Chapter 5: Heating, Ventilation, and Air Conditioning Systems and Components
5.1 General
- 5.1.1 Components of Heating, Ventilation, and Air Conditioning (HVAC) systems that may have risks associated with Legionella include air filters, humidifiers, condensate pans, and any other areas where water may be present.
5.2 Air filters
- 5.2.1 Design requirements
- 5.2.1.1 For new primary air handling equipment, excluding packaged type, provide high-efficiency filters with a minimum Minimum Efficiency Reporting Value (MERV) rating of 13. For packaged type primary air handling equipment provide high efficiency filters with a minimum MERV rating of 13 where possible.
- 5.2.1.2 For existing air-handling systems, consider filter upgrade to MERV 13.
- 5.2.1.3 Design the air filter assembly to help prevent contamination of the air supply during maintenance.
- 5.2.2 Operation & maintenance
- 5.2.2.1 Inspect filters, frames, chambers, and housing for general condition and integrity of fit weekly for primary air handling equipment and at least annually for terminal air handling equipment.
- 5.2.2.2 Replace filters found to be in poor condition.
5.3 Humidifiers
- 5.3.1 Design requirements
- 5.3.1.1 Humidifiers forming part of any new HVAC system shall be indirect steam injection type.
- 5.3.1.2 Systems that use untreated potable water are preferred as maintenance requirements are lower and chemicals are not released into the airstream.
- 5.3.1.3 Direct steam from treated boiler water or other treated sources shall not be used.
- 5.3.1.4 Evaporative pan, drum-type, water spray-type, sprayed coil-type humidifiers or air washers shall not be used in new building designs.
- 5.3.1.5 During renovation projects, existing humidifiers shall be replaced with approved types of humidifiers.
- 5.3.1.6 For existing buildings, existing humidifiers systems can continue to operate only if proper precautions are taken to minimize microbial growth, including regular scheduled maintenance, total avoidance of water stagnation in the humidifiers, the use of biocides, and chemical treatment. If this is not practicable, the humidifiers shall be taken out of service.
- 5.3.1.7 Avoid the use of room humidifiers and misters, as they can provide a ready source of aerosols for dissemination of bacteria.
- 5.3.1.8 Include a provision to drain the systems when not in use to prevent standing water.
- 5.3.1.9 Design systems to allow for adequate access for inspection and maintenance.
- 5.3.2 Operation and maintenance
- 5.3.2.1 Start-up and maintenance procedures must include cleaning and inspections for all key components of the systems.
- 5.3.2.2 Visually inspect humidifiers for signs of microbial growth, sediment or stagnant water at least once a month for non steam systems and every 3 months for steam systems.
- 5.3.2.3 If stagnant water accumulation is observed, follow the test protocol indicated in Section 5.3.3 below.
- 5.3.2.4 Maintain, clean and drain these systems following manufacturer recommendations when visual inspection indicates a problem
- 5.3.2.5 Disinfect system when bacterial testing results exceed action limits.
- 5.3.3 Minimum bacterial testing requirements
Water sampling locations
- 5.3.4 Water sampling locations for bacterial testing shall be in accordance with the facility Legionella Bacteria Control Management Program (LBCMP).
- 5.3.5 The facility LBCMP should consider, at a minimum, the following locations for water sampling:
- 5.3.5.1 Water reservoirs
- 5.3.5.2 Stagnant water
Bacterial testing results
- 5.3.6 Record the bacterial testing results on the facility LBCMP testing form (LBCMP-4).
- 5.3.7 Report the bacterial testing results in accordance with the regional and national reporting protocols.
Minimum bacterial testing requirements (normal operation)
- 5.3.8 While the system is in normal operation, perform dipslide tests monthly for non steam systems and every three months for steam systems to determine the total bacteria count (TBC) where stagnant water is present. Refer to Figure 3 located in Appendix D.
- 5.3.9 While the system is in normal operation, every three months perform Legionella bacteria culture tests on non-steam systems, to identify total Legionella pneumophila including all serogroups (LPTOT) bacteria levels. Refer to Figure 3 located in Appendix D.
Minimum bacterial testing requirements and frequency (emergency mode)
- 5.3.10 Use the emergency-mode bacterial test procedure if:
- 5.3.10.1 There have been multiple reported cases of Legionnaires' disease in the past 30 days in the region within a 10 km radius of the building location and/or,
- 5.3.10.2 The building has had recurring Legionella bacteria levels detected by the Legionella bacteria culture test that required disinfection of the system within the past 90 days and/or,
- 5.3.10.3 Regional Health authorities direct more stringent bacterial testing.
- 5.3.11 Unless directed otherwise by the regional health authority, or due to regional restrictions, a weekly Quantitative Polymerase Chain Reaction (qPCR) test should be performed to obtain rapid, Legionella specific results, to determine the Legionella Pneumophila bacteria count at each water sampling location.
