Sous-vide Immersion Circulator
Overview
I saw this nifty DIY Sous-vide cooker while surfing the web. wikipedia:Sous-vide looked interesting, but I figured it was well beyond my "oh, let's try that" budget. The least expensive ones run about $450, and are reported to be somewhat mediocre. I'm going to go the DIY route, but with slightly different parts than the original project. My total cost will be somewhere around $125, I believe.
This is the original parts shopping list:
- 3x NORPRO 559 Immersion Heater for Warming Liquids - $17.97
- 79 GPH Fountain, Hydroponics, or Aquarium pump VA80 - $9.99
- Dual Digital PID Temperature Controller Kiln Furnace - $28.95
- PT100 Thermocouple Probe - $5.99
- SPST Heavy-Duty Rocker Switch - $2.99
- 7-9VDC/12A SPDT Relay - $4.49
Tank
I'm not thrilled about using a plastic tub as the tank. I'll likely try to find a hotel pan and maybe build a wooden frame to hold and insulate it. In addition, rather than clamping the PID controller and heating elements to the tank edge, I'll remote the PID controller. This will require less complex acrylic work (since we don't need to worry about splash-proofing the controller), and make it easier to mount the heaters, pump and temperature sensor.
Possible pans to use:
- Katom - $69.14
- Katom - $78.52 (3 pack)
- Wasserstrom - $32.98
- Katom - $35.01 (+ $7.88 shipping)
- Wasserstrom - $44.11
- Citisco - $55.95 (special order)
- Katom - $328.04 (6 pack)
- Wasserstrom - $77.57
One thought I had with using the hotel pan is to drill and tap it for two 500 watt heaters such as a water tank would use. Putting an elevated metal grid over it would eliminate the possibility of the food bag bumping into the heating element(s) and burning through (although a grid could protect the immersion heaters just as easily).
PID Controller
Not sure what make and model this exactly yet, although I think it's a CD101. May be able to drop the cost a couple bucks with a better search.
- Dual Digital PID Temperature Controller Kiln Furnace - $35.94 (shipped)
Temperature Probe
The probe specified is great. I found some a little less expensive with a slightly different search term.
- 2m Thermocouple Thmperature Control Sensor PT100 - $6.60 (shipped)
Heaters
Turns out that finding 500W heaters is near impossible. One idea is to use 2 1500W heaters, and a small microcontroller to "dim" them down to 500W with a TRIAC or IGBT circuit. This would serve two functions: 1) eliminate the extra power relay (since the PID controller has a sufficient sized internal relay that can be used), and 2) allow tuning the heater power. If 600W is sufficient, why run 1000W? This will largely be determined by what sort of cycle rate we can tolerate and how closely we can still hold the target temperature.
Another possibility might be putting two 1500W or 2000W elements in series. The DIY design produces 900W from the (3) 300W immersion heaters. With a metal tank that's possibly slightly larger, 1000W should be no problem.
Heating elements:
- Camco 2000W 120V flange mount - $7.49 ($22.07 for 2, shipped)
- Rheem 2000W 120V screw mount - $6.99 ($20.83 for 2, shipped)
According to this article, screw mount heater elements are 1". BuyFittingsOnline.com has 1" stainless threaded nuts, as does McMaster-Carr
Pump
Pump selection (good to +105C):
- DC 12V Electric Centrifugal Water Pump 109 GPH (P-38E) - $32.00 (shipped)
- DC 12V 1A Power Supply Switch Adapter for CCTV Camera - $?.??
Documents & Schematics
- CD101 Dual Digital PID Temperature Controller
(944 KB) - CB100 Dual Digital PID Temperature Controller (1.03 MB) (apparent clone, better manual)
