Project Hot-tub Temperature
Last modified: 17.5.2020
Started: 8.5.2020
Modifying my hot tub project to allow programmatic temperature control via VoffCon.
The project code on GitHub
My goal is to enhance the hot-tub project by allowing programmatic control of the water temperature, eliminating the need for manual adjustments before use. In the future, I aim to integrate outdoor temperature data to dynamically adjust the water temperature based on weather conditions. I will continue using VoffCon to manage commands over the internet. Additionally, I plan to integrate Google Home and IFTTT for hands-free voice control while in the hot tub.
A key next step is implementing a PID control library to optimize temperature regulation.
Below are some experiments and tests conducted during development, along with images and videos documenting the progress.
Development setup
Setup for testing software communication with components. An ESP32 is connected to valves, temperature sensors, and pressure sensors. The date is 3. august 2021
Test setup wired to my plumbing system
Valves, pressure sensors, temperature sensor connected to my pluming system and the test setup connected to them showing a successful test. The date is 7. august 2021
PCB Designed, assembled and deployed
Every thing is working. The date is 15. october 2021
3D printed housing
I got help from friends on the Arduino - Íslands facebook group to 3D print protective housing for watermixer. The date is 27. october 2021
Experiments and tests
During development, I explored using a BC547-based circuit, suggested by Brjánn Guðjónsson, adjusting R4 and C1 to achieve a stable voltage output. Alternatively, I considered using an MCP4725 for better control.
Proportional Valve with Esp32
Convert from 3.3V to 5V
Filtering out noise from a PWM signal
Todo:
- Create environment so you can start sexperiment 7. That is connect the two valves to a water supply and connect the temperature sensor also.
- Finish test 7. That experiment should result in a program which can be used to mix the heat of the water flowing to the hot tub.
- Finish test 8. Think about the weather out side, if it's cold and/or windy out side we will need hotter water. (Maybe get info about current wether from vedur.is programmatically).
- Remove current fill motorized valve (R1) from the home plumming system.
- Plug proportional valve 1 into my house hot water pipe and connect it to the hot tub pipe.
- Plug proportional valve 2 into my house cold water pipe and connect it to the hot tub pipe.
- Plug the valve into my house hot and cold water pipes and connect it to the hot tub fill valve.
- Design a box around the project, glue it and put the project into it.
- Wire everything, put it into the box and mount it on a wall.
Tests
Test 1 - Arduino Nano connected to valve (fail)
Arduino Nano D5 pin connected directly to the valve green wire. V5 GND and 12V ground connected together. 12V+ connected to valve red wire. and 12V- connected to valve black wire.
Result
I consider this test as a fail because the valve was very jittery. That is, the valve did change position, but never completely stopped. Alway continues little irritating corrections.
Test 2 - Nano with RC filter (Success)
Using the RC filter (see image "RF filter") connected to D5 on a Arduino Nano. The test code makes the Arduino Nano read a value from the serial and writes that value to the D5 pin. Then nano will read a A1 pin which is connected to a feedback wire on the Valve.
Connections
- Arduino Nano Mini USB
- Is connected to Computer USB
- Arduino Nano D5
- Is connected to R6
- R6 1kΩ
- Is connected to Arduino D5, C5 and R1
- C5 0.1μf
- Is connected to Ground, R6 and R1
- R1 10kΩ
- Is connected to R6, C5, C1 and Valve green wire
- C1 10μf
- Is connected to Ground, R1 and Valve green wire
- Valve black wire
- Is connected to Ground
- Ground
- Is connected to Arduino Nano GND, Power supply 12V-, Valve black wire, C5 and C1
- Power supply 12V +
- Is connected to Valve red wire
- Arduino Nano A0
- Is connected to Valve white wire
- Valve yellow wire
- Should be, but isn't connected to R7
- R7 680Ω resistor
- should be, but isn't connected to 12V+ and LED
- LED 3.3V
- Should be, but isn't connected to 12V+ and R7
Result
Success, You can click here if you want to see a YouTube video of this test in action.The Test code
Test 3 - Esp32 with RC filter and logic level converter (fail)
Possible connections for test 3 - second image
Result
This experiment failed. The voltage on the output Green wire went from low: 1.2V to high: 3.2V, but needs to go from 0V to 5V. The valve was little bit open and then just opened just a little more. Never completely open nor completely closed.
