ACG 7th Annual Conference on Total Building Commissioning
COMMISSIONING ACTIVE BEAMS
Presented By
Darren Alexander
Twa Panel Systems Inc.
April 15, 2011
Agenda
Introduction to Active
(Chilled) Beams
Fan energy savings
De-coupled ventilation systems
Principles of operation
Active beam benefits
Suitable areas for active beams
Psychrometrics
Condensation risks
DOAS Information resource
Placement within the ceiling
Inherent comfort with active beams
Beam acoustics
1/3rd octave band analysis
Installation & Maintenance
Fastening beams to the structure
T-Bar mounting detail
Exposed / pendant type units
Installation “Tips”
Sample active beam packaging
Beam mounted with aircraft cable
IOM and precautions
Coil maintenance
Unit cleanliness prior to start-up
Agenda
Air-side control and
measurement
Ducting for equal static pressure
Vary primary air pressure for
capacity control?
Recommended CAV damper types
Damper “Tips”
Acoustics
Balancing and confirmation
Challenges
Water-side control and
measurement
Self-regulating thermal capacity
Modulating water flow
Challenges
“Tips” for easier commissioning
Start-up
Sample start-up sequence
Shop drawings and schedules as a
tool for commissioning
Sample spaces serviced by
active beams
Introduction to Active (Chilled) Beams
Introduction to Active Beams
Fan energy savings
Introduction to Active Beams
De-coupled ventilation systems
Fan Coil Units
VAV Systems
VRV System
(Variable
Refrigerant
Volume)
Active Beams
Energy Usage
Noise Level
Output
Comments
Medium/High
Medium
32-64 Btuh/ft2
Adaptable
solution
Low
Low/Medium
32-64 Btuh/ft2
Very efficient
all-air system
High
Medium
Btuh/ft2
Possible high
maintenance
costs
Btuh/ft2
Very low
maintenance
costs
Low
Low
48-64
32-125
Introduction to Active Beams
Principles of operation
Introduction to Active Beams
Active beam benefits
1) Lower overall air volume processed by the primary air handling unit. (0.25-0.5 cfm/ft2)
2) Higher entering chilled water temperatures: (55°F-61°F).
3) Lower hot water temperatures: Select beams for cooling duty, then choose
appropriate hot water temperature for heating.
(i.e. usually less than 120°F. Beam discharge air
should be less than 15oF warmer than room design
temperature to limit the risk of stratification.
4) Suitable for use with water-to-water heat pumps, and has the potential to double the
COP of a dedicated chiller loop.
5) Self regulating secondary capacity: Approach = Room Temperature - Supply water
temperature
6) VAV control:
Can be used to strictly limit room air velocity, provide linear
temperature control, and additional fan energy savings for areas with
highly variable latent loads.
(i.e. Labs, Boardrooms, coffee rooms, classrooms, etc…)
Introduction to Active Beams
Suitable areas for active beams
Yes / Maybe
Spaces with moderate latent loads
High sensible loads
Office spaces
Schools
Desktop farms
Labs – Check Psychrometrics and
codes
No
Kitchens
Atriums
Zones with high latent loads
Locker rooms
Pool areas
Entry vestibules
Computer rack rooms
Areas with high ceilings (i.e.
>14’)?
Patient Recovery Rooms (YES?)
Introduction to Active Beams
Psychrometrics
Option 1
Option 2
Primary air dew
point
48°F
51.5°F
Room air dew
point
55°F
57.8°F
Secondary CWT
55°F
58°F
Dehumidification
0.002 lbs/lbDA
0.002 lbs/lbDA
RESET FOR ENERGY
SAVINGS!
