Chiller Sizing Gurus Please Read

A

acroholic

Active Member
Lifetime
Messages
5,661
Reaction score
0
Guys,
I am planing on upgrading to a 1 HP or more chiller in the future, and I have a chance to get a nice 220 volt, 24000 BTU 2 HP chiller at a decent price. Question is this too big in the realm of upsizing for a 450 gallon net system with 2200 watts of halide lighting and 550 combined watts of pumps/Vortechs?

I know you can upsize without necessarily compromising efficiency to a degree, but wondered if this is acceptable or unacceptable overkill for my system? In all honesty, a 1 HP unit would probably be fine as well, but I am thinking of possible mega tank options in the future.
 
The chiller will likely suck down more power while it's on, but it will be on for a much lower period of time. So, overall, you'll run more efficiently.

Unlike a home A/C system, you don't want or need the chiller to run for longer time periods since it is not removing any moisture from the air.

I think you should be fine. Check the power consumption of the 2hp and the 1hp units. Depending on the brands, they may not be too far off from each other.
 
Skriz;620286 wrote: The chiller will likely suck down more power while it's on, but it will be on for a much lower period of time. So, overall, you'll run more efficiently.

Unlike a home A/C system, you don't want or need the chiller to run for longer time periods since it is not removing any moisture from the air.

I think you should be fine. Check the power consumption of the 2hp and the 1hp units. Depending on the brands, they may not be too far off from each other.
Click to expand...


what he said.
 
Agreed. Especially if you are talking about a 115v 1hp unit in your comparison. If they were both 230v it would be a larger difference.
 
I think you should consider the pull down capabilities of each. How much pull down you need. While it is true that you don't need them to run like a home HVAC they do not need to run too often as the start up of the compressor is when the most watts are pulled thereby shortening the life of the compressor. The heat transfer in the exchanger needs to be sufficient so as not to overload return back to the compressor. The 220volts versus the 110 will be minutely more efficient but IMO not worth consideration. Now if it was a three phase and you had three phase power then yes!

Edit: for instance on a 1/2 hp jbj
115 volt unit pulls 5.1 amps
230 volt unit pulls 2.9 amps
looking at that you would assume half the consumption until you do the math
volts x amps = watts
115x5.1=586.5 watts
230x2.9=667 watts

Edit: The reason the larger units run on 220+ volts is to reduce the gauge wire needed to run them and to distribute the load across both buss bars on your panel. While it may supply a cleaner supply it is not enough to significantly increase efficiency .
 
grouper therapy;620352 wrote: I think you should consider the pull down capabilities of each. How much pull down you need. While it is true that you don't need them to run like a home HVAC they do not need to run too often as the start up of the compressor is when the most watts are pulled thereby shortening the life of the compressor. The heat transfer in the exchanger needs to be sufficient so as not to overload return back to the compressor. The 220volts versus the 110 will be minutely more efficient but IMO not worth consideration. Now if it was a three phase and you had three phase power then yes!

Edit: for instance on a 1/2 hp jbj
115 volt unit pulls 5.1 amps
230 volt unit pulls 2.9 amps
looking at that you would assume half the consumption until you do the math
volts x amps = watts
115x5.1=586.5 watts
230x2.9=667 watts

Edit: The reason the larger units run on 220+ volts is to reduce the gauge wire needed to run them and to distribute the load across both buss bars on your panel. While it may supply a cleaner current it is not enough to significantly increase efficiency .
Click to expand...

How much temp pull down are you expecting to need?
 
grouper therapy;620352 wrote: Edit: The reason the larger units run on 220+ volts is to reduce the gauge wire needed to run them and to distribute the load across both buss bars on your panel. While it may supply a cleaner supply it is not enough to significantly increase efficiency .
Click to expand...

Thanks, I was misinformed (by an electrician, no less). :blush:
 
cr500_af;620365 wrote: Thanks, I was misinformed (by an electrician, no less). :blush:
Click to expand...
Don't get me wrong I think that the 220 units probably are more efficient especially since you don't have as much voltage drop across the two line as you would a single line ,just not significant. :)
 
grouper therapy;620352 wrote: I think you should consider the pull down capabilities of each. How much pull down you need. While it is true that you don't need them to run like a home HVAC they do not need to run too often as the start up of the compressor is when the most watts are pulled thereby shortening the life of the compressor. The heat transfer in the exchanger needs to be sufficient so as not to overload return back to the compressor. The 220volts versus the 110 will be minutely more efficient but IMO not worth consideration. Now if it was a three phase and you had three phase power then yes!

