Big Area Air Conditioning

Hi SE,

For the dogs it is too late now. And they poisoned one of my shepherds. G.A.

Do you think 10 unit of 20 tons are necessary? I was hoping to clean it up with maximal 50 tons for everything. What has Costco and Walmart (small store)on the roofs?

You could lower the heat load considerably by putting a dropped ceiling in(8'), with insulation 4" above tiles....The 20 ton units are 2-stage units which enable the units to be able to recover quickly in the mornings after being off all night....It also provides some back-up if a compressor should fail in one of the units, you can just just switch 1st stage to good compressor....With minimal machinery and activity you could cut heat load to around 80 tons...In this case I would go with 5 ea 20 ton 2-stage cooling....This is the strategy of most large stores...

Any idea of the costs of operation in terms of kW or tons per area? Most HVAC systems I have seems are oversized. There are some weird thumb rules like the 400 and 600 SQFt per ton. Tks. D

There are on-line calculators you can use, or go to the site below for a complete rundown.

F28 Residential Cooling and Heating Load Calculations

Never been a fan of chilled water, myself.

I checked the website and these guys come with 20,5 seer. Seems to be very good?

Thank you Fredski.

The 20.5 was probably a commercial stunt from one of the vendors. In the catalogs I only found 16 as best number until now. (In the 1,5- 5 ton series)

I found that they also have bigger units.

they have a line that's rated closer to 18 Seer I would recommend before the 20. these machines are outstanding and have a proven track record for reliability and parts are more abundant than the

Strategos line

a couple of things. you said a "clean room environment". clean rooms are a specialty that require a lot of planning and more than a few bucks to build and maintain, are you sure this was the phrasing you intended?

Well, that's how they prefer to call it here.

The reality is that it will be a class 7. (a little bit better than your kitchen)

This part, will be bought prefab, probably in the USA and assembled here. The HEPA filter inlets will be connected to a duct system and 7.5 HP blower- air-handler per clean room (25 X 70 X 9 Ft). Initially 2 rooms, extendable to 4.

you mean in place of a ceiling tile like these?....using the ceiling as a charged plenum?http://www.cleanroomspecialists.com/products/documents/MicroSoundFilter.pdf

Hi Fredski,

This is about what one clean room supplier offers. It is from the company "clean room supply" or supplies. Some come with fan motor, others don't. These have a inlet collar

that connects to ducts, (for no fan types) under higher pressure to overcome the filter resistance, or when a fan is in the unit regular duct work, because the fan does the job.

In the first example all the ducts receive the air - most from recirculation - through the air handler again and boosted with the 7.5 HP turbine to feed 12 to 16 of these ceiling fixture filters.

We try to not expose the HEPA to air with too many impurities (dust), because of the maintenance work and cost.

The ceiling is a hard panel version that is completely sealed in a aluminum framework, designed for that purpose.

"We try to not expose the HEPA to air with too many impurities"

Pre-filter the air upstream of the HEPA filter. You probably knew that.

I've worked clean rooms for many years, from the lab at Loctite to manufactures of hard drives, and even balloon catheters for the medical world. there is no "rule of thumb for sizing one of these specialty rooms. usually only a smaller room is dedicated to actual "clean room duties". a bowling alley is a huge room! these rooms have special needs, problems, certifications. besides your ultra high local humidity and temperature, maintaining a positive room pressure at all times will be critical to keep foreign particles from entering you room. I hope you're working closely with an expert on your room so you don't flush good money down the drain.

I like the idea of cutting the heat load on the building with drop celings, just be sure to add some sort of venting for the dead air space. There are many new and repurposed buildings that are using layers to shield the building from the sun.

Some use solar sheilding to reduce heat on the sides because it makes your insulation (or lack of) work better.

Others use ivy and trellis for a green look, I also like green roofs but with a drop celing it would be less benefit (you can get away with using a white surface).

Drew K

The building is a square box with walls and almost no windows. It is build with concrete blocks and has isolation on the inside.

