7.8104.1 Mixing Valves

Topic: 
Water Heating
Subtopic: 
Distribution
Desired Outcome: 
Safe and reliable hot water delivery that meets the needs of the occupant/building management/building operations staff at the lowest possible life cycle cost
For supporting material, see Referenced Standards.
TitleSpecification(s)Objective(s)
7.8104.1a
Hazardous material removal

Health concerns in the removal and replacement of equipment (e.g., asbestos, other hazardous materials) will be identified

Written notification will be provided to occupants of the discovery of hazardous material, including contact information for regional EPA EPA U.S. Environmental Protection Agency, www.epa.gov asbestos coordinator

Occupant will be asked to contract with an EPA EPA U.S. Environmental Protection Agency, www.epa.gov -certified asbestos contractor to conduct abatement before decommissioning and replacement (occupant is responsible for abatement or remediation)

Remediate health hazards using EPA EPA U.S. Environmental Protection Agency, www.epa.gov -certified contractors

7.8104.1b
Removal

Existing mixing valves will be hydraulically isolated (shut isolation valves) and drained before removal

Existing mixing valves will be disconnected from electricity before removal

Safely remove the existing mixing valve

7.8104.1c
Installation

Mixing valve will be installed in accordance with manufacturer specifications and local code requirements

Controls, sensors, wiring, and other components will be installed in a manner that does not expose occupant/building operations staff/property manager to hazardous conditions

When controls are using low voltage, the low voltage and line voltage wiring will be separated

Controls, sensors, wiring, and other components will be installed in a manner that does not pose an unnecessary risk to the integrity of the installation (e.g., wiring, sensors)

Ensure the mixing valve is properly installed

Allow proper and effective function of the valve

Ensure long-term safety and durability of components

7.8104.1d
Location

Mixing valves will be installed at as many locations as necessary to ensure delivery of safe and adequate hot water

Mixing valve will be installed with a heat trap or at a distance from heat sources sufficient enough to prevent scaling or damage to the valve

Ensure water temperature is low enough to prevent scalding at all locations

Ensure water temperature is high enough to inhibit growth of pathogens (e.g., Legionella)

Ensure the valve does not fail prematurely

7.8104.1e
Mounting

Mixing valve will be mounted in accordance with manufacturer specifications

Prevent the mixing valve from coming loose

7.8104.1f
Accessibility

Mixing valve will be installed and plumbed to allow for inspection, maintenance, and replacement of the valve

Ensure the mixing valve can be easily maintained and replaced

7.8104.1g
Isolation valve

Isolation valves will be installed to isolate mixing valve

Allow for easy removal and maintenance of the mixing valve

7.8104.1h
Check valve

Check valve will be installed on the cold and hot water supply lines

Prevent crossover

7.8104.1i
Temperature gauges

Temperature gauges will be installed on hot, cold, and tempered supply water lines within line of sight of the mixing valve

Allow verification of proper operation of the mixing valve

7.8104.1j
Sensors

Controls and sensors will be installed or reconnected in accordance with design specifications

When controls are using low voltage, the low voltage and line voltage wiring will be separated

Installer will understand the function of the mixing valve as part of the hot water control system

Ensure proper function of the mixing valve

7.8104.1k
Discharge water temperature

Discharge water temperature will be set not to exceed 120 °F or as prescribed by local code

Install mixing valve when higher storage/generation temperatures are required

Ensure water temperature is low enough to prevent scalding

Ensure water temperature is high enough to inhibit growth of pathogens (e.g., Legionella)

7.8104.1l
Commissioning

The following will be checked:

  • System filled and purged
  • Water leaks
  • Valves open
  • Isolation and check valve orientation correct
  • Function of mixing valves across full range of incoming hot water temperatures

Relevant information will be added to operation manual

Verify operation of the mixing valve

7.8104.1m
Education

Completed work will be reviewed

Occupant/building operations staff/property manager will be educated on the safe and efficient operation and maintenance of the system, including:

  • Adjustment of water temperature
  • Proper use of isolation valves
  • Importance of keeping operating manuals accessible

Educate occupant/building operations staff/property manager about the safe, efficient operation and maintenance of the system