Ok, for those that are in a hurry and think they know it already, and just want the connection diagram...
This is how you connect the things together in its most basic form. For the vast majority of all users, it doesn't get more complicated than this.
Sure you are a pro, but for the rest of us... Please read the rest of this installation manual, there are more options and useful installation hints.
Kit version
If you ordered a so called kit-version, where you do the end assembly yourself, you first have to assemble the kit. The kit is pre-programmed, you only have to put the pieces together. See for detailed instructions the Generic Assembly page. In addition, if you ordered a relay, you also need to install this prior to installing the LCD.
Installation
Physical installation of the HotWaterManager
Ready to be embedded into a panel.
The tidiest installation is achieved when the HotWaterManager is embedded into a panel. The white bezel can be used as a template for the holes for the bolts.
Optional casing available for wall mounting.
The HotWaterManager does not require any airflow or cooling.
To embed the HotWaterManager inside a panel (or box), you just cut a hole large enough to get the circuit board through, and have the bezel and flanges of the front panel covering the cutout. The supplied 3mm stainless steel alan bolts are 10mm long.
The required cutout is 90mm x 50mm. You can make the cutout slightly bigger, the cutout will be covered by the bezel and flanges of the front panel. But make sure you leave enough space for the mounting screws.
The HotWaterManager can also be installed as a self contained unit if you ordered the optional casing. Of course it is also possible to use a standard electric junction box and cut out a hole in the front to embed the HotWaterManager.
Internal relay.
HotWaterManager with internal relay
If the HotWaterManager is equipped with the optional internal relay, you need to run the power cable of the water heater via the HotWaterManager, so in this case it is recommended to place the HotWaterManager close to the water heater to avoid excessive high power cable lengths.
HotWaterManager with remote relay
No internal relay.
The HotWaterManager can be installed wherever you want. The RemoteRelay module needs to be installed near the water heater.
You can use a standard network 8-wire cable between the HotWaterManager and the RemoteRelay module if you want to route all the wires to the RemoteRelay area.
Physical installation of the temperature sensor
Supplied digital sensor, USB for comparison
The temperature sensor should be installed in the upper top halve of the hot water tank and make contact with the metal.
Usually the area around the water heater connections contains a cover, if you open it you will probably find a place where you can push the sensor between the actual metal tank and its insulation. There is probably already a thermostat, thermocouple, or bimetal switch installed, this would also be a good place to install the temperature sensor. Note that the temperature sensor, because of its round shape, will make poor contact with the metal of the tank, therefore it is recommended to cover it with some insulation material.
Physical installation of the hot water solenoid
It is recommended to put the solenoid in the cold water supply of the water heater. If no cold water can come in, no hot water will exit, because there won't be any pressure.
Basic electrical connections
12/24V power supply
The 12/24V power supply is not critical. The HotWaterManager uses little power. Just make sure to connect it via an appropriate fuse, 1 Amp is sufficient.
Note that the HotWaterManager observes the battery voltage and bases its decisions on it, so you should avoid tapping the power from a shared bus. If other consumers on the shared bus draw power, the voltage will likely drop a little due to the resistance of the wires, and if this happens the HotWaterManager will think that the battery is less than full and refuse to start heating the water.
Please leave the HotWaterManager on all the time. A lot of features depend on constant tracking of boiler temperature and battery voltage. If you power down the HotWaterManager, the temperature-, legionella- and battery status will be lost.
Temperature sensor
See above for the physical installation of the sensor. There are three wires connected to the sensor: the black one connects to the Tsens- terminal, the yellow one to the TsensDat terminal, the red one to the Tsens+ terminal.
If the cable is too short, it is possible to make an extension.
Water heater
The water heater is somehow connected to your 115/230V system. Usually there are three wires: a green/yellow one, which is connected to ground. We leave that wire alone! Then usually a blue and a brown one. Although it doesn't really matter, it is a convention to place any switch in the brown wire, so let's follow that convention. The relay of the HotWaterManager needs to be spliced into this brown wire. The relay is symmetrical, both connections are equal, so the wire order doesn't matter. We leave the other wire (usually colored blue) alone.
If you bought the HotWaterManager without internal or remote relay, but provide your own relay: The relay should be a 12V relay, even if your system runs on 24V! For connection of the relay, read under "Remote Relay".
Advanced electrical connections
The following connections are optional.