If it seems cool compared to outside in the middle of the day it is probably ok, but you can almost always do more. In the long run reducing your heat load in the summer will save you energy. If you are in a tropic climate that doesn't ever see cool weather, you might consider extracting air from next to high temp or high wattage equipment that way you vent your heat outside.

My Dad once sealed a fridge into a door so that it blew it's heat outside instead of into the house.

Drew K

Using a chilled water system is going to require a big outlay of cash from the get-go, but will pay off with time. If you really think you can make a go of it with your new business then it may be the way to go. I am not trying to be pessimistic, but the reality of the market may not be in your favor. (I really am pessimistic.) You have to have the space to put all of the equipment required, as well (chillers, pumps, towers, etc.) You have a pretty small building, but it still comes under consideration.

The installation of chill water piping will either require a raised floor (plenum) or a system that would really benefit from a drop ceiling. The others have mentioned this as an effective way to keep the cool where you want it.

Outside of the building envelope, you would probably benefit from a battened roof layer. These types of roof structures can be installed easily, but again, require an outlay of cash that you may not see back in savings for years. Plus, you have to consider your location. High winds can heavily damage these types of roofs.

Thank you.

Can the cooling towers be made of PVC or PE tube? How can I prevent the chilled pipes inside the building from gathering condensate and dripping down? I had an idea when chilling to 4 degrees Celsius, this will happen?

Cooling towers made of pipe? I don't follow...

The "chilled' water doesn't have to be all that cold, especially with the temperature ranges you posted. 4 Celsius is pretty cold! You should only need about 8 or 9 C, but this is going to vary dependent on the dynamic load (work hours vs. non-work hours).

Insulation/cladding for the pipes. Drip pans and drain lines (evap pans) are usually necessary for those just in case events (say you open the place to outside air/humidity to move goods/equipment in and out). Breakout points in the runs will also develop condensate.

If you are going to build a cleanroom environment, you will most likely need to control for humidity as well, which will most likley require a system of 100% outside air or make-up units and a combination of interior recirculation units that only perform sensible cooling (I'm assuming thre will be some exhaust). Using 20 ton DX units to maintain humidity control, especially in a high humidity environment like the Bahamas, will be very difficult. I think you should not rule out chilled water.

Can you tell us more about the process that will occur within the building? It is important for understanding your AC needs.

We need 50%- 60% relative humidity and 72 - 78 degrees Fahrenheit.

The HVAC designing needs with proper professional input.

The process needs to be studied for requirements of fresh air and any pollutants being generated. Requirements of clean room needs to be satisfied.

You need to follow standards like ASHRAE 55 for comfort conditioning, AsHRAE 62.1 for indoor air quality and ASHRAE90 for energy standards.

Proper design will ensure good and healthy working conditions. This will result in increased productivity, and save money in operation of the system by reduced energy consumption.

he\s in the Bahamas, I doubt he's bound by AHRAE but he could certainly use their recommendations as a guideline depending on what product he intends to assemble/produce.

The ASHRAE guidelines will ensure proper and healthy working conditions as well as energy saving. Any problem solving after the systems are designed improperly and implemented would be very costly affair.

I would also add an Alarm System to the Systems that is tied to your security monitoring program. If the units are moved or the power is cut to them the alarm sounds, immediate vicinity horns as well as to police or security services.

There are a number of them on the market that work well and it may at least limit your loss. Also post signs letting people know the facility and the equipment is security monitored.

good advice. several years ago a group of meth-heads were working the Orange county area stealing every inch of copper drain line they cut rip out, a couple of months later they came back and had taken a Sawzall and took out all the condenser coils., so at first I was bombed with water leak calls, then no cool calls. a lot of monitoring systems were installed after the second hit.

I think you would be best to do a dropped ceiling with insulation. I calculated about 95 tons of cooling needed before the dropped ceiling. You will save money in the long run with a dropped ceiling, and also probably pay for it with the savings from not having to purchase 5 - 20 ton units. I would still have an HVAC contractor give you a bid on both with and without a dropped ceiling.

Thank you,

Your input is very much appreciated. D