Introduction to Active Beams
Condensation risks
Areas of greatest condensation risk:
1)
2)
3)
4)
Near points of entry to the building
At the perimeter, with mixed-mode ventilation
Structures with poor building envelopes, including retrofit applications
In areas with highly variable latent loads:
• Board rooms
• Lunch / coffee rooms
• Etc…
Condensation prevention strategies may include:
1) De-activation of secondary chilled water supply, by zone, via loss of dew-point from
sensors mounted to CWS lines. (… or via combination: DB / RH zone stats, or other…)
2) Tempering secondary chilled water supply by zone via:
• Three-way mixing valve
• Injection pumps
3) Etc…
Introduction to Active Beams
DOAS Information Resource
1) http://doas.psu.edu/
2) Not all primary air handling systems are DOAS!
Introduction to Active Beams
Placement within the ceiling
P2 drops rapidly
moving into the
room
P3 = ½ at 3ft into
occupied zone
Introduction to Active Beams
Inherent comfort with active beams
Active Beam
Diffuser
Introduction to Active Beams
Beam acoustics
45
LwA [dB(A)]
40
Chart reports
acoustic values
without room
attenuation
effect
35
30
25
2'x8' - D
20
Active beams can
be very quiet!
2'x8' - A
15
0.4
0.6
0.8
1
Plenum Pressure [“w.c.]
1.2
1.4
Introduction to Active Beams
1/3rd Octave band analysis
Owens Corning Acoustic Testing
• Acoustic test standards may include:
 ISO3741
 ASHRAE Std. 70
• Reverberant chamber (No Attenuation)
Manufacturer A = Worst Case
•
•
•
•
•
2’ x 8’ – D nozzle @ 1.20”w.c.
Peak in the 2.5 KHz Band
Lw (dB) = 39.1
LwA (dBA) = 38.8
NC = 24 !
Installation and maintenance
Installation and maintenance
Fastening beams to the structure
Upstream damper
at SMACNA
recommended
minimum distance
Drywall
N.B. - Include seismic restraint
where required by code
Installation and maintenance
T-bar mounting detail
Width
Length
Installation and maintenance
Exposed / pendant type units
Coanda wings
required for
proper throw
characteristics
Installation and maintenance
Installation “Tips”
1. “Rough-in”: piping, ducting, concrete threaded inserts, and beams, prior
to T-bar installation. Lower beams into T-bar for final positioning.
2. Store beams on-site indoors whenever possible, in a low traffic area, and
otherwise covered for protection from the elements.
3. Leave plastic film on each unit to minimize site damage, and prevent coil
/ unit fouling.
4. Match beam label to schedule; - beams look alike! Confirm that the right
beam is in the right room. Contractor suggestion: - Confirm packing slip
matches shop drawing requirements upon receipt of material.
5. Limit flexible duct to no more than 10’. Avoid sharp turns in ductwork.
Installation and maintenance
Installation “Tips”
6. Plan for access doors, and possibly welded-aluminum frames, with beams
mounted in dry-wall ceilings.
7. Manage glazing surface temperatures by planning discharge
configuration. With high quality glass, beams which discharge
perpendicular to the glazing, are typically preferred.
8. Stainless steel flexible hoses allow for some adjustment within the ceiling
grid.
Installation and maintenance
Sample active beam packaging
• Units remain “as-new”
until final commissioning
and “turn-over”.
• Recyclable packaging
materials.
• Face-to-face, and backto-back crating minimizes shipping damage.
Installation and maintenance
Beams mounted with aircraft cable
Note protective
film at inlet of
unit mounted coil
Installation and maintenance
IOM and precautions
• Read the manufacturer’s Installation Operation and Maintenance Manual
• Pay particular note of any precautions which have been identified as high
risk conditions. (i.e. minimum two people to handle beams 6’ and larger,
pulling on un-latched door may cause hardware failure, be cautious of
sharp edges, limit flex duct connections to 10’ maximum, etc…)
• Do NOT circulate water through the beam mounted coil until the “mains”
have been properly “de-greased” / flushed.
• Do NOT remove protective plastic film from beam body until the space
has been appropriately cleaned, to minimize fouling of the coil
• DO lower the secondary chilled water temperature slowly to limit the risk
of condensation damage during start-up.
