Brewpastor's Coldroom Build

[leboeuf]

Ahhh yes "warranties"... I'm bad at holding on to those...
On my ac unit the thermostat consisted of 2 blade connectors, not too sure if disconnecting those is a warranty voiding action.

Here's a goofy site about building small DC heaters:
Heaters

A quick trip to a thrift store would get you 99% the way there.

 

[dantodd]

Ahhh yes "warranties"... I'm bad at holding on to those...
On my ac unit the thermostat consisted of 2 blade connectors, not too sure if disconnecting those is a warranty voiding action.

that would sure make it REALLY easy.

Here's a goofy site about building small DC heaters:
Heaters

This site looks like the best solution. You can make as much heat as you need and have it controlled by the ranco just by wiring in a DC wall wart.

 

[Brewpastor]

You might also consider only running the heater when you are running the A/C, it might take a few minutes to come up to temp and kick the A/C on but it won't be constantly heating your room.

That is what the Ranco does. It turns the heater on and off based on the set points you select. When the heater is turned off the heater stops and so the AC's sensor reads "cold" and turns off. When the Ranco's sensor reads warm (based on the set points you select) it turns the heater on, which in turn causes the AC's sensor to read "warm" and turn on. Pretty simply and slick set-up.

 

[Brewpastor]

I think a simple light bulb next to the AC's sensor cable in a container would work well.

 

[leboeuf]

A small bulb would probably work, I would probably be worried about it making too much heat...

I would use a small length of heating pad wire wrapped around the probe. Then just insulate the probe/heating wire with some foam tape/heatshrink tubing/etc.

 

[Layne]

Man, this has me really thinking twice (or three times) about adding a Cold room to my 'back yard brew pub'. Hmmmmmmmmmmmm
Thanks for posting.

 

[dantodd]

That is what the Ranco does. It turns the heater on and off based on the set points you select. When the heater is turned off the heater stops and so the AC's sensor reads "cold" and turns off. When the Ranco's sensor reads warm (based on the set points you select) it turns the heater on, which in turn causes the AC's sensor to read "warm" and turn on. Pretty simply and slick set-up.

I think you misunderstood me. I meant to only turn on the heater (or light bulb) that is next to the A/C sensor when you are turning on the A/C. Is that a little more clear? I doubt you'd need two stage controller as you shouldn't need to be doing any room heating in your basement.

 

[Brewpastor]

We are talking about the same thing I believe, The AC unit only runs when the heater is on and the heater on runs when the room needs to be cooled. I will find the video from coolbot and see if that covers your thought or if I am just out of the loop so to speak,

 

[Brewpastor]

Here is the coolbot installation video. It hekps describe how the coolbot actually controls the AC unit.

[ame=http://www.youtube.com/watch?v=NUZ1azvgpfE]YouTube - CoolBot Installation Video from Store It Cold[/ame]

 

[Bobby_M]

Over thinking.... what's a reptile heater and a light bulb? Resistive devices.

Let's see, 120v / 2000ohms, = .06 amps and 7.2 watts. Get a 2kohm, 10 watt resistor and wire that in. Put it next to the bulb and wrap it with tape. Actually it looks like 2.2k is more common which is fine. Pay about 50 cents.

 

[Brewpastor]

Where do you get such a beast? You are speaking hebrew to a gentile here! I'll send you a PM.

 

[android]

looks awesome BP, i've always been awed by your setup and can't wait to see this one complete... i've showed my wife some pictures of your stuff before and said, 'you think i got a crazy setup...'

great looking work.

 

[dantodd]

We are talking about the same thing I believe, The AC unit only runs when the heater is on and the heater on runs when the room needs to be cooled. I will find the video from coolbot and see if that covers your thought or if I am just out of the loop so to speak,

I was assuming you'd also put the A/C unit on the RANCO so you wouldn't have to worry about cool down time on the resister/heater/nichrome wire or whatever you choose to use.

 

[leboeuf]

Where do you get such a beast? You are speaking hebrew to a gentile here! I'll send you a PM.

