Trenton Yarbrough, national sales manager, reviews two innovative products in the Titus booth from the AHR EXPO held in Chicago.
Thursday, January 11, 2018
One of the more frequently asked questions we receive in application engineering is in regards to surface mounting Titus diffusers. When a ceiling grid is not present, surface mounting is specified and the installation questions arise. Linear diffusers are available with concealed mounting, square and rectangular diffusers with square or round inlets are not.
The most important thing to know about surface mounting is that it normally requires additional framing to which the units will be secured. We often receive calls for mounting instructions after the sheetrock has been installed which is too late to provide framing without removing the installed surface.
|Titus mounting frames make installation of grilles, diffusers and other ceiling components in plaster and sheet rock ceilings as simple as inserting them in a standard T-bar type ceiling.|
Framing requirements will vary from one job to the next, but there are some general guidelines and terminology we use.
Obviously installing screws in the face of a diffuser will work as it does for grilles but the duct return flanges behind diffuser edges are generally not available to provide a secure mounting base for screws. Also, many surface mount frames do not have a flat surface nor is there a screw hole fastening option available. Furthermore, screw fastening certainly does not enhance the aesthetics of the installed diffuser.
All sheetrock is mounted to ceiling joists. Joists are usually parallel to each other and spaced at two to three feet apart depending on local building codes, and in most cases, the framing for the diffuser can be mounted to the top of, and perpendicular to the joists. Screws are then used to mount the back pan to the framing. Framing members should be centered on the diffuser location to allow sufficient clearance for the diffuser inlet and associated duct. Additional care must be taken so as to avoid any protrusions or features that will occupy the space necessary for the framing on the rear side of the diffuser. Framing should also be at a depth that will allow the diffuser to firmly seat against the sheet rock. Most diffuser back pan heights are less than the depth of the joist. The sheet rock or ceiling surface is installed into an opening provided for the diffuser.
The diffuser core should be removed prior to installation to allow for screws to be installed in the top of the back pan transition; this is the flat portion on the rear of the back pan. Screws are then used to secure the back pan to the framing. It is helpful to use washers to prevent the screw heads from being driven through the back pan if the framing is not flush to the rear of the pan. In most cases the screws can be placed in a manner to not be visible from the occupied space after the diffuser core or face is re-installed.
As an alternative to the framing process, and one that we suggest if the ceiling surface has been installed without prior framing for the diffuser mounting, is to use our rapid mount frame. The TRM frame can be installed in the space between the joists following the installation of the ceiling.
The TRM replicates a standard ceiling grid module and a lay-in (type 3) frame diffuser. The diffuser can then be laid in the TRM frame. The TRM frame does add a border to the finished appearance of the diffuser, but also can be utilized as an access port to the space above the ceiling by simply pushing the diffuser up and out of the opening.
While the TRM does represent additional diffuser cost, the reduced labor requirement and flexibility of the installation sequence offers a distinct advantage.
The TRM is available in steel and aluminum and is ordered as a separate line item. Remember, when using the TRM frame, the (type 3) diffuser frame must be used instead of the (type 1) diffuser frame.
For information on this topic/product, please contact Mark Costello at email@example.com or Titus Communications at communications
Monday, December 4, 2017
Laboratories are not known for their energy efficiency. These spaces can consume up to 10 times more energy than office buildings, leading facility managers and engineers to prioritize finding ways to reduce energy consumption and operating costs – without sacrificing efficiency. One way to do that is by using chilled beam systems, which have grown increasingly popular in the U.S. in the last decade. Chilled beams have proven to be viable alternatives to traditional Variable Air Volume (VAV) systems, demonstrating energy savings upwards of 20% in laboratories compared to VAV Reheat.
To better understand how and why chilled beams are effective in laboratories, let’s examine the usage of these systems, strategies for effective design and operation in laboratory environments.
How Chilled Beams WorkThere are two types of chilled beams, passive and active.
Passive chilled beams cool spaces using natural convective forces and include a heat exchange coil in an enclosure that is suspended from the underside of the building structure. Chilled water flows through the coil and cools the surrounding warm air; the denser cool air falls back into the space. Passive beams require separate air diffusers to carry dehumidified ventilation air into the space, usually at the floor level. For this reason, they are rarely, if ever, used in laboratories.
Active chilled beams rely on pretreated primary air delivered from central air-handling units (AHU’s) to pressurize a series of small induction nozzles within the chilled beam unit. These nozzles create jets of air causing room air to be induced across a coil where flowing water heats or cools this (secondary) air.
Both passive and active beams are designed to provide sensible cooling only with the latent cooling (i.e. space dehumidification) being accomplished by the central AHU’s. Depending on the lab use and loads, the primary air is delivered to the active chilled beams as constant or variable volume, with the cooling/heating output being controlled by either two position or modulating control valves to vary the water flow through the integral coils. Chilled beams can be integrated into suspended ceiling systems or hung from the structural slab for exposed use.
