Smart Thermostatic Control 32
for Tank Water Heaters Application Guide

Table of Contents


Smart Thermostatic Control 32 for Tank Water Heaters

The Smart Thermostatic Control 32 can be used simply as an on-demand controller for your recirculation pump or it can be configured to run on a timer via an iPhone or Android smart device so that it will keep the recirculation loop hot between specific times of day and on specific days of the week (up to 10 timers can be set). You can choose to use both on-demand and timers to customize the system to work best for you.

Even when a timer is active it only runs the pump until the recirculation loop has heated up and then it shuts the pump off while continuing to monitor the status of the thermostatic valves.

The app uses Bluetooth to communicate with the controller, so you must ensure Bluetooth is enabled on your smart device. The approximate range for Bluetooth reception is 30 feet from the controller.

The app can be downloaded for free from either Google Play  Android app from Leridian Dynamics for Smart Recirculation Control or Apple App Store  iPhone app from Leridian Dynamics for Smart Recirculation Control.

Do not “pair” the Bluetooth device, running the app will find and connect to the Smart Thermostatic Control 32 and display the “Live Data”TM.

The blue LED on the controller will illuminate when the app is connected.

Live Data

 (initial screen displayed)

The “Live Data”TM screen displays the temperature sensor value, the flow meter value, whether the pump is running, the current pump run time and if there is a timer active.

There is also a “Trigger Pump” button to activate the controller from the app.

This screen is useful for troubleshooting and configuration of the controller.

For example, if you find that the controller isn’t turning on when hot water is drawn from a faucet, the live data screen will show you the flow value the controller is detecting.

If the flow value on this screen is less than the Sensitivity setting, the controller will not turn on.

If the flow is greater than the Sensitivity setting and the controller doesn’t turn on then the controller has run within the last dormant interval and won’t run again until the dormant interval has expired.


This screen provides for controlling all the settings of the firmware. There is a list of basic settings and the ability to expand the settings to show “Advanced Settings”.

Basic Settings


The sensitivity setting allows the user to set how many pulses of the flow meter are required to turn the controller on. The default value is 20 which is fine for most installations.

If you find that the controller is not turning on when you turn a faucet on and off, you would decrease this value to make the controller more sensitive to flow (require fewer pulses to turn the controller on).

Correspondingly, if you find that the controller is turning on when there is no timer active and no hot water being drawn, you would increase this number to make the controller less sensitive to fluctuations in flow (require more pulses to turn the controller on).

Max Pump Run Time

The maximum amount of time in minutes that that the pump will run when triggered regardless of temperature sensor values. This is a fail safe mechanism in the event a temp sensor comes loose from the pipe or the low temp difference isn’t met for some other reason. Default of 15 min.

Timers Enabled 

This switch enables and disables the timers.

This can be used to turn the timers off when you go away on vacation or to simply turn them off if you just want to use the on-demand feature of the controller.

The Smart Thermostatic Control 32 implements “Smart Timers,” which, regardless of this setting, will automatically disable if no hot water usage is detected within 24 hours.

The timers are re-enabled as soon as hot water flow is detected, or the controller is connected to via the app.

Timers are disabled by default.

Advanced Settings

Dormant Interval

The dormant interval is the number of minutes that the controller lies dormant after sensing flow and heating up the loop.

As long as there is hot water flow within the dormant interval, the dormant interval timer is reset.

The dormant interval is also the number of minutes that the controller waits when a timer is active between pump runs. If you want the pump to turn on more quickly while a timer is active or more quickly between pump runs when you draw hot water, you will need to reduce this value.

The default value is 10 minutes which is fine for most installations.

Flow Meter Delay

The flow meter delay is the amount of time in hundredths of a second, during which the controller counts the number of pulses that occur in the flow meter.

If the number of pulses counted is above the sensitivity threshold, then the controller deems that there is flow in the hot water line.

The default value is 75 hundredths of a second, which is fine for most installations.

Initial Pump Run Time

The initial pump run time is the number of seconds that the pump runs when it first senses flow if the Dormant Interval has expired.

This is to ensure that the pump has time to get up to speed and start moving water through the thermostatic valve(s) before checking the flow value.

When a timer is active the pump will turn on every Dormant Interval for the length of the Initial Pump Run Time in order to check the state of the thermostatic valve(s).

The default value is 5 seconds which is fine for most installations. 

Bluetooth Advertising Power

This is the power at which the Bluetooth radio advertises its presence. The app searches for this signal when connecting. The higher this value, the further away from the controller the app can find and connect to the controller. The default value is 5. 

Bluetooth Transmission Power

This is the power at which the Bluetooth radio communicates with the app once its presence is detected. The higher this value, the further away from the controller the app can be taken once the app is connected. The default value is 5. 

Connect Without Scan (Android Only)

With this setting enabled the app will scan for the controller the first time and then once connected will store the MAC address of the Bluetooth device to be able to more quickly connect in the future.

If the device is not online it will perform a full scan.

If you have more than one controller it is recommended to disable this feature and the app will connect to the controller with the strongest signal (typically the closest controller).

Reset to Factory

This will reset the Smart Thermostatic Control 32 back to the factory defaults. If the controller isn’t operating as expected, resetting to the factory defaults is a good thing to try to resolve the issue. You must type “yes” when prompted in order for the factory reset to take place.


This screen displays the timers. They are black when the timers are enabled. If they are gray then they are disabled. Tap the timer to edit or delete it. To add a new timer tap the Add Timer button.

The real-time clock in the Smart Thermostatic Control 32 is set when you connect to the controller with your smartphone. The Smart Thermostatic Control 32 has a built-in power backup that will keep the clock’s time for approximately 48 hours without power. After which the clock will lose its time and the controller’s timers won’t function until the time is set by running the app and connecting to the Smart Recirculation Control 32.

The clock does not adjust for daylight savings time so when the time changes you will need to connect to the Smart Recirculation Control 32 with your smart device and the time will be set to the time of your smart device.


Displays a rolling log of the last 256 controller activations.


The firmware of the Smart Thermostatic Control 32 can be updated via the smartphone app. The app will notify you when you first connect if there is a new firmware available and selecting OK will navigate you to the Firmware screen.

By default, only the firmware for your type of controller will be displayed and if there is an update available it will be enabled. Tap on the firmware and then tap the “Update Firmware” button and the controller will begin the update process.

Do not allow the application to go to the background or the phone to sleep while the firmware update is running or the update will terminate. If the firmware is already installed it will be gray and not able to be selected.

The firmware release notes can be displayed by tapping on the question mark (?) or the firmware version number.

There is an option on this screen to “Show All Firmware Versions” which will display the firmware from our entire product line. The sensor requirements are different for the different firmware versions so updating to a different product without understanding the implications may provide unexpected results. Please see our web site for a description of the different products.