newbie PID questions. HELP!!

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rhino70

Fire Starter
Original poster
Nov 3, 2009
46
10
Hi All,

I am looking to put together a PID for a smoker i want to build, and need some advice as to whether this will work for me.

Here is the link to the how to guide i found:

http://www.susanminor.org/forums/showthread.php?t=315

My question is will a 25 Amp relay handle the 1500 watt brinkman drop in element?? I have read that if you try to run too much juice through these relays, they can heat up and fail. I am not an electronics guy at all, but really have no fear when it comes to DIY projects. However, I don't want to do anything that is going to burn down my house,and would like to make sure i have the right pieces to do this from someone in the know. Would a 40 amp relay be better for running this instrument??

Initially, i was going to just buy one of the plug and plays from auber, but then i saw that the smoker controller would only go up to 1440 watts, which i assume is no good for a 1500 watt element, and I don't really want to spend an extra 40 bucks on the next one up the chain when i can build the same thing with less that 100 bucks in parts.

Any help you could give would be much appreciated. Thanks guys.
 
Volts x Amps = Watts

I am going to assume you will use a 120V outlet so 1500W / 120V = 12.5A. There are some other things that influence this like wire gauge, stranded or solid, etc. but that formula should get you roughly what you are looking for.
 
Thanks so much guys. I will be starting a thread in a week or two when i get this smoker started I actually am going to look at an old fridge to do this in later this week, and will post pics of the progress. :)

I couldn't do it without you guys. Thanks again.
 
hello. i have been working with pid units for several years. i do have one hooked up to a smaller cabinet farm store smoker with propane set up is with a 24v propane furnace valve w\pilot and a 24vtransformer. i use american made dwyer controller for my pid head.I also hooked up a pid unit to my large smoker in my shop which is electric or gas.Trust me from my trial and errors that you need to hook this unit up to 240vac.I went to my local recycle yard and robbed a oven element out of a electric range. this is minimum for a refrigerator sized smoker.It will be run with half the amp draw and provide alot more heat.and half the electric cost over120vac.get yourself a good american made relay like whats in a old oven or from a industrial supply like grainger.if you have any questions just e-mail me and i would be glad to help you. i have some pics from when i built my smokers and would be glad to share my trial and errors with you on your pid set up. hope this helps. setitandforgetitsmoker.
 
i forgot to add a old fridge is not a real bad choice for a smoker but when i was looking for something bigger i found a huge upright cabinet cooker all stainless steel inside and out it is double wall with insulation with a darn near airtight door it is bigger than a upright freezer it already had the racks in it and is totaly kick*** for a smoker i found it on e-bay for $100.00 which saved me alot of time messing with a old fridge that would have only given 1\10th of what i got and it is all stainless steel inside and out.i belive the chinease rest. had it and were cooking chickens in it.you might also look for a restaurant upright food warmer i think they are made by alto. also food service grade and stainless steel and can be bought for next to nothing.
 
Good to know I have knowledge if somewhat limited of a pid controller( a class in process control) and I want to put one on my Lang this summer $40 off ebay is a lot better than $250 for a commercial unit.
 
I was gonna say you should get hooked up with Solar Yellow/Joel but !!!!! He kows all that fancy words stuff.
 
If you're using a solid state relay (SSR) like in the linked article, I believe the manufacturer suggests you use a fast-blow fuse at the minimum rating for your device. In this case the 12.5A your heater uses (or the next higher you can find- also note that I'm not checking anyone's math on that number)

I'm using the same 25A SSR as pictured, but since my heater is only rated at 500 watts, I'm only using a 5 amp fuse- barely enough to justify a heat sink.
 
Thanks for the help setitandforgetitsmoker. I'm not sure that i really want to run 240 out to where i will need to plug it in. The only place i even have a hookup is for the range in the house (i have a gas dryer). I'm still a newbie, and that will be a great idea for maybe my NEXT smoker, but i am only looking for something that i can do about 50 lbs at a time with right now, which will be a heck of an upgrade from the little chief i'm using now. Plus, i already have the fridge for free. Plus, i am already catching flack from the wife about having wheels on it so we can wheel it into the shed when we have company. Something that big might require proof of results first, OR, some sort of financial contribution to the family from making sausage for other people. :) I'm sure you understand.