Basically all resistors produce heat when they are passing current while under a voltage. As in P(watts)=I(amps)^2*R(ohms), or from the voltage point of view P(watts)=V(volts)^2/R(ohms)

So basically if you have a 12v supply and say a 500ohm resistor, the resistor will develop 0.288 watts of heat. So if you were to buy a 500ohm 1/2watt rated resistor and hook it up to a 12v supply that can provide 0.024 amps (derived using ohms law v=IR) you would have your little heater.

Walker supply has a decent selection of stuff locally. Heck I may have some 1/2watt stuff laying around if you can't find anything.
http://www.walkerradio.com/
Careful while you're in there though, my head always starts swimming with all the cool switches/transformers/they even had tube sockets the last time I was in there....

 

[Bobby_M]

I guess you'd have to experiment with different wattages to see if it:

1. Provides enough heat.
2. Heats up fast enough to make the AC react when necessary.
3. Cools down fast enough so you don't overshoot.

Any electronics supply would have resistors. If you use the ranco to switch the hot side of a 120v supply, the resistor would attach to that switched hot and the unswitched neutral. You'd want to be really careful that you don't leave any part of the wire or resistor leads exposed. In that regard perhaps a 12vdc supply would be safer but the resistor values would change.

12v / 100 ohm resistor = .120 amps and 1.55 watts. You'd need a wallwart that was capable of at least 200ma. I'm not 100% sure if 1.5 watts will be enough heat fast enough. It won't hurt to try though. If you need more heat, a 50 ohm, 10watt resistor 50 ohm 10W 5% Wirewound Resistor (2-Pack) - RadioShack.com would give you 2.8 watts of heat and you'd need a 12v, 300ma (minimum) wallwart for that.

It also wouldn't hurt to put a 500ma fuse inline with one of the wires from the power supply in case of a short circuit situation.


If the shutdown lags too long from residual heat on the resistor, you could try not insulating the bundle at all and just wrapping it with tape so that the coldroom air affect the bulb faster when the heat is off.

 

[leboeuf]

I'm trying to remember what wattage could be felt by touch. I don't think you need something over a watt. Also once you get above 2watt rated resistors, most are sand cast and will hold residual heat longer (I think it's 2watt might be 5).

I would definitely NOT use 120v ac for this. There's too much potential energy involved. A wall ac/low voltage dc adapter will isolate you from most of the harmful situations you could get into.

Resistors are reallllllly cheap so it may be worth while to just experiment as long as you're within the current specification of you power supply.

 

[Brewpastor]

So this could be a good use of all those AC adapters I have laying around from old cellphones, and cd players? Basically I would find out the specifications of my power supply, buy a 1 - 1.5 watt resistor, wire it into the AC adapter and I would be good? I am assuming the resistor would be wired with white wire one end, black on the other?

 

[freddyb]

If you want the temp sensor on the AC unit to be kept warm, can't you just run it out the back of the unit so it's outside of the cold chamber? Is it a resistive-type temp sensor? If so you could just measure the resistance at a warm temperature and replace the temp sensor with a resistor.

Then you could just run the AC unit through the temp controller as dantodd suggests. Is there any issue with the max current exceeding the rating on the controller? Since the Ranco doesn't have the cycle hysteresis setting, maybe the Johnson Controls version is better suited for this application. Not sure if it's really an issue.

 

[Brewpastor]

I have almost all of the insulation in (nasty stuff).

 

[Brewpastor]

If you want the temp sensor on the AC unit to be kept warm, can't you just run it out the back of the unit so it's outside of the cold chamber? Is it a resistive-type temp sensor? If so you could just measure the resistance at a warm temperature and replace the temp sensor with a resistor.

Then you could just run the AC unit through the temp controller as dantodd suggests. Is there any issue with the max current exceeding the rating on the controller? Since the Ranco doesn't have the cycle hysteresis setting, maybe the Johnson Controls version is better suited for this application. Not sure if it's really an issue.

