Cold Smoker With Working Mini Refrigerator

[webowabo]

The picture shows the concept of my indoor hot/cold smoker.

First, in the previous picture, the smoke form the generator goes thru a long brass flex stove gas pipe. The reason is the accordion fold and brass cools down the smoke and the pipe is very bendable to allow easy installation.

The smoke gets drawn in by a small DC blower "B" and gets blown into the smoker thru by-pass valve "D"

The smoke gets cold and a lot of creosol is condensed into collector "A" before it coats the food.

"E" is a clear viewing window which has a little LED light in it, The condition of smoke, TBS or white smoke, is clearly visible before it enters the smoker. I can adjust the blower speed and vent opening on the smoker to get exactly the quality of smoke I want by viewing the view window. There is no need to open the smoker to check. I highly recommend this feature for any smoke generator.

"C" is a DC blower. By turning the by-pass valve "D" and turning on the blower "C", all the smoke inside the smoker will be evacuated to outside of the house in about one minute, so when you open the smoker, you will not be smoking up the house.

dcarch

SMOKER14_zpsab95e760.jpg

• dcarch
• Aug 27, 2013

very well thought out...  ... what business are you in?  I can see mechanical, plumming, and electrical and in one pic.. so.. engineer ? 

 I like the condensate trap... and the exhaust blowout for when you do need to open the door.. very nice... 

 

[dcarch]

Well, the thing looks complicated, but it really is simple with all ready made components, Actually I did not even solder or glue many of the parts together, the friction is enough to keep everything in place. You absolutely don't need any engineering knowledge to put this thing together.

The two things which are not ready made are: The cutting of the round clear  plastic for the view window, and the drilling of a side hole on the cut-off by-pass valve.

The condensate trap seems to be a good thing. It collects a good deal of black liquid from each long smoke.

I asked someone what could the black liquid be, would that be Liquid Smoke? I was told, "No. Not Liquid Smoke. Cancer In A bottle!"

dcarch

creosote_zps1b6fbfc9.jpg

• dcarch
• Aug 27, 2013

 

[webowabo]

Well, the thing looks complicated, but it really is simple with all ready made components, Actually I did not even solder or glue many of the parts together, the friction is enough to keep everything in place. You absolutely don't need any engineering knowledge to put this thing together.

The two things which are not ready made are: The cutting of the round clear  plastic for the view window, and the drilling of a side hole on the cut-off by-pass valve.

The condensate trap seems to be a good thing. It collects a good deal of black liquid from each long smoke.

I asked someone what could the black liquid be, would that be Liquid Smoke? I was told, "No. Not Liquid Smoke. Cancer In A bottle!"

dcarch

creosote_zps1b6fbfc9.jpg

• dcarch
• Aug 27, 2013

Yum..lol.. . can be anyworse than my cancer sticks, dip, and booze ;) looks horrible though. And it does look like a highly concentrated liquid smoke..

 

[sigmo]

excellent points.. thoughts.. and concerns..... You for sure think Outside.. or welll, in this case, "inside the box"....

Ill have to ask around at work and see what could be the serious problems inside the fridge. SPecailly on the coils... and on the compressor, etc) I work in the HVAC biz, but Im a mechanical lead for commercial builds. I can fix your home/commecial ac/heat units..but I dont understand how they work..specially refridgeration... my company doesnt even mess with hvac"R" part...  if that makes since (hands on guy.. its broke, and I know whats broke.. I can fix.. if not I call the techs .) 

It's great to have so many people with experience and skills at all of this to draw upon!  And thanks to this site, we can all learn from each other!  I'm rethinking a lot of what I'd initially envisioned based on what I'm reading and seeing here!

The picture shows the concept of my indoor hot/cold smoker.

First, in the previous picture, the smoke form the generator goes thru a long brass flex stove gas pipe. The reason is the accordion fold and brass cools down the smoke and the pipe is very bendable to allow easy installation.

The smoke gets drawn in by a small DC blower "B" and gets blown into the smoker thru by-pass valve "D"

The smoke gets cold and a lot of creosol is condensed into collector "A" before it coats the food.

"E" is a clear viewing window which has a little LED light in it, The condition of smoke, TBS or white smoke, is clearly visible before it enters the smoker. I can adjust the blower speed and vent opening on the smoker to get exactly the quality of smoke I want by viewing the view window. There is no need to open the smoker to check. I highly recommend this feature for any smoke generator.

"C" is a DC blower. By turning the by-pass valve "D" and turning on the blower "C", all the smoke inside the smoker will be evacuated to outside of the house in about one minute, so when you open the smoker, you will not be smoking up the house.

dcarch

SMOKER14_zpsab95e760.jpg

• dcarch
• Aug 27, 2013

So the fridge you got has the condensing coils beneath the exterior metal skin of the fridge body.  I've seen that used more and more on modern fridges and freezers.  It is convenient because there's nothing sticking out to get snagged or damaged in shipment or when transporting the fridge.  And it gives good surface area for the heat exchange.

And also in your fridge, the evaporator coils are just beneath the interior skin of the unit.  Is that skin all plastic?  If so, one would think that the heat transfer might be somewhat inefficient, but hey - that's the way the fridge was designed, so they must have it worked out!

The beauty of that is that you don't need to worry about a difficult-to-clean surface.  That's great!  Also, if it's plastic, any condensation that might form would be harmless, one would imagine.  So that's a pretty great setup.


As you point out, you must be very careful about where you drill into the unit, though, because you need to avoid both the condensing and evaporating coils which could be anywhere.  How did you establish where it'd be safe to drill your holes?

I guess you could tell by "feel", actually, and be pretty safe.  Where's my x-ray vision when I need it?

We had a tech at one of the labs where I used to work drill into a brand new freezer to run a sensor cable and he hit one of the condensing tubes.  He wasn't aware that a lot of the newer fridges and freezers have the condensing tubes below the outer skin.  So much for that fridge!

You're using a dedicated smoke generator, and piping the smoke through the flex tube to cool and convey it to where you need it.  That's great!  It has to make a good cooler with its large surface area, great material, and wavy surface that has to stir things up as it passes through.

I like the idea of side-tracking and capturing any liquid before it can get to your small blower and into the smoker.

I'm sure some of what gets condensed and trapped is actually water because when you burn something, you get lots of C02 and water vapor.  So that gets stopped along with any heavy creosote/tar.  Excellent!

So the smoke is pulled from the smoke generator and pushed into the smoker by blower B.

I can't see exactly, but you said that you drilled valve D and added another port.  So that's where the piping from blower B goes, correct?  And you've turned valve D from a simple two-port on/off valve into a three port valve.  But if you turn the handle for valve D fully horizontal, there's no place for the smoke to go.  So am I correct in guessing that you set valve D to some intermediate position (say, 45 degrees) such that some smoke from blower B goes down towards window E AND some air from blower C also feeds down towards E?

Then, when you want to clear out the smoke so you can open the door, you set valve D to the fully vertical position shown in the photo, and only run blower C?  But when you're smoking, you're running both blower C and blower B?

Or am I not really seeing how the plumbing is attached coming down from blower B?

Also, I'm curious as to what the black box just above the toggle switch is.  It's got two wires going into the end we can see.  Is that a battery case?  Maybe for your smoke-viewing LED?

Have you had any problems with blower B getting gummed up?  The fact that you've condensed and trapped most of the nasty stuff ahead of the blower probably keeps it pretty clean.


What do you use the humidifier for?  Is this for smoking meats?  Or do you also use it when cold smoking cheese, for example?


I love your idea to have a smoke viewing light and window as well as your way of purging the chamber.  You really can't be opening a smoke-filled smoker in the house.  Very clever! 

Does the refrigerator have any problem keeping up with the "load" when you're blowing smoke through the unit?  Do you control the cooling with anything other than the factory thermostat?

Have you had any problems using the unit for hot smoking?  Does the plastic interior and insulation seem to be OK at the smoking temperatures you've used?  Around here, water boils at about 201 degrees F (fairly high elevation).  But I sometimes smoke meats at up to 225.  I like the stainless steel interior of my MES, but behind that is probably the same foam insulation that's used in your fridge!  So it's probably all fine.

I'm really just looking to set up a cooled cold-smoker, but hey - if you could hot smoke in something, too, that'd be a plus.  And your setup to let you smoke indoors is great!  So setting things up to accommodate that is something I need to consider!


I can appreciate how the halogen light puts out plenty of heat for your job.  I have built a few bacteriological incubators out of full-size freezers.  They run at warm, but not "hot" temperatures.  Usually 35 degrees C,  And the freezers are usually so well insulated that just the circulating fans can generate too much heat such that the problem isn't getting the temperatures up to the proper levels, but rather, keeping the temperatures DOWN!!  I've had to purposely sabotage the insulation in those units to allow them to "leak heat" so that I can control the temperatures precisely.

Being able to look at your pictures and read your explanations is a great help in trying to come up with a workable design for what I want to do.  I really appreciate it!

 

[dcarch]

As you point out, you must be very careful about where you drill into the unit, though, because you need to avoid both the condensing and evaporating coils which could be anywhere.  How did you establish where it'd be safe to drill your holes?

Let it run for a while. The cooling coils will have frost on them, and the condensing coils will be warm.

I can't see exactly, but you said that you drilled valve D and added another port.  So that's where the piping from blower B goes, correct? 

Yes

And you've turned valve D from a simple two-port on/off valve into a three port valve.  But if you turn the handle for valve D fully horizontal, there's no place for the smoke to go. 

It's OK for the smoker to have the smoke cut off for a few minutes, the flame will not be extinguished.

Then, when you want to clear out the smoke so you can open the door, you set valve D to the fully vertical position shown in the photo, and only run blower C? 

As I said above, the smoke generator is still operational, but the blower is not drawing any smoke with the valve in that position.

But when you're smoking, you're running both blower C and blower B?

Blower C only works when I want to open the door.

Also, I'm curious as to what the black box just above the toggle switch is.  It's got two wires going into the end we can see.  Is that a battery case?  Maybe for your smoke-viewing LED?

Just li-ion rechargeable batteries for the blower C, Blower B is powered by an adapter.

Have you had any problems with blower B getting gummed up?  The fact that you've condensed and trapped most of the nasty stuff ahead of the blower probably keeps it pretty clean.

No problems so far.

What do you use the humidifier for?  Is this for smoking meats?  Or do you also use it when cold smoking cheese, for example?

I use the humidifier for whatever I am smoking that I don't want to dry out. Like 24 hour low & slow pulled pork smokes.

I love your idea to have a smoke viewing light and window as well as your way of purging the chamber.  You really can't be opening a smoke-filled smoker in the house.  Very clever! 

Works very well. I am very happy with those two features.

Does the refrigerator have any problem keeping up with the "load" when you're blowing smoke through the unit?  Do you control the cooling with anything other than the factory thermostat?

The factory thermostat is disabled, temperature is totally controlled by a PID controller.

Have you had any problems using the unit for hot smoking?  Does the plastic interior and insulation seem to be OK at the smoking temperatures you've used?  Around here, water boils at about 201 degrees F (fairly high elevation).  But I sometimes smoke meats at up to 225.  I like the stainless steel interior of my MES, but behind that is probably the same foam insulation that's used in your fridge!  So it's probably all fine.

I don't smoke meat above 160F. All meat shrinks and gets tough above that temperature. 

I'm really just looking to set up a cooled cold-smoker, but hey - if you could hot smoke in something, too, that'd be a plus.  And your setup to let you smoke indoors is great!  So setting things up to accommodate that is something I need to consider!
 

Yes, Indoor smoking year round is a very happy thing. Precise temperature control from 32F to 212 F is a happy thing, and good smoke quality/quantity control is a very happy thing.

I can appreciate how the halogen light puts out plenty of heat for your job.  I have built a few bacteriological incubators out of full-size freezers.  They run at warm, but not "hot" temperatures.  Usually 35 degrees C,  And the freezers are usually so well insulated that just the circulating fans can generate too much heat such that the problem isn't getting the temperatures up to the proper levels, but rather, keeping the temperatures DOWN!!  I've had to purposely sabotage the insulation in those units to allow them to "leak heat" so that I can control the temperatures precisely.