Ignition wire
If you want the HotWaterManager to automatically switch off the heater when the engine is able to provide hot coolant, you can connect its "D" terminal to the 12V of the engine ignition. If you have a catamaran, usually only one of the engines is plumbed into the hot water tank, in that case of course you connect the ignition wire only to that engine. Chances are that the hot water tank is close to the engine, so you can probably use one of the unused wires in the network cable for the ignition signal. If your water heater setup does not have a coolant loop, leave the ignition wire disconnected.
Hot Water Solenoid
Optional Solenoid
If you installed the hot water solenoid, you connect one of its wires to the 12/24V plus, the other one to the "Control" terminal of the HotWatermanager.
If your system runs at 24V: The solenoid should be a 12V solenoid, as the HotWaterManager drives it at 12V. You still need to connect one of its wires to 24V!
Solar pump
If you want to use a water solar panel (not an electrical solar panel, but a panel that directly heats up the water) you need a temperature sensor at the output of the solar panel and a small circulation pump.
The temperature sensor can be installed in parallel with the other temperature sensor. That means connected all red wires together, all yellow wires together, and all black wires together.
The pump should be connected between the "Aux" terminal of the HotWaterManager and the 12V or 24V supply.
Remote relay
If you ordered the HotWaterManager with the Remote Relay, your HotWaterManager has no internal relay but instead a terminal block to drive the Remote Relay.
Commissioning
Once everything is installed, it is time to power up the HotWaterManager for the first time.
If you are impatient, and want to "play" with the HotWaterManager before you commit yourself to the installation, it is important that you connect at least the temperature sensor. If the HotWaterManager can not find a temperature sensor it will halt the startup process with an error message (for obvious reasons).
Wait until the normal operational screen appears. It shows the temperature and says "Automatic" on the bottom row.
Read the Menu section first, so you understand how to navigate the menu system.
There are a few settings that are important, like the System Voltage (12/24V) and whether you want to see the temperatures in Celsius or Fahrenheit. You can find these settings in the Setup Menu.
General notes
Factory reset
There are two ways to reset the configuration to the factory values:
Via the setup menu
In the setup menu, scroll to "Factory reset", select it, and change it to Yes. A reboot will follow immediately upon exit of the menu and all settings will have reverted to the factory values.
Via the boot menu
Reboot the HotWaterManager, and as soon as the LED turns off, touch the touch sensor and hold it until the "Hold button to reset sensors" message appears. Release the button. Hold it again when the message "Hold button to Factory Reset" message appears, until the message "Reset OK" appears.
Changing the sensor configuration
If you change the sensor configuration, add an additional sensor or replace a broken sensor by a new one, you will have to reset the sensor configuration.
There are two ways to do this:
Via the setup menu
In the setup menu, scroll to "Sensors reset", select it, and change it to Yes. A reboot will follow immediately upon exit of the menu and a search for the sensor configuration will be carried out.
Via the boot menu
Reboot the HotWaterManager, and as soon as the LED turns off, touch the touch sensor and hold it until the "Hold button to reset sensors" message appears. Hold the button until the "Sensors reset" message appears.
It will search for new sensors and tell you how many it has detected.
If you have two sensors connected (only possible with digital sensors), you might have to swap the sensors, either physically or in the menu. In case of the latter, scroll in the Setup menu until you find the the "Swap sensors" option and select it.
Switching the HotWaterManager on and off
It is best to keep the HotWaterManager always powered on, and use the menu option to switch the water heater off if necessary.
Reasons to keep the HotWaterManager running at all times are:
When the water heater is not powered, the HotWaterManager enters sleep mode and uses less than 1mA. So you will hardly save any power by switching the HotWaterManager off.
This HotWaterManager is equipped with a hardware watchdog. If a certain point in the software is not passed at least every 4 seconds, it will reset its microcontroller. In case of a nearby lightning strike or a software glitch, the HotWaterManager will recover by itself. There should never be a reason to cycle the power.
If the HotWaterManager is not powered, but connected to a solenoid or solar pump, some leak current will find its way into the HotWaterManager and it will (partially) power up, leading to unpredictable results.
Usage
Liquid Crystal Display
The LCD will show a variety of information.
Which temperature is being measured
Usually it says "Tank", but when you have an external solar- or heatexchanger- pump enabled, it will alternate the temperature with "Source", which is the temperature measured with the other temperature sensor.
Current temperature
The current temperature is displayed on the center of the top row. You can either select Celsius or Fahrenheit in the setup menu.
Trend
Behind the current temperature there is an arrow pointing up or down, which shows the trend of the current temperature. It is also possible that a question mark appears, this indicates an error reading the temperature.
