Overview

The objective of this project is to control the Jandy pool heater. We can either control the heater using it's REMOTE relays or interface with it's RS485 interface.

The equipment we will to interfacing with is the Jandy JXi Gas-Fired Pool and Spa Heater 260N.

Micro Controller

For this solution, we are using a Sonoff SV controller. This is a nice controller since it has everything we need to control the heater's remote relays. Additionally, we can power it from the heater itself since it accepts 5-24 volts input and the heater will supply us with 10v. We are going to use the Sonoff SV in isolation mode by removing the two resisters that would normally supply the power to the controller using the input voltage.

Wiring Diagram

Pictures

Adding a Temperature Sensor

We are going to add a temperature sensor to the heater so that we can turn the heater on or off based on temperature.

We are going to use

• Waterproof Digital Temperature Temp Sensor Probe DS18b20
• a 1/2″ male NPT x 1/4″ compression fitting
• 2x 1/4" o-rings

• 3/4" male NTP to 1/2" female NTP adaptor

• teflon tape

Put the temperature sensor, reducer and compression fitting together using teflon tape where needed.

<ADD PIC OF ASSEMBLED TEMP SENSOR>

We can add a temperature sensor to the heater's header using the following procedure:

• Remove drain plug from header and allow all water to drain from heat exchanger.

• Locate the threaded boss on the outlet port of the header, and find the dimple at the center.

• Use the dimple to center the drill bit. For header type A: Drill a 1/4 in (6.4 mm) diameter hole through the boss. For header type B: Drill a 3/8 in (9.5 mm) diameter hole through the boss. Take care not to damage the plastic threads. TIP: Drilling a 1/8 in (3 mm) diameter hole first will help prevent thread damage.

• Each male connection should be first wrapped in 5-6 turns of PTFE (Teflon) tape.
• Install the temperature sensor assembled with any required reducers at the heater header. Make sure to get a snug fit. Do not over-tighten.

References