We recommend hacking the Professional Series 30 cup coffee urn. It has built in convection with no need for a bubbler.
The tools you’ll need:
- Power drill, drill bits
- Philips screwdriver and glasses repair screwdriver
- Wire stripper
- Familiarize yourself. Open up what you’ll hack and get orientated the parts. You want to find where power comes in through the wall and where the main heater is. We don’t care about anything else, like the LED or “keep warm” heater. Small disks attached to the heater or elsewhere are usually thermistors that prevent overheating. You can leave them or discard them.
- Take off the part youíll drill into to attach the ember kit (usually the plastic base). Drill holes using included template into the base (or you could make one yourself, two smaller equidistant holes side by side a main larger hole).
- Drill holes into the ember kit box matching the base holes.
- Drill or poke a small hole (1/16″) in the water container near where the ember kit is being attached. This is for the thermistor. Put the thermistor through the hole
- Attach the box for the ember kit and string the wires from the tyco plug through the largest central hole.
- Strip and attach the wires from the tyco plug to the terminals you found: red goes to one end of the heater that connects to the wall. Black goes to the other AC terminal (from the wall). White goes to the opposite end of the heater from the red socket. We recommend you disconnect everything else. BE VERY CAREFUL HERE. Remember: red and black connect to the wall, red and white to the heater (white goes through SSR to black). Test with a multimeter.
- Attach the thermistor with Sugru.
- Thread the leads of the thermistor into the ember kit box and reattach the base.
- Screw the PCB into the lid.
- Attach the knob.
- Screw in the leads and plug in the tyco plug.
- Attach the lid to the ember kit box.
- Always plug in through a GFCI outlet/adapter to be safe.
1. Orient yourself with the device and locate where to unscrew it to take a look at the parts inside. If you are using a coffee urn, the panel to open it is on the bottom.
2. Take your Philips screwdriver and twist out all of the screws.
3. Lift and familiar yourself with the innards of the appliance. The coffee urn is hilarious and beautiful in its simplicity. All we will need is the main heater, but there are a few other things:
- The main heater is in the middle, fairly bulky, with the two connectors jutting out parallel to the bottom of the urn.
- The “keep warm” heater, which is usually a special wire covered in insulation, wrapped around the main heater.
- Small disks attached to various places. These are thermistors that prevent overheating. We you can discard the one that connects to the container but you should keep the one that connects to the heater.
- An indicator light.
4b. Strip the blue wire, which will later bring AC power to the Ember Kit.
5. Unscrew the red wire that is connected to the main heater.
6. Attach the base to your workbench with a C-clamp. Line the template up just to the right of the front so that the box will not overlap anything, but it is accessible. Drill holes using the template, starting with a small drill bit and working up to larger ones.
7. Remove the base then clamp down the Ember Kit box. Attach the template toward the left side (if the opening is facing you), but make sure there is room for the screw on the inside. Then drill holes in it with the other template.
8. Now insert the two long bolts and attach the Ember Kit to the base. Attach them together with the nuts.
9. Locate the place on the container you will be attaching the ember kit (line it up with the base to check). Near the ember kit location, not too close to the heater or wall, drill or poke a small hole into the base of the container. It doesnít need to be more than 1/16″, but if it is larger don’t worry, you can still cover it with the silicone sealant. The Professional Series is stainless steel, so our drill couldnít handle it. A hammer and awl did the trick.
10. Wrap the top part of the thermistor completely in a thin layer of Sugru. The Sugru needs to protect it from the water, but shouldn’t be too thick to prevent reading the right temperature. See the video for working with sugru if you have questions.
11. Put the thermistor wire through the hole, with the head in the container. Use sugru to seal the hole on the bottom of the container. Also apply sugru on the underside for strain relief.
12. Now thread the wires from the Tyco socket through from the box to the base. Our middle wire is green in this picture, but yours should be white.
13. Shorten the red and white wires so they are only about 8 inches long. Strip the ends of the wires and crimp on the ring terminals.
14. Screw them, with the red wire removed in step 5, to the terminals of the heater.
15. Take the blue wire we snipped from the keep warm heater a long way back (Step 4).† Strip it and the black wire, and crimp together with a butt connector.
16. Test the the tyco socket with a multimeter before packing everything up. There should be no connection between the black and either other lead. There should be 15 ohms or so between the red and white leads.
17. Now thread the leads from the thermistor into the ember kit box, and close everything back up!
18. Now turn to the PCB. Screw the PCB into the lid so the LED and rotary encoder go through the holes.
19. Attach the knob to the rotary encoder with the allen wrench provided. Pull the knob away from the face slightly so that it has room to spin and can be pushed in (it includes a push switch).
20. Now screw the leads from the thermistor into the screw terminal. You will need a very small screwdriver, we had a 1/16″ flathead.
21. Also attach the Tyco plug to the socket.
22. Now screw the faceplate onto the box! Looking sharp! You are almost done!
23. After the sugru dries (overnight), add water to the container and make sure it doesn’t leak. If it holds, go ahead and plug it in (to a GFCI outlet or adapter).
24. It should turn on and say the temperature! If this does not happen, unplug, remove the board and check for shorts. Check the connection of the Tyco plug electrodes (red and black) to the prongs on the coffee urn power plug. The most common mistake made is that you have inserted the microchip the wrong way.
25. It should also heat up! If you don’t notice boiling after 30 seconds, something is up. Unplug the coffee urn. If the LED indicating heat (behind the ember sticker) was not turning on, check for a short on your board. If the LED turns on but it is not heating, check the wiring (multimeter the red and white wires on the Tyco plug, should have a resistance of 12-20 ohms). If that is not working, check the resistor next to the SSR. We pulled the pad here on one setup. You can just short across the resistor if you need to (take the lead of a resistor you clipped, solder it to the two electrodes). With a multimeter, check the wiring of the SSR pin to the resistor, and the other SSR signal pin to ground.
26. You’re ready to get cooking! Try some eggs at 63 C for 45 minutes. Or one of our recipes at QandAbe.com. Enjoy! Tell us what you think!