modulation rate of the heater while the variable pump speed is operating at the maximum allowable operating level to cause a current water temperature to gradually approach a target temperature setpoint for the pool or spa water and minimize overshoot.