This is a simple project I did to avoid adding water into my machine each time I take a cup of coffee. It's a pretty simple system but it also requires basic plumbing knowledge and electrical / soldering skills :-). This DIY will work with B40/B60/B70 model or maybe other if you have enough place for the small bracket and water level sensor that we'll see in a moment. Note: some suggested in the comments a mini plastic float valve http://goo.gl/fbu2Jt if its size fits your reservoir it might be a simpler setup (I did not test it).
Step 1: Ice Maker Maker Tap Valve Kit
First, get an ice maker self tap valve kit available in most hardware store for 8$-10$
Tap Valve Kit
For 3/8" to 1" O.D. tube
Valve with 1/4" O.D. comp. outlet
25'x 1/4" O.D. polyethylene tube
1/4" O.D. comp. union
For installation of humidifiers, ice makers, and evaporative coolers
Step 2: Electrical Parts - Electric Solenoid Valve Water N/C 12V 1/4"
Next you'll need an Electric Solenoid Valve Water N/C 12V 1/4". It should be water type and "normally closed" to work with the system. I've got mine from Ebay for $12.50 http://www.ebay.ca/itm/300628527488
Step 3: Electrical Parts - 12 Volt Relay
Next you'll need a SPST 12 volt relay. 6$ online http://www.ebay.ca/itm/321025975659
Or you can use one you have lying around.
Step 4: Electrical Parts - 12 1Amp + Power Supply
Next you'll need a 1 amp + 12 volt DC power supply. 6$ online http://www.ebay.ca/itm/180883437481
Or you can use one you have lying around. If it's 12 volt dc and 1 amp or more
Step 5: Electrical Parts - Water Level Liquid Sensor Float Switch
Next you'll need a Water Level Liquid Sensor Float Switch. 2$ online http://www.ebay.ca/itm/160618121548
Step 6: Plumbing / Water Line Installation
You will need to follow the included instructions to install the water valve. The idea here is to get the 1/4 water tube to the Electric Solenoid Valve then to the brewer water reservoir so you can control water flow through the solenoid.
Step 7: Electrical Parts - Installation
*WIRING for reference only. Relay pin 85 & 86 are the coil, and 87 & 30 are the switched contactor.
You'll need to wire the solenoid, the relay, the water level switch and the power supply so that the water level switch control the relay that activate the solenoid.
Step 8: Fix the Custom Bracket
You will need to make a custom bracket to hold the water line (hose) and the level switch. You can use a thin aluminum plate and then fix it to the reservoir.
Step 9: Enjoy!
See demo video:
GlenA made it!