WEEK 18 APPLICATIONS AND IMPLICATIONS / PROJECT DEVELOPMENT

At this stage of the course, this week's assignment is fully focused on the final project.

The goal for this week is to provide the following information about it:

Plan a final project masterpiece that integrates the range of units covered, answering:

What will it do?

Once installed, my project is designed to prevent the daily water waste that occurs at every hot water tap while waiting for the water to actually come out hot after opening the valve.

Who's done what beforehand?

Yes, there are already similar systems on the market, such as Grundfos, that use cold water pipes for temporary DHW (Domestic Hot Water) recirculation. The difference is that they usually consist of large pumps and semi-manual setups. My system aims to be more compact, completely plug-and-play, and features an electronic control that allows the user to operate it much more efficiently.

What sources will you use?

My main inspiration comes from the Domestic Hot Water (DHW) recirculation systems already in use worldwide, but modified so that it can be retrofitted into an existing plumbing installation without any structural changes.

What will you design?

Except for the standard hydraulic components, which I will purchase and assemble myself, the entire system is my own design. This includes the electronics, the support bracket and enclosure, the remote control, and the protective covers to seal everything.

What materials and components will be used?

The main enclosure will be 3D printed using PLA filament, the remote control will be crafted from wood, and the protective covers will be laser-cut from acrylic (plexiglass).

The electronic components used are:

Microcontroller: 1x Seeed Studio XIAO RP2040
Motor Drivers: 2x Toshiba TB67H451FNG,EL
Voltage Regulator: 1x 5V / 1A LM2940CT-5.0/NOPB
Power Connector: 1x CONN PWR Jack 2.5X5.5MM Solder
Sensor: 1x NTC Thermistor (10kΩ, 3750K, 1206 package)
Display: 1x 0.96 Inch OLED Display Module SSD1306 I2C
Button: 1x Button PBS-110 NO
Passives & Hardware: Assorted connectors, capacitors, and resistors

The hydraulic components used are:

24V DC Circulation Pump
24V DC Electric Water Valve

Where will they come from?

The standard plumbing parts will be sourced from Saltoki supply warehouses. The water pump and the valve will be purchased from Amazon.

How much will they cost?

The hydraulic assembly is the most expensive part of the system, while the custom electronics and control components are highly cost-effective. Below is the detailed breakdown:

1. Hydraulic & Plumbing Components

Item	Description	Source	Cost
Water Pump	24V DC Circulation Pump	Amazon	€30.49
Solenoid Valve	24V DC Electric Water Valve	Amazon	€29.99
Plumbing Hardware	Assorted fittings, adapters, and hoses	Saltoki	€19.35
Subtotal:			€79.83

2. Electronic Components

Item	Description	Source / Link	Cost
Seeed Studio XIAO RP2040	Main Microcontroller Board	AliExpress	€4.99
NTC Thermistor	Temperature Probe Sensors	Mouser Electronics	€0.09
CONN PWR Jack 2.5X5.5MM Solder	Power Barrel Connector Jack 2.50mm ID (0.098"), 5.50mm OD (0.217") Through Hole, Right Angle	Digikey	€0.83
Driver Toshiba TB67H451FNG,EL	2 x Motor/Motion/Ignition Controllers & Drivers 50V/3A Brush Mtr Drv	Mouser Electronics	€2.28
Regulator LM2940IMPX-5.0/NOPB	Linear Voltage Regulator IC Positive Fixed 1 Output 1A SOT-223-4	Digikey	€1.61
0.96 Inch OLED Display Module SSD1306 I2C	0.96 Inch OLED Display Module SSD1306 I2C IIC SPI Serial 128X64 GND VCC SCL SDA LCD Screen Board	AliExpress	€0.92
Button PBS-110 NO	5PCS Small Round Button Switch PBS-110 NO PBS-111 NC 2Pin Self-resetting Button Switch 7MM Miniature	AliExpress	€0.40
TOTAL COST:			€11.12

Total Estimated Project Cost: ~ €100.95 (adding €10 for 3D printing and raw wood/acrylic materials sourced directly from the FabLab inventory).

What parts and systems will be made?

I will design and manufacture the entire electronic control board and all structural components, including the main enclosure, protective covers, and supports. The only parts that will be purchased off-the-shelf are the standard plumbing and hydraulic components.

What processes will be used?

The manufacturing of the project will involve several digital fabrication processes:

3D Printing (Additive Manufacturing): The main enclosure and internal mounting brackets will be 3D printed using PLA filament.
CNC Milling (Subtractive Manufacturing): The remote control housing will be precision-milled from wood.
Laser Cutting: The protective covers will be laser-cut from acrylic (plexiglass) sheets.
PCB Fabrication & Assembly: The custom electronic control board will be CNC-milled (isolation routing), followed by manual component soldering (SMD and through-hole).

What questions need to be answered?

The primary questions and critical challenges that need to be answered and tested during development are:

Form Factor and Integration: Can all components be successfully integrated into a relatively small space while remaining accessible?
Hydraulic Integrity: Are the custom-assembled plumbing connections completely secure and free of water leaks under operational pressure?
Electronic Reliability: Does the custom control board, along with the sensors and drivers, function correctly and execute the recirculation logic as intended?

How will it be evaluated?

The success of the project will be evaluated based on the following milestones:

Electronic Validation: The custom control board must power up safely and the microcontroller must execute the firmware code without stability issues.
Interface and Remote Control: The remote control unit must reliably communicate with the main system and accurately trigger its corresponding functions.
Hydraulic and Thermal Performance: The system must successfully drive the water flow through the plumbing loop, and the temperature sensor must accurately detect the heat rise to stop the pump when the water is hot.