Timer bucket
If you activate the optional hot water solenoid, this "bucket" will appear and slowly empty until the timer expires.
Legionella warning
A scary face will appear if the legionella time window has expired without at least once reaching the configured "legionella killing temperature".
Lightning bolt or clock
If a clock appears this means that the battery full voltage has been reached, but that the HotWaterManager is "paused" to allow for the absorption phase of the batteries. A lightning bolt indicates that the heater is switched on.
Operation mode
This is displayed in the lower left corner. The operating mode is selected in the main menu.
Voltage
The voltage, as seen by the HotWaterManager, is displayed in the lower right corner. The voltage determines when the water heater switches on in automatic mode.
LED
The LED, embedded in the touch sensor, by default confirms touching the touch sensor. However, in the setup menu you can choose to have the LED show other things instead:
Touch
This is the default LED mode. It will just light up when you touch the touch sensor.
Warm water
In this LED mode, the LED will light up when the water in the tank has reached the target temperature.
Heating up
In this LED mode, the LED will light up when the water heater is powered up.
Solenoid
In this LED mode, the LED will light up when the optional solenoid is activated and the warm water system is pressurized.
Legionella
In this LED mode, the LED will light up if the legionella time window has expired without at least once reaching the configured "Legionella killing temperature".
Menu interface
Navigating the menu is easy with the touch button interface. The touch button is the rounded square on the front panel. You can either tap or hold this touch button. By default the LED will light up when the sensor detects your finger.
Tap
This means shortly touch it. This is used for menu navigation and progressing through options.
Hold
This means keeping the finger on the touch button until the menu changes. This is used for selecting and confirming an option.
When editing a setting in the setup menu, after tapping to the selected value, you always have to confirm the change by holding the button until the "edit mode" is exited, indicated by the > arrow moving to the top row.
When a numeric value needs to be adjusted in the setup menu, tapping the button will increase the value step by step. To lower the value, you have to tap until the upper limit is reached and the number wraps back to the lowest value. The menu is designed in such a way that the difference between the lowest and highest value is rarely more than 15 steps. Most of these options are only set once during setup, to be never altered again.
Main menu
The main menu is used to select the operating mode. Hold to enter the menu. Tap to browse through the menu, hold to select the displayed mode. To exit the menu without selecting another mode, just stop interacting, and the menu will time out.
Automatic mode
This is the default mode. It will prioritize charging the batteries, and then use the surplus energy to heat up the water, up to the upper limit as long as the surplus energy allows.
This is how it works:
Once the "battery full" voltage has been reached, the "pause timer" starts running so that the batteries can finish a good part of their absorption phase. When the timer expires, the water heater is powered up. The voltage will likely go down, and if it hits the "float" value, the water heater switches off. The voltage will now increase again, and when it again reaches the "battery full" voltage, it will wait:
One minute if the water temperature is still below the target temperature.
Two minutes if the water temperature is above the target temperature but a legionella prevention cycle is due.
Five minutes if the water temperature is above the target temperature but below the legionella prevention temperature.
Ten minutes if the water temperature is above the legionella prevention temperature.
If the battery voltage drops below the "off" voltage, the "pause timer" will be enabled again, and it starts counting down when the "battery full" voltage has been reached.
Pause
This activates the pause timer again. This is useful if you want to give your batteries more "absorption" time, or when you plan to run another high power consumer and want to prevent the HotWaterManager to power up the water heater. Once the other high power consumer is powered up, the voltage will likely drop and the HotWaterManager will, even if the pause timer expires, not activate the water heater.
WarmUp
This manual program will switch on the water heater until 40°C is reached, (only of course if the battery voltage remains above 12.5V), after that it will revert to automatic mode. In the tropics, the water is already 30C to begin with (or more if you had a heating cycle the previous day) and it takes 1/3 of the power to heat the water to 40°C instead of 60°C, and it will not try to maintain this temperature once it has been reached. This option enables you to take a shower without using up too much energy: just press the button, wait for the temperature to reach 40°C and take your shower. Once the target temperature has been reached, the mode will revert to "Automatic" again.
Sanitize
Use this mode to immediately warm up the water to the legionella killing temperature. The "off" voltage will be obeyed however, and when the legionella killing temperature has been reached, the mode will revert to "Automatic" again.
Thermostat
In this mode the hot water manager will not be very "smart" but just maintain a temperature of 40°C with a periodical heating up to 60°C to kill Legionella. This mode is intended to be used when connected to shore power. If you would leave the program on "automatic mode" it would become very greedy due to all the apparent "free" energy and boost the boiler up to the upper limit (80°C) just to be able to surprise you the next day with still hot water when no "free" hot water would be available anymore.