• This list is NOT exhaustive, co-ordinate the start-up
requirements with the mechanical consultant.
Installation and maintenance
Coil maintenance
• Active beams require practically no maintenance. If the coil remains dry, as
expected, there is very little risk of fin “bridging”.
• Recommended cleaning schedules typically involve lowering, or removing
the perforated doors / panels, in front of unit mounted coil, at 6-Months,
and 1-Yr., to establish a maintenance schedule. Areas with higher airborne
contamination require more frequent cleaning.
• Often, cleaning schedules can extend to between 3-5 years in spaces
subject to weekly housekeeping.
• Higher housekeeping frequency, reduces the intervals between coil
maintenance.
Installation and maintenance
Coil maintenance
Vacuum with or
without a “horsehair” bristle brush
Installation and maintenance
Unit cleanliness prior to start-up
• Leave active beams wrapped to prevent fouling unit or coil.
• Wipe unit with a damp rag to remove surface dirt, or vacuum with a
horse-hair bristle brush.
• Do NOT scrub the paint. Damage to the finish may occur.
• A soft bristle brush and mild detergent with water, can be used to remove
stubborn “smudging”, if required.
• Beams ship with repair kits for surface scratched units. Do NOT spray
the unit directly with “spray-bomb” type matched paint. Use artist paint
brush, supplied with repair kit, to apply the paint to the affected areas.
Air-side control and measurement
Air-side control and measurement
Ducting for equal static pressure
Pt = Ps + Pv
Pt = total pressure (”w.c.)
Ps = static pressure (”w.c.)
Pv = velocity pressure (”w.c.)
If velocity pressure is kept negligibly low, then the same static pressure will
hold throughout the duct. ( i.e. Only if transport loss can be neglected).
Pv = 0,5 x r x v2
Pv = velocity pressure (”w.c.)
r = air density (0.075 lbs/ft3)
v2 = air velocity (fpm)
At < (590 fpm) duct air velocity Pv < (0.02”w.c.)
At < (590 fpm) transport
Ø = (5”) < (0.001”w.c/ft.)
Ø = (8”) < (.0007”w.c./ft.)
Low air volumes required for beams makes using round ducting practical
and low air velocity achievable.
Air-side control and measurement
Vary primary air pressure for capacity control ?
Total capacity
• CAV primary air flow is
typically simple with
orifice plate “Iris” type
dampers.
• Varying the plenum
pressure yields a non-linear
capacity response. Tight
control with variable
plenum pressure is typically
impractical.
Static pressure
Air-side control and measurement
Vary primary air pressure for capacity control ?
Total capacity
• VAV airflow solves the issue
of over-cooling a space with
un-tempered primary air.
• Plenum static pressure
range (0.3”-1.2” w.c. max)
• VAV diversity advantage with
tight P-band control.
• Eliminates last limitation of
VAV systems.
Primary air volume
Air-side control and measurement
Recommended CAV damper types
Iris Dampers –
(angled multi-leaf blades)
Pressure independent –
butterfly type
Iris Dampers
Air-side control and measurement
Damper “Tips”
1. Size dampers for flow and pressure drop.
• i.e. Do NOT oversize the damper by simply installing a nominal duct
diameter damper. Check range of flow control, step-down if required.
1. Venturi – style dampers are typically only used with labs, and narrowband pressurization control.
3. Check for flow generated noise with larger pressure drops.
• Add duct silencers if necessary.
4. Consider VAV air valves for spaces with highly variable latent loads.
• Be aware of additional control requirements
• Consider “occupancy” type (i.e. 2-position) air valves for these spaces
in an effort to manage control costs.
Air-side control and measurement
Acoustics
• Watch for flow generated noise across Iris damper.
• Add duct mounted silencers if required.
Air-side control and measurement
Balancing and confirmation
• Beams are considered a constant volume device. Apply a known plenum
static pressure, and the cross-sectional area of each nozzle sums to yield
the total primary air delivered by the beam. Adjust orifice ∆P for beams
of common pressure; - their nozzle determines the primary air flow rate.
