APOLLO Wi-Fi Pool Thermostat / Aquastat

A pool thermostat — technically called a pool aquastat because it senses water rather than air — regulates your pool or spa water temperature. A sensor strapped to the plumbing reads the actual water temperature, and when it drops below your setpoint the thermostat closes a relay that calls your pool heater to run. The APOLLO Wi-Fi Pool Thermostat / Aquastat ships with a 35 ft pool sensor and stainless mounting clamps, displays the water temperature on a 3.5-inch color touchscreen, and adds Wi-Fi app control so you can manage pool heating from anywhere.

A regular thermostat measures air temperature and controls a furnace or air conditioner. An aquastat measures water temperature directly through an immersed or pipe-mounted sensor and switches heating equipment based on the water reading. For a swimming pool this matters because air temperature tells you nothing about how the water feels — only a water-sensing controller like the APOLLO can hold your pool at an exact swimming temperature and avoid wasted heater runtime.

The APOLLO works as a universal pool heater thermostat for equipment that accepts an external thermostat or dry-contact call: gas pool heaters (via the remote thermostat / fireman's switch terminals), pool heat pumps, and hydronic setups where a heat exchanger transfers heat from a boiler or air-to-water heat pump into the pool loop. The output is a 5A SPST-NO relay — for electric resistance heaters, the relay drives the heater's contactor rather than switching the element load directly. Power is flexible too: 12–24VAC/DC or 110–240VAC supply.

Yes. The APOLLO connects to a 2.4GHz network using IEEE 802.11 b/g/n with WPA/WPA2 security. From the companion app you can check the current water temperature, change the setpoint, and manage schedules from anywhere — useful for warming the pool up before you get home or confirming the heater shut off after a swim. For automation and building management integration it also supports Modbus RTU, Modbus TCP, and BACnet, plus Google Home monitoring.

Yes. Freeze protection is built in: when the sensed water temperature approaches freezing, the thermostat closes its relay to call the connected equipment, protecting the pool plumbing and heater from ice damage during cold snaps. This makes the APOLLO useful year-round in climates where an unattended pool or spa line could freeze in winter.

The included pool sensor has a 35 ft cable and mounts to your pool plumbing with the two supplied stainless steel clamps, sized for 1.5-inch and 2-inch PVC pipe — the standard sizes in residential pool circulation loops. Strap the sensor to the return or suction line near the equipment pad, route the cable to the thermostat, and connect it to the sensor terminals. The Pool Sensor Installation Guide is available for download in the documents section of this page.

In most cases, yes. If your pool heater currently runs from a mechanical dial thermostat or an external controller wired to its remote thermostat terminals, the APOLLO can take over that call with the added benefit of a digital display, precise setpoints, scheduling, and Wi-Fi remote access. Because it accepts both 12–24VAC/DC and 110–240VAC supply power, it fits the wiring found at most equipment pads. Check your heater's manual for its external thermostat or remote terminals before ordering.

Yes. The APOLLO supports pool and spa water temperature control, including the higher setpoints spas require — the device supports water temperatures above 100°F. The same 35 ft sensor and relay output work whether the heated loop serves a pool, a spa, or a pool-and-spa combination with a shared heater.

The pool aquastat is part of the APOLLO Wi-Fi thermostat platform, which also includes dedicated models for fan coil units, radiant floor heating, boiler room-thermostat control, boiler aquastat (water temperature) control, snow melt systems, and electric baseboard heaters. Each model is pre-configured for its application — select the one that matches your system from the dropdown at the top of this page.