Window Unit Wiring Opinon Request

I'm building a large fermentation chiller (4'x3'x6' exterior dimensions) and planned on using a compressor from an old dorm fridge to cool it. Once all wired up, the little fridge just doesn't have the capacity to cool 45 cubic feet of space. D'oh!

Plan "B" is to use a (brand new) 5000 BTU Window A/C unit. I already have a Johnson Controls temperature controller wired into the box.

So the question is, how should I wire this thing? I could:

• A) Use a Power Relay to switch the whole unit on and off
• B) Disassemble the control panel temperature control and use a small coil relay to switch the compressor on and off
• C) Screw the Johnson Controller and fiddle with the temperature control on the A/C panel to dial in my temperature

This list is a wealth of information so your opinion is valued. At this point, it's been six months so simple and quick is the order of the day, but I don't want to mess up.

"My name is Mel and it's been six months since my last brewing session"

Thanks,

What is the amp draw of the window unit and what is the rated amp load of the temp controller?

If the rating of the temp controller is greater than the draw of the window unit, wire it directly to it. If it is not, then go with the seperate relay.

This is what the CoolBot is for, but at $300 is a little pricey.

A Love Controller might make more sense.

Chris

goybar said:

This is what the CoolBot is for, but at $300 is a little pricey.

A Love Controller might make more sense.

Chris

Click to expand...

I've looked at the Coolbot and while very cool If I had an extra $300 lying around, I'd buy a boilermaker and replace my crappy keggle.

KCBrewer said:

What is the amp draw of the window unit and what is the rated amp load of the temp controller?

If the rating of the temp controller is greater than the draw of the window unit, wire it directly to it. If it is not, then go with the seperate relay.

Click to expand...

Wish I'd thought of that

According to this pdf, the current rating of the controller is 16A (if I'm reading it right, on page 2)

According to this pdf (page 9), the outlet specification is 15A. It doesn't say (in the manual) what the actual max current draw is, but I'm guessing it is less than 15A.

So, I'm not electrician, but I did take AC and DC theory in college. It looks to me like it will work being wired directly to the controller. Anyone see a reason why I shouldn't do that? I'm sounding off so you can prevent me from doing something stupid.

I actually ran a dedicated 20A circuit from the breaker panel just for this project and used GFI protection, so that part I'm not concerned with.

Thanks again everyone for the sanity check.

I would install a recepticle (which you are doing anyway) to power the unit. I would use the controller to break the power supply to the recepticle only (this recepticle should not have other recepticles wired to it on down the line). You will however need to jump out the thermostat control in the unit if you want to get the temperature really cool inside you area. This is not hard to do and can be returned to normal operation at any time later on.

Salute!

3 Dog Brew said:

Wish I'd thought of that

According to this pdf, the current rating of the controller is 16A (if I'm reading it right, on page 2)

According to this pdf (page 9), the outlet specification is 15A. It doesn't say (in the manual) what the actual max current draw is, but I'm guessing it is less than 15A.

So, I'm not electrician, but I did take AC and DC theory in college. It looks to me like it will work being wired directly to the controller. Anyone see a reason why I shouldn't do that? I'm sounding off so you can prevent me from doing something stupid.

I actually ran a dedicated 20A circuit from the breaker panel just for this project and used GFI protection, so that part I'm not concerned with.

Thanks again everyone for the sanity check.

Click to expand...

If the unit only calls for a 15A circuit, and the controller is rated for 16A, you're good to go with a direct wiring.

FYI, the GFI may give you some trouble. Electric motors can fake out GFI's often, and cause them to trip unnecessarily. You don't need a GFI circuit for an A/C unit anyway, so if it does start to randomly trip on you, just remove the GFI circuit.

FYI, the GFI may give you some trouble. Electric motors can fake out GFI's often, and cause them to trip unnecessarily. You don't need a GFI circuit for an A/C unit anyway, so if it does start to randomly trip on you, just remove the GFI circuit.

Click to expand...

Thanks, I didn't know that.

3 Dog Brew said:

Thanks, I didn't know that.

Click to expand...

NP, glad to help.

If you used a GFI circuit breaker, I would go ahead and replace it with a standard breaker and return it now, if it's not too late. I know there's quite a difference in price on those depending on the brand. I've installed some that were $50+ where a standard breaker was around $5. If it is too late to return it, you could always swap it with a kitchen or bath breaker of the same amperage, somewhere it truly is worth having.

What kind of temps are you looking for? If you plan to try lager fermenting, you may need to get the stock temp probe to extend a bit around the side of the cabinet so it never sees a real temp below 60F (or whatever the stock controller will go down to). There's a thread somewhere around here where we discussed DIYing a poor man's coolbot by making the contoller supply power to a power resistor wrapped against the stock controller probe. Basically it fools the air conditioner into thinking the ambient temps are higher than they really are.

KCBrewer said:

NP, glad to help.

If you used a GFI circuit breaker, I would go ahead and replace it with a standard breaker and return it now, if it's not too late. I know there's quite a difference in price on those depending on the brand. I've installed some that were $50+ where a standard breaker was around $5. If it is too late to return it, you could always swap it with a kitchen or bath breaker of the same amperage, somewhere it truly is worth having.

Click to expand...

I use this same 20 Amp line for my brewery (which does combine water and electricity, oh and FIRE! ) so I can just move the GFI further down the line. Thanks for the suggestion.

What kind of temps are you looking for? If you plan to try lager fermenting, you may need to get the stock temp probe to extend a bit around the side of the cabinet so it never sees a real temp below 60F (or whatever the stock controller will go down to). There's a thread somewhere around here where we discussed DIYing a poor man's coolbot by making the contoller supply power to a power resistor wrapped against the stock controller probe. Basically it fools the air conditioner into thinking the ambient temps are higher than they really are.

Click to expand...

Funny story, I'm actually allergic to Lager Yeast which is how I got into home brewing in the first place. I've read that thread about fooling the temp sensor, I'll have to search for it to refresh my memory.

One last thing, since I'm home now, I went outside to look at the A/C unit and the current rating is 4.8 Amps. I don't know if that's peak or continuous, but it gives me some peace of mind.

I have a newish 5000 btu air conditioner for my ferm chamber. I just disconnected the internal thermostat by using a spade terminal jumper connector. Took a few minutes to do. I run it plugged into a Love controller.

samc said:

I have a newish 5000 btu air conditioner for my ferm chamber. I just disconnected the internal thermostat by using a spade terminal jumper connector. Took a few minutes to do. I run it plugged into a Love controller.

Click to expand...

That sounds like what I was wanting to investigate, but I
a) couldn't find a wiring diagram for this unit, and
b) never thought it might be as easy as spade lugs

UPDATE:
Look what I found:


Modified like this should provide what I want:

I also found where the thermostat is connected to the black and brown wires with SPADE LUGS!

see here: