Understanding a waterchiller

Kami Samurai

Well-Known Member
I have a couple questions:
1.) when you size your water chiller will be using a higher rated HP reduce the electricity used since the machine itself will have to work less. E.g. if I buy a 1/2 HP chiller over a 1/4 HP for 60 Gallons.

2.) if a chiller is listed with a maximum flow rate are you able to exceed that @ the cost of efficiency. I’ve found some very economical choices only 100$ more then a typical but they have flow rates around 300GPH but I need around 800 for my system.
 

Airwalker16

Well-Known Member
I have a couple questions:
1.) when you size your water chiller will be using a higher rated HP reduce the electricity used since the machine itself will have to work less. E.g. if I buy a 1/2 HP chiller over a 1/4 HP for 60 Gallons.

2.) if a chiller is listed with a maximum flow rate are you able to exceed that @ the cost of efficiency. I’ve found some very economical choices only 100$ more then a typical but they have flow rates around 300GPH but I need around 800 for my system.
If iylts only 60 gallons you need to chill, a 1/10HP could probably do it. But a 1/2 is way overkill. 1/4 is perfect if you wanna go a bit larger.
 

Kami Samurai

Well-Known Member
If iylts only 60 gallons you need to chill, a 1/10HP could probably do it. But a 1/2 is way overkill. 1/4 is perfect if you wanna go a bit larger.
It’s suppose to say 90. It’s more a question of watt efficiency. How many watts would each use to cool the same volume of water?
 

5BY5LEC

Well-Known Member
1. Oversizing within reason is ok. 60 gallons would be perfect for 1/4.
2. You do not exceed the maximum flow rate. You actually get better performance with slower flow I would think, since the water has more time to hang around the heat exchanging coil. Thus absorbing more of it's heat.
 

Airwalker16

Well-Known Member
1. Oversizing within reason is ok. 60 gallons would be perfect for 1/4.
2. You do not exceed the maximum flow rate. You actually get better performance with slower flow I would think, since the water has more time to hang around the heat exchanging coil. Thus absorbing more of it's heat.
He's actually chilling 90gals
 

ttystikk

Well-Known Member
1. Oversizing within reason is ok. 60 gallons would be perfect for 1/4.
2. You do not exceed the maximum flow rate. You actually get better performance with slower flow I would think, since the water has more time to hang around the heat exchanging coil. Thus absorbing more of it's heat.
No.
 

ttystikk

Well-Known Member
The advantage of a chiller is that once it reaches the desired setpoint, it can shut down, taking advantage of the thermal density of water vs air. This means that a larger chiller will spend more time shut down and thus overall power used will be similar.

Don't run your setpoint and rise too close together or the chiller will cycle too much, or 'short cycle'. This hurts efficiency and accelerates wear.

Insulate your cold water lines and reservoirs. This keeps inefficiency related to thermal loss to a minimum and reduces condensation.

Place the chiller somewhere where the rejected heat will dissipate, not in an enclosed space that will get hot. Just like any heat pump, they work best with a good temperature differential. Now that it's getting to be wintertime, feel free to use that heat to keep your house warm! Done wisely, it can even be a way to help keep temperatures in your grow area stable overnight.

I'm pretty well versed in water cooling; AMA!
 

Kami Samurai

Well-Known Member
The advantage of a chiller is that once it reaches the desired setpoint, it can shut down, taking advantage of the thermal density of water vs air. This means that a larger chiller will spend more time shut down and thus overall power used will be similar.

Don't run your setpoint and rise too close together or the chiller will cycle too much, or 'short cycle'. This hurts efficiency and accelerates wear.

Insulate your cold water lines and reservoirs. This keeps inefficiency related to thermal loss to a minimum and reduces condensation.

Place the chiller somewhere where the rejected heat will dissipate, not in an enclosed space that will get hot. Just like any heat pump, they work best with a good temperature differential. Now that it's getting to be wintertime, feel free to use that heat to keep your house warm! Done wisely, it can even be a way to help keep temperatures in your grow area stable overnight.

I'm pretty well versed in water cooling; AMA!
The higher end water chillers have good guides in the manuals to compare watt efficiency to usage/volume rate but companies like active aqua I’ve sent emails to see if they have the information. Thank you for your response very informative.
 

