Difference between exhaust fan / dehumidifier / gas exchanger

dzhuo

Active member
Post in the Equipment forum but figure the big reefers might have more experience ...

I am planning for my ~150g (+ 50g or 60g sump) and I figure I will need some way to handle the evaporation of the tank. I have heard people using exhaust fan, dehumidifier and gas exchanger but I have never really understand the difference between them, how they work and which one will be more suitable for my need. Does anyone have experience with them? I would prefer something that's easy to install so I can do it myself and does not require a hole in my wall (wife will potentially shut down that idea). Any help would be great. Thx!
 
What part of the country do you live in?

With 200gal setup you may not have to worry about the evaporation.

an exhaust fan is like you would find in a lot of bath rooms, it takes the air and moves it outside. the make up air is from the leaks in your window and doors.

a dehumidifier is an AC unit that removes humidity by condensing it on the evap coil and collecting it in a bucket. These are very power hungry and put out a lot of heat because the condensing coil is also in the house. they are good in cold humid locations of the country.

the gas exchanger takes outside air and exchanges it with inside air. it uses a heat exchanger to recover the difference in air temp to lower heating and cooling costs.
 
i am in SF, CA. with these device, (generally speaking), how loud they are? and which one would you recommend?
 
yes there is an AC unit but we don't use it even in the summer due to health issue a family member.
 
it's not that bad in SF, CA, fortunately. :) i live in a 3 stories building and even during the real short hot time in summer, the second floor as well as the basement (where the tank will be) is still relatively comfortable. plus, the place i live has a fairly strong wind all year long so temp has never been a real problem for us.

would this make choosing one of the above any differently?
 
would this make choosing one of the above any differently?

I would say yes.

If your house has ac and you run it I would probable just use some fans. The ac would take care of any of the humidity when ran.

This sound like it might not be an option for you.

I would think your proposed set up might put off 3 gal a day of water.

If your area has generally high humidity (70%+) this could be a problem for you.

If you have a low humidity say 25%-40% the extra water could be a welcome relief.

I would try some fans at first just to move the air and see if makes the house uncomfortable to you.

If it does I would look at a hosed vent fan out a window. this way you would not have to make a new hole in the wall. The vent fan will be a small initial investment with a low electrical usage.

I'm guessing SF has a relatively mild climate all year so the cost of a gas exchange might not make it worth your while.

If you lived in MN and it's -30 and the water was condensing on the walls the dehumidifier would be a better option.

I hope this makes it a little more clear for you.
 
thx Big! maybe just a small dehumidifier (one of those portable) on top of the tank running it a couple hours a day will work (?) how noise are the dehumidifier anyway? again, generally speaking...
 
In San Francisco? 100 degree temps? HA! Once every few years it gets to mid-90s for a couple days. But you have A/C... *IN* San Francisco? Must be a newer house ;)

Basics though
Exhaust fan, just pulls air out of the area, works better if the area is enclosed.

Dehumidifier is like an AC, in that it condenses the air (and more specifically the water in the air) on coils, and collects that water.

Not sure I understand what your concern with evaporation is, water getting in the house? or the water itself evaporating? either of these won't help much if its the later. The former you'd probably want to stick with a dehumidifier, as the exhaust fan would require that you exhaust it somewhere (poking a hole in a wall).

You could always just keep windows open if its that big of a deal.
 
yes it's a new house. it's about 10years or so old.

my concern is just moisture from evaporation that damage the house, the wall, etc... i have heard that a large tank can do some serious damage just by the amount of evaporation the tank has. i don't know if a 200g will actually be that bad but i just want to plan ahead.

are dehumidifier normally pretty loud? also how do you know when to turn on and off the dehumidifier?
 
Well there can be issues with evaporation, I mean just look at a 2 liter of soda, approximately half a gallon, I evaporate about 2-3 gallons a day, so 4-6 of those bottles full of water go into the room, it could be damaging. However how much it matters with something as "small" as 200g worth of water depends how much circulation & ventilation there is in the room. With a newer house this might actually be much worse since they typically are much more airtight than older houses, as a result the moisture could potentially stay in the room causing damage or mold issues (the later is probably more important as it can be a direct health issue).

Not all dehumidifiers are that loud, depends upon the kind you get, the larger then are usually the more sound they'll make, also how "cheap" it is can play into things. Some have auto-shut off sensors and the like, others are off/on things.

If you absolutely are going to setup a tank, go to home depot or lowes and check out some dehumidifiers, although around this area they might be a seasonal item. But they both have very nice return policies, so you can try them out to see how loud they are, then just pack them back up. Also if it were me, I'd first see if one is needed before going and and spending money on them. I have on the order of 350 gallons downstairs, and some days in the morning I definitely can tell there's moisture in the air, other days not so much, however I notice that the moisture depends on how humid the air is outside, i.e. is it a rainy day, etc. basically drier days allow the downstairs to air out more than on rainy days.

If you can have the tank enclosed, like an "in wall" setup, probably is the best thing if you're really that worried about moisture, because then you can close it off from the rest of the house and simply have the dehumidifier in the "fish room" behind the tank, or a ventilation fan connected to a humidity sensor. But then again, you have to let the wife ok the project which I know, can be next to impossible ;)
 
thx for taking the time to answer my question. yes the first thing i need to know is if 200g will be an issue but like i mentioned earlier, i like to plan ahead and make sure i am ready if the need arrives. maybe it won't be a huge issue for the relatively small tank and i will just use a small portable dehumidifier and run it a couple of hours a day.
 
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