Open topped tanks, evaporation, and escalating A/C costs...

Cearbhaill

Cearbhaill

Reads the Gribble Report
Mar 22, 2003
1,395
0
0
South Florida USA
Visit site
Since I put in the open topped reef tank my air conditioning/power bills have just skyrocketed- like 33%. The watts on the tank don't add up to the wattage increase on my bill, so I really think that my A/C is working overtime to compensate for all the evaporation- is that possible?

I have to keep it open topped with two fans (and a couple of inches of free falling water to the sump) to keep the water temperatures down, and some days I top off over three gallons in a 24 hour period. A chiller would heat up the room as well (nowhere else to put/hide it), is expensive to boot and I just don't want to go there.

Would adding a dehumidifier to the room help at all? Would it just suck even more water out of the tank by drying the air? Would the unit itself heat up the room enough to be more harm than help?
Do I just not understand what air conditioners do or how they work?
 
I dont think its the light causing all the heat. Its your aquarium heater. Since you have an open top, im guessing that the heater is working overtime to try to keep that aquaium heated up. Then your AC is trying to cool everything down. When you put a lid on the aquarium, you are seperating them with insulation, so the aquaium stays hot, and the room stays cold. I would build a lid for the aquarium that goes over the light to try to lower air conditioning cost. A dehumidifier would increase evorapation. As far as your question to how an air conditioner works, it compresses freon gas causing it to heat up. Then the hot gas goes through coils to cool it disapate the heat, and turns into a liquid. It then runs through an expansion valve to become cold low pressure freon gas. Then it runs through coils again to asorb heat, and cool down your house.

So in effect, your aquairum is heating up the room, and the AC is trying to cool it down, so both are using more electricy than normal.

Info on Air conditioning taken from www.howstuffworks.com/ac.htm How Stuff works is a great website, check it out.
 
I believe you misunderstand me- the tank is not heated.
The problem is keeping it cool.
Fans work in this regard, but increase the evaporation. The evaporation increases the humidity in my home. I think this is why my A/C is running more.
 
Opps, sorry about that. That throws my theory out the window. If you dont mind me asking, how does the tank stay heated up without a heater. I wouldnt think that the light would do much.
 
Not marine, but my FW tank room requires and air-to-air heat exchanger with the outside to be able to control temp/evaporation from >20 tanks, most planted, most multifiltered, and for me to keep the tempearture down to the low 80's. In summer it is on my AC, and adds significantly - the heat from the lights and filters and the humidity from the tanks is a killer. I have not used heaters in decades. Even moderately lighted planted tanks in normally heated homes rarely need heaters unless the the tanks are nano such that they lose heat during the dark cycle.

Dehumidifiers add too much heat to the area.
 
Toni, RTR is right the dehum will just add more heat to the room. It more or less works on the same principle as an ac unit or a fridge. The only thing I can think of that might help would be an exhaust vent or heat exchanger. On the other hand though I can't think how raising the humidity would make the ac work harder either unless you lowered the temp to compensate for it. The thermostat on the ac wouldn't know what the realative humidity was. The moist air would carry heat a little more but, not 33% . Have you made sure you intakes are clean on the ac unit if it gets dirty they will work a lot harder. I worked for Whirlpool to pay my way through school so if you need any more help let me know. I'd check my intakes and if it has a pad that might need a good cleaning as well. Those are the simplest we can go from there if you need any more help.
Chris
 
If you dont mind me asking, how does the tank stay heated up without a heater.
Click to expand...
I live in a very hot climate, both the husband and I work outside so we keep our indoor temps right around 79ºF. That and a rack of lights will do it.

RTR and maxilaria- I have heard mention of heat exchangers before but don't know anything about them. Expense, suitability to my climate, installation issues?
We have a good A/C system that I maintain fiercely- I even had them disconnect the whole thing snd clean all the innards this last spring.

It's always possible that all these tanks are just adding up to more than I realized. I'm about to enter my cool season, so it will calm down a bit. It's just that the last couple of bills really shocked me.
And we have a lot of rare books and electronics in the house also, and the amount of topping off I do means that water is going somewhere. I just don't want to wake up to a giant mold problem down the road.
I can't think how raising the humidity would make the ac work harder either unless you lowered the temp to compensate for it.
Click to expand...
Yes- I think I am misunderstanding how A/C's work- I thought that a lot of what they did was pull water out- lots sure runs out of the "pipe" outlet thing.
I did lower the thermostat setting by 1ºF. But I also had a new roof put on, more insulation added, and had my venting up there upgraded.

I wonder what a vent in the room would do. The rest of the house is substantially warmer than the end we have the reef tank in- that's the only reason we located it in here. Venting air out would draw warmer air from the rest of the house in here- right? Would an active vent in the "warm end" of the house accomplish the same thing?

Just trying to cut costs anywhere I can. And like I mentioned the humidity thing scares me. I think I will get some sort of humidity meter and see what the real story is!
 
AC's need to dehumidify before they can cool the air effectively for a couple of reasons, the biggie being that the warm air can hold more moisture and if it were cooled too much you would be in fog - indoors- plus having condensation and mold everywhere. Also because it takes much less energy to cool the drier air, so the efficiency thing gives lower power usage after dehumidification.

Air to air exchangers save your heat in the heating season and and cool and reduce the humidity of the incoming air in the cooling season. The air streams in and out travel though adjacent thin channels, so can exchange heat to and fro, pre-warming cold outside air in the winter (saving a bit on the heating bill) and lowering the temp of the incoming air in the cooling season.

I don't know the value of these units in a climate such a S. Florida - check with a local HVAC engineer of applicability.

We have to humidify the air in the heating season and dehumidify the rest of the year, but my exchange unit is operated more fall to spring than in summer, when it is not as effective.

Even though or power load for the house itself should be pretty even summer and winter, our total bills are much higher in AC season, due to the large number of tanks, about half of them open, and the heat & humidity added in AC season,but trading off in heating season by not requiring as much heat from the central unit as a non-trivial heat load is added by lights and filters year-round.
 
Last edited:
You may want to put in an exhaust fan & pipe it up through your attic or wall to the outdoors. This gets the extra humidity out of the house, and you could box it in to make it look a little more attractive. Noise consideration? Put the fan on the roof & let it pull, rather than push. Much quieter!
Its not particularly hard to do-my hubby & I installed our own central a/c unit this past spring. The main thing that makes it viable is those wonderful flex-tubes they use for ducting now-they come in sizes from 3 inch all the way up to 12 (probably bigger, but that's all I recall seeing at HD). You hook them together with zip ties, then tape off the joints with this aluminum tape.
 
You must log in or register to reply here.
AquariaCentral.com
Top Bottom