Humidifier For HVAC System | Air Conditioning Systems

This article describes the minimum requirements for humidifiers for use with HVAC systems, including in duct mounted and space mounted humidifiers.

Humidifier Working Principle

A humidifier is a device, primarily an electrical appliance, that increases humidity (moisture) in a single room or an entire building. In the home, point-of-use humidifiers are commonly used to humidify a single room, while whole-house or furnace humidifiers, which connect to a home’s HVAC system, provide humidity to the entire house. 

Humidifier For HVAC System | Air Conditioning Systems

Submittals

Product data shall include rated capacities, operating weights, certified dimension drawings, furnished specialties, and accessories.

Shop Drawings:

a. Wiring diagrams indicating power, signal and control wiring. Wiring diagrams shall differentiate between manufacturer installed and field installed wiring.

b. Access requirements around other work, including working clearances to mechanical controls and electrical equipme

Operation and maintenance data shall be submitted for humidifiers to include operation and maintenance manuals.

Quality Assurance

Electrical components, devices, and accessories shall be listed and labeled as defined in NFPA 70, Article 100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended use. Humidifiers shall comply with ARI 640.

Heated Pan Humidifiers

• Humidifier heat source shall be steam, hot water or electrical immersion elements.
• Housing shall be ASTM A 666, Type 304 or 316 stainless steel with stainless steel lid, overflow fitting, and drain fitting.
• Controls shall be solenoid fill and automatic drain valves shall maintain water level and temper hot drain water; field adjustable timer shall control drain cycle for flush duration and interval.
• Dispersion tube shall be stainless steel, duct mounting, single or manifold grid tube extending across entire width of duct; connected to heated pan housing with flexible hose and equipped with mounting brackets for both ends of tube; or inverted U-tube when humidifier is directly mounted under the duc
• Accessories, when required by humidifier application:

1. • a. Wall mounted, return duct mounted or duct mounted, high limit humidist
   • b. Airflow switch to prevent humidifier operation when there is no airflow.

Self-Contained Humidifiers

• Self-contained humidifiers shall have electric resistance or electrode type, electric immersion heaters within a cylinder to generate steam. Enclosure cabinet shall contain equipment components.
• Self-contained humdifiers shall be remotely mounted with flexible hose connecting dispersion tube in duct airstream or space mounted with integral fan for discharging vapor directly into conditioned spac
• Dispersion tube shall be stainless steel tube interlocked with integral fan for discharging vapor directly into conditioned space or stainless steel tube extending across entire width of duct and equipped with mounting brackets for both ends of tube.
• Cabinet shall be sheet metal enclosure for housing heater cylinder, electrical wiring, components, controls, and control panel. Enclosure shall include baked enamel finish in manufacturer’s standard colors, hinged or removable access door, and threaded outlet in bottom of cabinet for drain piping.
• Control panel shall be factory wired disconnect switch; liquid crystal display, programmable keyboard; set point adjustment; warning signal indicating end of replaceable cylinder life; low voltage control circuit; diagnostic, maintenance, alarm, and status features; and high-water sensor or float to prevent overfilling.
• Controls shall be solenoid fill and automatic drain valves shall maintain water level and temper hot drain water; field adjustable timer shall control drain cycle for flush duration and interval.
• Accessories, when required by humidifier application:
  1. Humidistat shall be solid state, electronic sensor controller capable of full modulation.
  2. Duct mounted, high limit humidistat.
  3. Network capability.
  4. Airflow switch to prevent humidifier operation when there is no airflow.