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Old 26-01-2005, 07:48 PM   #1
BarraCuda™
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Default How to maximise chiller efficiency

Sizing of chiller

First of all, size yr chiller according to the heat load and tank capacity. A oversized chiller will consume more power even when the operation time is shorter. A undersized chiller will overwork resulting in higher wear&tear and high operation time. More info here


Flowrate

I heard many said that the chiller need a slower flowrate in order to chill but I would say, the higher the flowrate, the better it is. Here's why.

The slow flowrate only works when the water only passes through the chiller once. That is because water need more contact time to try to equalize with the cooling coil. If the flowrate is too fast, the water coming out would not be chilled. However our aquarium chiller and tank is in a continous loop and the same water will pass through the chiller many times until its chilled.

Temperature difference
Heat loss/gain is greater when there is a higher temperature difference between 2 matter. E.g If 30C water going into the chiller, the output maybe 27C which is a difference of 3C. Now if 25C water goes into the chiller, the output maybe only 24C with a difference of 1C.

The higher the water temperature going into the chiller, the greater the temperature difference between the input and output. I personally set the chiller at 26-28C.

Now the process is reversed when we talk abt lighting. The lower the water temperature, the higher the heat gain! Thus if you set the water temperature low, the water will be slower to chill and yet faster to heat!

Temperature equalization
I suggest high flow is because of the above theory. If the flowrate is slow, the water will be chilled rapidly within the heat exchanger thus reducing the temperature difference between the water and the heat exchanger. The idea is to make sure that the water temperature within the heat exchanger is as close to the main tank as possible.

Compressor workcycle
If the flowrate is slow, you risk the temperature probe registering a false reading. This will cause the chiller to start/stop regularly, sometimes 4-5 times/hr. E.g if the water do not leave the heat exchanger fast enough before the reaching the preset temperature, the chiller will sense that the water is chilled thus shutting down the compressor. When warm water from the tank gradually replaced the chilled water, the chiller will again start the compressor because now the water is warmer than the preset temperature!

Power consumption
The compressor will consume much more power during initial start up and it will take a few minutes for the chiller to start cooling. So if yr chiller have a frequent start/stop cycle, you are using more electrical power (higher power during start up) at lower chilling power (few minutes for the heat exchanger to start cooling). All these will add up to yr monthly bills!

Wear & tear
The compressor suffers the most wear & tear during start up. The higher the start/stop frequency, the faster the wear & tear.

Temperature differential

Most set the temperature differential between 0.5C to 3C. The lower the differential, the higher frequency of the start/stop cycle but if its too high its stressful to the fishes/corals due to temperature fluctuation. IMO, 2C is a good balance.


Heat exchanger coil

The heat exchanger coil is the only place where chilling occurs so its important to ensure that the coils are clean and have maximum contact with the water. Connect the input of the chiller to a high powered pump to flush out the dirt accumulated inside. You can also run vinegar to dissolve calcium deposits.

Condensor coil

This is the coil where the chiller loses heat to the environment. The more heat the chiller lose to the environment, the more heat the chiller gain from the aquarium water (faster chilling effect, thats why the chiller run less on cooler days). A dirty condensor coil will increase the electrical consumption by 10-20% and increase the chiller operation time. Its very important to keep the condensor coil clean to ensure max air flow thus max heat loss.

Vacuum the condensor coil at least once a month and perform a chemical wash every 6months. More info here

Summary

As you can see, the most neglected parameter like the flowrate have a larger chain effect on the overall efficiency of the chiller. Size it correctly, apply the max flowrate and do yr monthly cleaning that will ensure that yr chiller is working at its peak efficiency.
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Old 26-01-2005, 08:18 PM   #2
Maculosus
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Good write-up. Thanks!
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Old 31-01-2005, 04:25 PM   #3
tagore
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alamek. bought already...artica 1/3

but i set temperature to 26, it will only turn on maybe every 1 or more hours and only in 1 minute temp drops up 1 degree. my point is that maybe it runs less than 3 hours a day.
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Old 31-01-2005, 09:35 PM   #4
BarraCuda™
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Quote:
Originally Posted by tagore
alamek. bought already...artica 1/3

but i set temperature to 26, it will only turn on maybe every 1 or more hours and only in 1 minute temp drops up 1 degree. my point is that maybe it runs less than 3 hours a day.
It all depends on yr heat load and tank size.

The smaller yr tank .. the more frequent the chiller will turn on/off.
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Old 31-01-2005, 10:38 PM   #5
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Bro,
What u say is very true?
Recently I find the flow rate affect the way our tank is being cool.
Before last week my Chiller was sharing the DYNA 3000 with my FR.
The chiller use to cool down to set temperature very fast but the water temperature also increase very fast.This result in the chiller cutting in and out very often.
Last week I got a separate PH for my FR.Now the chiller is solely connect to the Dyna 3000 PH.
I observe the chiller now cut out about the same as before but it now take longer for the chiller to cut in again.
So I conclude the increase in flow rate actually help in the better control of chiller cutting in and out.

