Presented By Darren Alexander Twa Panel Systems Inc. April 15, 2011 ACG 7 th Annual Conference on...

Presented By

Darren AlexanderTwa Panel Systems Inc.

April 15, 2011

ACG 7th Annual Conference on Total Building CommissioningCOMMISSIONING ACTIVE BEAMS

Agenda

Agenda

Introduction to Active (Chilled) Beams

Introduction to Active Beams

Fan energy savings

Introduction to Active Beams

De-coupled ventilation systems

Energy Usage Noise Level Output Comments

Fan Coil Units Medium/High Medium 32-64 Btuh/ft2 Adaptable solution

VAV Systems Low Low/Medium 32-64 Btuh/ft2 Very efficient all-air system

VRV System (Variable

Refrigerant Volume)

High Medium 48-64 Btuh/ft2

Possible high maintenance

costs

Active Beams Low Low 32-125 Btuh/ft2

Very low maintenance

costs

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

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) Near points of entry to the building2)At the perimeter, with mixed-mode ventilation3)Structures with poor building envelopes, including retrofit applications4)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

Active beams can be very quiet!

Chart reports acoustic values

without roomattenuation

effect

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

Drywall

Upstream damperat SMACNArecommended minimum distance

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 wingsrequired 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 back-to-back crating mini-mizes shipping damage.

Installation and maintenance

Beams mounted with aircraft cable

Note protective film at inlet ofunit 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 “horse-hair” 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 + PvPt = 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 ?

• 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.

Air-side control and measurement

Vary primary air pressure for capacity control ?

• 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.

Air-side control and measurement

Recommended CAV damper types

Iris Dampers – (angled multi-leaf

blades)

Iris Dampers

Pressure independent – butterfly type

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 narrow-band 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

(1365 Btuh)

(682 Btuh)

Example 1Room Temp = 75oFWater temp = 61oFApproach temp = 75oF-61oF

= 14oF Capacity = X

Room Temp = 68oFWater Temp = 61oFApproach temp = 68oF-61oF

= 7oF Capacity = 1/2X

Water-side control and measurement

Modulating water flow

Turbulent flow

Laminar flow

Single circuit water flow

•Non-linear•Expensive•Maintenance issues?

Temperature controlled water

•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 “as-new” 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-upShop drawings and schedules as a tool for commissioning

Sample space serviced by active beamsChild care classroom, California