Dipslide testing limits and actions
- 5.3.12 (Level D1—Green)—When the TBC is less than 1,000:
- 5.3.12.1 Continue with normal O&M.
- 5.3.13 (Level D2—Yellow)—When TBC is greater than or equal to 1,000 and less than or equal to 10,000:
- 5.3.13.1 Review and adjust the O&M procedures and ensure proper drainage.
- 5.3.13.2 Continue operation with adjusted O&M.
- 5.3.14 (Level D3—Orange)—When TBC exceeds 10,000:
- 5.3.14.1 Clean and disinfect the system within 48 hours.
- 5.3.14.2 Review and adjust the O&M procedures and ensure proper drainage.
- 5.3.14.3 Continue operation with adjusted O&M.
- 5.3.14.4 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 5.3.15 through 5.3.19.
Legionella bacteria culture testing limits and actions
- 5.3.15 Perform Legionella bacteria culture test in accordance with ISO 11731-1998 and ISO/TS 11731-2-2004.
- 5.3.16 Where the analysis result indicates interfering flora are present that may have affected the results:
- 5.3.16.1 Perform a running disinfection of the system within 48 hours.
- 5.3.16.2 Review and adjust the O&M procedures and the water treatment program as required to ensure acceptable bacterial levels in the system.
- 5.3.16.3 Wait 2 to 7 days then perform a Legionella bacteria culture test in accordance with clauses 5.3.15 through 5.3.19.
- 5.3.17 (Level C1—Green)—When the LPTOT count is less than 1 cfu/mL
- 5.3.17.1 Continue with normal O&M.
- 5.3.18 (Level C2—Orange)—When the LPTOT count is greater than or equal to 1 and less than or equal to 100 cfu/mL:
- 5.3.19 (Level C3—Red)—When the LPTOT exceeds 100 cfu/mL:
- 5.3.19.1 Immediately shut down the system and clean and disinfect the system before putting it back into service.
- 5.3.19.2 Review and adjust the O&M procedures and ensure proper drainage.
- 5.3.19.3 Continue operation with adjusted O&M
- 5.3.19.4 Wait 24 hours then perform a qPCR test in accordance with clauses 5.3.20 through 5.3.23.
Quantitative polymerase chain reaction testing limits and actions
- 5.3.20 Perform qPCR Test in accordance with ISO/TS 12869
- 5.3.21 (Level Q1—Green)—When the Legionella pneumophila bacteria count is less than 10 GE/mL:
- 5.3.22 (Level Q2—Yellow)—When the Legionella pneumophila bacteria count is greater than or equal to 10 and less than or equal to 100 GE/mL:
- 5.3.23 (Level Q3—Orange)—When the Legionella pneumophila bacteria count exceeds 100 GE/mL:
5.4 Operation, maintenance and testing schedule for humidifiers
- 5.4.1 Table 5.1 below indicates a summary of the minimum frequency for operation, maintenance and testing requirements of humidifiers:
Table summary
This table indicates a summary of the minimum frequency for operation, maintenance and testing requirements of humidifiers.
| Activity | Item | Frequency |
|---|---|---|
| Operation & maintenance | Inspection |
|
| Cleaning |
|
|
| Disinfection |
|
|
| Testing | Dip-slide test |
|
| Legionella bacteria culture test |
|
|
| qPCR test |
|
5.5 Drain pans
- 5.5.1 Design and requirements
- 5.5.1.1 This section applies to new equipment and to major upgrades to existing equipment.
- 5.5.1.2 Drain pans shall be designed for easy cleaning.
- 5.5.1.3 Drain connections shall be in the bottom or in a depression in the side of the pan to eliminate standing water in the pan.
- 5.5.1.4 Drain pans shall be equipped with deep seal trap rated for twice the maximum static pressure in the system.
- 5.5.2 Operation and maintenance
- 5.5.2.1 Start-up and maintenance procedures must include cleaning and inspections for all key components of the systems.
- 5.5.2.2 Visually inspect drain pans for signs of microbial growth, sediment and/or stagnant water at least once a month for primary air handling equipment and annually for 20% of terminal air handling equipment such that all of the equipment is inspected over a 5 year period.
- 5.5.2.3 Check for water accumulation in drain pans, and if there is any water accumulation, ensure that the drain pans are draining properly.
- 5.5.2.4 Maintain and clean drain pans following manufacturer recommendations at least yearly.
5.6 Operation and maintenance schedule for drain pans
- 5.6.1 Table 5.2 below indicates a summary of the minimum frequency for operation and maintenance requirements of drain pans:
Table summary
This table indicates a summary of the minimum frequency for operation and maintenance requirements of drain pans.
| Activity | Item | Frequency |
|---|---|---|
| Operation & maintenance | Inspection |
|
| Cleaning |
|
|
| Disinfection |
|
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