5BY5LEC

Well-Known Member
No to which one?
What is the duty cycle supposed to be? 10 min? 1hr? If so as long as it runs at least THAT long then however long it has to run after that is actually increasing wear. If you size a chiller a bit over what you need I think you could potentially lengthen its life.
It seem reasonable to think that the longer the water is in contact with the heat exchanging coil, the more its temp will be lowered. Can you clarify?
Some cool shit you been into. Kind of a legend on here I would say.
 

ttystikk

Well-Known Member
No to which one?
What is the duty cycle supposed to be? 10 min? 1hr? If so as long as it runs at least THAT long then however long it has to run after that is actually increasing wear. If you size a chiller a bit over what you need I think you could potentially lengthen its life.
It seem reasonable to think that the longer the water is in contact with the heat exchanging coil, the more its temp will be lowered. Can you clarify?
Some cool shit you been into. Kind of a legend on here I would say.
Running water more slowly doesn't aid heat transfer. It can also cause a lot of other problems.
 

dstroy

Well-Known Member
No to which one?
What is the duty cycle supposed to be? 10 min? 1hr? If so as long as it runs at least THAT long then however long it has to run after that is actually increasing wear. If you size a chiller a bit over what you need I think you could potentially lengthen its life.
It seem reasonable to think that the longer the water is in contact with the heat exchanging coil, the more its temp will be lowered. Can you clarify?
Some cool shit you been into. Kind of a legend on here I would say.
It’s just a misconception on your part.

The most important thing to remember in heat transfer above all else is the differential temperature, the larger this number the greater the potential of heat transfer.

Then you can take materials into consideration and their efficiencies, and then you can get a ballpark rough estimate of heat transfer you should expect for a given surface area.

So, the longer the water stays in contact with the transfer area and sheds heat, the smaller the differential temperature becomes and the lower the potential for heat transfer is.

Therefore, you want to pump the water through the heat exchanger as quickly as possible for the tubing size without adding extra heat. Which is where you take the recommendation of the manufacturer and use the pump size they suggest.
 

5BY5LEC

Well-Known Member
It’s just a misconception on your part.

The most important thing to remember in heat transfer above all else is the differential temperature, the larger this number the greater the potential of heat transfer.

Then you can take materials into consideration and their efficiencies, and then you can get a ballpark rough estimate of heat transfer you should expect for a given surface area.

So, the longer the water stays in contact with the transfer area and sheds heat, the smaller the differential temperature becomes and the lower the potential for heat transfer is.

Therefore, you want to pump the water through the heat exchanger as quickly as possible for the tubing size without adding extra heat. Which is where you take the recommendation of the manufacturer and use the pump size they suggest.
In a nutshell what you are saying is..consider the temp of the water vs temp of the heat exchanger. Differential.
Basically the longer the water is in contact with the heat exchanger, the more "cold" is taken away from the heat exchanger and therefore cannot cool the next "batch" of water coming in because it has already given its energy away.
Thanks for the good info!
 

5BY5LEC

Well-Known Member
The advantage of a chiller is that once it reaches the desired setpoint, it can shut down, taking advantage of the thermal density of water vs air. This means that a larger chiller will spend more time shut down and thus overall power used will be similar.

Don't run your setpoint and rise too close together or the chiller will cycle too much, or 'short cycle'. This hurts efficiency and accelerates wear.

Insulate your cold water lines and reservoirs. This keeps inefficiency related to thermal loss to a minimum and reduces condensation.

Place the chiller somewhere where the rejected heat will dissipate, not in an enclosed space that will get hot. Just like any heat pump, they work best with a good temperature differential. Now that it's getting to be wintertime, feel free to use that heat to keep your house warm! Done wisely, it can even be a way to help keep temperatures in your grow area stable overnight.

I'm pretty well versed in water cooling; AMA!
Wintertime here...lol. Great thing about that..... is that about now you can pack the chiller up for the winter! Mine has not run in days since this cold front.
I poked around for a heater but actually the air pumps are keeping me around 64 so I am "cool" with that for now.
 
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