Is this enough tonnage for my small restaurant? Frustrated...

[meehow]

Hi all - Thank you in advance for the help. I'm in a very frustrating situation having just opened my small takeout restaurant during a very hot NJ summer only to learn that the AC system I had installed is not able to cool the space sufficently. I know there are many variables to consider, but I'd just like to get an idea if it's possible that my 3 ton AC unit is big enough for this space (I am thinking it isn't and the load calculation that was done was incorrect). I am no expert when it comes to HVAC so forgive me for any poor terminology or irrelevant information. I am at my wits end because some of the contractors I have been working with have been very difficult and refuse to work with each other to figure out the issue and offer a solution. Here is all the information I have on the situation (most complicating factor being the exhaust hood over a few cooking appliances).

- The space is ~700 sq. ft. (~18 ft x 40 ft)... the longer walls are interior walls with a residential unit on one side and a commercial unit on the other.
- The space has a single large window on the storefront (shorter) wall which is about 8 ft x 4 ft.
- The ceiling is 8 ft but there is another 4 ft of space above the ceiling tiles
- The space is split roughly in half by a wall which has an open doorway to connect the two rooms
- There are ceiling AC returns in each room, about 2 feet in either direction from the dividing wall
- There are 6 ceiling mounted AC registers
- There is a kitchen in the front section of the space which includes a commercial 4 burner stove/oven, a 4 ft flat top grill and a fryer
- A 12 ft commercial hood is above all this equipment with intake and exhaust fans (there is slight negative pressure in the building presumably due to the exhaust fan pulling out too much air relative to the make up air coming in (which is not heated or cooled)
- In this front section there are also two standing refrigerators
- The back section of the space has 2 large standing freezers, a large standing refrigerator, and a hot water heater
- At any given time, there are anywhere from 2-12 people in the space. Average number of people is about 6.

With no kitchen equipment running and the hood fan off, the space stays cool. However, with even light use of the cooking appliances which necessitates the hood fan to be running, on a relatively warm day (75-80 degrees), the space gets cooled only to about 75 degrees. The AC system is running at full blast and the temperature will not fall below this. During several hot days when it was over 90, the space would not cool below 82 degrees. I have a portable AC in the front which keeps things cool for customers, but this is a temporary solution and doesn't help the employees. I understand that the hood issue which is causing negative pressure in the space could be contributing to the cooling problem, but I'm not convinced that it's making that much of a difference (please tell me if I'm wrong in thinking this). My theory is that the 3 ton AC unit that was recommended and installed is not sufficient for the space and the amount of heat being generated by my equipment. Any thoughts you may have would be very much appreciated so I can figure out my next steps to get this resolved. Thank you!!

[micdundee]

contractor(s) you are working with???????
If (they) were "contractors", did you, one, have a calculator?

[BALloyd]

Since this is a commercial space and also a kitchen, did an engineer complete a Manual N load calculation and then design the space and provide drawings and equipement specifications?

[Gib's Son]

Hi all - Thank you in advance for the help. I'm in a very frustrating situation having just opened my small takeout restaurant during a very hot NJ summer only to learn that the AC system I had installed is not able to cool the space sufficently. I know there are many variables to consider, but I'd just like to get an idea if it's possible that my 3 ton AC unit is big enough for this space (I am thinking it isn't and the load calculation that was done was incorrect). I am no expert when it comes to HVAC so forgive me for any poor terminology or irrelevant information. I am at my wits end because some of the contractors I have been working with have been very difficult and refuse to work with each other to figure out the issue and offer a solution. Here is all the information I have on the situation (most complicating factor being the exhaust hood over a few cooking appliances).

- The space is ~700 sq. ft. (~18 ft x 40 ft)... the longer walls are interior walls with a residential unit on one side and a commercial unit on the other.
- The space has a single large window on the storefront (shorter) wall which is about 8 ft x 4 ft.
- The ceiling is 8 ft but there is another 4 ft of space above the ceiling tiles
- The space is split roughly in half by a wall which has an open doorway to connect the two rooms
- There are ceiling AC returns in each room, about 2 feet in either direction from the dividing wall
- There are 6 ceiling mounted AC registers
- There is a kitchen in the front section of the space which includes a commercial 4 burner stove/oven, a 4 ft flat top grill and a fryer
- A 12 ft commercial hood is above all this equipment with intake and exhaust fans (there is slight negative pressure in the building presumably due to the exhaust fan pulling out too much air relative to the make up air coming in (which is not heated or cooled)
- In this front section there are also two standing refrigerators
- The back section of the space has 2 large standing freezers, a large standing refrigerator, and a hot water heater
- At any given time, there are anywhere from 2-12 people in the space. Average number of people is about 6.

With no kitchen equipment running and the hood fan off, the space stays cool. However, with even light use of the cooking appliances which necessitates the hood fan to be running, on a relatively warm day (75-80 degrees), the space gets cooled only to about 75 degrees. The AC system is running at full blast and the temperature will not fall below this. During several hot days when it was over 90, the space would not cool below 82 degrees. I have a portable AC in the front which keeps things cool for customers, but this is a temporary solution and doesn't help the employees. I understand that the hood issue which is causing negative pressure in the space could be contributing to the cooling problem, but I'm not convinced that it's making that much of a difference (please tell me if I'm wrong in thinking this). My theory is that the 3 ton AC unit that was recommended and installed is not sufficient for the space and the amount of heat being generated by my equipment. Any thoughts you may have would be very much appreciated so I can figure out my next steps to get this resolved. Thank you!!

That is your answer. You will have the opposite come winter. A 12 ft hood: the make up air that is being put into the space is probably around 1900 cfm....of untreated air. Assuming you have a dedicated make up unit, Code requires the temperature differential between makeup air and the conditioned space shall not exceed 10 degrees F, except where the added heating and cooling loads of the makeup air do not exceed the capacity of the HVAC system.

If you have any diffusers in the kitchen off that 3 ton unit, it is a code violation. If there are none, then...well you will have very unhappy employees because you have no conditioning except the air that is transferred from the dinning into the kitchen.

Your solution is to condition the makeup air.

[Gib's Son]

As a follow up:

Using generic values for the kitchen equipment described, the radiant total load added to the kitchen is about 2 tons for the appliances under a hood.

The OP did not mention what part of NJ they are in, so using Trenton weather data it looks like the total sensible load of the outside air at 95/74 is just a little short of 4 tons. Sensible and Latent come in about 6 tons total.

I would say the 3 ton unit for comfort cooling is fine, but there is no way it will keep up with the amount of OSA your likely bringing in, again assuming about 1800 cfm outside air. BTW, your building should be neutral to slightly positive pressure, but not negative. The kitchen, however, needs to be negative.

[dan sw fl]

----- CKV IS COMPLEX ------------
________ even Small ones
_________ 12 foot Hood IS NOT Small

https://fishnick.com/ventilation/des...e_1_031504.pdf


First of three dozen or so info inquiries for YOUR Situation:

1
Exhaust Fans nameplate information is required.

2
Do the Exhaust Fan(s) match the original design intent?

3
How is the make-up air fed to the Hood?

4
Design drawings for the 12 foot hood are required.
MFG: ?
Date: ? 2000, 2010, 2018?

5
PROVIDE COMMISSIONING REPORT.

6
W.A.G.N.I.R.: Upto 9 tons may be necessary.

7
DO YOU wish to keep the kitchen at < 78'F, 80'F, 82'F when it is > 88'F outside?

8
Getting to first base on this CKV Design might be quite time consuming.