I don't trust my contractors, HELP!

[AIRICCC]

I did some free engineering for you... quick and dirty calculations and I think there is something wrong with your numbers. I assumed high bay industry (40 workers) and retail space (66 customers) in your metal building with NO WINDOWS and you will already need 20 tons in the production area and 10 tons in the retail space. Without visiting the site, windows measurements, counting workers, having actual orientations my numbers can be anywhere from low or high (see attached for calculations). But for sure, there is no way 9 tons will work for a 6000 SF & 15 foot ceiling metal framed building. I don't know how critical it is to maintain 60 F everyday... are you are okay with 74-78 F on a 91 F day.

To answer your other question, one perk of multiple units is redundancy and energy efficiency. A single 9 ton have several problems. (1) Most manufacturers only makes 8.5 tons, then skips the 9 ton with the next being 10 tons. (2) I wouldn't be surprised if 3 ductless mini-splits are cheaper than a packaged heat pump. (3) They are also trying to avoid structural engineers, by not putting units on the roof. Your 9 ton will probably need to be on the ground too unless you want to hire a SE.

It needs to be 60 constantly. 2 workers average in the 4500 sf production area.

[AIRICCC]

That's what I was thinking. Otherwise, a small Chiller. The OP needs to better understand what his contractor is proposing.

I believe it is a refrigeration fan rather than ductless, that's my inexperience talking.

[jtrammel]

The hvac contractor that quoted the job has actually seen the drawings/building and designed the system. No one on this site has so it is only speculation, sounds like what the contractor is on the right track and is going to satisfy your needs. Applications such as yours are NOT cheap endeavors so a 5 figure number does not sound out of line.

[chillerout1]

sounds like refrigeration units for warehouse which would be normal,but because it is split into several units if one goes down you would at least maintain some cooling in the area. hopefully the contractor ran heatload calc on space, the insulation in warehouse area seems a little light to me dont know why they arent using insulated cooler walls because you will need to be tight in the cooler area otherwise you will have moisture problems in walls

[dan sw fl]

I am building a 6000 sq ft facility that is split into a production and retail area. The cielings are 15' tall and the building is 75' square. The split is 1/3 retail and 2/3 production. The production side needs to be maintained at 60 degrees and the retail side is supposed to be maintained at 70ish, whatever is comfortable. The production side has several vessels that are maintained at 60 degrees or below by glycol jackets which is separate from this discussion. The building is metal construction with R13 walls and R19 ceiling. The floors are 6" concrete. There will be very little heat produced in the production facility to the extent that we did not take it into consideration when assessing our cooling needs. The doors will remain closed 98% of the time. We are located in Northern Indiana (for reference to outside temps)

The retail area is quoted for a regular heat pump duct system with two condensers at 3.5 ton and two air handlers. This is the scope of work and I am not happy with the cost.

Why must there be a ductless system to maintain 60 degrees? I think I am being taken for a ride...
on top of that, I learned that my contractor subbed a contractor to sub out the work... hes just a middle man and I don't like him...

Please help confirm my suspicions!

Pricing not allowed.

Mod

FIRST, YOU MOST LIKELY DON'T NEED 60'F ROOM IF THE PROCESS IS COOLED SEPARATELY!
And it is certainly not a separate discussion, it is the essense of WHAT ACTUALLY IS REQUIRED !

[dan sw fl]

http://www.trane.com/COMMERCIAL/DNA/View.aspx?i=1062

http://www.trane.com/download/equipm...RC007EN_r2.pdf


At first glance, one 20 ton unit seems to be MORE THAN sufficent for both the Production and retail space.
I believe that cooling in each area is << 10 tons.

DX based equipment is frequently Going in the Wrong direction for industrial applications.

If one ACTUALLY Neeeds < 72'F room temperature, a very small chiller and a few air handlers will meet requirements.

[dan sw fl]

Small chiller, 20 ton, Page 41
http://www.trane.com/download/equipm...RC007EN_r2.pdf

Figure DD-3 — CGAF-C20 Unit Dimensions

or 15 Ton might be the needed capacity, page 40.

[dan sw fl]

The GC approved it, the walls are thirteen, the ceiling is 19...
________________ I wondered about that too...

I might not have to much problem deciding on
_________ Who's recommendation to follow ?
___________ Your G.C. or my 3 year old grandson.

Example...
Perimeter = 75 +50 +50 = 175 feet
A = 175 * 15' height = 2,625 sq feet; roughly 3,000
Q wall production area = A * dt / R = 3,000 * 30 / 20 = 4,500 BTU/hr

... minimize condensation issues .:. Supply Air at ~ 50'F with 8 or 10-row coil.