Chiller efficiency help

[Carb]

Hello, I am new here to the forums, hope you guys can help me on chillers..

I bought a resun CL-280. It says it is 1/10 hp, with refrigeration capacity of 280w. A few questions entered my mind adter using this several months,
a) what does 1/10 hp mean? I know that 1 hp is 746 watts. But my power reader is showing around 180-200watts energy consumption.

B) i read about Coefficient of performance(COP) and it says the higher the better. Am I correct to say that the COP of my chiller is only 1.4? (280/200=1.4)

C) afterthinking about question b, i keep going back to asking what 1/10 hp mean. Coz originally, i thought it is the projected energy consumption when chiller is on. So 280/74.6 = 3.7 COP

reason i'm asking cuz i want to see which chillers are efficient.. Thanks

[David]

Hello Carb

First and foremost, my sincere apology for missing your post.

Yes you are correct that I Horse Power = 746 Watts. Your chiller is rated at 1/10 HP means that for every 1 turn of your compressor is consuming 74watts up to a maximum of 280watts. This will be the maximum the compressor can go 280watts.

I think your COP calculation may be wrong. It should be 200/74 that is a COP of 2.7 to almost 3.

While you are calculating all this factors, there are environmental factors that controls efficiency.

1. Ambient Temperature to Target Temperature

2. Volume of Water

3. Volume of Water over Chiller Volume Rating

4. Flow rate from tank through chiller

At the end, no matter how efficient any equipment is, as long as you have to plug it in 24/7 means its inefficient as far as consumption is concern. However its the tangible gains of possibilities of what a temperature controlled closed eco-system offers back in return for the energy consumption.

[Carb]

Hello David,
thank you for replying.

I was not aware that the energy consumption can go from 74-280 in this case. Is it also the same for other chillers?

As for the external factors affecting the energy consumed, I have not seen my reader go below 180watts even when I saw the reading seconds before the compressor turned off. That would mean the water temp is almost at the target temp, but energy consumed is still 200watts.

Also may I ask for explanation on calculation for COP that you provided?

Is it possible that the 1/10 hp rating does not refer to energy consumed but to cooling capacity in BTUs? Consider that the advertised cooling capacity of cl280 is 280watts, and 1 hp is approx 2544 BTUs, then 1/hp will roughhly provide 254 btus. Thats pretty close to 280watts cooling power

Many thanks

[David]

Hi Carb

Yes you are correct that the 1/10 HP is the rating which also can be expressed by Watts or BTU. The rating does not equate to consumption. However I am pretty sure that my memory is still serving me that it's 1/10HP or 74watts per compressor turn which determine the sizing of the chiller compressor.

As for the calculation I did on COP, what I did was this: Power Input / Norminal Power. On hind side, after I replied you, I was getting the feeling I could be wrong as aquarium chillers has never been known for its efficiency. This is because Inverters Till today has still not being introduced which I think is because of cost.

So I checked and your first calculation is right. Which is Power Output / Power Input. This means your COP of 1.4 is correct which is not that bad as your chiller is only 0.6 away from 2?

[Carb]

I see, so indeed it is correct to say that the 1/10 HP does not refer to the power consumed by the chiller, but its power output or cooling capacity, which is ~280 watts.

I think for those who want to do their homework before purchasing a chiller, this info might help them. Thank you for clearing this up David When I bought the CL280, I wanted to know the power consumption first. I thought it would only consume me 74 watts. I guess I was wrong. Good thing it was still sufficient for my needs

Last question, what would be a really good COP for a chiller?

[David]

Hey Carb

Slight correction the capacity is still 1/10HP or 74 watts. It's maximum consumption of 280watts determines it's ability to cool a given volume of water.

This is why manufacturers recommend a certain HP chiller to a fixed range of water volume.

However, this being said, most aquarist who have had experienced with chiller tend to take a one-size up for their tank. This is because it takes a shorter duration of time to chill the water down thus reducing consumption.

With regards to COP, my take is that any chiller is able to hit near 2 will be consider pretty good.

[Shadow]

1/10hp = 74.6 watt is the cooling capacity. Its different than 280 Watts power consumption. In other word, with 280 Watts electric power consumption, it can only generate 1/10hp or 74.6 watt cooling power. Remember, those 280 Watts is used to power the fan, the electronic and the motor to compress the refrigerant.

As far as COP, I have no idea, I only know such think today

[Carb]

Thank you guys for helping out I think I understand better now the specs of chillers hehe.

Btw, would it be good to use a resun sp-6000 @ 2800L/Hr for resun cl280? my head is around 1.5ft into chiller, then go back down and straight around 2 ft.

[BFG]

I would suggest that you modify your chiller to include an external temperature sensor. With this modification, your chiller is taking the actual temperature of your tank water instead of the water in the chiller tank compartment itself. This modification would not hamper you with the usage of a lower flowrate water pump as recommended by the chiller manufacturer. Using a lower or higher flowrate water pump may cause the dreaded stop start chiller operation that other chiller owner experienced. The minimum flowrate water pump that I have tried is 500lt/hr with the external temperature sensor modification.




Hope this helps.