Author Topic: window AC for cold room  (Read 607 times)

Online Joe Sr.

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2818
  • Chicago - NORTH SIDE
    • View Profile
window AC for cold room
« on: May 25, 2014, 11:41:17 AM »
Got a new (to me) AC for my cold room today.  The old one was just too small, I think.

Anyway, tore the new one open and it has two temp sensors.  One in the duct for the cold air (to the room) and one attached to the coils.

I don't recall a two sensor thermostat on the other ACs I've opened.

I'm going to go ahead and put the cold air thermostat into the can with the light bulb to make it think the room is warmer, but curious about the other stat.

It is, of course, a unit with digital controls unlike my old unit.

Anyone familiar with AC units?
It's all in the reflexes. - Jack Burton

Offline Steve in TX

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2638
    • View Profile
Re: window AC for cold room
« Reply #1 on: May 25, 2014, 11:55:21 AM »
That second sensor is most likely there to detect ice build up on the coils and prevent damage to the unit
Vote Jonathan Fuller for AHA Governing Committee. For every yes vote, Jonathan will send you a can of Heady Topper.

*** This message has not been approved by Jonathan Fuller. All claims of free Heady Topper are in jest and not to be taken seriously. But seriously, he is a great brewer that is 100% committed to helping the AHA and all homebrewers prosper.

Online Joe Sr.

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2818
  • Chicago - NORTH SIDE
    • View Profile
Re: window AC for cold room
« Reply #2 on: May 25, 2014, 12:20:30 PM »
That is exactly my theory.  Just cut the larger opening to put it in the window, so now i'm committed.
It's all in the reflexes. - Jack Burton

Offline Steve in TX

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2638
    • View Profile
Re: window AC for cold room
« Reply #3 on: May 25, 2014, 02:47:19 PM »
You may want to look into a coolbot. A buddy of mine tells me they are worth every penny.
Vote Jonathan Fuller for AHA Governing Committee. For every yes vote, Jonathan will send you a can of Heady Topper.

*** This message has not been approved by Jonathan Fuller. All claims of free Heady Topper are in jest and not to be taken seriously. But seriously, he is a great brewer that is 100% committed to helping the AHA and all homebrewers prosper.

Offline james

  • Brewer
  • ****
  • Posts: 361
    • View Profile
Re: window AC for cold room
« Reply #4 on: May 25, 2014, 10:20:19 PM »
With the digital ac unit I modified into my glycol chiller i measured the resistance on the thermostat at 2 different temps (like 65 and 85) and have a relay switch between 2 different resistors to trick the unit into thinking it os high or low.

Of course I trashed my ac and voided the warranty, so if you dont want to void the warranty go the coolbot route

Online Joe Sr.

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2818
  • Chicago - NORTH SIDE
    • View Profile
Re: window AC for cold room
« Reply #5 on: May 26, 2014, 07:21:22 AM »
I'll see how it goes as is. I don't need to get down to 35 and the cool it is kind of pricey.
It's all in the reflexes. - Jack Burton

Offline Jeff M

  • Brewmaster
  • *****
  • Posts: 821
  • Currently upgrading to Brewery 3.0
    • View Profile
Re: window AC for cold room
« Reply #6 on: May 26, 2014, 07:30:39 AM »
You should be able to set the AC as cold as it can be set and attach it to a Johnson/Ranco controller.  The controller will then get it as cold as it can i believe.  Otherwise you can set it to the temp you are looking for via the controller.
Granite Coast Brewing Company.
Building a clone of The Electric Brewery to use as a pilot system for new recipes!

Online Joe Sr.

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2818
  • Chicago - NORTH SIDE
    • View Profile
Re: window AC for cold room
« Reply #7 on: June 06, 2014, 02:02:39 PM »
You should be able to set the AC as cold as it can be set and attach it to a Johnson/Ranco controller.  The controller will then get it as cold as it can i believe.  Otherwise you can set it to the temp you are looking for via the controller.

Yes, but this will only get to 60 which is the lower limit set on the internal AC controls.

The hurdle is apparently the sensor on the coils.  I pulled that and stuck both sensors in the can.  As long as I keep the coils from freezing it seems like it will get as cold as I want it to.

I've got the A/C plugged into a timer, so it only runs 15 minutes at a time to avoid icing the coils.  I have no idea how much it is actually running, but it doesn't seem like much.  The room is mid-50s at the floor, 60 at the ceiling.  I'll see if I can take the whole room down to 50 but I don't think I need to go any lower.

This is my ghetto coolbot.  A can to keep the sensors warm, a timer to keep the coils defrosted.
It's all in the reflexes. - Jack Burton

Online Jimmy K

  • Official Poobah of No Life.
  • *
  • Posts: 3505
  • Delaware
    • View Profile
Re: window AC for cold room
« Reply #8 on: June 06, 2014, 02:17:36 PM »
I think brewhemoth has instructions to turn an ac into a glycol chiller and part of the process is overriding the built in thermostat.

Sent from my XT1030 using Tapatalk

Delmarva United Homebrewers - President by inverse coup - former president ousted himself.
AHA Member since 2006
BJCP Certified: B0958

Online Joe Sr.

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2818
  • Chicago - NORTH SIDE
    • View Profile
Re: window AC for cold room
« Reply #9 on: June 06, 2014, 02:36:37 PM »
I've over-ridden it, but in a way that I can easily restore the AC to it's intended use.

I just hadn't seen that second therm on the coils before.  Could be that it was there and I missed it and that's why my last AC didn't cool as well as I would have liked, but I think it was undersized anyway.
It's all in the reflexes. - Jack Burton

Offline bigchicken

  • Assistant Brewer
  • ***
  • Posts: 226
  • Lincoln, NE
    • View Profile
Re: window AC for cold room
« Reply #10 on: June 06, 2014, 07:26:42 PM »
That second sensor is most likely there to detect ice build up on the coils and prevent damage to the unit

^^^This

Depending on the age of the A/C, that thermostat may kill the compressor allowing the coil to de-ice while the fan still runs. Its not going to cool well in that cycle, but protects the unit. It will work much like the primary thermostat that controls your desired temperature. If its a super fancy window air, that second thermostat could control a warming device to prevent the icing.
It sounds like you have an option figured out. If you get curious, search the model# on the net and you may come up with a schematic. Sometimes a super cheap option is to replace the temperature setting thermostat with a refrigerator or freezer thermostat of the same voltage. Tricks it into thinking it is a refrigerator.
TJ Cook
Proud paying member of the AHA since 2013.

On Deck: Chocolate Cherry Stout, Northern Brewer Dry Irish Stout
Fermenting: Magnum Blonde
In bottles:Northern Brewer Munich Helles, Snow Eater Winter Warmer 2012, Apple Wine

Offline euge

  • I must live here
  • **********
  • Posts: 7396
  • Estilo Casero
    • View Profile
Re: window AC for cold room
« Reply #11 on: June 07, 2014, 07:52:23 AM »
The coils shouldn't ice up if you can keep the humidity low in the cool room.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman