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Kitchen Hood FAQ
Q: What kind of kitchen hood do I need?
Q: Are your hoods code compliant?
Q: What is a low profile hood?
Q: What is make-up air?
Q: What is tempered make-up air?
Q: Do I have to have heated make-up air?
Q: Do you do fire suppression?
Q: Who should install my restaurant hood?
Q: Do I need a permit?
Q: How do I get a permit?
Q: How do I make the hood activate when cooking occurs. (IMC 507.2.1.1)
Q: What is a three inch standoff or air gap?
Q: What size fan do I need
Q: I have a pitched roof. Do I need a kitchen roof platform?
Q: What kind of kitchen hood do I need?
A: There are several factors that apply to hood design. First you decide what you are going to be cooking, which will dictate your equipment, which in turn will dictate what type of hood you will need. There are also several code issues that will decide the specific hood that will suit your needs. To help us gather the information we will need to spec your kitchen hood design.
Q: Are your hoods code compliant?
A: Yes. Our hoods are ETL tested, listed and labeled to UL 710 standards. We are also listed NSF and NFPA 96. However, those tests are mostly performance based and will pass inspection and receive approval, but an improper installation can make any kitchen hood fail. That is why we spend the extra time on the phone with our customers to investigate the environment in which the hood will be placed. Some of the items we will ask about are clearance to combustibles, duct sizing for proper volumes and velocities and most importantly finding out what is under the hood.
Q: What is a low profile hood?
A: A low profile hood has a shortened face to lower the whole canopy in order to gain the minimum clearance to combustibles of 18".
Q: What is make-up air?
A: Make-up air is air brought in to compensate for what the exhaust system is removing. Proper make- up air is essential to your kitchen hood's performance. Imagine trying to suck the air out of an empty two liter bottle of soda. You can't. However, poke a hole in the side and voilà, you can breathe. In this scenario you are the exhaust fan and the hole is the make-up air. Your exhaust simply will not work with out the hole in the side of the bottle, check out our make-up air units.
Q: What is tempered make-up air?
A: Tempered make-up air is exactly the same as regular Make-up air with one exception. Tempered MUA is heated and is required any time you bring it directly into a room via a front make-up air unit or ceiling diffusers. This is a code issue. The International Mechanical Code states that when MUA has the ability to decrease the comfort of the room, it must be heated. But be careful, tempered make-up air units are very costly and with proper design may be avoided.
Q: Do I have to have heated Make-up air?
A: That depends on the type of hood being used or your location (some states or cities require everything to be heated). Internal compensating hoods direct the MUA internally so that the air never enters the room, therefore the MUA in this instance has no ability to decrease the comfort of the room. There are situations where heated MUA must be applied. Internal compensating hoods or ICH, operate on an 80:20 exhaust to supply ratio. For example, if you are removing 1000 CFM (Cubic Feet per Minute) the supply would be 800 CFM, leaving the building's HVAC to supply the remaining 200 CFM. In this example the 200 CFM is nominal and acceptable. However, on larger systems where the deficiency exceeds the capacity of the HVAC system, additional tempered MUA must be added.
The majority of the time, new construction does not need tempered MUA. If the hood system and the HVAC system are designed to compliment one another ahead of time, a costly heated unit can be avoided
New construction should does not have to be equipped with heated MUA, because when the designers are aware of the negative pressure caused by the hood ahead of time, the HVAC system can be sized to compensate for any lacking air. This is more cost effective than going with a tempered unit.
Q: Do you do fire suppression?
A: Yes we can provide fire suppression, however we have found that having a hood system pre-piped does not save money and will cause undue headaches in the long run. If a system is pre-piped, a licensed installer will still have to be contracted to perform the final hookup and to do the necessary testing for the local authorities. It is usually better to have a local installer provide the whole system in order to avoid confusion and to allow the install to run smoothly.
Q: Who should install my restaurant hood?
A: It is of the utmost importance to have a licensed contractor with experience in hanging commercial kitchen hood systems. Although KSH is always available to support your installation process all the way through to the end, an experienced professional will save time and hassle.
Q: Do I need a permit?
A: A permit is required for hood approval and installation. Obtaining the permit is the responsibility of the licensed or HVAC contractor. Trying to circumvent getting a permit can cause major problems, because eventually somebody will find out that you don't have one. Whether its the fire marshall or the health department, the building department will get involved at some point and will ask where the hood permit is.
Q: How do I get a permit?
A: First, find out who will be issuing the permit. It will be the state building department, the city building department or the county building department. If you are not sure, simply contact any of the three (start locally before calling the state) and give them the project address and they will tell you if you are in their jurisdiction. Once you have established that you are talking to the right department, simply ask what the process is. Whoever is installing the system will generally have to be registered with them. They will ask you for a set of three or four stamped drawings with a permit application. There may be other steps and we always recommend politely asking what else is needed to save time in the future.
Q: How do I make the hood activate when cooking occurs. (IMC 507.2.1.1)
A: IMC 507.2.1.1 states that when cooking occurs the exhaust system is to automatically turn on. 507.2.1.1 was created due to a few unfortunate individuals who started cooking without turning on the hood system. When that happens, heat rapidly builds up in the canopy melting the links in the fire suppression thereby detonating the fire suppression itself. To say the least, this has presented quite a problem due to the fact that most cooking appliances are fueled with natural gas and electrical interlocking is difficult and very expensive. The simplest solution to this problem is to use an electrical package accompanied with a heat probe. If the hoods are not turned on, the heat will build up, but now the probe senses the rise in temperature and automatically turns on the fans.
Q: What is a three inch stand-off or air gap?
A: A standoff is used to gain clearances from combustible walls or ceilings. It is highly recommended that you check with your local building authority to find out if this is acceptable or not. Many building departments will not agree with this. Since hood installations are very expensive, it makes great economic sense to verify and disclose all information before proceeding. The building department WILL MAKE YOU REMOVE AND REINSTALL THE HOOD!
Q: What size fan do I need?
A: The size of the exhaust fan and make-up air units are dictated by the equipment under the hood and the size of the hood. KSH offers a wide variety of exhaust and supply fans but they need to be specified individually. Many factors will affect fan sizing. Things like duct runs, transitions and static pressure all can affect what a fan will push or pull.
Q: I have a pitched roof. Do I need a kitchen roof platform?
A: More and more, building departments are enforcing IMC 306.5.1. When equipment is installed on roofs with a pitch of 3:12 or greater, and 30" or more off grade, then a service platform will be required. These stainless steel roof platforms must comply to IBC and IMC guidlines. Plus, kitchen roof platforms can be a serious liability to the design professional who omits them. KSH custom manufactures pitched roof platforms for all types of equipment saving the owner, contractor, achitect or engineer the time and cost of designing and then finding a suitable fabricator to build it.
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