Because chilled beams provide most of a space’s sensible cooling, the central air handling system can be much smaller than usual since its primary purpose is to provide the ventilation air and latent cooling to the space. This effectively decouples the sensible cooling from the ventilation requirements. And since chilled beams have no moving parts, maintenance is limited to infrequent cleaning of the coils.
Laboratory HVAC Energy Use
The ventilation requirements for laboratories are different from the needs of a typical office building. Minimum ventilation rates are dictated by safety requirements rather than cooling or heating loads, while maximum rates are determined by either the make-up air requirements for the fume hoods or the sensible cooling requirements of the space (if the equipment cooling load is high). There are special requirements for laboratories where chemicals or gases as present as well. They cannot use recirculating AHU’s, so the ventilation air must be 100% outdoor air at all times.
Overall, these parameters can result in an air system sized for ventilation air changes rates from 6-to-12 or more, depending on the lab use and equipment loads.
A traditional "all-air" system will typically deliver cool air to the building at around 55°F when there is demand for OA dehumidification, or to satisfy the sensible cooling requirements of the highest load lab in the building. This often results in a mismatch of ventilation air and cooling requirements, forcing the zone VAV boxes to reheat the cooled air to prevent over-cooling the space when sensible loads are low. Even more reheating occurs when ventilation air is increased to provide make-up air for the fume hoods, resulting in lower efficiency.
And decreased efficiency hurts the bottom line: Energy studies have shown that cooling and reheating air can account for as much as 20% of the total HVAC energy costs in laboratories.
Eliminating Reheat and Saving EnergyActive chilled beams can help boost energy efficiency in a number of ways.
One is by eliminating most of the reheat energy resulting from decoupling ventilation and cooling demands. With active chilled beams the ventilation air can be delivered at a warmer temperature through a 100% outside air AHU, commonly known as a dedicated outdoor air system (DOAS). With the DOAS primary air set to around 65-70°F space overcooling is far less likely to occur, even in labs calling for high volumes of make-up air for the fume hoods. The water coils within the chilled beams provide cooling or heating capacity on a zone-by-zone basis. During OA dehumidification hours, the DOAS unit removes moisture by cooling the air to 55°F or below and is reheated with energy recovered from the exhaust air using enthalpy wheels, heat pipes or run around coils.
Another is through using water to transport heat, resulting in an air system size reduction of 60 percent compared to VAV Reheat. This feature reduces overall fan energy consumption and is ideal for laboratories with high sensible loads and low fume hood densities.
The increased efficiencies associated with chilled beams also help laboratories maximize their space. The reduced reheat and boosted transport efficiencies of water mean the main plant items (chillers, boilers and AHU’s) can be smaller than with a traditional system’s. The duct distribution system is also more compact, which reduces service congestion in the ceiling interstitial. Finally, a smaller system can translate into lower first costs for an HVAC system compared to VAV Reheat.
There is a challenge with using chilled beams in labs, however: the need for dual chilled water temperatures. Specifically, a low temperature circuit (LTCHW, 40-45°F) for the DOAS and medium temperature circuit (MTCHW, 56-58°F) for the active chilled beams. The most common strategy is to design a closed secondary loop separated by a plate and frame heat exchanger, ensuring that the LTCHW cannot accidentlly find its way into the active chilled beams. That could potentially cause condensation on the coils.
Building Humidity Control
The best chilled beam system designs equip the building with a small number of room dew point sensors. This allows the building management system to monitor the humidity across the building and reset the DOAS air dew point or reschedule the MTCHW loop temperature if the space dew point rises above a preset temperature. Facilities engineers can use the room dew point sensors to precisely control the amount of OA latent cooling at the DOAS unit to further reduce energy costs, an operational strategy that is more difficult to accomplish with a VAV Reheat system. Despite being used in early system designs; pipe mounted condensation sensors are rarely used today since room dew point monitoring provides enough advance warning of potential condensation.
Chilled Beams Misconceptions
Despite growing in popularity over the last 10+ years, there are still a number of persisting myths and misconceptions about chilled beams. For instance, despite there being several successful installations in the likes of Florida, Hawaii and even the Caribbean, there is still hesitancy among designers and owners to use the system in humid climates because of condensation concerns. The reality is the system can be used in any building where the space humidity can be controlled; however, energy savings will not be realized in applications where the internal latent gains are high, such as wet labs. In other cases, engineers may be reluctant to consider active chilled beams because they are simply unfamiliar with the design of these systems.
Cost is also a concern. Mechanical contractors unfamiliar with chilled beams will be wary of underpricing a system they have never previously installed, but several case studies have shown chilled beams have been installed cost competitively with traditional systems.
