FAQ Topics

Control & Backdraft Dampers

Do building codes explain how to install fire, smoke, and combination fire/smoke dampers?

Yes, building codes do provide guidelines and requirements for the installation of fire, smoke, and combination fire/smoke dampers. These codes are crucial for ensuring the proper function and effectiveness of these dampers in containing the spread of fire and smoke within buildings.

The specific details and requirements may vary depending on the region and local building codes, but generally, they cover the following aspects:

Placement and Location: Building codes dictate where fire, smoke, and combination fire/smoke dampers should be installed within the HVAC system and building. This includes requirements for their placement in fire-rated barriers such as walls, floors, and ceilings to maintain the integrity of fire separations.

Fire Resistance Ratings: Building codes specify the required fire resistance ratings for the dampers based on the location and use of the building. Different parts of the building may require dampers with varying fire resistance ratings to meet safety standards.

Ductwork Penetrations: Guidelines cover how ductwork penetrations through fire-rated barriers should be constructed and protected with fire and smoke dampers to prevent the spread of fire and smoke between compartments.

Testing and Certification: Building codes often require fire, smoke, and combination fire/smoke dampers to be tested and certified by recognized testing agencies to ensure they meet the required performance standards.

Installation Standards: Codes may outline specific installation standards, including clearances around the dampers, proper sealing techniques, and firestop materials used in conjunction with the dampers.

Maintenance and Inspection: Codes may include requirements for regular maintenance and inspection of the dampers to ensure they remain in proper working condition and can function as intended in the event of a fire.

It's essential for building owners, contractors, and HVAC professionals to be familiar with the relevant building codes and standards in their jurisdiction when installing fire, smoke, and combination fire/smoke dampers. Compliance with these codes is crucial for the safety and fire protection of occupants and property within the building.

Keep in mind that building codes are periodically updated, so it's essential to refer to the most current version of the applicable codes and consult with local building authorities or fire marshals for specific requirements in your area.

When do I use a 1.5-hour fire damper, and when do I use a 3-hour fire damper?

The selection of a 1.5-hour fire damper or a 3-hour fire damper depends on the specific fire protection requirements of the building and the location of the damper within the HVAC system. Fire dampers are designed to prevent the spread of fire and smoke through ductwork and openings in fire-rated barriers. The numerical value (e.g., 1.5 hours, 3 hours) represents the damper's fire-resistance rating, indicating the duration of time the damper can withstand exposure to fire before it fails.

Here are some general guidelines for when to use a 1.5-hour fire damper and when to use a 3-hour fire damper:

1.5-Hour Fire Damper:

  • Low to moderate fire risk areas: In locations where the risk of fire is relatively low to moderate, a 1.5-hour fire damper is commonly used. These dampers can withstand fire exposure for 1.5 hours before failing, providing sufficient time to contain the fire and prevent its spread through the ductwork.
  • Non-critical areas: Areas that are less critical from a life safety perspective or have less sensitive equipment may require a 1.5-hour fire damper.

Examples of where a 1.5-hour fire damper might be used include standard office spaces, corridors, storage areas, and other non-critical parts of a building.

3-Hour Fire Damper:

  • High fire risk areas: In locations where the risk of fire is higher, or where stricter fire safety requirements are mandated by building codes or regulations, a 3-hour fire damper is employed. These dampers can withstand fire exposure for a more extended period, providing enhanced fire protection and containment.
  • Critical areas: Areas that are critical for life safety or house sensitive equipment may necessitate the use of a 3-hour fire damper.

Examples of where a 3-hour fire damper might be used include stairwells, elevator shafts, mechanical rooms, data centers, and other critical parts of a building.

It is essential to consult local building codes and fire safety regulations when determining the appropriate fire damper rating for a specific application. Building codes often dictate the locations and required fire-resistance ratings for dampers based on the building's occupancy type, size, and intended use. A qualified fire protection engineer or building inspector can help ensure compliance with relevant codes and standards.

What brand of actuators does United Enertech stock?

Will United Enertech supply and mount other manufacturers actuators besides Belimo and Siemens?

Yes, we can buy any manufacturer's actuators and mount them onto our dampers.

Will United Enertech mount a customer supplied actuator?

Yes, but a few things need to be verified:

  1. We will need to verify the actuator models and torque to make sure that it can operate the damper size. Also, additional mounting hardware may be needed at additional cost.
  2. The lead time for manufacturing may be extended since the clock does not start until after we receive the actuator and verify that it works.
  3. United Enertech's product warranty does cover a customer supplied actuator.

Can a standard control damper be mounted in the field with vertical blades?

No, standard control dampers do not have thrust bearings to hold the blades into place so the damper may not function properly or reduce the longevity of the damper and/or not operate at all.

Can a single section damper with an external mounted actuator have the actuator relocated to in the airstream (internally)?

Yes, but in most cases a jackshaft will have to be added and, in some cases, this may be not so easy of task to perform.

What blade seal material does United Enertech use on their control dampers?

We use a verity of material for our blade’s seals and blade seals are optional on most models. See chart below.

Damper ModelStandard or OptionalSeal Material

What damper model should I use in coastal regions (salt air)?

Model SW-155 (Opposed Blade) and SW-156 (Parallel Blade).

The dampers are constructed of clear anodized extruded aluminum frame and blades material, hollow aerodynamic shaped blades with end caps, linkage is aluminum and 316 stainless steel, bearings are two parts bearings with the inner made of acetal copolymar and the outer part is polycarbonate, blade seals and jamb seals are santoprene (TPV).

These materials hold up to salt-laden air and other chemicals.

What is the difference between a Backdraft Damper and a Pressure Relief Damper?

Backdraft dampers are designed to allow airflow in one direction and prevent reverse airflow. Pressure Relief dampers have an adjustable open trigger pressure and close upon a decrease in the differential pressure across the damper. Pressure relief dampers also prevent backdraft air flow.

Does United Enertech have counterweight kits for your backdraft/pressure relief damper?

Counterweight are primary factory installed but can be installed in the field with some difficulty.

Can United Enertech provide Explosion Proof (NEMA 7) or Weather Resistance (NEMA 4) actuators?

Yes, we use the Belimo ZS-260 housing with the Belimo Actuators.

Housing Listing - UL and CSA; Class I, Zone 1&2, Groups B, C, D, (NEMA 7), Class II, Division 1&2, Groups E, F and G, (NEMA 9), Class III, Hazardous (classified) Locations, outdoor application NEMA 4.

Are United Enertech manual balancing dampers supplied with a hand quadrant?

Yes, all manual balancing dampers are supplied with a factory mounted or shipped loose hand quadrant.

Does United Enertech have a thermally broken insulated blade damper?

Yes, Model TB-155/156

The thermally broken frame provides an insulating barrier in the ductwork. Thermally broken blades separate the warm and cold air inside the ductwork. Sanoprene jamb seals effectively seal the penetration of air from one side of the blade to the other.

Does United Enertech have a stainless steel commercial control damper?

Yes, Models CD-120/121 heavy duty 18-gauge frame and blades are available in 304 or 316 stainless steel construction.

Can I get replacement parts for my damper?

Yes, we can supply replacement parts like blade seals, actuators, hand quadrants, jack shafting, and in some cases, some linkage parts. We cannot supply replacement frames or blades. Consult United Enertech for details.

What is air performance/pressure drop? Why is it important?

Air Performance is the damper’s ability to pass air through open blades with minimal resistance.

HVAC equipment in your ductwork will cause a certain amount of static pressure. Static pressure will resist the dynamic pressure of airflow as it passes through the control damper, which creates a pressure differential that lowers the airflow’s dynamic pressure. This difference in pressure is commonly known as “Pressure Drop”.

A lower pressure drop means less restricted air flow and ,ore efficient air performance across the HVAC system.

What is air leakage? Why is it important?

Air leakage is the damper’s ability to close tightly to limit the amount of air passing through the damper.

In other words, Air Leakage is that wisp of air that get through the closed blade damper.

There will always be some air leakage, since no damper is airtight, but too much leakage can cause trouble. If left unchecked, this leakage can hinder performance and cause excess strain on your HVAC system.

What is an actuator and how is it different than a motor?

Damper actuators are either an electric or pneumatic device for positioning of dampers in HVAC systems. Actuators for dampers are supplied in multiple operation for example two-position non-spring return, two-position spring return, proportional (modulating) spring or non-spring return.

What is the difference between airfoil blades vs v-groove blades?

An airfoil blade is shaped like an airplane wing and provides excellent strength and control.

Triple V-Groove blades are flat-steel reinforced with V-shaped grooves for strength and are ideally suited for HVAC systems of 2,000 fpm and less air low.

What is the difference between an airfoil blade and aerodynamic shaped blades?

An airfoil blade is shaped like an airplane wing and provides excellent strength and control.