The Test code
Test 4 - Esp32 with BC547 (fail)
Using the BC547 (see image Schematic with BC547) and the RC filter (see image RC filter) connected to the Esp32. Then nano will read a A1 pin which is connected to a feedback wire on the Valve.
Perhaps I could get away with wiring like this
Possible connections for test 4 - second image
I tested powering the Esp32 with 12V via til VIN pin. This resulted in the on board voltage regulator heating up to 56° while just blinking one led, no wifi operations where even running. After little googling I found out this is a issue with the Esp32, it's probably best to be in the 5-7V range. The valve will run on 9V. So may be I'll try that. I would like to have only one power source powering the Esp32 and the valve. Maybe I can step down the voltage from 12V before connecting it to the VIN.
Result
The experiment was a Fail. Because there are issues, like little jittering and out max output to the green wire is just over 4 volts, but should be max 5 volts.
If you want to see the experiment in action click here to see it's YouTube video.
The Test code
Test 5 - Esp32 with PWM to Voltage converter module (Success)
Using the PWM to Voltage Converter module (see product PWM to Voltage Converter on aliexpress)
Wiring the experiment
Valve wire colors
Wiring diagram
GND +12V
│ │
│ │
╔═══════════╗ ╔═════════════╗ │ │
║ -ESP32- ║ ║ PWM to ║ │ │ ╔══════════════╗
║ ║ ║ voltage ║ │ │ ║ Valve ║
╔══════════╗ ║ ║ ║ converter ║ │ │ ║ ║
║-HLK-PM01-║ ║ ║ ║ ║ │ │ ║ PWM Out-╟─(WT)─
║ ║ ║ ║ ║ GND -╟──┘ │ ║ ERR -╟─(YW)─
║+Vo (+5V)-╟───╢ VIN ║ ║ VCC -╟──────┴─(RD)─╢- VCC ║
║ -Vo -╟───╢-GND GND -╟──────╢- GND GND -╟────────(BW)─╢- GND ║
╚══════════╝ ║ D26 -╟──────╢- PWM VOUT -╟────────(GW)─╢- LIN ║
╚═══════════╝ ╚═════════════╝ ╚══════════════╝
Ps. Instead of using 12V power supply you could any source ranging from 12v to 24V.
Image of connections for test 5
Result
The experiment was a total Success. No jittering problems and the voltage range is from 0 - 5V volts.
The Test code
Test 6 - Esp32 reading from temapture sensor (success)
Reading values from DS18B20 (see product DS18B20)
Wiring the experiment
Wiring diagram
╔═══════════╗ ╔═══════════╗
║ ESP32 ║ ║ DS18B20 ║
║ ║ ║ Sensor ║
║ ║ ║ ║
║ GND -╟────────────────────────╢- GND -║
║ 3V3 -╟──┬─────────────────────╢- VCC -║
║ ║ │ ╔═══════════╗ ║ ║
║ ║ │ ║-Resistor -║ ║ ║
║ ║ └──╢- 4.7kΩ -╟──┬───╢- Signal -║
║ ║ ╚═══════════╝ │ ╚═══════════╝
║ G12 -╟────────────────────┘
╚═══════════╝
Result
The experiment was a Success. The sensor I used did not react quickly to temperature change but I think that will be ok if i use the PID library.
The Test code
To use this code you must first get these two libraries- OneWire library by Paul Stoffregen
- DallasTemperature by Miles Burton.
Test 7 - Create a water mixer program (not started)
Create a program which can be used to mix the heat of the water flowing to the hot tub. Best would be to use a the PID library to do mix the water.
- Reading values from DS18B20 (see product DS18B20)
- Using two PWM to Voltage Converter module (see product PWM to Voltage Converter on aliexpress) to control the two proportional valves.
Result
todo:
Test 8 - Get the current local wether (not started)
Get the temperature and wind outside so you can deside if the water flowing to the hot tub needs to be a little warmer or colder
Result
todo: