Sta-Rite Max-E-Therm heater Design and Operation

The Sta-Rite Max-E-Therm® Pool and Spa Heater is highly efficient Low NOx certified, low profile heater with advanced features such as digital control panel, Dura-Glas® rustproof exterior and easy to install and operate design.

The Sta-Rite Max-E-Therm® Pool and Spa Heater is operated through an externally mounted Operating Control Center. Pool and spa settings, a digital temperature display, and a system operation indicator LEDs are located on the touch-senstive Membrane Pad. The indicator LEDs monitor a series of electronically controlled safety interlocks. The function of each Operating Control is listed below.

Sta-Rite Max-E-Therm Control Board Membrane Pad

Operating Control	Action/ Result
POOL ON	Press: Pool water temperature setting now drives the heater control system
SPA ON	Press: Spa water temperature setting now drives the heater control system
OFF	Press: Switch off the heater
TEMP	Press: Raise the pool/spa temperature
TEMP	Press: Lowers the pool or spa temperature setting

Indicator Light	Light ON indicates:
POOL ON	Heater is on. The pool water temperature is controlling heater operation
SPA ON	Heater is on. The sp water temperature is controlling heater operation
HEATING (Steady)	The thermostat is calling for heat; burner is firing
HEATING (Blinking)	The thermostat is calling for heat; burner is NOT firing
SERVICE SYSTEM	There is insufficient water flow to the heater
SERVICE HEATER	There is fault in the heater, its control, or the gas supply

Electrical Flow

Sta-Rite Max-E-Therm Electrical Flow

	Electrical Flow Through the Max-E-Therm Heater
1	The Thermistor senses the inlet water temperature.

2	If the temperature sensed is lower than that set on the Operating Control , power is supplied to the Ignition Control Module through s series of safety interlocks

3	The water Pressure Switch senses whether or not there is adequate water flow through the heater

4	The high limit switch monitors the outlet water temperature and will open if malfunction causes the outlet temperature to excess 135 degree F or 57 degree C

5	The automatic Gas Shutoff Switch (AGS) monitors the outlet temperature from the heat Exchanger and will open if malfunction causes the water outlet temperature to exceed 140 degree F or 60 degree C

6	If the High Limit Switch and the Water Pressure Switch are OK, the Ignition Control Module starts the combustion Air Blower.

7	When the Blower comes up to speed the Air Flow Switch (AFS) senses air flow across the air Metering Office

8	IF the airflow is sufficient, the AFS closes, completes the ignition circuit, and supplies power to the Ignition Control Module.

9	In 20 seconds the Hot Surface Igniter (HSI) element heats to ignition temperature. The Combination Gas Control Valve then opens and the burner flame ignites

10	The HSI element automatically switches from ignition mode to flame sensing mode to monitor the flame

11	The Stack Flue Sensor monitors the flue collar temperature and will shut down the heater if the temperature exceeds 500 degree F or 260 degree C

12	The Burner in the Combustion Chamber fires until the desired water temperature is reached. Once reached, the burner shuts off and the Blower continues to run for about 45 seconds (known as "post purge")

13	If the burner does not ignite in seven seconds, the system shuts down and will not restart. The heater must be turned off and turned back on again at the Membrane Pad (wait 5 seconds) before it will start

14	If the flame is extinguished during operation, the Combustion Gas Control Valve closes and the ignition cycle reactivates

15	If any safety interlocks open during Burner operation, the Burner immediately shuts off, but the Blower continues to run for about 45 seconds.

Gas and Air Flow

Sta-Rite Max-E-Therm Gas and Air Flow

	Gas and Air Flow Through the Max-E-Therm Heater
1	The Blower draws ambient air into the Burner System by negative pressure through the Air Office

2	The Blower at the same time is drawing Natural or Propane Gas into the Burner System by negative pressure through the Gas Office

3	The air and gas are thoroughly mixed in the Mixing Tube.

4	The Blower then forces the air / gas mixture into the Flame Holder in the Combustion Chamber under a slight positive pressure

5	The mixture is ignited in the Combustion chamber, around the circumference of the Flameholder. Combustion continues until the preset water temperature is reached

6	The Heat Exchanger tubes surrounding the Burner / Flameholder extract heat from the hot flue gases and heat the water flowing through the tubes

7	The cooled exhaust is collected in a sealed Exhaust Plenum, then is discharged out the Vent Body

Water Flow

Sta-Rite Max-E-Therm water flow

	Water Flow Through the Max-E-Therm Heater
1	The pool os spa circulating pump supplies water to the heater through the Inlet

2	Water passes to and from the heater through 2 inch PVC piping to the Manifold and the Manifold Adopter

3	A spring-loaded Automatic Bypass Valve in the Manifold bypass water in excess of the required by the Heat Exchanger

4	The Manifold Adopter distributes water to the individual tubes of the Heat Exchanger

5	Water is heated in the coils of the Heat Exchanger and returned to the Manifold Adopter

6	The Thermal Regulator controls the flow of water out of the Heat Exchanger to maintain a water outlet temperature above 120 degree F or 49 degree F

7	The water flows from the Outlet to the pool or spa