Kcal/hr ?

[Heuer]

Hi folks,

What does this mean? i found this on the manual of a chiller which state

Cooling capacity - 670 kcal/hr

can anyone advice.

thanks.

[bclee]

It means it has the capacity to transfer 670kcal of heat per hour.

670 kcal/hr = 2805.3 kJ/hr

Heat capacity of water = 4.18 kJ/(kg.°C)
... which means you need to add/remove 4.18kJ of heat per kg of water to raise/lower the temperature by 1°C.

BC

[Heuer]

ha, bclee, i am expecting you to answer this question

but... i still don't understand. Too chim

can you give me an example like a 400L tank at 30 degree C and if i need to lower to 25 degree C, how does this apply?

Thanks

[tawauboy]

400l equals to about 400kg of water.
to cool it by 5 degrees, you'll need to remove 400 x 5 x 4.18kJ = 8360kJ of heat.
so the chiller will require about 3hr to cool your tank from 30 degrees to 25 degrees.

[crandf]

There will be heat gain from surroundings as well. so the calculated values using just the chiller specs will definitely be off.

[tawauboy]

the figures will be off but not much.
unless the tank is under direct sunlight or near a source of heat.

[crandf]

Assuming of course that this chiller is powerful enough wrt the heat gain elsewhere. So the morale of the story is to not use lights that are hot, but you'll only know for sure how much if you run the thing with lights and without lights

[Heuer]

Hi guys,

Thanks for the info.

Tawauboy, you are right. my chiller took about 2 1/2 hr to lower the temp. to 25C. i am using about 300W of PL light. without the chiller, temp is about 30C with 2 fans blowing.

With the chiller, my living room feel much more cooler. and plants grow has improve especially HC, bubble like mad. Yamato seem to be affected by the drop in temp within that 3 hr. no death yet but not as active. need to monitor tonight.

Is it better to lower the temp from 30C to 28C for a few day then to 25C? worry the life stock can't take the drastic drop within that few hours.

Cheers

[tawauboy]

you should gradually reduce the water temperature to allow your critter to acclimitize. take about a week to 2, dropping 1 degrees every few days.

[Heuer]

Yes, you are right!! almost lost all my yamato last night when i came back from office. manage to save all by putting them into another tank. Fishes are also very inactive. stay at the corner most of the time. already increase the temp. one lesson learn!

cheers!