National Academy of Forensic Engineers FE ANALYSIS OF LATENT WATER DAMAGE TO BUILDINGS

Transcription

1 National Academy of Forensic Engineers FE ANALYSIS OF LATENT WATER DAMAGE TO BUILDINGS July 10, 2005 CHICAGO RENAISSANCE HOTEL How Could Anything So Small Cause So Much Damage? PRESENTED BY PAUL J. HALYARD, P.E.

2 ABSTRACT During the design and construction of an air conditioning project, considerable attention is given to sensible and latent loads, psychrometrics, equipment size and configuration, ductwork and diffuser location, filtration, duct sizing, air distribution and noise. Condensate drains and condensate disposal is often left to the discretion of the installer. We ve found that many installers do not handle this responsibility properly. Damage due to incorrect condensate disposal can be extremely expensive and sometimes even exceeds the original cost of the entire project by a factor of 10 to 100 times. In summary, some of the greatest potential project liability is being left to the discretion of installers who are not qualified to manage it.

3 The History During 2001 through 2003, our firm was asked to investigate the cause for property damage at three different locations. These three vignettes will be discussed in detail and used as case studies.

4 Case Study One The residence is located in an estate section of an exclusive gated community around a golf course in south Orlando, FL

5 Gatehouse for Exclusive Golfing Community

6 The Less Exclusive Section

7 Case Study One Homeowner in Switzerland from mid July to mid August

8 Case Study One Subject Residence

9 Case Study One Flooring system on ground floor had buckled and standing water in kitchen Water under appliances and cabinets Wood kitchen cabinets had swollen due to presence of water for extended time

10 Upon Arrival Inspection Team Found Engineering flooring system removed and laying in yard Drywall cut up approximately 4 feet exposing wood studs and mechanical chase that led to second floor

11 Current Condensate Drain Location

12 Upon Arrival Inspection Team Found (Cont.) Mechanical chase contained liquid line, insulated suction line and condensate line The ground floor concrete was almost dry

13 Original Termination Elevation

14 Arrival discovery continued: In late afternoon in August in Orlando the air temperature was approximately 92F The humidity is high and the concrete at the bottom chase read 60F I questioned the accuracy of my new toy I read the temperature of the concrete in the sun outside the house and the hand held thermometer read 100F

15 Hand Held Non-Contact Thermometer

16 Arrival discovery continued: I went back into the house and it read 60F at the mechanical chase Fact: Concrete slab on grade is not 60F in Florida in August Cause The presence of condensate for an extended period of time had cooled the concrete slab to 60F Origin The condensate drain line was breached and the condensate discharged inside the house at the lower elevation The water accumulated for two weeks while the owner was on vacation Over $100,000 of damage was done

17 Summary The correct termination point for the condensate line was a less expensive location than the location directed.

18 Correct Termination

19 Summary It was also interesting to note that the mechanical contractor performed the installation as directed.

20 AHU Location

21 Summary Total cost of the condensate line would have been well under $100 and the total cost of the repairs was over $100,000 a ratio of 1000:1

22 Case Study Two An attorney living in an upscale section of Winter Park asked for help in determining why there was always an accumulation of water in the garage on the left side of his car

23 Continued.. The automobile air conditioning condensate discharged on the right side of the car It started in March of 2003 Attorney contacted the writer September 12, 2003

24 Continued During initial walk through there was a large accumulation of water on the left side where the automobile is typically parked Closer examination found that there was a residue trail leading diagonally toward the garage personnel door Homeowner s original drawings indicated the condensing unit s location (north side of house)

25 Continued Air handling location Ductwork routing No mention of refrigerant line routing No mention of condensate routing or size Although heavily landscaped, no condensate discharge line was observed around the total perimeter of the house

26 Continued Baseboard removal yields condensate drains in the southwest quadrant of the house

27 Continued A shovel taken around the perimeter of the southwest portion of the house located the two condensate lines buried under about 12 of dirt The condensate lines were covered with earth and were blocked, causing the condensate to overflow, run down the mechanical chase and cause mold and mildew inside the house as well as the garage

28 Continued When the concrete floor temperature was 65F on design day in Orlando, I knew we were close to the location of the condensate water

29 Summary Original plans did not make any reference to drywell Cost of the drywell was approximately $250 Cost of repair of the drywall and replacement of ductwork and plywood air handling unit platform was $5,000 20:1 ratio of the amount it would have cost to terminate the condensate properly This does not include the potential for Indoor Air Quality (IAQ) issues

30 Case Study Three 8 story 233 room hotel Certificate of Occupancy April 6, 2001 Wing closed due to low occupancy Memorial Day sold out wing open and problem found Site visit 9:00 a.m. water flowing down building exterior like a waterfall RFI No. 1 contractor requests confirmation that condensate drain system is not required from PTAC units Manufacturer told engineer, told architect, told contractor condensate drain system not required

31 Investigative Findings Condensate drains thru weep holes Weep holes do not drain due to negative pressure in guestrooms Condensate overflows draining to electrical conduit and into electrical panels Hotel/motel rooms negative air pressure can cause problems

32 Investigative Findings 7 th floor electrical room puddle on floor Non-contact thermometer read 58F

33 PTAC Condensate Clue on building exterior

34 PTAC Condensate

35 PTAC Condensate

36 PTAC Condensate

37 Investigative Findings Test and Balance report Building is operating in negative pressure Design has building at neutral Guest rooms are negative with respect to corridors and ambient Ventilation air to corridors is saturated at 75.8 deg F Corridor walls are wet

38 Design Considerations Outside ventilation air requires dehumidification. Outside ventilation air needs to be filtered (Min MERV 6 filter). Select correct ambient design conditions. Use piping for condensate at PTAC. Provide positive pressure in building.

39 RE-CAP Cost for condensate drain systems as percentage of total bid cost Roof top equipment projects without roof drains 3.2% Roof top equipment projects with roof drains 2.1% Indoor central station air handlers.09% Split system air handlers vertical 1.2% Split system air handlers horizontal 2% All above are insulated copper and include roof supports or hangers

40 Re-Cap continued Cost of condensate drain system is between 1% to 3% of total cost of job State Farm Insurance web site describes Air Conditioning Condensate Line Water Damage ( consumer/vhouse/articles/aircond.htm) Hand held non-contact thermometer is good tool to identify condensate issues, both cause and origin of problem

41 CONCLUSION Condensate lines need thought and attention during design, installation, and maintenance. Once the condensate drain system has been designed and installed, proper maintenance is key to loss prevention.

42 Questions & Answers