therma-fuser

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FORM 11.2 REV

LOWER COSTINSTALLATION

Even systems with large VAVzones cost more than systemswith Therma-Fuser diffusers.No special skills or equipmentare required to install Therma-

Fuser VAVjust connect thesupply air duct. Expensiveelectrical or pneumaticconnections and complicatedcontrols are eliminated. Delicatesystem powered devices whichneed larger more expensive fansare not involved. Maintenanceand recalibration are eliminated,even over the long term, due tothe dependability of the durablewax motor.

INDIVIDUAL COMFORTSELECTION ANDCONTROL

Every Therma-Fuser diffuser is aVAV zone of temperature controlproviding pleasing comfort inboth heating and cooling. The

built in thermostat sensesaverage room air temperaturefrom a sample of air induced intothe unit. It controls air flow toprecisely match the comfortrequirements of the room orportion of the room served.Occupants breathe easierknowing that their personaltemperature choice will not bechanged by someone else.

ONLY THERMA-FUSEVAV OFFERS THESEBENEFITS

Superior air distributionlongthrows, no dumping, moreentrainment, even temperaturdistribution, higher ADPI* and

better ventilation effectiveness Lowest cost per zone of contro

Lowest energy VAV terminalgreen VAV.

Low to no maintenance10 ywarranty.

Easily adapts to office change

*ADPI (Air Diffusion PerformancIndex) is defined in the ASHRAEFundamentals Handbook.

THE ECONOMICAL

THERMA-FUSER

THERMALLY POWERED VAV DIFFUSER

TB-CW VAV Cooling and Constant Volume Heating

TB-C VAV Cooling only


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How It WorksModel TB Therma-Fuser diffusers are 24 x24 (600mm sq.) ceiling diffusers with built inemperature controls and VAV damper. Theound damper moves up to close and down to

open, metering air flow into the room inesponse to room temperature. The damper is

mechanically positioned by a thermostat,which is both room thermostat and actuator.The room thermostat/actuator is a large brasscylinder containing a petroleum based wax.The wax melts and expands when heated,pushing the piston outward. A spring pulls thepiston inward when the wax cools.

Room Air Sensing

As with all diffusers, air circulates around theoom in a circular motion. Secondary air rises

under the diffuser, passes beneath theappearance panel and entrains with theprimary air at the outside edge of the diffuser.This secondary air best represents averageoom temperature.

Some of the average room temperature air isdrawn around the appearance panel and overhe room thermostat by the low pressure area

below the diffusion disc. This low pressurearea is created below the edge of the diffusiondisc by the venturi of primary air formedbetween the disc and the outside of thediffuser. When the Model TB is shutoff it

actually anticipates warming of the room.With no primary air flow, hot room air risescausing the room temperature sensingelement to warm and open the diffusion discslightly in advance of an increase in averageoom temperature.

Cooling Moden the cooling mode the damper opens on aise in room temperature. As the room warmshe wax in the room thermostat melts and

expands. This pushes the shaft out from theelement causing the control arm to go downopening the diffusion disc. When the waxcools and contracts, springs raise the controlarm closing the diffusion disc.

Warm-up (TB-CW only)

The warmup thermostat located in the neckof the Model TB senses primary airemperature as it enters from the duct. The

warm-up thermostat begins to operate at74F/23C and completes warm-up around80F/27C. Expansion of the warm-uphermostat moves the warm-up arm

downward pushing the diffusion disc open toachieve fast warm-up. Minimum Flow stopsare recommended for the TB-CW to allowwarm air to quickly reach the warm-uphermostat.

Options1) The TB Therma-Fuser diffuser is available

in types: TB-CW VAV Cooling andConstant Volume Heating, TB-C VAVCooling only and TB-D ManuallyAdjustable Damper

2) Frames are available for most ceilingtypes. See Acutherm ceiling approachesbrochure (Form 10.3).

