Summer is coming. Chiller or AC and what size?

[chemaholic]

I am working on setting up a 4x4x1 frag tank to go with my 3x3x2 grow out tank. The total volume with the sump will be around 300-350 gallons. The setup is in my garage. They will be sharing a sump to make things easier.

My question is should I get a chiller or should I install a mini split AC system in the garage.

I estimate that on a really hot day my garage may hit 95F. If I want to keep the tanks at no more than 80F then I would need a 15F drop. On this worst day I would need a 45,000 BTU chiller which is not in the cards for me. My garage is 20 x 20 roughly. Based on some formulas I have seen this would require 10,000 BTU to cool. Obviously this formula is making assumptions about insulation and flooring.

Does anyone have any suggestions about where to look for the information I would need to figure all this out?

 

[scottw]

mini split would be my choice. Make it comfortable for you to work in, and for the tanks.

 

[chemaholic]

We have any HVAC folks that could help size this thing? I think I either need the 500 sqft one or the 750 sqft one. The garage space is about 400-500 sqft but it has little insulation except the wall it shares with the house and the tanks will be putting heat into the room as well.

 

[enderg60]

Its always easier and cheaper to condition the space. What you quoted (45kbtu) is about 3 tons. Thats the size used for a 1500-2000 sqft house.

I used a portable one ton(12,000 BTU) heat pump for my 1 car garage. I have the exhaust ducted outside and the drain connected to it. It works great even on the 95+ days. What you will actually need will depend on the insulation of the garage but unless its just sheet metal I doubt you will need more than 1.5 tons (18,000 BTU) to keep that garage cool.

If you still need a chiller after that put it outside in the shade and pipe it back inside if you can. I doubt you will need more than a 3/4 hp chiller unless youre running halides.

All that together is still under 30,000 BTU and you end up with a conditioned space. An a/c unit and a smaller chiller will be WAAAYYY cheaper than a 3 hp chiller.

 

[enderg60]

Correction, I still use the heat pump in my garage.

Oh and get a heat pump not an a/c unit. That way you have both heating and cooling.

 

[chemaholic]

Correction, I still use the heat pump in my garage.

Oh and get a heat pump not an a/c unit. That way you have both heating and cooling.

I was looking at a Mrcool DIY mini split heat pump. Good tip on the chiller. Thanks!

 

[scottw]

I was looking at a Mrcool DIY mini split heat pump. Good tip on the chiller. Thanks!

Mrcool is what I will be installing this summer in my fish room. I know many people running them and love them. I believe @Adam will be installing one at some point in his fish room.

 

[chemaholic]

That makes me feel better.

 

[jcook54]

Sound like you've got a plan but I wanted to pipe in and mention that awesome power of evaporative cooling. Every late spring I am amazed at how much cooling I get in all of my systems bu adding a small fan. I imagine it could be much better with a higher powered fan and/or a better setup that I have. I went and borrowed a portable AC unit and it worked great but it was expensive to run and buy. A $12 fan got me to where I needed to be and I never ended up buying one.

I'm not suggesting that would be the end-all in your situation but a cheap fan can certainly get you a few degree drop without any issues.

 

[chemaholic]

Might be worth trying anyway. I have never actually measured the temp in my garage in the summer.

 

[ichthyoid]

Fwiw,
Water evaporation requires 1,836,776 joules of energy per mole of water (18.02 grams)

By knowing -
-volume of evaporation per unit of time, and
-total system volume

You can approximate temperature drop.

As mentioned, the cooling effect of evaporation is significant.

 

[chemaholic]

We used to run chillers at work on our vacuum pump system. They make a huge difference. I am definitely considering doing something like that. I just have to figure out how to treat the water to prevent legionnaires. I do not know if that is even necessary in a saltwater system but it was in our freshwater.

 

[chaples55]

I installed a MrCool Universal 4-5 ton heat pump on my house about 2 years ago. It was a PITA to install, but that's mostly because it was a huge unit and it was in the crawlspace and I did it 100% solo. It's been working great and is extremely quiet. The no vac line set was really convenient. Never needed an HVAC tech to come out.

I bet their mini split would be super easy to install.

 

[chaples55]

I would get the 18k btu since it doesn't cost that much more and would be able to more quickly cool down the garage if the door was opened. It would also be more capable of keeping it cool on an exceptionally hot day, especially if you don't have attic insulation over the garage.

My understanding is that you don't have to worry as much about "short-cycling" with these inverter driven variable speed units. They'll regulate their speed based on the actual cooling/heating needs, rather than turning off and on constantly.

 

[Adam]

Go with the larger MiniSplit. For those that don't know, beyond just heating and cooling, they have a dehumidify setting. The heat will stay outside when on that setting and this is the primary reason I am putting one in.

 

[chemaholic]

Make sure you take advantage of Federal and GA Power credits and rebates.