Digital A/C for walkin cooler

I have a digital A/C that I am going to use for my walkin cooler. I am looking at making a DIY Coolbot to control the A/C. With a control like this I assume the fan in the A/C will run constantly. Can anyone confirm that is correct?

Having the fan on all the time seems a waste to me. Would it not be better to just have the fan come on when the compressor kicks in?

Is there a way to do this?
Or a reason not to?

Thanks
Zac

The fan running continuously will help prevent stratification. Without the fan, the bottom will be much cooler than the top.

Thanks. I will try it with the fan on low and see how we go.

Subscribed (as long as there are pics of the process )

I bought a cool bot and it is great for 60 degrees and below. I wish someone would create one for BCS or Brewtroller. I would automate my cool room then. I would also be interested in your DIY Build. My fan does work 100 % of the time, but I think that is a funtion of the AC, not the cool bot. My AC fan would cut on every 3 minutes or so I think if I put in Energy Saver Mode. I have never done that as we leave the fan running.

What is a digital A/c?? Is that the same as a window ac unit? If so, why not just wire the ac unit up to a temp controller (johnson, or ebay aquarium temp controller DIY). It will only kick the unit on when it needs too. It works for my make shift wine cellar well.

But if I'm not understanding correctly......disregard....

A digital A/C is the same as a window A/C unit, just with digital controls. My understanding is with these, you can't just plug it into a temp control, as when it powers up you need to press the on (cool or power) button on the front of the unit. So a control that just cycles the power to the until wont work.

You can rewire the unit to work with a temp controller, and I have seen a few threads on here on how to go about doing that. The idea of using a DIY Coolbot is that I wouldn't need to rewire it as such.

My DIY Coolbot is using a length of Flexwatt Heat tape to wrap around the temp sensor from the A/C, to trick it into thinking it's warmer than it is. The temp controller I have is reading the temp from the cool room and when it gets above temp it turns the heat tape on, which in turn triggers the compressor on the A/C. Unlike the Coolbot my DIY version does not have a second temp sensor to check if the coils are freezing over. So I will need to keep an eye on this.

I think I will just set the fan to low for now and see how that goes. I'll try and post some pics of the build shortly, there is one of it almost finished on my facebook page here.

Cheers
Zac

I use a digital ac unit plugged into an eBay aquarium controller. It works fine. When it turns on it goes to the temp I previously set. However the energy eff setting won't stay set. The Non energy eff mode just turns the fan on for a couple minutes first to stir the air to determine if it needs to cool.

But I also only keep the room at 64 so I don't have to overrun the ac temp sensor.

so.. how much do these ac units usually run you guys?

Mine was about US$260, however I live in Peru. So I am sure you pay less for them in the US.

Euphist said:

The fan running continuously will help prevent stratification. Without the fan, the bottom will be much cooler than the top.

Click to expand...

Yep - every commercial refrigeration unit & walk-in cooler I've worked on runs the evaporator fan(s) continuously.

With reach-in freezers, the fans stop when the door is opened & during defrost when the compressor is off and the evaporator heaters are on.

I just installed a $99 box store mechanical AC unit. I bypassed the onboard thermostat and connected it to an acquarium controller. The controller is set to 13C. My chamber is a dual purpose fermentation room and storage unit (its only 46" square, with 9 ft ceilings).

I like the mechanical unit because there is less electronics to try and disable. I was able to disconnect two spade connectors (that switch the compressor on/off, then hook those to the acquarium controller. Job done.

Seems to me that the DIY coolbot idea is a perfect clone, except for the icing condition. This should be able to be avoided if the 'crash' cooling is at a minimal rate. This rate I do not know. If maintaining, say, 42degF, the coils should not ice. If, however, the chamber was set to reach 42degF from, say 66degF, a 'slow enough' crash cooling rate should suffice. Any ideas/experience on what rate will not ice up a standard/cheapo window ac unit?

I still haven't got the walk-in sealed up as tight as I want, so I haven't got it running yet. When I do get it turned on, I was going to try and drop the temp by about 4 or 5 degF per day, see how that goes. The temp in my brewery is already below 60F and I only need to get it down to about 40F. Will try it over the weekend when I can keep an eye on it.

The issue is that the evaporator coils run about 20 degrees colder than the cold air. So, when the air is 52 you are dangerously close to the coils at 32. More airflow through the evaporator can help. Mine froze up at somewhere below 12C. I found it frozen with temps slowly rizing above 11.7.

I'm thinking about fitting an additional fan on the inlet.

have you guys ever thought about just getting a walk in cooler evaporator and condensing unit? I got a matching pair off of ebay for my restaurant walk in cooler for $250 +$125 shipping. Don't see why you guys couldn't do the same, AND then have a super efficient and COLD unit at your house.

I have priced them here in Peru, and unfortunately I can't get one for anywhere near my price range. The down side of living in South America.

I have one side (Condenser) given to me. The other side would cost about $300 but how much to hook it up? We had a cold room where the Window would get down to 65 or so but we wanted to try a lager in our Stout 27 Gallon Conical. the CoolBot was $299 and took about a minute to hook up and works like a charm. It is our plan to create a smaller chamber for Lagers with a small A/C unit and the coolbot. There is a lot of good info at CoolBot's website about how to build cool room.

The local refrigeration place has a Brand new evaporator that I was going to buy as a spare for $200. They have it because a contractor ordered the wrong size unit. I'm sure other parts houses in other areas of the country may have similar deals. i have no idea what the install cost is, because i did my own.