Q: When do I use a Relay Box instead of a KFCC?
The relay box is much less expensive and you would use it instead of a KFCC if:
- Only one supply and one exhaust
- Single phase only
- Fans must have thermal overloads.
Q: Does Greenheck comply with International Mechanical Code (IMC) 507.2.1.1?
A: Yes, Greenheck has a heat sensing temperature interlock option that satisfies the IMC code.
Q: Who is the Greenheck representative in my area?
A: You can find your Greenheck representative by selecting the "Find My Rep" section on the homepage of Greenheck.com.
Q: What causes smoke and grease laden air to move horizontally and spill out from under a kitchen hood?
There can be many different reasons for this condition to occur. Consider the following:
- Not enough exhaust air for the cooking load.
- The kitchen hood is undersized for the application.
- Cross drafts in the kitchen.
- Excessive velocities from the face and/or air curtain registers.
- Not enough supply air brought back into the kitchen.
Q: When is it necessary to provide make-up air to a system?
A: Always. Codes like NFPA 96 require the following: "Replacement air quantity shall be adequate to prevent negative pressures in the commercial cooking area(s) from exceeding 0.02 in. water column (4.98 kPa)."
Q: What are typical applications for a Type I and Type II kitchen hood(s)?
A: According to the International Mechanical Code: "A Type I hood shall be installed at or above all commercial food heat-processing equipment that produces grease vapors or smoke. A Type I or Type II hood shall be installed at or above all commercial food heat-processing equipment that produces fumes, steam, odor or heat."
Q: What are the minimum and maximum allowable airflow velocities at the exhaust duct collar of a Greenheck hood?
A: Minimum = 1500 feet per minute. Maximum = 2100 feet per minute. (Except when used in a Variable Volume System, Minimum = 500 feet per minute)
Q: Are round duct collars available on U. L. Listed kitchen hoods?
A: Duct collars are available as square, rectangular and round configurations on U. L. Listed without fire damper type kitchen hoods. The maximum allowable size is dependent on the style of hood.
Round duct collars are not available on U. L. Listed with fire Damper type kitchen hoods.
Q: Can Greenheck provide an exhaust duct collar mounted on the rear or back of the hood?
A: Exhaust duct collars can be mounted on the rear of baffle filter style hoods at no additional charge. However, there is a limitation to this alternate location. The rear of the hood limits the maximum height of the exhaust collar to be 12" for canopy style and 10" for proximity style. Rear mounted exhaust collars are not available on Water Wash Style kitchen hoods.
Q: Can the exhaust duct collar be moved to the right or left of the standard centered position?
A: The U. L. Listing allows the exhaust duct to be located within 48" from the center of the hood to the center of the collar. However, construction limitations prevent the exhaust collars being placed within eight inches of the hood end panels.
Q: Can the exhaust duct collar be moved forward on the hood to give a greater clearance behind the duct?
A: The UL Listing allows the exhaust duct to be moved forward from the standard location. The maximum distance from the back of the hood the collar can be moved is based on the style of hood and the width of the collar. The farther forward the collar is placed the narrower the collar must be.
Q: Can a flexible duct connector be used to attach an exhaust duct to a utility set exhaust fan?
A: NFPA 96 2008 states the following: 126.96.36.199 The fan shall be connected to the exhaust duct by flanges securely bolted…..or by a system specifically listed for such use. 188.8.131.52 Flexible connectors shall not be used.
Q: Are PCU's required by code?
A: There is nothing currently in the International Mechanical Code (IMC) or NFPA 96 requiring the use of PCUâ€™s. Local codes are starting to be passed in certain areas of the country that require the use of PCUâ€™s, however, the majority of PCUâ€™s are customer requested, not necessarily code mandated.
Q: Can a PCU Unit serve kitchens hoods located on different floors of a building?
A: The International Mechanical Code (IMC) 506.3.5 requires a separate grease duct system to be provided for each Type I hood unless all four of the conditions below are met-
1. All interconnected hoods are located within the same story.
2. All interconnected hoods are located within the same room or in adjoining rooms.
3. Interconnecting ducts do not penetrate assemblies required to be fire-resistance rated.
4. The grease duct system does not serve solid-fuelfired appliances.
Q: Can the PCU's be used with multiple hoods?
A: Yes, multiple hoods can be tied to the PCU like any other exhaust fan.
Q: Does the PCU require a fire suppression system?
A: Yes, a fire suppression system is required and typically must be tied into the kitchen hood fire system, so both will go off at the same time.
Q: What type of filters should be used at the hood?
A: The more grease that can be removed at the hood the lower the operating cost of the PCU, as it prevents grease build-up in the PCU. Greenheck recommends using Grease X-Tractorâ„˘ filters in the hood which will be approximately 70% efficient.
Q: What types of filters are used in the Grease Trapper units?
A: The filtered units will use 3 sets of filters. A metal mesh filter to remove the larger particles of grease, a MERV 8 filter bank with a 78% efficiency and a MERV 15 filter bank with a 95% efficiency. A carbon filter section is used to remove odors from the airstream.
Q: What types of PCU's are commonly used in restaurants?
A: Two types of PCUâ€™s are commonly available, filtered and electrostatic precipitator (ESP) models. The Grease Trapper and Triple Play filtered PCU models have 3 sets of mechanical filters and an odor removal section. The Power Play model contains an
electrostatic precipitator and an odor removal section to remove the grease and odors.
Q: When is a Pollution Control Unit (PCU) necessary?
A: A PCU works best in applications where the restaurant would like to remove more of the grease, smoke and odor from the exhaust airstream. A good example would be if they are on the ground floor of a multi-story building and must discharge the exhaust out the sidewall or have neighbors that do not want the odors or grease present. A PCU will help to eliminate the need for a long, cost prohibitive duct run to the roof and prevent grease build up on windows, sidewalks or adjacent buildings.
Q: When should a filtered unit be used?
A: The filtered units offer a lower upfront cost than the ESP units but typically are twice the cost to operate and maintain annually due to the filters needing to be replaced. The annual maintenance costs can vary based on cooking load, hood filters and the type of food being cooked.
Q: When should an Electrostatic Precipitator (ESP) unit be used?
A: The Power Play units contain an ESP section to help remove grease and will have an integral wash down system for daily washing and maintenance. These units will have a higher initial cost due to the ESP cell and wash down system but have lower annual operating and maintenance costs. When long term costs are important, an ESP unit is the best option.
Q: Why are there three different types of safety listings on PCU's?
A: There are three different safety listings that can be found on PCUâ€™s in the industry from either ETL or UL. ETL and UL are the two listing agencies typically used for certifying all of the products within a kitchen exhaust system and are both widely accepted within the industry. When filtered PCU units were first developed for use in kitchens, neither ETL nor UL had a specific listing for filtered PCUâ€™s. Because there was a need to ensure the safety of these units, ETL developed a listing based on the UL 710 Standard that is used to certify hoods and hood accessories. The Triple Play is ETL Listed to UL 710 Standards. As these units became more common in the industry, their function in the overall exhaust system was reviewed. It was determined that these units were closer to exhaust ducts than a hood or hood accessory so a different listing may be more applicable. UL 1978 is the standard that covers factory built grease duct used in the kitchen exhaust systems. The Grease Trapper model is UL 1978 Listed to grease duct standards. The ESP models contain an electrostatic cell to remove grease instead of mechanical filters like the filtered PCU units. These units will be ETL Listed to UL 867 Standards which is applicable to electrostatic air cleaners.