Chiller Versus AC for Garage Tank

[chemaholic]

I have a large frag system in my garage right now of about 400 gallons. I currently use a mini split AC to keep the temps under control. I run my tank around 80F all the time.

The problem is my power bill is killing me. It costs me roughly $400 a month in the summer just to keep this tank cool and $200 a month the rest of the year.

Would a chiller be a less costly solution from a power standpoint? I am not sure how hot the garage gets without the AC so I am not sure how much of a chiller I would need. In my mind it seems like the chiller would be more efficient than cooling the entire garage though. Does anyone have any experience with this?

 

[ecoreefguy]

My power bills is always 400-500 in summer even without a tank. AC takes A LOT of energy. What is the cost per kW in your area

 

[chemaholic]

What I mean is without the garage AC, my power bill would be $400 less than it is now. My power bill would normally be about $400 or so in the summer without the garage AC. With it, I am paying $800 or more.

 

[hzheng33]

running a chiller will help. however, you need to step up on on the size since most chillers are based on the water volume and the ideal water temperature range (i.e. +/-5F or +/-10F). in the garage, you will easily each 100F depending on the insulation or the lack of.

furthermore, you need to keep an eye on the heater(s) during winter since the opposite will also be true during colder seasons.

 

[enderg60]

If you go with a chiller, put it outside so it dumps the heat out there at a minimum.

Cooling the space will be far more efficient in terms of power usage. A 1 or 2 ton window unit will more than cool a garage along with the tank and it will dehumidify the air for you. Plop a fan on the frag tank and youre good to go. You and the tank will be happier in the garage and it will cost less than the chiller. Plus keeping the garage cool has the added benefit of taking some of the load off of the main house HVAC system.

FYI for sizing units. 1 ton = 5 hp = 12000 BTU.

 

[enderg60]

Oh and if you get a heat pump unit it will do heating and cooling. Thats what I have in my garage.

 

[ecoreefguy]

What I mean is without the garage AC, my power bill would be $400 less than it is now. My power bill would normally be about $400 or so in the summer without the garage AC. With it, I am paying $800 or more.

Oh damn. Yea definitely get a chiller. If you can put it outside in a small shed or vented box it’d be even better

 

[chemaholic]

Thanks for the info. I appreciate it. If I do go with a chiller, I am going to install it outside the garage for sure.

 

[chaples55]

I feel like if it's costing $400 to cool the garage, and you already have a mini-split, the money you would spend on a chiller may be better spent on insulation? It should drastically reduce the power bill while preserving the comfort in the space. Mini splits are generally very efficient, but I'm not sure how they compare to chillers. I have my doubts about chiller efficiency though...

Blowing insulation into the walls and attic isn't that big a job and not too expensive. If you buy enough insulation you get a blower machine rental for free. The attic will make the biggest difference.

Make sure your garage door(s) go down all the way and form a tight seal with the ground. It's easy to adjust via a small screw/knob on the opener. Also make sure the weather stripping around the doors is good and consider adding insulation to the doors (it comes in kits, or you can cut it yourself). An additional layer of foil bubble can help.

If the garage has any windows or if the doors have windows, add a tinted film that blocks radiant heat. For my garage door windows I also cut and adhered some acrylic panels to turn the windows into double pane windows. In aggregate it all makes a big difference.

 

[ichthyoid]

Jeez, I thought a $170 power bill was bad, even for two HVAC systems!

Of course Larry, aka @itsamyheff, did a stellar job of installing them. (Shameless plug )

A 1hp chiller provides approx. 1ton or 12,000 btu’s of cooling and is adequate for a 300 gal system. So a 1 1/4 to 1 1/2 hp chiller would be called for on a 400 gal system. That may require a 230 VAC/30 Amp circuit.

Insulation would help. Garage outer walls & possibly ceilings are often not insulated, especially in older homes. I had 2 inch foam core garage doors installed and that made a big difference both summer & winter.

Directly cooling the water will use less power than cooling an entire garage, in order to cool an aquatic system. The total mass is just less.
-My $0.02

 

[msporleder]

I have a large frag system in my garage right now of about 400 gallons. I currently use a mini split AC to keep the temps under control. I run my tank around 80F all the time.

The problem is my power bill is killing me. It costs me roughly $400 a month in the summer just to keep this tank cool and $200 a month the rest of the year.

Would a chiller be a less costly solution from a power standpoint? I am not sure how hot the garage gets without the AC so I am not sure how much of a chiller I would need. In my mind it seems like the chiller would be more efficient than cooling the entire garage though. Does anyone have any experience with this?

show some pics of the garage walls and ceiling!

 

[gill]

Have you tried fans aimed at the surface? Your evaporation will go nuts, so your ATO will need more water, but I find that does wonders for cooling. It must be less electricity than AC or chiller. Might get you part of the way there, at least.

 

[msporleder]

echoing @chaples55 -- if you don't want to insulate your entire garage then you should build a little "room" for the tank and insulate that (you can, literally, build it with rigid insulation) so the AC can focus on that space.

 

[chaples55]

Have you tried fans aimed at the surface? Your evaporation will go nuts, so your ATO will need more water, but I find that does wonders for cooling. It must be less electricity than AC or chiller. Might get you part of the way there, at least.

Yes! Evaporative cooling is no joke. I was curious so I looked it up and it turns out you can find out how far below ambient temp you can theoretically go based on the humidity and air temperature in the room:

Can a fan cause a liquid to cool below room temperature?

I enjoy the occasional hot drink, but place it below a small fan in order to cool it to a drinkable temperature. Unfortunately, as expected, I commonly forget about my drink, and it ends up very co...

physics.stackexchange.com

I'd monitor the humidity in the garage though if going this route. Wouldn't want to create a sauna for mold to grow

 

[rajkrishnan8]

I'd monitor the humidity in the garage though if going this route. Wouldn't want to create a sauna for mold to grow

+1 Humidity is no joke. 400 gallons in a garage space is a huge amount of water. I've a 650 gallon tank in the house and I've been fighting humidity since I set it up. I imagine it would be much worse for your setup.

My tank is SPS dominant and I had high temperature issues because of the lights, pumps and UV so I added a fan to bring down the temp. The evaporative cooling introduced a lot of humidity into the house, reaching up to 60%. I installed a dehumidifier centrally, which was effective in winter/spring. But once summer came, the temperature of the tank bumped up a couple of degrees and got close to 82 degrees from 79/80. I added an additional fan, which brought down the temp to 78 degrees but the humidity has been at 60%+.

I finally bought a Teco 2000 chiller and installed it a few days ago. I'm still waiting to get a clear picture of the results. But so far, I've taken off the new fan. The ATO usage has gone down by 30%. The temperature has been ranging from 76.5 -> 78 deg. The chiller kicks in at 78 and runs a few hours to bring it down a degree and a half before shutting down. It might take a few days to see the results with the humidity in the house but it already dropped from 67% 3 days ago to 58%. Hopefully some of the additional cost from the chiller is offset by the dehumidifier having to run less. The chiller does produce heat so if you can dump the exhaust outside, that would be optimal.

The chiller I got is 440 Watts and runs about 12-14 hours. I think that equates to about $30-40 per month to operate it. You might need to buy a chiller rated for a much larger system if you're not going to run the AC. It still might be cheaper than the AC and less dangerous than high humidity.