• Since the induction ratio is exceedingly difficult to field measure, the most
accurate means of determining the primary air delivery, is to rely on the
manufacturer’s plenum pressure vs. volume relationship, which is typically
measured with a precision orifice. Confirmation of zone flow rates can be
accomplished via a duct traverse at a node of common intersection.
• Flow hoods cannot be used to determine total air flow into the space due
to the recirculation component of the room air.
Air-side control and measurement
Challenges
• Nominal duct size vs. ∆P across Iris dampers.
• Zoning to minimize capital costs.
• Night-time set-back.
• Simultaneous perimeter heating with core cooling.
• Air-side free-cooling.
• Dew-point control.
Water-side control and measurement
Water-side control and measurement
Self-regulating thermal capacity
Secondary capacity
(1365 Btuh)
(682 Btuh)
∆T water/room
Example 1
Room Temp
= 75oF
Water temp
= 61oF
Approach temp = 75oF-61oF
= 14oF
Capacity = X
Room Temp
= 68oF
Water Temp
= 61oF
Approach temp = 68oF-61oF
= 7oF
Capacity = 1/2X
Water-side control and measurement
Turbulent
flow
Secondary Capacity
Secondary Capacity
Modulating water flow
Laminar
flow
Water gpm
00
50
0.22
∆T water/room
100
0.44
Single circuit water flow
Temperature controlled water
• Non-linear
• Expensive
• Maintenance issues?
• Restricted to zone control
• Expensive
• Maintenance issues?
Water-side control and measurement
Challenges
• Water-side free cooling
• Zoning
• Chilled water reset by zone
• Valve authority
 (Ensure that the control valves are sized based on Cv, NOT
line size)
Water-side control and measurement
“Tips” for easier commissioning
1. Use pressure independent flow regulating valves
2. Reverse-return piping can sometimes make life “easier” in each zone
3. Apply venting “liberally”
•
Pressure independent
water control valve
(Constant Flow Rate)
Start-up
Start-up
Sample start-up sequence
1. Confirm start-up and operating sequence with the: plans, specifications, and
consulting engineer.
2. Confirm primary air ducting is free of dirt and debris to prevent beam nozzle
clogging.
3. Seal all duct leaks, and ensure all duct access ports are affixed to the duct to
achieve specified duct leakage rates.
4. Slit protective film at the active beam discharge to allow primary air to enter the
space. Do NOT remove the protective film, until the work space is in an “asnew” condition.
Start-up
Sample start-up sequence (cont’d)
5. Do NOT operate the active beams for temporary heat without prior written
approval from the consulting engineer.
6. Close all operable windows, and ensure building exit doors are sealed to assist in
the envelope dehumidification.
7. Commission and operate the primary air handling unit for building envelope
dehumidification.
8. Balance supply air ducting to each zone.
Start-up
Sample start-up sequence (cont’d)
9. Ensure a clean environment within which the active beams will operate (i.e. no
gypsum dust or other construction contamination)
10. Remove protective film from active beam units
11. Ensure piping “mains” have been flushed and “leak-tested”, prior to being
connected to the beam coils
12. DO NOT UNDER ANY CIRCUMSTANCES FLUSH THE PIPING SYSTEM
THROUGH THE BEAM MOUNTED COILS.
Start-up
Sample start-up sequence (cont’d)
13. Confirm that all air has been removed from the distribution piping. Deliver
excess water by increasing the pump flow, or by closing other zones to assist in
the removal of air from the system.
14. Once the building envelope dew point has been reached, slowly lower the
secondary chilled water temperature to the scheduled design value. Note that
dehumidifying the building envelope may require several days, or up to a week
initially, to completely dehumidify the space.
15. Confirm secondary water conditions regularly to ensure that it is properly
filtered, and appropriately inhibited.
Start-up
Shop drawings and schedules as a tool for commissioning
Sample space serviced by active beams
Child care classroom, California