3) Other Therma-Fuser diffusers are availablein 1x1/300mm sq. sizes, for linearapplications and interoperable VAVdiffusers for DDC networks.

4) Return air units are also available in allsizes.

Adjusting TemperatureThe room temperature set point is adjusted by screwing the thermostat in or out - in for coolerand out for warmer. Determine the set point by aligning the white indicator with the F or Cnumbers on the temperature scale. The room thermostat will screw in and out easier when thecontrol arm is held down.

Appearance panel hinged down

Denotes 750 fpm / 3.81 m/sec. inlet velocity. NC based on Lw (10-12 watts reference)10db.* Throw data is for air 20F/11C lower than room temperature. Throws for isothermal air are 40 to 50% greater.

Tested in accordance with ANSI/ASHRAE 70-1991, ANSI S12.31, ARI 890-2001, ISO 5219 and ISO 3741.

Ratings independently verified by Intertek Testing Services.

When using Acutherm directional baffles for other than four way blow patterns, reduce the maximum airvolume as shown in Acutherm Form 11.1.

When using Acutherm R-Rings, throws may be as low as 90% and NC 2db higher than those listed in the

performance guide.Metric performance guide available on request.

Performance Guide

Temperature set pointindicator (white)

Nominal Inlet Static Maximum Maximum Flow 25% Maximum Flow

Inlet Pressure Flow Throw - Feet* Throw - Feet*

Diameter In. wg cfm Vt50 Vt100 Vt50 Vt100

.05 100 3 2


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(con

Economical Individual Temperature ControlEach Therma-Fuser diffuser is a VAV zone. The thermostats, actuator and damper are built intothe diffuser. Temperature set point for cooling is adjustable between 70F/21C and 78F/26C.It easily zones open offices. Thermostat adjustment is right above the hinge down appearancepanel, and is easily accessed, but concealed and out of casual reach for tampering by others.

Superior Air DistributionUnlike the fixed opening diffusers used with VAV boxes, Therma-Fuser diffusers vary thedischarge opening as they vary air volume. The result is a constant discharge velocity with

comfort benefits of higher throws, no dumping, better room air movement and uniformtemperature distribution especially when turned down. For IAQ considerations minimum flowstops are available.

Better Senses Average Room TemperatureUnlike wall thermostats, Therma-Fuser thermostats are never in the wrong location. Theymaintain average temperature within 1F/0.9C of set point by sensing secondary air.Secondary air is the return air of the space the best place to sense the average roomtemperature.

Lowest Cost Per Zone of ControlA single trade can install Therma-Fuser VAV because it is self contained. When comparing totalinstalled cost including labor systems with Therma-Fuser VAV are clearly the lowest costof any VAV alternative because Therma-Fuser diffusers do not require wiring and are moreeasily installed. The Therma-Fuser diffuser directly accepts fire dampers as nothing protrudesabove the inlet.

Lowest Energy VAV TerminalTherma-Fuser diffusers have the lowest pressure drop of any VAV terminal which allows lowpressure systems and low energy fan motors. Fan energy is further reduced by a variable speeddrive when the system turns down. It saves refrigeration and heating energy because no portionof the building is overcooled or overheated. No energy is required to operate the Therma-Fusercontrols.

Low to No MaintenanceCustomers using Therma-Fuser diffusers for as long as 20 years testify that no maintenance atall has been required. What VAV box or control offers similar results? Or the Acutherm 10 yearwarranty? The construction is simple very few moving parts. The construction is robust large thermostats, heavy metal, and large tension springs. Forces between thermostats are inone straight line. The complete mechanism is visible for trouble shooting by simply hingingdown the appearance panel. Undo four screws to remove the complete mechanism.

Easily Adapts to Office Layout ChangesNo Therma-Fuser zone is split when office walls are put up or moved, a common problem withVAV boxes.