The construction of a typical refrigerator makes temperature control a very simple task.

Being able to look at your pictures and read your explanations is a great help in trying to come up with a workable design for what I want to do.  I really appreciate it!

We share experiences, that's what a forum is for.

dcarch

 

[sigmo]

Originally Posted by Sigmo  
 

As you point out, you must be very careful about where you drill into the unit, though, because you need to avoid both the condensing and evaporating coils which could be anywhere.  How did you establish where it'd be safe to drill your holes?

Let it run for a while. The cooling coils will have frost on them, and the condensing coils will be warm.

I can't see exactly, but you said that you drilled valve D and added another port.  So that's where the piping from blower B goes, correct? 

Yes

And you've turned valve D from a simple two-port on/off valve into a three port valve.  But if you turn the handle for valve D fully horizontal, there's no place for the smoke to go. 

It's OK for the smoker to have the smoke cut off for a few minutes, the flame will not be extinguished.

Then, when you want to clear out the smoke so you can open the door, you set valve D to the fully vertical position shown in the photo, and only run blower C? 

As I said above, the smoke generator is still operational, but the blower is not drawing any smoke with the valve in that position.

But when you're smoking, you're running both blower C and blower B?

Blower C only works when I want to open the door.

I guess I'm still not fully understanding how your modified valve works because I'd think that the only way to get smoke to go into the fridge would be to have the valve set to something between "on" and "off" otherwise the smoke would be blocked.  And with the valve halfway, and blower C not running, wouldn't smoke be able to just escape (backflow) through blower C?  I guess the problem is that I can't see how, exactly, you have Valve D modified.

But it doesn't matter, really.  Just so it works for you!

Also, I'm curious as to what the black box just above the toggle switch is.  It's got two wires going into the end we can see.  Is that a battery case?  Maybe for your smoke-viewing LED?

Just li-ion rechargeable batteries for the blower C, Blower B is powered by an adapter.

Have you had any problems with blower B getting gummed up?  The fact that you've condensed and trapped most of the nasty stuff ahead of the blower probably keeps it pretty clean.

No problems so far.

What do you use the humidifier for?  Is this for smoking meats?  Or do you also use it when cold smoking cheese, for example?

I use the humidifier for whatever I am smoking that I don't want to dry out. Like 24 hour low & slow pulled pork smokes.

I love your idea to have a smoke viewing light and window as well as your way of purging the chamber.  You really can't be opening a smoke-filled smoker in the house.  Very clever! 

Works very well. I am very happy with those two features.

Does the refrigerator have any problem keeping up with the "load" when you're blowing smoke through the unit?  Do you control the cooling with anything other than the factory thermostat?

The factory thermostat is disabled, temperature is totally controlled by a PID controller.

So you're running the refrigerator's compressor with the PID controller?  When I've done that, it was through a second channel that the PID controller had, which I set up to NOT operate in PID mode (simple on-off mode only) and with enough hysteresis to guarantee that the compressor would not be "short cycled".  Is that what you're doing, too?

I used the first channel in the PID controller to run the heater in these particular gadgets in PID mode because the heating elements don't mind being cycled on and off very rapidly.  And I set the differential between the two channels to be great enough to keep the compressor/AC unit from "fighting" with the heater.  So the temperature cycles up and down when in the "cooling mode" but draws a straight line when it gets down into the heating mode.  That's OK for what I was using these systems for because all that was needed was to keep the temperature in these cabinets between two limits.  The temperature required is near room temperature, but we still needed to have better control than what the normal HVAC systems give us in the rooms in which these units are placed.  We needed to hold 23 degrees C plus or minus 2 degrees C and couldn't guarantee that any room could actually hold that.  So we built enclosures that we could put in the rooms and control with a small air conditioner and a small heater.