It didn’t happen overnight, but a larger number of engineers and facility managers have realized – and are realizing -- the advantages chilled beam systems can offer to laboratory applications, specifically in terms of energy and space savings. Debunking misconceptions and educating laboratory owners on the construction of and design using chilled beams is the first hurdle to overcoming barriers to adoption. Then it’s about showing what the technology can do. Those who have installed these systems have realized greater energy efficiency, substantial cost savings and improved performance.
For information on this topic, please contact Nick Searle at firstname.lastname@example.org or Titus Communications at communications
Tuesday, October 10, 2017
Monday, September 11, 2017
Titus has participated in the variable air volume (VAV) diffuser market for a number of years now. We currently offer two great options; our T3SQ-4 Thermal version and T3SQ-2 Digital version. They both have features that make them great for their particular application. The benefit of the thermal T3SQ-4 is that it requires no power, making it ideal for applications where energy is the focus. The benefit of the digital T3SQ-2 is you get the great accuracy you normally get with digital controls as well as the added benefit of individual comfort control.
Helios - the ambient-light powered digital vav diffuser
Introducing HELIOS, the new line of energy-harvesting VAV diffusers that creates a new standard of individual comfort and control for indoor environments. Powered by the same ambient energy-harvesting technology as our popular EOS diffusers, HELIOS is easy to install, requiring no special wiring or ductwork. That saves money!
Wherever individual indoor comfort is needed, HELIOS is a perfect solution. It’s easy to install. Each individual unit uses a unique digital logic system so it can operate on a narrow temperature band, giving more unique zones and much greater user control. Gone the days of inter-office thermostat feuds.
HELIOS solves many problems for engineers and contractors. The individual comfort functionality addresses LEED EQ Credit 6.2, while the fact that units require no outside electrical power means complying with LEED EA Credit 1, too.
The HELIOS brings new meaning to the term "stand-alone". For the installer, and the individual placing the order, the best feature for this diffuser is no complicated wiring or cabling to count or keep track of. No longer do you have to concern yourself with whether or not you have enough, or the correct, cables. The distance from the power supply is not an issue anymore because the power source is the light in the room. No longer will you have to drag cables across ceiling plenums and down walls or do any time-consuming trouble shooting because you suspect a cable is bad. Like our T3SQ, the HELIOS still has various neck sizes to accommodate different size ducts. It also has a neck heater for supplemental heat. Look for this innovative product to be available in the Fall of 2017.
Wednesday, August 16, 2017
Throw value means how well air moves across a room from a vent, or diffuser. A major factor in the throw value is the terminal velocity of the air coming from the diffuser. When air flows out of a supply, we’d like to know the result. Since we cannot see what is happening, we use throw as one indicator of a register’s performance abilities.
Throw is measured in feet from the face of the register along the primary direction of flow. However, a throw distance is meaningless unless given a point of reference.
We use the term terminal velocity in conjunction with throw to describe what the air is doing at the end (or terminus) of the designated throw. A typical terminal velocity is 100 feet per minute (FPM). This means that no matter how fast the air is blown out of the register, the throw tells us, at that distance, the air has slowed to 100 FPM. Titus throw values are presented using three industry standard terminal velocities: 150 FPM, 100 FPM, and 50 FPM. All throw values are obtained utilizing isothermal air (ASHRAE Standard 70-2006). Isothermal air is the same temperature as the room air allowing test data to be repeatable and predictable.
The supply air velocity measured at the register face determines how far the throw will be. The faster the air exits the face, the farther the air will travel into the room. The resistance of room air to the supplied air will cause the supply air to slow down.
Eventually, the supply air will slow enough to become ineffective in mixing with room air. The point that air velocity becomes ineffective is called the terminal velocity. Generally terminal velocity ranges from 150 down to 50 FPM.
The distance from the face to where this terminal velocity occurs is the throw.
Throw patterns of a sidewall grille that illustrates the air velocity becoming gradually less the farther away it moves from the grille
EXAMPLE: The performance data for a sidewall supply register states that all throws are at a terminal velocity of 100 FPM. No matter what the face velocity is or how much air is being delivered, each throw is measured at the point where the supply air stream has slowed down to 100 FPM.
If we use 50 FPM as the terminal velocity, the throws are longer (farther from the face). At the register face where the throw is "0," the velocity of the supplied air is highest. No matter what distance we choose to stop moving away from the face, there will always be a corresponding velocity that becomes less and less the farther away we move.
For more information on this topic, please contact our GRD department at email@example.com or Titus Communications at communications
Thursday, July 6, 2017
Providing thermal comfort for occupants is a primary goal of any air-distribution system. Industry guidelines offer designers a roadmap on how to attain those goals along with meeting codes such as LEED. ASHRAE Standard 55-2013 Thermal Environmental Conditions for Human Occupancy and ASHRAE Standard 62.1-2010 Ventilation for Acceptable Indoor Air Quality are two such guidelines. These standards can help optimize the health, comfort and energy efficiency in buildings.
