FREQUENTLY ASKED QUESTIONS
AIR SCRUBBERS/NEGATIVE AIR MACHINES
Q. What is the difference between an air scrubber and a negative air machine?
A. The terms “air scrubber” and “negative air machine” are often used interchangeably; however, the two terms refer to different applications.
An air scrubber stands alone in the center of a room with no ducting attached. The air is filtered and recirculated, greatly improving the general air quality. An air scrubber can be used as a negative air machine, but it requires ducting, a sealed housing, precise airflow adjustment, and a variable speed blower motor. A negative air machine uses ducting to remove contaminated air from a sealed containment area. The filtered air is exhausted outside of the containment area. This creates negative air pressure (a vacuum effect), which helps limit the spread of contaminants to other areas inside the structure. Here’s examples of where negative air machines and air scrubbers are used.
• Water/Fire/Disaster Remediation
• Asbestos & Mold Abatement
• Construction
• Drywall Dust Air Cleaning
• Paint Fume Air Cleaning
• Renovation Projects
• Bio-Hazard Removal
Q. What is a HEPA filter and what is its ideal application?
A. HEPA is an acronym for "high efficiency particulate absorbing" or "high efficiency particulate arrestance" or, as officially defined by the Department of Energy (DOE) "high efficiency particulate air". This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 micrometers (μm) at 85 liters per minute (Lpm).
HEPA air filters have been traditionally used in hospital operating and isolation rooms, pharmaceutical and computer chip manufacturing, as well as in other applications requiring "Absolute" Filtration. Today HEPA air cleaners, and air filters are used in a wide variety of critical filtration applications in the nuclear, electronic, aerospace, pharmaceutical and medical fields. HEPA air cleaners, vacuum cleaners and air filters are required by law to be used in all equipment for asbestos, lead, toxic chemical and mold abatement.
Q. How do I size a room for an air scrubber/ negative air machine?
1. Figure out the total square footage of the area/ room, times the height of the ceiling to get the total cubic footage of the area/room. ( L * W * H )
Example: A 2,500 sq. ft home with a 10 foot ceiling will have a total cubic foot measurement of 25,000 cubic feet.
2. Take the total cubic foot measurement of the home and divide it by the c.f.m. ability of the Neg-Air machine.
Example: 25,000 cubic home divided by a 2,000 c.f.m. Neg-Air = 12.5. It will take 1 (one) 2,000 c.f.m. Neg-Air machine 12.5 minutes to change the air in the area 1 time.
3. Divide 60 minutes (1 hour) by the 12.5 minutes it takes to change the air in a room 1 time.
Example: 60/12.5 = 4.8. This is the number of times this 2000 c.f.m. Neg-Air machine will change the air in this size building in one hour.
In this case more c.f.m. will be needed to meet the standard of 6 times per hour.
AIR CONDITIONING
Q. How do I size a room for an A/C?
A. Typically in the rental industry you can asses the calculation of one ton per every 400 square feet. Although sometimes it isn’t that simple, there are many contributing factors involved with cooling a room.
• Wall insulation (is it a tent?)
• Electronic devices in room
• People per square foot
• Temperature and time of day
• Windows and ceiling height
Contact us with any sizing questions and or concerns. We will be happy to answer them for you.
Q. What is the difference between water cooled and air cooled air conditioners?
A. When a liquid converts to a gas (in a process called phase conversion), it absorbs heat. Air conditioners exploit this feature of phase conversion by forcing special chemical compounds to evaporate and condense over and over again in a closed system of coils. In an Air cooled air conditioning unit, the heat from the condenser coil is evacuated by a condenser fan that blows air through the coil itself. In a Water cooled air conditioning unit that same heat that builds in the condenser is evacuated by water passing through the condenser coil. Both applications allow for a unique removal of exhausted condenser air depending on the buildings limitations.
Q. What is the difference between an evaporative cooler and air conditioning?
A. Air conditioning uses a refrigerant in a vapor compression cycle to cool and/or dehumidify a substances or space, like a refrigerator cabinet, room, office building, or warehouse. An evaporative cooler, sometimes referred to as a swamp cooler, is a device that cools air through the evaporation of water. Evaporative cooling differs from typical air conditioning systems which use vapor- compression or absorption refrigeration cycles. Evaporative cooling works by employing water's large enthalpy of vaporization. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor, which requires much less energy than refrigeration. In extremely dry climates, it also has the added benefit of conditioning the air with more moisture for the comfort of occupants. Unlike refrigeration, it requires a water source, and must continually consume water to operate. In high humidity level environments evaporative coolers are not an efficient way to cool an area.
Q. Is an air conditioner also a de-humidifier?
A. In a short answer, yes. Air-conditioning equipment usually reduces the absolute humidity of the air processed by the system. The relatively cold (below the dew point) evaporator coil condenses water vapor from the processed air (much like an ice-cold drink will condense water on the outside of a glass), sending the water to a drain and removing water vapor from the cooled space and lowering the relative humidity in the room. A regular air conditioner transfers energy out of the room by means of the condenser coil, which is exhausted outside the room. That is, the room can be considered a thermodynamic system from which energy is transferred to the external environment. Conversely, with a dehumidifier, no energy is transferred out of the thermodynamic system (room) because the air conditioning unit (dehumidifier) is entirely inside the room. Therefore all of the power consumed by the dehumidifier is energy that is input into the thermodynamic system (the room) and remains in the room (as heat).
Q. Can your portable A/C units be used in a residential setting?
A. In theory, yes they can, although, our units are intended for a commercial setting. Exhausting the hot condenser air is always more of a struggle in a home or residence. In commercial buildings hot condenser air is exhausted using a duct system that is attached to the t-grid ceiling or placed outside a window or door. A local home improvement store will usually carry indoor residential units which may be better fit for your home.
HEATING
Q. How do I size a room for a heater?
A. There’s a little math involved to calculate how much heat you will need to achieve your desired temperature. I will take you through a series of simple steps to guide you along in the sizing process. 1) Measure your room or space that you are heating and get the total cubic feet (width x length x height). 2) Determine your target temperature then subtract the current temperature from that number. 3) Multiply the cubic feet by (.133). 4) Take that number then multiply it by the number in step two. 5) This number is the calculated (BTU) necessary to achieve your desired room temperature.
1. Room: 20 (length) x 40 (width) x 10 (height) = 8000 cubic feet
2. 75 degrees target temp – 50 degrees ambient = 25 degrees
3. 8000 cubic feet x (.133) = 1064
4. 1064 X 25 degrees = 26600 BTU
Q. What is the difference between Direct and Indirect heat?
A. A direct fired gas heater is sometimes called, or known as, a salamander. Direct fired gas space heaters can contain a fan that pushes air past an open flame. Direct fired heaters have fumes as a byproduct: Smoke and carbon monoxide (CO). This style of heater can only be used in well-ventilated areas. An indirect fired gas space heater is a very different machine than direct. Indirect heaters burn much cleaner and without any fumes in the heat area. They do this by burning their gases in a combustion chamber which is separately vented from the heat through a stack. These styles of heaters are very effective in spaces which need to be heated quickly and which contain a strong presence of people.