Have you had any problems using the unit for hot smoking?  Does the plastic interior and insulation seem to be OK at the smoking temperatures you've used?  Around here, water boils at about 201 degrees F (fairly high elevation).  But I sometimes smoke meats at up to 225.  I like the stainless steel interior of my MES, but behind that is probably the same foam insulation that's used in your fridge!  So it's probably all fine.

I don't smoke meat above 160F. All meat shrinks and gets tough above that temperature. 

OK.  That explains it.  I'd be kind of worried about the plastic and insulation at higher temps.

I'm really just looking to set up a cooled cold-smoker, but hey - if you could hot smoke in something, too, that'd be a plus.  And your setup to let you smoke indoors is great!  So setting things up to accommodate that is something I need to consider!
 

Yes, Indoor smoking year round is a very happy thing. Precise temperature control from 32F to 212 F is a happy thing, and good smoke quality/quantity control is a very happy thing.

Right on!  I love the idea of an indoor smoker.  It gets nasty around here in the winter!!!

I can appreciate how the halogen light puts out plenty of heat for your job.  I have built a few bacteriological incubators out of full-size freezers.  They run at warm, but not "hot" temperatures.  Usually 35 degrees C,  And the freezers are usually so well insulated that just the circulating fans can generate too much heat such that the problem isn't getting the temperatures up to the proper levels, but rather, keeping the temperatures DOWN!!  I've had to purposely sabotage the insulation in those units to allow them to "leak heat" so that I can control the temperatures precisely.

The construction of a typical refrigerator makes temperature control a very simple task.

Yep.  Sometimes they're actually insulated TOO well.  

Being able to look at your pictures and read your explanations is a great help in trying to come up with a workable design for what I want to do.  I really appreciate it!

We share experiences, that's what a forum is for.

dcarch

Thanks again!!!  I'm sure more people than just me will read your posts and learn from them!  I appreciate you taking the time to help out and post the pictures and explanations.

Jim

 

[webowabo]

Wow... just wow...

I just learned from your questions Jim.... and dcarchs explanations to thkse said questions. . Thats good stuff...

 

[Scooter137]

I know I'm resurrecting an old thread, but I was just thinking of doing the exact same thing.

Using a WORKING mini-fridge for a cold smoker so the fridge would actively keep its contents cool while smoking cheese in particular, but anything that needs to be kept cold or cool while smoking.

If you're using an AMNPS, you'd need to provide a heat-proof pan and maybe something to prop it up on to keep the heat from the AMNPS from melting/burning the plastic interior of the fridge, of course.

And you'd need a bottom vent as well as a top vent because the AMNPS needs air flow to keep the pellets burning.

I'd need to figure out if the fridge had enough heat pumping capacity to overcome the heat generated by the AMNPS as well as keep up with the heat in the air that's flowing through the smoker, too.

That may be a tall order for a mini-fridge's little compressor system.

Also, you WOULD need to keep the fridge's evaporator clean to maintain its efficiency.

I wonder if anyone has any more thoughts on this idea.

 

[Scooter137]

I started out with an ice chest and reusable ice packs for cold smoking, works really well except i would have to monitor the temperature frequently and it was a 30 minute setup process. hI Icould do about 10 lbs of cheese. I shared with friends and got more request for cheese than my ice chest could handle so I graduated to something bigger that could do more quantities. The only thing I have to do is clean the evaporator fan from time to time and replace the small 4 inch fan I have inside for air circulation.

 

[smovider70]

Sorry for bringing this up, but I have been out for a while and I am now in the position of playing with my BBQ/Smoking gear again. I will be repurposing a Smoke Daddy Big KaHuna Venturi Smoker. I have a small fridge much like the one dcarch has in this thread. Very cool design and extremely impressive @dcarch. @Scooter137, jealous of your cold smoke real estate.

Based on this thread it does appear to be possible to cold smoke using the refridgerator as the cooling source. I believe my only issue is creating an air flow in the fridge so the smoke keeps flowing and does not get stagnant.

Is anyone here familiar with Venturi smokers? I wanted to know if it is ok to change the output path of the smoke to go through a series of bends so I can direct the smoke output at the bottom of the fridge. this would then force the smoke to travel up towards vent I plan on installing at the top of the fridge.

I hope this makes sense.