My Fermentation Chamber Build

[Ace_Club]

looking good. im just about done with mine, but i just used 2" of insulation and was thinking that would be enough to hold lagering temps. should i add more insulation?

Depends on the size fridge you are using, the normal ambient temps (i.e., how great a temperature difference you are trying to maintain) and the size of your chamber.

 

[emjay]

That fridge is very small... I have to wonder if it can provide the cooling power you need for a chamber that size.

 

[Ace_Club]

That fridge is very small... I have to wonder if it can provide the cooling power you need for a chamber that size.

The calculated heat load for the chamber (using conservative numbers) ranges from 50 to 100 BTU/hr depending on the temperature difference in my basement. The cooling capacity of the mini fridge is 232 BTU/hr. This gives me margin so that the duty cycle time is low for the unit.

 

[emjay]

The calculated heat load for the chamber (using conservative numbers) ranges from 50 to 100 BTU/hr depending on the temperature difference in my basement. The cooling capacity of the mini fridge is 232 BTU/hr. This gives me margin so that the duty cycle time is low for the unit.

Ah, for some reason I thought this was going in your garage, in which case it might not have been able to keep up in the summer.

Just for the sake of my own calculation (different from yours), what's the r-value of your insulation, as well as the temp range in your basement? I'm interested in determining the particular capabilities of that system, for the hell of it (and since eventually I'll want to replace my chest freezer with something similar.)

 

[Ace_Club]

Ah, for some reason I thought this was going in your garage, in which case it might not have been able to keep up in the summer.

Just for the sake of my own calculation (different from yours), what's the r-value of your insulation, as well as the temp range in your basement? I'm interested in determining the particular capabilities of that system, for the hell of it (and since eventually I'll want to replace my chest freezer with something similar.)

R-value = 17.5

Temp range in basement = 60F to 75F

 

[emjay]

Are you sure about that 232 BTU cooling power? After doing the calcs, it seemed to be off a bit, and after some quick checking, it definitely seems to be unusually strong for a fridge anywhere near that size.

Because 232BTU would support a temperature delta (in your case) of between roughly 40-50° (depending on a few things)... even at the high end of your temperature range AND the low end of the cooling capability, you'd still be able to lager in that thing. The idea that it could support, essentially, a giant freezer, seems a bit strange.

What particular model is it? If that figure is accurate, I may want to get the same one!

 

[Ace_Club]

232 BTU/hr is the cooling power listed for the compressor that comes with the fridge. However, you'd want to keep the load that you are cooling at no more than 50% of that to ensure that you don't burn it out by having it run all the time. Plus, accounting for inefficiencies and everything, it's realistically around 150-175 BTU/hr, which is still adequate for this application.

Since the box is small(ish) and well insulated, and because there isn't a huge heat load, it should be fairly easy to maintain the required temps with a low duty cycle.

With this box, the fridge will probably run quite a bit to get the starting temp down, but then it should be pretty easy for it to maintain the temps, assuming I have no huge leaks to the outside.

 

[kenc_zymurgy]

With this box, the fridge will probably run quite a bit to get the starting temp down, but then it should be pretty easy for it to maintain the temps, assuming I have no huge leaks to the outside.

It does seem like a big box for a small fridge. However, you do have it well insulated, so hopefully you'll be good.

TIP: Regarding getting the starting temp down - Freeze a bunch of water bottles or make a bunch of ice cubes in your main freezer/fridge ahead of time, and set them in the chamber at the start to overcome the initial heat soak. Take 'em out when the temp has come down. No sense making your little fridge work so hard.

Four of the 1 liter bottles of ice will provide over 1000 BTUs as it melts ( ~8 pounds * 144 BTU/# through phase change = 1152 BTU), plus a bit as freezers are ~ 0F, so another 60 BTU going from 0F to 60F. Small would be best so they melt faster to absorb the heat.

Also, could you show your calculations for BTU/hour? I came up with ~55 BTU/Hr for a 4x4x4 box with R 17.5 and a 15F delta.

( 64 sq ft * 15F delta * 1 Hour ) / ( 17.5 R Factor) = 54.9 BTU/ Hour

Is the difference a fudge factor, or is my calc off?

Project looks good!

-kenc

 

[Ace_Club]

It does seem like a big box for a small fridge. However, you do have it well insulated, so hopefully you'll be good.

TIP: Regarding getting the starting temp down - Freeze a bunch of water bottles or make a bunch of ice cubes in your main freezer/fridge ahead of time, and set them in the chamber at the start to overcome the initial heat soak. Take 'em out when the temp has come down. No sense making your little fridge work so hard.

Four of the 1 liter bottles of ice will provide over 1000 BTUs as it melts ( ~8 pounds * 144 BTU/# through phase change = 1152 BTU), plus a bit as freezers are ~ 0F, so another 60 BTU going from 0F to 60F. Small would be best so they melt faster to absorb the heat.

That's a good idea, I may try that.

Also, could you show your calculations for BTU/hour? I came up with ~55 BTU/Hr for a 4x4x4 box with R 17.5 and a 15F delta.

( 64 sq ft * 15F delta * 1 Hour ) / ( 17.5 R Factor) = 54.9 BTU/ Hour

Is the difference a fudge factor, or is my calc off?

Your calc is off slightly. Your area is only assuming four of the six sides of the chamber. Bump that up to 96 sq ft and you'll be using the same numbers I do. (Also, the hour unit is included in the R factor, so no need to include it separately.)