Anyhow, for the element i may need to go with a 120V, and the fridge isn't huge, but it is big enough to put several racks of sausage in. I'll include a pic. I was going to get the 1500 watt brinkman drop in, or the old smokey 1250 watt drop in, but in light of the space i have, i may have to go with a hot plate or two mounted in the bottom panel. Do you foresee any problems with being able to get up to temperature (230 to 250 degrees) with this unit using that as a heat source?? I mean, If i can get it that hot, won't the PID hold the temps where i need them?? Also, gas makes me really nervous for something i am building.

Actually, robbing an old range is a great idea. I could get all of the burners that i need, as well as the mounting sockets, wiring, relays, and the whole shooting match. Thanks for the idea. I will definitely do that. We actually have a junkyard close that i should be able to get into.

Also, I would love to see your pics from the builds. And am always open to trial and error knowledge, as i will probably do a fair share of it with my maiden voyage with this smoker. I just am nervous about working with heating elements and things that could potentially cause a fire. For instance, do i need to worry about the insulation in the fridge catching on fire?? Are there any types of insulation that would need replacing rather than just going with it as is?? I'll include some pics of it, and as you can see, it isn't huge, and requires a lot of cleanup, but it will allow me to hang approximately 20- 3 lb sausage sticks in it, and probably 40 ring bolognas. which will be plenty for me for now. Eventually, i want to get into ribs and briskets and higer temperature BBQ type stuff, but sausage is my primary concern.

Any advice you could give would be most helpful. thanks again.
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you can buy a pid for $40.00 new on e-bay that is from china. i paid $60.00 for a american made dwyer on e-bay it was new as well. this technology is nearly all gone most all things have switched to plc etc... also mine even came with a type j thermocouple and wire. so their are deals out there on good quality american units.
 
if you dont want to use gas and you dont want to use 240vac electric than my sugesstion would be to make it a stick burner and use the pid
and a actuator to control the air to the firebox which will control temp. put a damper on the bottom and have it open and close with the pid. robbing a old oven will only work if you were going to use 240vac.you will not get the heat that you hooking up a oven element or burner to 120vac.i have tried many different setups over the years and the propane unit i built is by far superior to any automated setup that i have seen.just my two cents worth.
 
Just want to point out something here. The cost of running it on 120 vs 240 would be the same. Since electric companies charge by the kilowatt-hour running a 1500 watt element on either would still net you the same amount of energy used. The only difference is how many amps you're drawing and how big of a wire gauge it requires.
 
I have heard the 240/120 cost saving argument before.

While it has been a while since I was in school, I always thought (P)power= (I)Amperage X (E) Voltage.

1500 watts is 1500 watts. Or is there a different way to figure load on the electric meter?

I feel for the size of the smoke boxes that I build an oven coil would be over kill.

The 1500 watt element I am using has pretty quick heat up and pretty quick recovery.

The issue that I have is the PID that I am using is so sensative after it auto tunes it cycles on and off too much. Maybe this is normal but I think that it will shorten the life of the coil.
 
I don't know about shortening the life, but my assumption is that if it cycles a lot, at least the heating element stays pretty much a constant temperature instead of heating up and cooling down a lot. I figure thermal cycling itself would be worse for the element.

Also, temperature controllers (which implicitly are connected to either heaters or refrigeration units) allow settings to cycle the SSRs fast, implying they don't think there's much of a problem, vs. the relay setting recommendations which are a lot slower to reduce the stress and cycling on the relays. Though they recommend not cycling refrigeration units fast (due to wear on the motor), PID instructions don't seem to make any similar recommendations for resistive heating elements.

But if you really want to, most PID controllers allow the user to adjust the period which the SSRs or relays cycle over.
 
So with that thought process I would be better off using SR for a heat element versus the relay I have now.

The only reason I used a relay is that a friend of mine gave me a new PID for free.

I am still in prototype mode so I can go any direction

Thanks.
 
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