Chiller/water cooler info

[facilitieseng]

Our company presently utilizes 20 ton commercial HVAC units to "try" and moderate temperatures in a 500K facility in the deep south. These units are working constantly, consuming massive power, and only make a 5 degree cooler workplace. I am looking into possibly going to chiller type unit. Any suggestions or comments?

 

[quark]

If you don't mind, can you take the pain of explaining the thing a little bit?

What do you mean by commercial HVAC units? Do you mean split or window type air conditioners?

By 5 degrees, do you mean ⁰C or ⁰F?

What temperature do you exactly require to maintain?

By deep south I don't mean Antarcitica (no pun intended )

Anyhow if you are using freon directly to cool the air, that is the better option for your capacity. (because you are avoiding three tier inefficiency viz., air or cooling water to freon, freon to chilled water and chilled water to air)

If you find this post to be incompetent skip it and pardon my ignorance.

By the way what is a 500K facility?

Best Regards,

 

[facilitieseng]

My appologies. I assume too much!
20 ton rooftop A/C w/ gas heat package units. The largest Rheem makes. 5 deg. F cooler than the norm outside temp of 95 - 100 deg in our 500 K sq. ft. facility located in central Alabama. Anartica would work better for us. Just crack the windows!
Since the HVAC systems in the plant are being replaced on average of 6 per year, just trying to explore alternative methods of keeping this plant cooled to a bearable temperature of around 75 - 80.

 

[robinxie]

It's unbelievable. You just use 20ton unit for 500K sq.ft. space. My guess is you need 5 of them (20ton unit, so 100ton min.).

 

[facilitieseng]

try 77 20 ton units, (when they're all running).

 

[ChasBean1]

Your statement "in the plant" leads me to believe this is a large, open area, is this correct? I assume the units to be ~7,500-8,000 cfm a piece, giving ~1.1 to 1.4 cfm per square foot of area. 1 cfm per ft2 is suggested by ASHRAE for office space but seems woefully inadequate here. Processes, exhaust needs, and heat gains determine loads. Do the units return air and use an economizer or are they 100% outside air? How much process exhaust exists (i.e., is the space net neutral or positive)? How high is the ceiling - it might not be practical to condition the entire space when spot cooling could be used. 77 separate units (77 thermal zones) could find themselves battling each other without some sort of averaging control.

Also, six units per year replaced indicates an average useful life of less than 13 years for each. I tend to think you'd be better served by having a central chiller and boiler plant and eight well-made AHUs (~100,000 cfm variety each) serving the space.

These are initial thoughts; the best-fit depends largely on the plant processes and needs, as well as the company's performance and stability.

 

[PacificSteve]

Clearly, no matter what energy usage and demand cost is, you would have a quick payback by going to a water cooled liquid chiller, maybe in the 200 ton range, maybe even higher depending on your building envelope and assumed industrial process generated heat.

Pick a "large tower" to allow cool condenser water to be produced, this will allow the chiller to operate at very efficient kW/ton.

Your bills must be truly enormous, but I am certain you can cut them in half, which producing better cooling especially during peak ambient temperatures (where capacity of air cooled units falls off quickly, and the kw/ton increases rapidly also, by the way.)

With the costs you are talking about, it is certainly justifiable to hire an energy consultant / HVAC engineer

Other option -- move to Hawaii

Pacific Steve

 

[lilliput1]

This company may be able to help you. They do a lot of energy study & alternate energy sourcing for industrial facilities such as Wyeth Ayerst, worldwide. They can estimate project cost & paybacks. They can do complete plant audit for possible energy savings. They will rank possible energy savings in order of cost effectiveness. Ask them for engineering study cost proposal.

PWI Energy
327 N. 17th St
Philadelphia, PA 19103
Phone 215-241-9100

 

[ClydeMule]

Being in Alabama, you probably have a high latent load.

If this is a manufacturing facility, you probably have a lot of equipment that generates heat. Some of it may be aircooled (like a radiator on a hydraulic press) or you actually have small air cooled process chillers. It may be worth it to make some of that equipment water cooled with a central process chiller that is outside. This might help reduce the cooling load to the space.

The BTU's are the same whether or not you cool the air heated by the machinery or the machinery directly, but it would probably be more efficient and give you better control. THe cost to retrofit equipment to water cooled woould be kind of pricey though.

Good Luck.

Clyde

 

[ChillerGuy]

Drop me an e-mail and I can send you some information on HVAC systems that would better suit your needs.

hvacservice@juno.com

 

[DouginMB]

What's type of roof/wall insulation is installed? If it's a typical metal building, it may have as little as R-13 rated insulation in the roof and walls. You could knock off about 30+ tons by simply adding roof insulation up to R-30. Just a thought.