I am new and stupid

[fredman]

I have been reading threads about chillers and mini fridges not working because the gradiant between the tank water and the fridge temp.
Keeping a tank 76-82 temp range would be the goal. In summer I keep the house around 80 with AC so the ambiant temp of the water should be near 80?
Now assuming the extra heat comes from lights mainly with some input from pumps/motors wouldn't a two pronged plan of decreasing the heat from lights and a small fridge work?
When I asked about the heat from my 2x96w pc lights and puting a fan in the hood I will build I was told it wasn't needed. To me those lights throw off big heat, I can't imagine what MH is like heat wise.
So am I crasy in the head or what? Fred

 

[lhoy]

Nothing stupid about being new. I find my tank (with 3 MH lights) runs anywhere from 2 to 6 degrees above ambiant room temperature.

I am hot natured so I couldn't live in a house at 80. ; )

With just 2 96W pc lights you might need a fan, but not nearly as hot as MH.

Lee

 

[Icefire]

just put a fan for the light and one across the water, no fridge

 

[ronjeremy311]

<a href=showthread.php?s=&postid=11641106#post11641106 target=_blank>Originally posted</a> by Icefire
just put a fan for the light and one across the water, no fridge

Ditto. I had a 55g planted fresh water with 4x54w PC and they really don't put that much heat into the water.

 

[MeuserReef]

Its not so much temperature gradient that you need to be concerned with as much as the constant supply of BTU's to the fridge (resulting in a constant run time of the fridge's compressor).

A fridge (as I understand it) had two jobs; (1) remove the BTU's from items placed inside.... and (2) keep the items at a certain temp as heat enters the fridge (ie when you open the door).

The problem with using this idea long term on any tank other than a nano, is that you never reach the point of "rest" that the fridge's compressor is desperately trying to achieve. The compressor also depends on a steady supply of cold refrigerant to cool the windings in its motor.Supplying a large amount of constant heat to the fridge will elevate the temp of the refrigerant (too much superheat) and eventually cause damage to the compressor.

Its similar to opening all of your windows on your house in the middle of the summer and expecting your A/C to keep your house cool.

 

[fredman]

makes sense

 

[BeanAnimal]

Exactly Meuser!

Fredman, how big is your tank (total water volume, including sump, etc)?

 

[rlabriola]

I believe that with just the PC lights an oversized fan would work fine. By pointing the air supply down on the water it will cool better...Couple this with an Auto Top Off unit and your set...just fill the mini fridge with beer and GO!!!

 

[K' Family Reef]

for what its worth

live in desert - where temps stay over 100degrees about all summer long.

210gal system sitting on western wall of house
(hottest side of house - afternoon sun/heat)

all last summer was able to keep the aquarium temps
around 78-84 most everyday using fans... thats also w/ the house a/c set at 80' (80' in desert in summer feels like an igloo - but electricity $ here is also thru the roof as well!)

worried might have to get a chiller
but after all last year being able to keep temps down w/ fans - thought would get away w/o the added expense of purchasing a chiller AND running one on top of everything else!

then it was pointed out to me
that should the A/C ever go out in the house - then everything will be 'up in smoke' in the tank!

doesnt seem like a possibility
but that 'chance' does exist - and choosing not to get a chiller = taking that chance.

by this summer will have a new chiller
and will still try to cool w/ fans and dont plan on running the chiller any more then need too - w/ so much time and money 'invested' - would hate to see it all go down the drain in the event of an a/c failure - i now think of getting one as disaster 'protection'

regards

 

[bimmerzs]

The problem with using this idea long term on any tank other than a nano, is that you never reach the point of "rest" that the fridge's compressor is desperately trying to achieve. The compressor also depends on a steady supply of cold refrigerant to cool the windings in its motor.Supplying a large amount of constant heat to the fridge will elevate the temp of the refrigerant (too much superheat) and eventually cause damage to the compressor.

Its similar to opening all of your windows on your house in the middle of the summer and expecting your A/C to keep your house cool. [/B]

I have heard that having a coil submersed in water inside the "fridge", would help alleviate this issue. Do you think that idea hold's weight.

Cheers,

 

[lakee911]

Coil in water in fridge is the same thing. You're still dumping a lot of heat in the fridge and it needs to rest some time.

 

[BeanAnimal]

The coil does nothing to increase the efficiency of capacity of the fridge. So no the idea does not hold weight (or water)

 

[Pbrown3701]

<a href=showthread.php?s=&postid=11644924#post11644924 target=_blank>Originally posted</a> by WarrenAmy&Maddy
for what its worth

live in desert - where temps stay over 100degrees about all summer long.

