Quick electrical help for frags

[GaryP]

Not only will you be pulling 95 degree air in, you will be pulling in humid 95 degree air at the same rate that the exhaust is blowing out. Having a higher humidity in the house will impact the evaporation rate of your tank, thus making your chiller work harder too.

[scuba_steveo]

My problem is hot damp air. I am running 4 – 400W bulbs on an HQI ballast so each one is running at 430W so my halides alone are producing 1720W. Add ballasts, other lights, and pumps and you got one hot room. I want to suck the air out. I do have a window unit a/c (12,000 BTU I think but it could be 8000 BTU) but it does not work that well. I think my best bet is going to be a combination of pumping cool air in with the window unit a/c and sucking the hot air out with a vent. So here are the two fans I am looking at. Option 1 is the large fan on the roof. I would use a fan like this one:
http://www.homedepot.com/prel80HDUS/...rchResults.jsp
Option 2 would be a smaller fan placed in the ceiling above the tank and vent it outside using a fan like this one:
http://www.homedepot.com/prel80HDUS/...rchResults.jsp
I think either one will work and be a cheap easy solution. So, what I am overlooking or missing?

[GaryP]

If the fan is pulling air out faster then the AC is blowing outside air in, the the rest of the air will probably come through the outside door to your fish room. What you could end up with is a zero sum net gain, at best. If the AC is set to recirculate the room air, then all the new air is going to come from outside. I believe an AC unit works more efficiently when its recirculating room air because the air is already cooler then outside air. MAAST needs to recruit an AC guy for stuff like this. I think the term the HVAC folks use for this is air balancing.

[villjr]

Steve probably the best thing would be to try and figure out how much total heat everything in the fish room is generating. Then how much cooling the a/c is producing, which apparantly isn't enough. I've done calculations for this type of problem before but can't find my files on it. I have some thermodynamics books you can look at.

[Bill S]

My math says for your lights, you need almost 6000 btu. Wow! That's a half a ton!

Gary, it runs most efficiently because it's cooling air that's already cool. For instance, if your fish room is at 85 degrees and you cool to 70 degrees, you are cooling 15 degrees. If you are cooling outside air that's at 95 degrees, you have to cool it down 10 degrees MORE. However, if the outside air is 80 degrees, you are better off using outside air.

[villjr]

Wow. 1/2 a ton. That is a lot for such a small room. So maybe a smaller fan right above the lights would be best. Even if your a/c is only producing 8000 btu's, if bstreep is correct, you are generating 6000 btu's. The a/c may be enough just have to exhaust the heat. If not I know some guys at York International and they could give you a deal on a 600 ton chiller. :o

[Bug_Power]

You can pick up a wall unit pretty cheap. I have one for my bedroom I got because I like to sleep in the cold. It was on sale at Lowes or HD and is 8000but with thermostat. It will turn blower and everything off when not needed. I would do that over an exhaust fan.

[hobogato]

he already has one of those for the fish room.

[brewercm]

Not to mention if you run too large of a fan you will build a negative pressure in the room. What this means is every time you open the door or any other crack where air can get in so will dust and anything else that is in the other areas. Standard dust and all is probably no big deal just make sure that if you use anything like bug bombs or pest companies come to spray adjacent areas that you turn the fan off during that time.

[scuba_steveo]

The window unit A/c that I have is not enough.
I need to suck out the hot air also.
I understand that I will cause a negative pressure in the room if I suck out more than the A/C blows in but as long as it is not a big pressure difference I think it will be alright.