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Any commercial AC guys out there?

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Any commercial AC guys out there?

Old 08-17-2016, 05:27 AM
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Default Any commercial AC guys out there?

We own a restaurant that has 3 seperate ac systems. The kitchen exhaust hood is sucking out all the cold air because the system has virtually no makeup air. We have to leave a back door partially open so that customers can open the front door. Our regular ac guy said that we need an expert who can calculate the exhaust in order to calculate how much makeup air we need. There is a 12 inch pipe that feeds to the exhaust hood. I called 3 different companies, one wants to add an inline fan in the 12 inch pipe, one looked at it and won't return my calls and one won't return my calls to set up an appointment. It seems that this is a specialized field. I'm about ready to try to fix this myself and I would at least like to know if the one company that wants to install the fan is fixing it correctly. Our exhaust fan pushes somewhere between 1500-2700 cfm depending on the ducting size and bends. It is a straight shot from the hoods through the wall mounted exhaust fan so I think our cfm is probably at the higher end. I just find it hard to believe that a fan mounted in a 12-inch pipe with three or four 90s is going to be able to push enough air to make the system work correctly. My research has shown that we need approximately 90% make-up air, that's around 2400 cfm. At this point I'm pretty frustrated that I haven't been able to find somebody who really seems to know what they're talking about or who I can fix this.
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Old 08-17-2016, 05:43 AM
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Look for an authorized Captiveaire installer, doing it right will save money in the long run.
If you don't interlock equipment correctly and there is a fire, you can have a homemade blast furnace.
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Old 08-17-2016, 05:49 AM
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Originally Posted by hevysrf View Post
Look for an authorized Captiveaire installer, doing it right will save money in the long run.
If you don't interlock equipment correctly and there is a fire, you can have a homemade blast furnace.
That's the third guy I called who won't return any phone calls. I was really hoping to get him out to look at it.
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Old 08-17-2016, 05:56 AM
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Send a quick email to captiveaire corporate, they are really trying to build a customer service reputation, I'm sure they can set up some help for you.
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Old 08-17-2016, 06:55 AM
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Most states require an outside make-up air supply for vents over a specific CFM. You really need this to run through your A/C system to keep from dumping unconditioned air into a room. It should have been spec'ed when the system was designed and should have also been checked during building inspections. You need an A/C company that's familiar with restaurant systems.

We're not in the A/C business but one of the services we provide (not for restaurants) is the certification of vent hoods for airflow and all of the companies we do this for have very elaborate air make-up systems. We also do clean-rooms but their make-up systems are there to provide a positive pressure differential. My point with this is there are A/C companies that do this. You just need to find one.
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Old 08-17-2016, 07:03 AM
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I would recommend against hiring an HVAC contractor as they are typically going to throw 'stuff' at the problem, vice doing the math to engineer it first.

You need a mechanical engineer to do the commercial equivalent of a 'manual-j' for your space which should tell you everything you need to know from make up air, to HVAC BTU rates etc etc.

HTH
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Old 08-17-2016, 09:21 AM
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Originally Posted by mikefloyd View Post
Most states require an outside make-up air supply for vents over a specific CFM. You really need this to run through your A/C system to keep from dumping unconditioned air into a room. It should have been spec'ed when the system was designed and should have also been checked during building inspections. You need an A/C company that's familiar with restaurant systems.

We're not in the A/C business but one of the services we provide (not for restaurants) is the certification of vent hoods for airflow and all of the companies we do this for have very elaborate air make-up systems. We also do clean-rooms but their make-up systems are there to provide a positive pressure differential. My point with this is there are A/C companies that do this. You just need to find one.
Our hood has a built in vent near the front that connects to the 12 inch pipe that goes outside. The theory is that as the exhaust is sucking air out it is supposed to be pulling from the vented part of the hood. The way it was installed though they never put in a fan on the intake side of the 12" pipe so it hardly does anything. If I have all the doors to the building closed tightly that vent pipe outside will just about suck your hand into it. But the second you open a door it stops immediately. There is no roof access to our building so I can't have a traditional rooftop make-up air unit installed. The system we have is used in many other restaurants and works great when installed right.
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Old 08-17-2016, 12:38 PM
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38P6

I am a commercial A/C and refrigeration contractor that has a niche in the restaurant industry. I must say, you know more about your problem than any restaurant owner I have encountered and more than most A/C guys. Only a small percent of contractors know about air balance or even kitchen refrigeration for that matter.

What the one company is recommending is that you contact a Test & Balance company. It is a specialized business that all they do is check CFM and air balance. might not be a bad idea, since you don't know exactly what you are working with.

You are correct in that you need a forced air make up fan equivalent to about 85% of exhaust CFM. The pipe or duct out the wall never works with out a make up fan, Preferably a belt drive, so you can fine tune the CFM with the pulley. Inline fan ain't gonna cut it. Can you mount a fan where ever the duct exits the building?

Now Captiveaire does make a in line make up fan the can be installed in the attic or such places, but it is a huge box with a belt drive fan in it with a in and out duct. Not sure what the other guy was recommending. We recently installed one on a building with no more room on the roof. Hope this helps.

Oh, and as mentioned above, it does need to be wired thru the fire/ansul system to shut down in case of fire. Trust me, if not and you have a fire the lawyers and insurance companies will own you.

Last edited by AC; 08-17-2016 at 01:00 PM.
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Old 08-17-2016, 01:09 PM
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Originally Posted by AC View Post
38P6

I am a commercial A/C and refrigeration contractor that has a niche in the restaurant industry. I must say, you know more about your problem than any restaurant owner I have encountered and more than most A/C guys. Only a small percent of contractors know about air balance or even kitchen refrigeration for that matter.

What the one company is recommending is that you contact a Test & Balance company. It is a specialized business that all they do is check CFM and air balance. might not be a bad idea, since you don't know exactly what you are working with.

You are correct in that you need a forced air make up fan equivalent to about 85% of exhaust CFM. The pipe or duct out the wall never works with out a make up fan, Preferably a belt drive, so you can fine tune the CFM with the pulley. Inline fan ain't gonna cut it. Can you mount a fan where ever the duct exits the building?

Now Captiveaire does make a in line make up fan the can be installed in the attic or such places, but it is a huge box with a belt drive fan in it with a in and out duct. Not sure what the other guy was recommending. We recently installed one on a building with no more room on the roof. Hope this helps.

Oh, and as mentioned above, it does need to be wired thru the fire/ansul system to shut down in case of fire. Trust me, if not and you have a fire the lawyers and insurance companies will own you.
The second guy who came out seemed to know what he was talking about and he mentioned putting an exterior wall mounted fan right where the 12-inch pipe exits the building. He said it would look almost exactly like the fan that exhausts out but smaller. We are in a 2 story building on the bottom floor so there is no way to put anything on the roof. I started looking at these wall-mounted fans and it seems like I might be able to get one that pushes enough CFM and then use a variable speed switch to fine-tune it. Is there any reason why that wouldn't work and I could do this myself? I already know that I have to have it get wired up to the Ansel system and will hire electrician for that. I'm not sure why the second guy won't get back to me I do know he is very busy but he won't even return a phone call so at this point I'm not going to chase anyone around to spend my money. I'm pretty handy and if this is something I can try to handle myself I'm ready to just do it.

