The Austin Driskill
This landmark luxury property has been welcoming guests since its opening in 1886. Entrenched with timeless charm and elegance in every detail, The Driskill is located in a prime location in downtown Austin, Texas.
Hyatt engaged AirRevive to refurbish and re-commission 107 units in the historic tower and 77 units in the new tower. The units were manufactured in 2006.
Fan Coil Units Manufacturer: MagicAire
Models#: 006-CHWA, 012-CHWA, 018-CHWA, 024-CHWA , 030-CHWA
Project Scope of Work: Guest room horizontal fan coil unit refurbishment, valve replacement and EC motor retrofit.
Challenge: The units were not heating and cooling as designed primarily because of the following:
- Dirty coils were restricting airflow.
- Dirty fins were inhibiting efficient heat transfer.
- Insufficient airflow was preventing unit from attaining temperature set point.
- Airflow was not aligned with the unit’s design specifications.
- The control valves were bypassing causing simultaneous heating and cooling.
- The actuators were malfunctioning.
- Existing 2 hot water shut-off valves and 2 cold water shut-off valves were at the end of their life and some were leaking.
- The water supply and return pipes were not wrapped correctly causing humidity and condensation above the guest room ceiling.
- The boot and supply duct were not attached to the unit correctly causing vibrations.
Findings:
New Tower:
- Coil temperature averaged 56.73℉.
- Supply temperature averaged 59℉.
- 100% of the unit’s supply temperature was above 55℉.
- Airflow for both low and high setting was overblowing above the manufacturer’s design curve.
- Airflow averaged 619.67 CFM on high setting and 477.58 CFM on low setting.
- Sound decibels averaged 61.3 dB.
Historic Tower:
- Supply temperature averaged 57℉.
- 63% of the unit’s supply temperature was above 55℉.
- Airflow for both low and high setting was below the manufacturer’s design curve.
- Airflow averaged 438.62 CFM on high setting and 398.85 CFM on low setting.
- Sound decibels averaged 61.1 dB.
Solution: The refurbishment solutions included the following:
- Coil rejuvenation from the front to back to deep in the core.
- Refurbish and apply epoxy to the condensate pan.
- Clean and disinfect the blower assembly and wheel.
- Clear out, clean and disinfect the drain line.
- Replace fiber insulation with anti-microbial fiber-free foam insulation.
- Replace hot and cold 3-way control valves, equipment valves and 2 flow control valves as needed;
- Wrap supply and return pipes with anti-microbial fiber-free foam insulation; and attach boot and supply duct as needed.
- Coil rejuvenation resulted in lowered coil temperature and unrestricted airflow preparing the coils for the EC motor retrofit.
- The EC motor retrofit solution included programming the EC motor to supply airflow consistent with each unit’s specification, room area and building nuances; installing motor and controller; and wiring motors to thermostat for proper functioning.
Results
New Tower:
- Coil temperature dropped by 3.13℉ from an average coil temperature of 56.73℉ to 53.6℉.
- Supply temperature dropped by 4℉ from an average supply temperature of 59℉ to 55℉.
- Sound decibels decreased by 15% from an average of 61.36 dB to 51.55 dB.
- Sample airflow readings from the 5th floor demonstrate a reduction of 144.78 CFM from an average of 619.67 CFM to 474.89 CFM on high setting and a reduction of 109.89 CFM from an average of 477.56 CFM to 367.67 CFM on low setting. Airflow for all units in the new tower that were overblowing are now within the manufacturer’s design curve.
- Guest rooms are cooling within minutes and maintaining temperature set point.
Historic Tower:
- Supply temperature dropped by 2.35℉ from an average supply temperature of 56.7℉ to 54.35℉.
- Sound decibels decreased by 10% from an average of 61.1 dB to 55 dB.
- Airflow on low setting increased 125.28 CFM from an average of 398.85 CFM to 524.13 CFM.
- Airflow on high setting increased 216.48 from an average of 438.62 CFM to 655.1 CFM.
- Airflow for all units in the historic tower are within the manufacturer’s design curve.
- Guest rooms are cooling within minutes and maintaining temperature set point.
Before & After Supply Temperature Data
The graphs below display before and after supply temperature for the New and Historic Towers. The red lines from left to right represents the supply temperature before service from high to low. The blue lines demonstrate the supply temperature after service ranged from 63 degrees to 54 degrees in the Historic Tower and from 64 degrees to 56.3 degrees in the New Tower. The horizontal axis represents the room numbers.