Regards
Sherman
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Old 25-04-2005, 02:38 PM   #6
slcw
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Quote:
Originally Posted by BarraCuda?
Sizing of chiller

First of all, size yr chiller according to the heat load and tank capacity. A oversized chiller will consume more power even when the operation time is shorter. A undersized chiller will overwork resulting in higher wear&tear and high operation time. More info here


Flowrate

I heard many said that the chiller need a slower flowrate in order to chill but I would say, the higher the flowrate, the better it is. Here's why.

The slow flowrate only works when the water only passes through the chiller once. That is because water need more contact time to try to equalize with the cooling coil. If the flowrate is too fast, the water coming out would not be chilled. However our aquarium chiller and tank is in a continous loop and the same water will pass through the chiller many times until its chilled.

Temperature difference
Heat loss/gain is greater when there is a higher temperature difference between 2 matter. E.g If 30C water going into the chiller, the output maybe 27C which is a difference of 3C. Now if 25C water goes into the chiller, the output maybe only 24C with a difference of 1C.

The higher the water temperature going into the chiller, the greater the temperature difference between the input and output. I personally set the chiller at 26-28C.

Now the process is reversed when we talk abt lighting. The lower the water temperature, the higher the heat gain! Thus if you set the water temperature low, the water will be slower to chill and yet faster to heat!

Temperature equalization
I suggest high flow is because of the above theory. If the flowrate is slow, the water will be chilled rapidly within the heat exchanger thus reducing the temperature difference between the water and the heat exchanger. The idea is to make sure that the water temperature within the heat exchanger is as close to the main tank as possible.

Compressor workcycle
If the flowrate is slow, you risk the temperature probe registering a false reading. This will cause the chiller to start/stop regularly, sometimes 4-5 times/hr. E.g if the water do not leave the heat exchanger fast enough before the reaching the preset temperature, the chiller will sense that the water is chilled thus shutting down the compressor. When warm water from the tank gradually replaced the chilled water, the chiller will again start the compressor because now the water is warmer than the preset temperature!

Power consumption
The compressor will consume much more power during initial start up and it will take a few minutes for the chiller to start cooling. So if yr chiller have a frequent start/stop cycle, you are using more electrical power (higher power during start up) at lower chilling power (few minutes for the heat exchanger to start cooling). All these will add up to yr monthly bills!

Wear & tear
The compressor suffers the most wear & tear during start up. The higher the start/stop frequency, the faster the wear & tear.

Temperature differential

Most set the temperature differential between 0.5C to 3C. The lower the differential, the higher frequency of the start/stop cycle but if its too high its stressful to the fishes/corals due to temperature fluctuation. IMO, 2C is a good balance.


Heat exchanger coil

The heat exchanger coil is the only place where chilling occurs so its important to ensure that the coils are clean and have maximum contact with the water. Connect the input of the chiller to a high powered pump to flush out the dirt accumulated inside. You can also run vinegar to dissolve calcium deposits.

Condensor coil

This is the coil where the chiller loses heat to the environment. The more heat the chiller lose to the environment, the more heat the chiller gain from the aquarium water (faster chilling effect, thats why the chiller run less on cooler days). A dirty condensor coil will increase the electrical consumption by 10-20% and increase the chiller operation time. Its very important to keep the condensor coil clean to ensure max air flow thus max heat loss.

Vacuum the condensor coil at least once a month and perform a chemical wash every 6months. More info here

Summary

As you can see, the most neglected parameter like the flowrate have a larger chain effect on the overall efficiency of the chiller. Size it correctly, apply the max flowrate and do yr monthly cleaning that will ensure that yr chiller is working at its peak efficiency.

thanks, this has been helpful. My chiller has been running non stop. I am asking technican to check it out. just installed 2 weeks back
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Old 26-04-2005, 12:06 AM   #7
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Quote:
Originally Posted by slcw
thanks, this has been helpful. My chiller has been running non stop. I am asking technican to check it out. just installed 2 weeks back
How big is ur tank , heat load and what chiller u use? Have a friend who use a PC1/2hp on his 3footer with 800w of light and it running non stop.
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Old 26-04-2005, 12:22 AM   #8
dr evil
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im always interested in chiller performance. as spoken, maybe we do a comparison on how superior a chiller can be.

built to be the ultimate
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Old 26-04-2005, 12:29 AM   #9
BunnyMan
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Default How to maximise chiller efficiency

Hi Burracuda thanx for the info. Juz a Q abt the flowrate. Wont the high flowrate than those recommended resulted in high pressure and cause leakage as mentioned in my chiller manual?
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Old 26-04-2005, 12:35 AM   #10
BarraCuda™
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Quote:
Originally Posted by BunnyMan
Hi Burracuda thanx for the info. Juz a Q abt the flowrate. Wont the high flowrate than those recommended resulted in high pressure and cause leakage as mentioned in my chiller manual?
Yr normal powerhead would not be able to damage the sealed heat exchanger. Let me know which brand you are using if the heat exchanger explodes

Some chillers have a restrictor built-in so no matter how much pressure the pump exert, only XXXL/hr will go in & out. In this case, there is nothing you can do.

However, if your chiller comes with a screw-in hose adapter, you can change it to a larger diameter to accomodate higher flow.
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