Aesthetic Appearance, Architectural LookThe clean lines of the architectural square panel harmonize with the ceiling resulting in avirtually unbroken ceiling plane. Large solid appearance panel has no distracting holes or slots.

Special Features

Tight ShutoffZero leakage upon shutoff up to 0.4wg/100Pa static pressure (.36wg/90Pa for neck models). To speed opening of theTB-CW model for warm-up either minim

flow stops or blow open are recommendeinitially cause warm supply air to reach twarm-up thermal element.

Minimum Flow StopsMinimum flow stops are available as a fainstalled option or can be field installed tprovide minimum airflow at all times.

Maximum Flow StopsMaximum flow stops are factory set toachieve the rated air flows.

Blow Open For PurgeBuilding purge is useful for smoke evacution, morning stale air removal and mornwarm-up. The 12 neck size is recommeto blow open. Use reducers to connect it

smaller duct sizes. Flow through a Modelwith 12 neck is 300cfm/510CMH at.7wg/175Pa and 600cfm/1020CMH at.85wg/210Pa.

COANDA EFFECT

10 neck at 25% of maximum cfm with55F supply temperature

ENTRAINMENT EFFECT

Based on 0.2 cfm/sq. ft. with 55 F supair temperature.

Warm Up Arm (TB-CW Only) Warm Up Thermostat (TB-CW Only)

Control ArmAppearance Panel

Room Temperature

Sensing Thermostat

Diffusion Disc

Copyright Acutherm 1995, 2008


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Copyright Acutherm 1995, 2008

Subject to change without notice.Form 11.2 REV 0801 Supersedes Form 11.2G295Printed in the USA on Recycled Paper with Soybean Based Ink

1766 Sabre StreetHayward, CA 94545Tel: (510) 785-0510Fax: (510) 785-2517http://www.acutherm.come-mail: [email protected]

The Individual

Temperature Control People

TEN YEAR WARRANTY

Acutherm warrants that its Model TB Therma-Fuser diffuser, exclusive of any options

and accessories (whether factory or field installed) shall be free from defects in material

or workmanship for a period of ten (10) years from the date of shipment and agrees to

repair or replace, at its option, any parts that fail during said ten (10) year period due toany such defects which would not have occurred had reasonable care been taken,

provided that such parts have been inspected by Acutherm and found defective and

provided that the diffusers have been given normal and proper usage and all parts and

controls remain unaltered. Acutherm makes NO WARRANTY OF MERCHANTABILITY

OF PRODUCTS OR OF THEIR FITNESS FOR ANY PURPOSE OR ANY OTHER EXPRESS

OR IMPLIED WARRANTY WHICH EXTENDS BEYOND THE LIMITED WARRANTY

ABOVE. ACUTHERMS LIABILITY FOR ANY AND ALL LOSSES AND DAMAGES

RESULTING FROM DEFECTS SHALL IN NO EVENT EXCEED THE COST OF REPAIR

OR REPLACEMENT OF PARTS FOUND DEFECTIVE UPON EXAMINATION BY

ACUTHERM. IN NO EVENT SHALL ACUTHERM BE LIABLE FOR INCIDENTAL,

INDIRECT OR CONSEQUENTIAL DAMAGES OR DAMAGES FOR INJURY TO PERSON

OR PROPERTY. Acutherm shall not be responsible for freight to or from its plant in

connection with the inspection, repair or replacement of parts under the terms of this

limited warranty nor for cost or installation.

SYSTEM DESIGN

The best control for heating/cooling unitssupplying air to VAV terminals is a dischargehermostat which maintains a constant supply

air temperature. With DX equipment these area high and low limit. Use a room thermostator changeover between heating and cooling

modes. For hybrid systems (part VAV andpart constant volume) control the heating/

cooling supply unit with a thermostat in oneof the rooms with a constant volume diffuser,preferably the space with the greatest load.For both VAV or hybrid systems, the fanshould run continuously.

