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Discussion in 'Fridge/Freezer Builds' started by smokednarwhal, Mar 24, 2010.
I would be interested in that also (since I'm stalking this build and using some of your ideas)
I am not an expert by any means.
The way I read the programming instructions is you could disable autotune by setting At = 0. (section 6.5.3) This should prevent the controller from cycling so much. I think the controller is trying to be a little to accurate when it is autotuned.
I then set Hy = 3. If you read in section 6.5.2, it says this will protect it from high switching frequencies. You could set Hy to 1 or 2 and it would keep the temp a little tighter but there would be more cycling. The element does not respond instantaneously, it has to heat up when turned on and it takes a while to cool off when turned off. I felt like a 6 degree swing (and it is probably a little more than that due to the lag in the element I just mentioned) was ok for my use. I might try lower settings but the 3 seemed to work ok when I smoked some Andouille the other day.
Here are some pictures of the completed controller. I took out the green light since it showed the controller was on and that was a bit redundant since the lights on the controller were on anyway. Put in a 20a switch for on/off control. Attached the top with some gap between the sides and the top for air exhaust (the fan brings air in from the back)
I'll probably have to follow this post up later of some questions regarding how you put the outlet in the box. I saw the directions for how to wire the PID-- but as far as the more advanced parts like installing the outlet and leading a plug from the PID control box-- is something the PID installment directions dont touch on.
I am watching this very closely also. I just got my metal for the door of my build back from the machine shop today and will start putting that on tonight when I get home tonight. I really like the PID control and the Grainger heating element. So I am planning on using all of these ideas. I sure hope that is OK
there is no need to put an outlet in the box. I did that to plug in a fan which is probably not necessary anyway. Since it was there I also plugged in the PID to it also. Should put a fuse on the PID but didn't. I think they recommend a 1 amp to protect the unit. The PID can be wired directly into the terminal strip. I did put in a switch and a cute red light which in on when the element plug is active. Hard to see in the sunlight though. There is a small light on the PID that shows when the relay is on.
Yep no need for an air pump, just good draft.
Top down view
Notice the thumb screw on bottom. that is to tighten up the bottom baffel, which is an 4" outdoor electrical outlet
Bottom up view
Hey guys, it is great to see all the replies and posts of other projects. I finally found some time to get out to the workshop and here are a few photos of what I got done.
Here is the cut and test fitted bezel edges that used to be made of plastic. I used some recycled aluminum tread plate that was once pickup truck bed rail covers.
In this photo I drilled the holes and mounted the heating element. These are just some fire bricks I had laying around. I plan to line the entire bottom with bricks eventually.
Here is a close up shot of the stainless steel nuts and bolts that make up the simple but effective element mounting system.
This part was a challenge. I had a tough time finding a grommet small enough for the single pieces of high temp wire entering the box. These are the perfect fit, so I know the wire will be secure and the insulation will not be worn by the edges of the metal box.
And finally, my 4" stainless steel smoke stack with damper. I'm really not looking forward to drilling the box and the outer shell with a 4" hole saw.
I'm planning to spend some more time tomorrow working on it and I will continue to take photos of the project. Thank a lot everyone for helping to keep me motivated.
Where did you get that exhaust stack with the damper?
From sausagemaker.com it was about $20 shipped.
Finished filling screw holes, made a few patches and finished fabricating the grate brackets. Everything was sealed with high temp silicone before final mounting.
Keep up the good work and the photos. We all are enjoying and learning!
What are you going to use to seal the door? I played with some samples of braided wood stove gasket today and it looks like my unit is going to take the 3/4in stuff but that stuff is almost 3 bucks foot! Have you come up with a cheaper solution?
Anyone use magnetic refrigerator seals? The recessed design of these old doors would keep it away from some of the heat. Anyone have any success using it?
I just found some on ebay. I ordered the 3/8 inch and it was .99 cents a foot 1/2 inch was 1.25. not sure about 3/4 but all you need to do is tell them how many feet you need and you will get it all in one piece.
you dont really have to worry about a smoke distribution system. the convection of hot air off of the element will move the smoke around all by itself. if there is hot air rising over the top of the element, there is a corresponding downdraft somewhere else to feed it.
and you will need to put a piece of metal flashing (i used a piece of metal gutter) over the top of your strip heater to prevent flash fires and crud buildup. especially the fires, if the fire gets started in your drip pan, all bets are off. also, once the crud gets thick enough that it is no longer able to radiate heat in a few spots, the element will die from hot spots. i killed a $40 element on the second smoke because of that.
So hows the project coming along, smokednarwhal?
Question for those doing a similar build: Where, or how far away are you placing the PID thermo probe from the heating element? I'm getting closer to setting mine up and just not sure where to place it.
Unfortunately I have not had time to work on it, maybe this evening I will be able to get out there.
Good question, I've been trying to figure that out too. Hopefully someone with experience will chime in.
I can't thank you enough for this GREAT !!! post. I just about have my freezer done and I used a bunch of your ideas. I have fired it up and added some smoke from the smoke Daddy. It works great. I wouldn't have been able to get it done without all of your help. I think it deserves double points.
i am assuming that your heater will be in the bottom of your unit.
i worked on a few commercial bakery ovens back in the day. the single sensor types usually put the temp probe about 3/4 of the way to the top on the side nearest the door opening. some waring and blodgett ovens have two probes and they are about half way up on the door opening side and 7/8 of the way up on the opposite side. most convection ovens have a probe in the air stream near the circulating fan.