AntiFreeze
In this mode the HotWaterManager will only maintain the configured minimum temperature.
It was just easy to program this feature (heating on when the temperature drops below 4°C) but of course keeping the hot water tank and water system filled while it is freezing is just asking for trouble. The freeze prevention can only work while the battery voltage is above 12.5V; if there is no shore power the batteries will probably not last very long to keep the freeze protection running, not even to mention that all the hoses and faucets will remain unprotected anyway.
Heater On
This will turn the heater on, until the upper temperature limit has been reached, or until the battery voltage drops below 12.5V. This mode is useful if you want to bypass the HotWaterManager entirely and just hand over control to the water heater as if the HotWaterManager is not there.
Pump On
Activate the (optional) external pump.
Off
As you might have guessed already, this disables all activity.
Setup
If you select this, you will enter the Setup menu.
Setup menu
System volts
Although the HotWaterManager will automatically detect the system voltage when it first powers up, you can override the system voltage here. You can toggle between 12Volt and 24Volt. Changing the voltage will reset all configurable voltages to their respective default values. It also changes the voltage range in the setup menu. In addition this also determines the power to the heater relay and it is possible to destroy the relay if you configure the HotWaterManager for 12V while it is running on 24V.
Temp units
You can toggle between a display indication in "Celsius" or "Fahrenheit".
Min Temperature
This sets the minimum temperature, which is relevant for the freeze protection.
Target Temp
This sets the temperature you desire for showering. This is relevant for the "Automatic" mode, because it becomes less "aggressive" when this temperature has been reached, and for the "WarmUp" mode.
Max Temperature
This is the maximum temperature, a hard limit, even if the batteries are full and there is plenty of energy available.
Sanity Temp
This is the legionella killing temperature. The HotWaterManager will periodically try to reach this temperature, and issue an alarm if it can not be reached.
Sanity Interval
This sets the period in which at least once the "Sanity Temp" needs to be reached. If this time window is exceeded the HotWaterManager will show an alarm.
No Sanity below
Below this temperature the development of legionella is stalled. The "Sanity Interval" timer will be paused below this temperature.
Start Voltage
This voltage needs to be reached in "Automatic" mode to start a heating cycle.
Float Voltage
In "Automatic" mode, if the voltage drops below this value, the water heater will be switched off, until the "Start Voltage" is reached again.
Abort Voltage
If the voltage drops below this value, the heater algorithm is reset. The Start Voltage needs to be reached again, a "absorption pause" will follow, before the heater will be activated again.
Select a voltage that is normally reached during the night.
Pause Duration
This is the "absorption" time of the batteries, which follows when the voltage has previously dropped below the "Abort Voltage". Note that the goal is not to fully charge the batteries but to find a nice balance between charging the batteries and enabling heating of the water. The HotWaterManager prioritizes reaching the "Target Temp" (shower temp) and after that it will back off and allow more time for charging the batteries further.
Hold on time
In "Automatic" mode, the HotWaterManager will interrupt the heating cycle when the voltage drops below the "Float Voltage". In some systems, solar chargers or a lithium BMS will need some time to react on the sudden load of the water heater and the voltage will drop momentarily. The "Hold on time" determines how long the voltage is allowed to drop below the "Float Voltage" before the HotWaterManager interrupts the heating cycle.
LCD Brightness
You can configure the LCD brightness here.
LCD NightBright
This configures the LCD brightness at night. The LCD will automatically dim the LCD to this value when it is dark.
LCD NightSensor
This configures at what value of the light sensor the automatic dimming will commence. A lower value will shift that moment to a more dark environment.
LCD timeout
You can specify the amount of seconds after which the LCD backlight should be switched off if the button is not pressed. This to save energy or light pollution. If the value is zero, the LCD backlight will stay on indefinitely.
If the LCD timeout is activated, the first button press will be "used up" for switching on the backlight.
LCD glow
After the LCD has timed out, the LCD will be completely dark, unless you switch on the LCD glow feature. This will allow a very small leak current through the backlight, so it "glows in the dark".
LED mode
With this option you can select the LED mode according to the operations described in the LED chapter.
VoltCalibration
If you think that the voltage displayed is not correct, you can adjust the calibration here.
Pump Source
If you have a solar or heatexchanger pump installed, you can configure what kind of icon it should display on the LCD.