Edit: for instance on a 1/2 hp jbj
115 volt unit pulls 5.1 amps
230 volt unit pulls 2.9 amps
looking at that you would assume half the consumption until you do the math
volts x amps = watts
115x5.1=586.5 watts
230x2.9=667 watts

Edit: The reason the larger units run on 220+ volts is to reduce the gauge wire needed to run them and to distribute the load across both buss bars on your panel. While it may supply a cleaner supply it is not enough to significantly increase efficiency .
Click to expand...

Yep. But you can always manage that by adjusting your tolerances. GIve yourself a 2 degree swing and you won't have a huge issue (unless your tank heats up at a ridiculous rate). BUT, do take it into consideration.
 
All that said. It is usually the under sizing of chillers that most people do which will kill one quicker than anything else and run that power meter into high gear.

Edit:
Skriz;620370 wrote: Yep. But you can always manage that by adjusting your tolerances. GIve yourself a 2 degree swing and you won't have a huge issue (unless your tank heats up at a ridiculous rate). BUT, do take it into consideration.
Click to expand...
That is a good point as well . Might even run the tank a littler cooler than usual also.
 
I think that 1hp pacific coast is rated at 10 degree pull-down on 1000-1200 gallons

Edit: I just checked a website for the PC chillers
1 hp 110 volts 10 degree pull-down 1000 gallons 1980 watts
2 hp 220 volts 10 degree pull-down 6000 gallons 4840 watts!!!
 
grouper therapy;620397 wrote: I think that 1hp pacific coast is rated at 10 degree pull-down on 1000-1200 gallons

Edit: I just checked a website for the PC chillers
1 hp 110 volts 10 degree pull-down 1000 gallons 1980 watts
2 hp 220 volts 10 degree pull-down 6000 gallons 4840 watts!!!
Click to expand...


So, the 2 hp should do a 10 degree pulldown on 1000 gallons using only 806 watts, right (roughly)? That would be a massive difference from the 1 hp unit!
 
Acroholic;620282 wrote: Guys,
I am planing on upgrading to a 1 HP or more chiller in the future, and I have a chance to get a nice 220 volt, 24000 BTU 2 HP chiller at a decent price. Question is this too big in the realm of upsizing for a 450 gallon net system with 2200 watts of halide lighting and 550 combined watts of pumps/Vortechs?

I know you can upsize without necessarily compromising efficiency to a degree, but wondered if this is acceptable or unacceptable overkill for my system? In all honesty, a 1 HP unit would probably be fine as well, but I am thinking of possible mega tank options in the future.
Click to expand...

Dave,

Some things to consider:

1 horsepower = 745.7 watts

1 watt = 3.414 btu's

You may find these beneficial when calculating your total heat load.

As for whether 110 or 220 is better, watts are watts.

Having said that, you will have a slight</em> advantage during start up of the compressor due to the 220 volt having twice the EMF (electromotive force) that 110 volt does. This is analagous to electrical 'pressure'. In short, a 220 motor will start the compressor a little faster. Mathematically, there is a steeper dv/dt curve (change in voltage over change in time) with 220, for the engineers in the crowd.

Resistance loss (resistance of the wire) is equal to P = I^2 R, or a function of the square of the current. In 220 volt systems the current is half that in 120 volt systems, so the resistance loss is 1/4th. This a a very small factor in overall power used though.

Of perhaps more importance is that if you use a much larger capacity than required, you may end up 'short cycling' the system. Short duration periods of operation. You might separate the heat exchanger and temperature probe by some distance to help reduce that.
 
Skriz;620405 wrote: So, the 2 hp should do a 10 degree pulldown on 1000 gallons using only 806 watts, right (roughly)? That would be a massive difference from the 1 hp unit!
Click to expand...
No

Edit: I wished it did work that way.
 
grouper therapy;620458 wrote: No
Click to expand...

Lol. Explica, por favor. As Jason can attest, electrical is not exactly my strong suit!

Also, here's how I came up with that:

1 hp chiller uses 1980 watts per hour on. It will be on for 1 hour on a 1000g system and pull it down 10 degrees.

The 2 hp chiller will take 1/6th time to pull down the same water 10 degrees (based on being able to pull down 6000g of water 10 deg), thus using 1/6th of the 4840 watts since it will not run for the entire hour (instead, only 10 mins).
 
If that were the case a 20 hp/ton would only use 80 watts. It is not a linear equation.

Edit: Too that would be assuming the same rate of flow through the heat exchanger which would change the heat exchange rate as well.
 
d@mn, thar's some techno-linguistics goin' on in this hare therad... !
 
You must log in or register to reply here.

Similar threads

A
Electrical Gurus Please Read
Replies
15
Views
198
acroholic
A
Back
Top