Holy crap, I just noticed you are in Florida. Please tell me you're somewhere near Merritt Island????
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Old 08-17-2016, 01:53 PM
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W38P6 where are you located? I may be able to help out as I am a mechanical engineer and have designed more than a few kitchen systems. I also own a small MEP/FP design company.
A/C's recommendation is pretty good but there are other systems out there that can save energy.
There are a few ways to approach this but lets talk budget first.
Exhausting anything into a public way or in a way to cause a nuisance is against code.
Do you want the kitchen air conditioned? Depending on what part of the county and size of restaurant some don't condition the air, only heat it.
If you have a set of plans or can get one, lets start there.
Next get a balancer into taking air flow readings.
We can compare the real life to the " designed" and see if there are problems then we can move to a permanent solution. Any more than that and I will have to bill you..
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Old 08-17-2016, 01:58 PM
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i am a hvac contractor in nj were are you located
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Old 08-17-2016, 01:59 PM
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Originally Posted by g2man View Post
i am a hvac contractor in nj were are you located
see above, he must be near merrit island FL
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Old 08-17-2016, 02:12 PM
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Yes, Merritt Island Florida very close to Port Canaveral. Our kitchen is open to the rest of the restaurant and gets its ac from 1 of the 3 units we have.
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Old 08-17-2016, 03:49 PM
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Measure the hood;

L x W = SqFt
you need 100 Ft/min for a hood with 4 exposed sides( free standing)
75 Ft/Min for 3 exposed sides( one side against the wall)

SqFt x Ft/min = Ft3/min (CFM) this should be your exhaust CFM

Like AC said, 85% of the exhaust CFM is what you need for makeup air. Get a supply fan,
get AC to do it, he knows what he is talking about.
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Old 08-18-2016, 05:21 AM
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I have a call in to an ac test and balance company that is supposed to specialize in this stuff. I think AC is out by Ocala.
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Old 08-23-2016, 04:30 PM
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So the test and balance guy told me that I need to find someone willing to do the work after he tests the system. He gave me 2 names and told me to get one of them on board before he comes out. One of the names he gave me was one that I already tried and he diidnt get back to me. The second name he gave me is a large local company that was also recommended to me by one of my customers who is a building contractor. I contacted the owner of the company personally and he told me that he was going to have a regional guy from captive aire come out with him to evaluate the system. He said I will have a confirmation email within the hour.
A week goes by and nothing. The building contractor has been building in this area a very long time and he wasn't surprised at all. Apparently this is typical either in this area or in Florida. I have pretty much given up, I'm not doing business with people like this. I'm not trying to rag on Florida, I love it here but man I don't know how these guys stay in business.
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Old 08-23-2016, 05:51 PM
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Originally Posted by 38P6 View Post
So the test and balance guy told me that I need to find someone willing to do the work after he tests the system. He gave me 2 names and told me to get one of them on board before he comes out. One of the names he gave me was one that I already tried and he diidnt get back to me. The second name he gave me is a large local company that was also recommended to me by one of my customers who is a building contractor. I contacted the owner of the company personally and he told me that he was going to have a regional guy from captive aire come out with him to evaluate the system. He said I will have a confirmation email within the hour.
A week goes by and nothing. The building contractor has been building in this area a very long time and he wasn't surprised at all. Apparently this is typical either in this area or in Florida. I have pretty much given up, I'm not doing business with people like this. I'm not trying to rag on Florida, I love it here but man I don't know how these guys stay in business.

Find out who does the hood service at your local McDonald's. They have it down and design around it from the get go.

You need a captive hood that will be at best creating a 10% negative in your space. Then, via make up air your HVAC will have to make up the rest of the exhaust.

I would call Test and Balance Corp and get their ear. They have folks all over Florida and are in tune with hood systems such as Melink and others.

Our exhaust fan pushes somewhere between 1500-2700 cfm depending on the ducting size and bends.

You must make up the CFM of exhaust and Hopefully it is done with a captive type hood or you will need to treat 90 plus degree OA make up at the tune at about 10 tons of A/C to maintain temp in the space for 2500 CFM of exhaust.

Your issue is in the hood and you must address it. Pumping non captured air into the space is no different than leaving the front door open. You can't run your building in a vacuum.

http://www.tabconline.com/ It's gonna cost ya but worth it
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