210gal system sitting on western wall of house
(hottest side of house - afternoon sun/heat)

all last summer was able to keep the aquarium temps
around 78-84 most everyday using fans... thats also w/ the house a/c set at 80' (80' in desert in summer feels like an igloo - but electricity $ here is also thru the roof as well!)

worried might have to get a chiller
but after all last year being able to keep temps down w/ fans - thought would get away w/o the added expense of purchasing a chiller AND running one on top of everything else!

then it was pointed out to me
that should the A/C ever go out in the house - then everything will be 'up in smoke' in the tank!

doesnt seem like a possibility
but that 'chance' does exist - and choosing not to get a chiller = taking that chance.

by this summer will have a new chiller
and will still try to cool w/ fans and dont plan on running the chiller any more then need too - w/ so much time and money 'invested' - would hate to see it all go down the drain in the event of an a/c failure - i now think of getting one as disaster 'protection'

regards

You're lucky that you live in a desert as there is very low humidity. Fans work better in low humidity environments because more evaporation can be achieved.

 

[MeuserReef]

<a href=showthread.php?s=&postid=11645130#post11645130 target=_blank>Originally posted</a> by Pbrown3701
You're lucky that you live in a desert as there is very low humidity. Fans work better in low humidity environments because more evaporation can be achieved.

Very good point. Fans barely work here in Houston during the summer because there is already a TON of moisture in the air!

The humidity, coupled with a wife thats cold-natured, and 10WPG of MH lighting in a canopy, forced me to go the chiller route.

would hate to see it all go down the drain in the event of an a/c failure - i now think of getting one as disaster 'protection'
regards

Why not take the $$$ for the chiller and invest in a generator for your home. That way you and your tank can stay cool in the desert during a power outage

 

[K' Family Reef]

<a href=showthread.php?s=&postid=11645157#post11645157 target=_blank>Originally posted</a> by MeuserReef
Very good point. Fans barely work here in Houston during the summer because there is already a TON of moisture in the air!

The humidity, coupled with a wife thats cold-natured, and 10WPG of MH lighting in a canopy, forced me to go the chiller route.



Why not take the $$$ for the chiller and invest in a generator for your home. That way you and your tank can stay cool in the desert during a power outage

wasnt worried abou the power outtage
(although we have those too!)... the concern was addessing was in case the a/c ever decides to go out.

regards

 

[fredman]

I am not looking for a chiller, I was reading a post about fridge use as a chiller. My thoughts were:
1. if house air temp is 80 water temp should be 80 except for heat added from lights and pumps so why not cool off lights and pumps?
2.If you control for the most part the heat going into the tank you should only have to drop tank temp a couple of degrees. So have a mini fridge set at the highest temp, you wouldn't need to cool the water to 39 degrees just to 80 degrees.

Fred

 

[jnarowe]

Another more energy efficient method is to use a ground loop and heat exchanger. The short explanation is that you bury a copper loop under ground and attach it to one side of the heat exchanger.

The other side is for tank water flow. You use a temp. controller to start and stop the flow through one or both of the "loops". This is a very low electrical use solution that is being used around the World.

This UK Tank is but just one example. I personally use blowers over my reef and an exhaust fan with an open return from under my deck, but I did allow for an extra valve off my manifold in case I needed to install a ground loop.

 

[BeanAnimal]

Fred,

It is a simple matter of thermal capacity. Even a modest pulldown of only a degree or two can be very taxing on a mini refrigerator.

It takes 1 BTU to raise (lower) 1 pound of water 1 degree F.

A dorm fridge is capable of about 100 BTU/h and at least 30%-50% of that capacity is just needed to keep the unit cool even if the door is not opened or any other form of heat added.

Lets be nice and say that there are 75 BTUs of cooling left per hour!

A 50 gallon tank has 416 pound of water in it.

Lets say during the hottest part of the day that 50 gallon tank goes from 80 degrees to 82 degrees in 4 hours. That is a 2 degree swing or 816 BTUs of heat that now need to be removed from the tank. The dorm fridge can take out 75 BTUs per hour. It would take the dorm fridge over 10 hours to remove that heat. The dorm fridge will 10 hours + the 8-10 hours it already runs a day. In other words it will run nearly 24/7. Worse, it will run at a very high internal temperature because it never really "catches up". The compressor will live a short life.

Back to reality...

Now remeber the hot part of the day is likely longer than 4 hours and closer to 10 hours. So in reality somewhere around 2000 BTUs of heat will need to be moved from the real world tank. The dorm fridge does not have an ice cube's chance in hell of keeping up.

 

[BeanAnimal]

Now Fred...

On the other hand. You get over 8000 BTUs of cooling per gallon of water that evaporates out of your system. A small 20W fan can (and will) cool that 82 degree tank rather quickly via evaporation.

 

[fredman]

Thats what I was thinking that a fan for most cases would be ok. Again I have pc lighting, will run a fan byn the lights to remove that heat before it reaches the tank and duct a fan to blow over the water if needed. Fred