Again, those numbers are a little conservative as the 4x4x4 is the approximate outside dimensions of the box. The inner dimensions are slightly smaller due to the insulation thickness and other material.

 

[kenc_zymurgy]

Your calc is off slightly. Your area is only assuming four of the six sides of the chamber. Bump that up to 96 sq ft and you'll be using the same numbers I do.

Ahhhh, brain fart - I was doing volume rather than surface area - thanks for straightening me out.

Please report back on how this works for you, it looks really good. What did the insulation cost?


-kenc

 

[Ace_Club]

Please report back on how this works for you, it looks really good. What did the insulation cost?

IIRC, the insulation ran between $15 and $20 per 4'x8' sheet.

 

[barrooze]

IIRC, the insulation ran between $15 and $20 per 4'x8' sheet.

I'm so jealous. All I can find is .75" thick sheets... No Menard's down in TX...

 

[itsme6582]

I'm so jealous. All I can find is .75" thick sheets... No Menard's down in TX...

2 x 0.75 + glue = 1.5

 

[ChandlerBang]

2 x 0.75 + glue = 1.5

*4. Even better.

 

[scottsr123]

This is a cool idea! You have me thinking about building one. A question - what type of controller are you using, and does it control both heat and cooling?

Thanks!

 

[Ace_Club]

This is a cool idea! You have me thinking about building one. A question - what type of controller are you using, and does it control both heat and cooling?

Thanks!

Go up to post #12 to see the controller I am using for this. It's from ebay, it does control heating and cooling, but it only displays in Celsius and you have to do the internal wiring and housing yourself. All that's not too bad for the price, though. I used the build information from this thread to make it.

 

[barrooze]

2 x 0.75 + glue = 1.5

WOW, REALLY?!:cross:

 

[ChandlerBang]

WOW, REALLY?!:cross:

Well you don't have a Menards, fair assumption you don't have math either.

 

[Ace_Club]

WOW, REALLY?!:cross:

Well you don't have a Menards, fair assumption you don't have math either.

Hey, let's keep it civil in my build thread. Capice?

 

[ChandlerBang]

Hey, let's keep it civil in my build thread. Capice?

Alright, alright. It was all in good fun.

 

[runstop]

Would something like this work well in the winter? Could I hook up a 100w incandescent light bulb to the 'heat' side of the temp controller for use in the winter? I'm thinking of making one of these in my non-insulated garage. It gets mighty cold up here (Ontario, Canada), but I figure a well insulated box with a light bulb might be able to keep it slightly warm.

ok, maybe not ale temp warm, huh?

-runstop

 

[Ace_Club]

Would something like this work well in the winter? Could I hook up a 100w incandescent light bulb to the 'heat' side of the temp controller for use in the winter? I'm thinking of making one of these in my non-insulated garage. It gets mighty cold up here (Ontario, Canada), but I figure a well insulated box with a light bulb might be able to keep it slightly warm.

ok, maybe not ale temp warm, huh?

-runstop

Something like this would easily work for keeping the fermenters warm in colder temps. Again, your best bet would be to calculate the required BTUs/hr needed to maintain your desired temp inside the box and use that to size the insulation and heat source. I plan on eventually installing a reptile heat cable in mine to provide heating if necessary.

 

[BYOBKC]

<a href="http://www.flickr.com/photos/_jfiegl_/5105222121/" title="Homebrew by BYOBKC, on Flickr"><img src="http://farm2.static.flickr.com/1099/5105222121_839476ffdd.jpg" width="375" height="500" alt="Homebrew"></a>

I was restricted on space and built mine just big enough to fit two car boys. I use a digital johnson controller A490? to controll the cooling element in the summer and throw a small space heater in there in the winter. Works great for me. Sensor is place in a thermowell through the carboy bung.

 

[BYOBKC]

:cross: how do we delete a post?

 

[runstop]

Something like this would easily work for keeping the fermenters warm in colder temps. Again, your best bet would be to calculate the required BTUs/hr needed to maintain your desired temp inside the box and use that to size the insulation and heat source. I plan on eventually installing a reptile heat cable in mine to provide heating if necessary.

Interesting idea with the reptile heat cable. Any idea how many BTUs/hr that will put out?

 

[Ace_Club]

Interesting idea with the reptile heat cable. Any idea how many BTUs/hr that will put out?

Depends on the wattage rating of the cable (they come in different sizes). For example, a 15W cable would produce about 51 BTU/hr, IIRC.

 

[runstop]

I was restricted on space and built mine just big enough to fit two car boys. I use a digital johnson controller A490? to controll the cooling element in the summer and throw a small space heater in there in the winter. Works great for me. Sensor is place in a thermowell through the carboy bung.

How big is the space heater that you use? Any worry about scorching the insulation?

 

[runstop]

Depends on the wattage rating of the cable (they come in different sizes). For example, a 15W cable would produce about 51 BTU/hr, IIRC.

Would these be cumulative? Ie - two 15w heat cables = ~ 102btus/hr?

 

[Ace_Club]

Would these be cumulative? Ie - two 15w heat cables = ~ 102btus/hr?

Yes.

 

[Chrisl77]

I use a reptile heat cable in my chamber under the shelf for the fermenter. It works good it heats the chamber up just fast enough so it will not over shoot the temp setting.