Pump Delta
For this feature you need to have a second temperature sensor installed. This sensor should be placed as close as possible to the hot water source. If the source temperature is higher than the tank temperature *plus "Pump Delta"* then the pump starts running. The temperature difference is expressed in degrees Kelvin. One degree Kelvin equals one degree Celsius.
Pump Afterrun
Once the pump starts running, this value defines how long the pump should keep running even if the temperature difference is below the "Pump Delta" value.
Hot Water timer
This configures the time that the hot water solenoid stays open after activation.
Hot Water pwr
Usually, a solenoid needs most power during opening, and can remain open at a lower power setting. With this option you can configure how much power the solenoid needs to remain open. A lower value saves electrical power and increases the lifespan of the solenoid coil.
Relay hold pwr
Usually, a relay needs most power during closing, and can remain closed at a lower power setting. With this option you can configure how much power the relay needs to remain closed. A lower value saves electrical power and increases the lifespan of the relay coil.
Thermistor R
This option is only used when you choose to use a Thermistor to measure the temperature. The supplied temperature sensor is digital and it ignores this option.
Thermistor Beta
Like with the option "Thermistor R" this option is only to be used if you use a Thermistor to measure the temperature. The supplied temperature sensor is digital and it ignores this option.
Swap Temp Sens
If you installed the secondary temperature sensor for a pump source, you have to tell the HotWaterManager which one is the tank sensor and which one is the source sensor. Switch on the water heater and observe which sensor shows an upward trend, this is the tank sensor.
Reboot
You have installed the HotWaterManager from its own power source without an on/off switch? Great! But if you want to restart it without disconnecting... Well, you can use this option.
Factory reset
Select this option if you want all settings to revert back to the factory settings. Note that no confirmation will follow other than a reboot.
Sensors reset
Use this option if you replaced the temperature sensor or installed an additional one.
Versions
This option shows the software- and hardware versions used, which might be asked for if you need product support.
Serial number
This option shows the serial number, which might be asked for if you need product support. You can "select" this option if you want to block the menu timeout.
Troubleshooting
Sensors not found or erroneous values
Check the wiring to the sensors. Try to keep the wires as short as possible. If the problems occur especially when the heater is on or the solenoid is engaged or the pump is running, it is possible that the temperature sensor wires pick up noise from the other connections. Try to keep a separation between the temperature sensor wires and the other wires, or use shielded wires. If using a network cable, run the minus and data wires (black and yellow sensor wires) via one twisted pair of wires. Do not share the temperature sensor ground with anything else.
Automatic mode never reaches the target temperature
Heating up water takes lots of energy. Your charging capabilities might just be too little for your tank size.
There are a few things you can do to optimize your setup and reduce the power needed. See my article Hot Water System Optimization, which also contains some handy online calculators about the amount of battery or solar capacity needed to heat up a certain volume of water with a certain amount of degrees.
Bimetal switch
The temperature does not increase above 60°C
Most likely your water heater has a bimetal switch that limits to this temperature. If you want to have a higher temperature, you have to modify your water heater. In many cases, this is just a matter of replacing the bimetal switch with another type.
The water heater switches on and immediately off again
If this is caused by a voltage drop below the "Float Voltage", try to see if a longer "Hold on" value solves the problem. You can also lower the "Float Voltage".
If the cause is not a voltage drop, set your "Relay Hold pwr" setting to 100% and see if this solves the problem.
When the heater is switched on, the solenoid is activated for a few seconds
This is intentional. When water heats up it expands. Some water will be expelled from the tank. To make up for this loss, the solenoid is shortly opened to top up the tank and to equalize the pressure at the beginning of every heating cycle.
The indicated voltage fluctuates randomly
Most likely the power for the HotWaterManager is tapped from a shared bus, and other consumers are disturbing the voltage. Try connecting the HotWaterManager power supply directly to the battery.
The indicated voltage does not agree with other voltage monitors
There are several possibilities:
The other voltage monitor might be wrong, and/or averages, rounds or filters the voltage data differently.
Due to component tolerances, it might be necessary to calibrate the HotWatermanager
The HotWaterManager is running of a shared bus, and other electrical consumers on that bus are causing voltage fluctuations.
The voltage curve might not be linear. Calibrate the HotWaterManager for the middle of the curve and adjust the "Start Voltage" and "Abort Voltage" according to the displayed voltage.
Note that the HotWaterManager is not designed to be a Battery Monitor, the voltage is used more in a relative way than an absolute way.