Well, I do not know. I guess the thing to do is experiment! I wonder if the temp sensor can simply be removed/unplugged, or do you think it would need to be replaced with a jumper wire or something, which I think is your idea with a resistor. Would I measure the resistance with a voltage meter? The problem with running it outside the cold room is distance. The coolbot solves these issues by leaving everything alone in the AC unit and just manipulates the temp sensor with its little heater to cycle the AC unit. But it seems I shouldn't need to spend $300 to do that.

 

[freddyb]

Here are some helpful links:

Walk in Cooler
Brewshed and Cooler

Also, I sent you a PM Brewpastor...

 

[bigdug]

Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.

 

[Brewpastor]

Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.

So in other words, forget the plastic, and install from the inside. I am glad to know I did it right! Thanks.

 

[springer]

Going back to page one and the insulation facing. In home building the term used to decide which way the vapor barrier faces is conditioned space so the barrier would face insde. If you use a vapor barrier on the unconditioned side it will trap moisture and cause mold. That is why the new external house wraps (tyvek) are "one way" barriers and allow moisture to escape. I am not a fan of plastic as as I have seen alot of moisture buildup and run to the bottom of the wall. Most builders I have worked for opt for the kraft (paper) backing.

But in building the conditioned side is the side that is heated. Heated air holds more moister than cold air. There will be an imbalance in moisture as the A/C is going to dry the air inside the coldroom. The warm moist air will go towards the cold in the insulation and as it hits the colder vapor barrier on the inside wall it will condense. Its not like a/c in the house during the summer you aren't getting the home down to 35-40°. The cold inside wall is going to act like a cold bottle of beer on warm summer day.

tyvek is great but you still need a some type of barrier to stop the moisture from migrating on the warm side. So the rules need to be reversed here.

 

[Bobby_M]

That's pretty much what I said twice but my additional 2 cents is that the guys saying "on the conditioned side" are probably from the Northern climates where the heating season is equal to or longer than the cooling season. Think of the temperatures involved up North. During the summer you have a typical 80-90F at 60% humidity. If that air hits the inside cold side of the wall, that wall will be about 75F and you'll maybe get a touch of condensation. Reverse that to the winter when it's 20F outside and 68F inside at about 30-40% humidity. Here's where you really want to keep the warm air away from the cold side. Look at the temp delta there.

In Southern humid states it's exactly the opposite. The warm moist air is always outside ambient. The cold side is always inside the house. Vapor barrier on the outside.

Western dry states? Who knows. If I guess, Brewpastor's garage is most humid during a brew session. If it stays that way long enough, it could get into the cold room wall and condense against the cold side. Problem, likely not.

 

[springer]

but even in the deep south the gradient isn't to the extreme of our winter nobody cools their home to 30°. So I would think its the same as our conditions in Summer. This is why tyvek is required on new construction. it allows the moist air that does get threw the wall to escape and doesn't let the outside moisture in. I don't know the humidity levels in NM but I assume they do get rain and some moist days . I would say if the vapor barrier is on the inside wall of the coldroom I would put some tyvek on the outside just to keep any moisture from getting to the cold.


And the A/C will make the inside dry as a bone.

 

[Brewpastor]

New Mexico is dry, except for today when it is really wet. But the rain will stop and it will be really dry again. It is so dry here we complain when the humidity is over 30%! Not like SW Missouri where I grew up.

 

[springer]

Ya we get some real soupy conditions here. My central A/C sometimes the pump is going all day to drain the drip pan and my fridge will sweat .

 

[dantodd]

BP, check your A/C sensor. If it is one of the plug-in types you can just replace it with a switch and be done with it. If it is soldered in and not replaceable either a resistor or nichrome wire (my preference can accomplish what you need. But figuring out resistor values and heat generation based on wall warts you have lying around doesn't really make much sense if you have a removable sensor.

 

[bigdug]

I live in central nc where, 90 plus dgrees and 90% humidity is the norm all summer, and the vapor barrier ( plastic or kraft backed paper) is required on the conditioned side of the wall. My understanding is that is why you need a vapor barrier with a lower perm rating on the exterior (housewrap,tyvek, asphalt impregnated sheathing) on the outside to allow moisture to escape back out and not be trapped inside the wall. In New mexico with the constant low humidity it may be a moot point.