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Thread: Glycol Chillers-HP vs BTU/HR

  1. #1
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    Glycol Chillers-HP vs BTU/HR

    I'm pricing out some different chiller options for our fermenters. I'm a little confused as some vendors often express cooling capacity in terms of HP. However, I see that different chillers have different BTU/HR ratings at any given HP.

    For instance, I found one chiller that is rated at 6,000 BTU/HR using only a 4gal reservoir and 1/2 HP while other 1/2HP chillers are only rated at 3,000 BTU/HR.

    Correct me if I'm wrong but shouldn't I be focusing on BTU/HR rather than HP?

  2. #2
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    Quote Originally Posted by d_striker View Post
    Correct me if I'm wrong but shouldn't I be focusing on BTU/HR rather than HP?
    Yes, you should.

    I think part of the reason for the discrepancy is that there are several common definitions of what a horsepower is, and the other part is that the cooling provided by a given amount of compressor work depends on other factors. From what I gather, 1 HP is about 7,000 BTU/hr under typical brewery conditions.

  3. #3
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    You're right, there's really no direct correlation between HP to BTU/HR Capacity. Compressor manufacturers have a number of different ways of rating their compressors- often not even using HP, you'll see the same model compressor used on two different manufacturers equipment, one will classify it a 12 HP and the other a 13.5 HP.

    Another factor you need to consider are the operating conditions, for example a 5 HP System that is used to cool a room, operating at 45 F Leaving Glycol Temperature, will have a cooling capacity of approximately 60,000 BTU/HR. That same system operating at brewery conditions, 28 F Leaving Glycol Temperature, will have a decreased cooling capacity at around 40,000 BTU/HR. (the 7,000 BTU/HP rule of thumb isn't too far off)

    The safest way to compare two systems is request the operating cooling capacity in BTU/HR at 28 F Leaving Glycol Temperature and 90 F Ambient, anyone that is supplying systems to the craft beer market should be able to quickly provide this information.

    Good Luck,

    Jim

    Jim VanderGiessen Jr
    Pro Refrigeration, Inc
    Tel: 253-218-3029| Mobile: 253-732-9402| Fax: 253-735-2631
    www.prochiller.com | www.prochillerparts.com | jimvgjr@prorefrigeration.com

  4. #4
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    Quote Originally Posted by jimvgjr View Post
    You're right, there's really no direct correlation between HP to BTU/HR Capacity. Compressor manufacturers have a number of different ways of rating their compressors- often not even using HP, you'll see the same model compressor used on two different manufacturers equipment, one will classify it a 12 HP and the other a 13.5 HP.

    Another factor you need to consider are the operating conditions, for example a 5 HP System that is used to cool a room, operating at 45 F Leaving Glycol Temperature, will have a cooling capacity of approximately 60,000 BTU/HR. That same system operating at brewery conditions, 28 F Leaving Glycol Temperature, will have a decreased cooling capacity at around 40,000 BTU/HR. (the 7,000 BTU/HP rule of thumb isn't too far off)

    The safest way to compare two systems is request the operating cooling capacity in BTU/HR at 28 F Leaving Glycol Temperature and 90 F Ambient, anyone that is supplying systems to the craft beer market should be able to quickly provide this information.

    Good Luck,

    Jim

    Jim VanderGiessen Jr
    Pro Refrigeration, Inc
    Tel: 253-218-3029| Mobile: 253-732-9402| Fax: 253-735-2631
    www.prochiller.com | www.prochillerparts.com | jimvgjr@prorefrigeration.com

    Thank you very much Jim.

    Question-Why does glycol with a lower leaving temperature have less cooling capacity? Seems counter-intuitive.

  5. #5
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    It takes more energy to cool the glycol to a lower temperature.

    So if your glycol is at a higher temp, your chiller has the ability to chill a higher VOLUME of glycol. If it is cooling MORE, to a LOWER temperature, then the volume is less. Less volume of glycol moved is less cooling capacity.

    Make sense?

    Hopefully Jim doesn't jump in and make me look like an idiot, now :-D

  6. #6
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    The decreased cooling capacity is actually due to the decreased vapor density of the refrigerant as the refrigerant drops in pressure/temperature.

    Your compressor is essentially a pump. The capacity based on the volume (Lbs/HR) of refrigerant it "pumps" through the system. As the refrigerant becomes less dense, your cooling capacity decreases.

    Hope that makes sense!

    Thanks
    Jim

  7. #7
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    Thanks again Jim.

    You are an incredible asset to this board. Your staff is extremely knowledgeable and provide exceptional service in this high demand period for brewery equipment.

    We look forward to doing business with you.

  8. #8
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    Quote Originally Posted by d_striker View Post
    Thanks again Jim.

    You are an incredible asset to this board. Your staff is extremely knowledgeable and provide exceptional service in this high demand period for brewery equipment.

    We look forward to doing business with you.
    Thank you very much, I really appreciate hearing that and will relay to the team.

    Good Luck,

    Jim

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