Hello all.
Over the last 9 months or so I’ve been “dialing in” my process and my recipe for traditional baguettes, and I’m getting pretty consistent results. But now I want to control more of the variables and start tweaking the nuances. To that end I want to construct a small retarder/proofer. I’m handy and have some experience with marine refrigeration. I’ve also been researching components - evaporators, heaters, controllers, fans. But before diving in I’m wondering if anyone has some practical experience doing the same thing and might help me avoid any “oops”.
Thanks!
A small (or large) refrigerator with a heating pad and a temperature controller will provide a wide range of well controlled temperatures at low cost with very little hacking
Gary
I have a small heating pad that I use in a small cooler that works well for T ≤ 30 °C. What I'm looking for is a way to maintain ≈40 °C (CLAS temperature) in a cooler or even in a small toaster oven; the heat mat won't hit that temperature. You once used a mug warmer as a heat source. Do mug warmers provide more heat than the reptile/seed mats?
P.S. I am currently testing a 50 W mini ceramic heat bulb in a toaster oven and it seems to have the output necessary, but I'm open to more options.
The wattage is all that matters. The seed warming mat I used was 21 watts. An incandescent light bulb will easily give you 100 watts or more of heat.
I think the best way to maintain CLAS temperature is a crockpot with a temperature controller. I put mine in a jar and put enough water in the crockpot to match the jar level. I put the probe for the controller in the external water so I don't have to wonder what metal the cheap controller uses in the probe. I've done pumpernickel the same way.
Gary
Gary is on the money. Another option, if you don't need much interior space, instead of a small fridge, get a used small wine cooler - they can usually be found fairly cheaply . The small ones use Peltier effect for cooling, instead of a compressor, so they are very quiet, but won't get as cold as a fridge if you keep them in warm location ( like my garage in the summer ). But I don't need to get it but so cold - many will hold temps in the 40 to 60 F range. I use a small heating pad ( make sure it is the kind without the safety shut off every 20 minutes ) , and a digital controller for proofing.
I've built three proofing cabinets of varying sizes (standard, mini and nano) and all have air circulating fans inside to give a consistent temperature throughout the cabinet.
The best design is an insulated cabinet with a "false" base. The fan and heater are under the false base which has air holes in it to give a ducting effect so that cool air drops down from above and is blown over the heater by the fan and travels up into the proofing area.
The heater is a series of 50 watt mains voltage rated resistors mounted on a finned heatsink - resistances are selected to give the desired heating wattage.
Control can be by on/off stat or (better but not strictly necessary) PID control.
The cabinet sections can be hinged to fold down for storage.
Admittedly, this doesn't cool, but I have a small compressor fridge (again modified with ducted air circulation and a digital controller) for that.
I would avoid Peltier fridges - they are only 30% efficient at best, have poor cooling power and use lots of electricity.
Lance
Thanks Lance. A couple of follow- up questions:
What does PID stand for?
Do you have a schematic for your proofer?
Have you ever thought of combining the ideas of retarder/proofer in the same insulated box?
I ferment my dough in a 12”dia x 5”high glass bowl and would want my box to accommodate three such bowls… so the interior conditioned space would be just a bit over 1.5ft cubed.
I’m always hassling with space in the kitchen refrigerator to retard my dough, so I wondered “why not add a retarding element to a purpose built proofer”?
Do you have any thoughts on that?
PID is short for proportional–integral–derivative. I have some experience using PID controllers in a lab setting. They allow tuning of the controller to the load and other parameters to minimize variation around the setpoint. They are a generally more expensive than on-off controllers. I'm also interested in Lance's design, but I don't know if I'm handy enough to execute it.
Proportional–integral–derivative controller - Wikipedia
This is my Mini Proofer design. Just big enough for a 3 litre bulk fermenter - not intended for final proof. Enough dough for 2 x 900g loaves at up to 60-70% bulk increase.
Lance
Are those power resistors the heating elements?
They're in parallel, so about 65 watts with our 240v AC mains voltage.
Impressive! Seeing your design confirms my belief that I doubt I could replicate your proofer. It's a beauty!
Cheers Alcophile. It was quite a lot of work at the time (I made it about 5 years ago), but I was pleased with the outcome. I seldom use my standard sized proofer now, just this one for bulk and the nano proofer for starters. Shaped dough I retard or use the heated proofing board.
Lance
If you want a one box solution, I don't think adding a retarding facility to a proofer is going to work well - you would need to incorporate a fridge plant, ie compressor, evaporator and condenser, probably connected by flexible pipes - such solutions probably exist, but they won't be cheap. Better to go with Gary's idea of a fridge with added proofing facility. The insulation will be better too.
If you are not well versed with electronics, it would be better to use a ready made controller - check out the Inkbird range for example.
Lance
Dorm fridges are relatively inexpensive and available in various sizes. We bought one for my daughter when she went to UNC and I ended up using it in my office for 17 years. A conventional fridge has much greater cooling power than Peltier coolers. I recommend one without a freezer compartment to avoid issues with it frosting up.
A controller like this one https://a.co/d/cPbI5AR will handle both the heating and cooling.
If you have issues with stratification of the air inside a small fan as suggested above would cure that. I would measure the air temperature in various places using a bluetooth thermometer before I added a fan.
I would drill a small hole for the sensor and heating element wires to pass through the refrigerator wall.
Gary
"PID" refers to a "proportional" controller. That means it's not just on-or-off, but the amount of control applied is proportional to the error. It's like braking hard when you need to stop suddenly, vs braking gently when you are going slowly. In this case, if the temperature is way low, the PID controller will send a lot of power to the heating element, and if the temperature is only a little low it will send a small amount of power.
TomP