The switch for the water heater has a nice light that comes on when you first
turn on the DSI, but then it goes away when the burner lights. After that, there
is no telltale to let you know that the water heater is turned on. So, I added a
99 cent LED that is on whenever the DSI switch is in the "ON" position. The LED
I used is rated for 12V (it has a built in resistor that drops the voltage), which
I obtained at Fry's. The LED came with a plastic bezel that it snaps into. the bezel
itself snaps into a hole that you drill. There are some fancier and larger ones
as well. Radio Shack sells similar components. I chose a small one so I could mount
it in the DSI switch plate itself.
(Click on an image to enlarge it)
Step 1. Remove the existing switch plate which contains the switch and pilot light.
Step 2. Solder a pigtail onto the leads of the LED. Use a low wattage soldering iron to avoid overheating the LED. Insulate the leads with heat shrink tubing. (You can get LEDs with the wires already attached if you don't want to do the soldering).
Step 3. Drill the appropriate size hole in the switch plate. (I chose to mount the LED about halfway between the switch and the lower mounting screw hole). Snap the LED bezel into the hole.
Step 4. The switch is mounted snuggly in a square cutout. I drilled a hole in the paneling just under the bottom edge of the square hole and trimmed it into a "U" shape. This gives clearance for the LED.
Step 5. Connect the LED to the switch and pilot light wiring. The + side of the LED connects to the BROWN wire on the switch. This wire will be +12V whenever the switch is in the ON position. The - side of the LED connects to the WHITE wire which is attached to the existing DSI light which is part of the switch assembly. This wire connects to ground. I cut off the female spade terminal connectors off the Brown and White wires. After stripping the ends of the wires, I twisted the appropriate wires from the LED onto the wires. Then I crimped a new slide on terminal to the twisted ends.
Step 6. Reinstall switch panel. The left picture shows the switch panel with the water heater switch turned off. You can see the green LED is extinguished. The right picture shows the switch in the ON position. The red light is extinguished because the burner is lit. The Green LED is illuminated to let me know the water heater us turned on.