The constant discharge velocity of Therma-Fuser diffusers at varying air flow providesgood room circulation which reduces strati-ication. Keeping heating supply air tempera-ures as low as possible will further reduce

room air stratification to a negligible level.

Static pressure at the inlet of the Therma-Fuser diffuser should be between .05wg./12Pa and .25wg./62Pa, at full and partial airlows. Static pressure below .05wg./12Pa will

result in low air flow and less induction.Above .25wg./62Pa, Therma-Fuser diffusersoperate well but excessive noise may result.Use minimum flow settings where Therma-Fuser tight shut off is not needed.

f the system turns down more than 30%,static pressure should be controlled. Includedn the options for static pressure control arean speed control and bypass dampers. Zone

dampers are recommended where severalzones share a higher pressure duct or riser.

When designing ducts, if Therma-Fuserdiffusers are to deliver nominal volume at inletSP of.15wg./37Pa and if a maximum SP of25wg./62Pa is to be held for quiet operation,

size the duct for a maximum pressure drop of1wg/25Pa between the first and last takeoff.

Manual balancing dampers should be used athe takeoff for each diffuser. Manual balancing

dampers may not be required with ductsdesigned to Acutherm specifications.

Because Therma-Fuser diffusers control roomemperature by sensing room air induced uphe center of the space, care should be taken

not to disturb room air induction andentrainment. For example, location next towalls or dropped lights results in the reflectionof primary air back at the Therma-Fuserdiffuser.

Avoid this with a three-way blow pattern orrelocate either the Therma-Fuser diffuser orhe light.

Acutherm has how to system designbrochures for almost every ducted air system.For specific recommendations refer to thebrochure for your system.

GUIDE SPECIFICATION

(Suitable for Part 2 of CSI Specification section 15840) Material in italics applies only to modelTB-CW.Delete the italics for model TB-C.

2.2 Thermally Powered VAV Diffusers

A. Thermally powered VAV diffusers shall be a complete VAV terminal and thermostatself-contained in a nominal 2 X 2/600 x 600 mm diffuser. They shall be thermally poweredwith one room thermostat/actuator and one changeover thermostat/actuator. External wiringor pneumatics shall not be allowed.

B. The VAV diffusers shall have a micrometer type temperature set point adjustment with anindicator that moves along a 70F/21C to 78F/26C temperature scale. The initial set pointshall be factory set at 74F/23C.

C. In the cooling mode the VAV diffusers shall open on a rise in room temperature.

D. The diffuser shall be equipped with a changeover thermostat. The changeover thermostatshall be factory installed and adjusted to fully open the diffuser when the supply air tempera-ture rises above 80F/27C and return to the cooling mode when the supply air temperaturefalls below 68F/20C. Nothing including the changeover mechanism shall extend above theinlet of the diffuser.

E. The diffuser shall have zero leakage upon shutoff for static pressure below 0.4wg (0.36wgfor 12 neck models) Maximum flow shall be factory set for the rated air flow. Optional:Minimum flows shall be factory set at ___ % of maximum flow.

F. Manufacturers ratings for flow and sound shall be verified by an independent testing labora-tory certified for industry testing. The manufacturer shall warrant that the VAV diffuser shallbe free from defects in materials and workmanship for a period of ten years from date ofshipment.

G. The VAV diffusers shall have a solid (no holes or slots) appearance panel which unlatchesand hinges down to allow hands to be free for adjusting temperature set point or minimumflow. The appearance panel shall have a latch clip. Instructions for the diffuser shall be on theinside of the panel. The complete control mechanism shall be visible when the panel ishinged down.

H. Supply air to the VAV diffuser shall be constant temperature (may be reset to anotherconstant temperature). Supply air shall be limited to no lower than 50F/10C on cooling andno higher than 120F/49C on heating. The heating high limit shall be as low as possible butno lower than 80F/26.5C.

THERMA-FUSERTHERMALLY POWERED VAV DIFFUSER

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