Defining ASHRAE Standards
The occupied zone is defined by ASHRAE 55-2013 as: The region normally occupied by people within a space, in absence of known occupants, generally considered to be between the floor and 6 ft. level above the floor and more than 3.3. ft. from outside walls/windows or fixed heating, ventilation, or air-conditioning equipment and 1 ft. from internal walls.
An adequate supply of ventilation air to the space’s breathing zone is also a design requirement. Ventilation air is defined by ASHRAE 62.1 2016 as: That portion of supply air that is outdoor air plus any recirculated air that has been treated for the purpose of maintaining acceptable indoor air quality. And the breathing zone is the region within the occupied space between planes, 3 and 72 inches above the floor.
Thermal Comfort: Not One-Size-Fits-All
Temperature: ASHRAE 55 requires allowable vertical air temperature difference between head and ankles to be no more than 5.4F (3.0 C).
Humidity: There is no defined range of humidity level but the dew-point temperature is required to be less than 62.2 F.
Clothing insulation: Keep in mind the range of operative temperatures where people wearing lighter clothing (shorts, skirts, short-sleeve shirts, etc.) and heavier clothing (pants, long-sleeve shirts, etc.) is narrow.
Air velocity: Spatial velocities should be less than 50 feet per minute (fpm) during cooling mode and less than 30 fpm during heating mode.
Activity level of the occupants: An office's metabolic rate is typically between 1.0 (sedentary) to 1.3 (casual movement)
Partially mixed (most underfloor air distribution systems)
Fully mixed (overhead distribution)
Fully stratified (displacement ventilation)
Conserving energy by comfort-conditioning a space’s lower occupied level and stratifying its upper level is the goal of partially mixed systems. Swirl diffusers or rectangular-shaped outlets that deliver conditioned air from the plenum under the floor help enable occupant comfort.
A challenge for these systems are perimeter zones for partially mixed systems. For one, the loads are dynamically changing due to outdoor solar and air temperature changes. And two, choosing outlets limit the throw of the air pattern present a design hurdle. Placing a low-profile fan-powered terminal unit below the floor near the perimeter is one way of designing for perimeter zone control.
Partially mixed systems have a number of advantages. They are ideal for situations where cabling is provided to each work stations. They can also have a lower first cost than fully mixed systems, depending on the design. And because these systems are designed with low supply air pressure, they help save fan energy.
When selecting an air outlet consider the air’s pattern of delivery to the space. For example, a ceiling diffuser typically has either a circular (radial) or cross-flow (directional) discharge air pattern. By providing less drop and more uniform temperatures, a circular pattern is ideal for variable air volume (VAV) cooling. The cross-flow air pattern has longer throw, but its reduced induction means it may lose ceiling effect, which creates drafts in the occupied zone.
Perimeter heating is another factor. ASHRAE Standard 62.1-2016, which ensures ventilation air supplied to a space also be delivered to the breathing zone, has a list of requirements that must be accounted for (Table 6-2). For ceiling supply of warm air with a ceiling return, the requirements for heated air are to reach a terminal air velocity of 150 feet-per-minute to within 4.5 ft. of the floor. The differential temperature between warm supply air and space temperature with a ceiling return must be 15 degrees or less. When the heating supply-air temperature exceeds the 15 degree limit, the ventilation air volume must be increased by 25%.
Thanks to their flexibility, fully mixed systems can meet most applications’ air distribution challenges. They also can be very economical, since they typically have the lowest first cost.
Fully stratified system shown at left
Through an outlet placed at floor level that’s centrally located or near or in walls, these systems condition spaces via discharged cool supply air. Low velocity air (<80 fpm) is discharged horizontally across the floor; until it hits a heat source this air moves with little mixing across the floor. This cooled air will mix with radiant heat, form a source, then stratify toward the ceiling.
Thermal displacement ventilation (TDV) systems offer energy savings and efficiency that other systems can’t match. They require less ventilation air to comply with ASHRAE 62.1, and they can use air side economizers and warmer temperatures to match supply air temperatures. And while TDV systems of the past typically required a heating system that was separate, but new systems are able to heat and cool using a single DV unit, simplifying their installation and maintenance.
Designing for Comfort Pays Dividends
There are many ways to establish and maintain occupant comfort. Which system best accomplishes this depends on what your space requires, but the important thing is to keep people comfortable, period. After all, studies have shown that occupants whom are comfortable are more productive, which will pay dividends for years to come.
For information on this topic, please contact Jim Aswegan at firstname.lastname@example.org or Titus Communications at communications