Humidity and Humidifiers Chapter 35

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Questions and Answers

What is relative humidity?

The temperature at which air becomes saturated.

The amount of moisture in the air.

The ratio of the moisture in the air compared to the maximum amount of moisture that the air can hold at its current temperature. (correct)

The total volume of water in a room.

What does an atomizing humidifier do?

Projects small water droplets into air either by mechanically flinging water or by forcing water through a nozzle.

What happens when humidity is too high in a building?

Growth of mold, bacteria, and fungus, formation of condensation on cold surfaces, swelling of hygroscopic materials.

What is the purpose of a float switch in a humidifier?

Shuts off the compressor, stopping the production and accumulation of moisture before condensation spills out of the humidifier. Signup and view all the answers

When a humidifier adds moisture to air already heated by a furnace, then the temperature of the air _____

decreases somewhat Signup and view all the answers

The Air Changes Per Hour (ACH) refers to replacing the entire volume of air in one hour.

True Signup and view all the answers

Which humidity range is considered comfortable for humans?

30% to 50% Signup and view all the answers

What type of humidifier uses its own heat source to create steam?

Vaporizing Humidifier Signup and view all the answers

A humidifier's water feed line should be tapped into a building's _____

cold water line Signup and view all the answers

What is a desiccant?

Special chemicals exposed to conditioned air to absorb moisture and release it outside Signup and view all the answers

What is the function of a frost control element?

To prevent or undo the blocking of airflow through a humidifier by shutting off the compressor. Signup and view all the answers

A portable humidifier is best for humidifying an entire building.

False Signup and view all the answers

What is demineralized water?

Water that has been treated to remove minerals. Signup and view all the answers

Dehumidifiers remove moisture from the air by maintaining a coil _____ of the air.

below dew point Signup and view all the answers

What does the term 'soft water' refer to?

Natural, untreated water with a low mineral content. Signup and view all the answers

Study Notes

Humidity and Humidifiers

Relative Humidity: Ratio of moisture in the air compared to the maximum it can hold at the current temperature.
Atomizing Humidifier: Projects small water droplets into the air using mechanical methods or nozzles.
Evaporative Humidifier: Adds moisture through evaporation.
Bypass Humidifier: Installed between supply and return plenums in central heating systems.
Frost Control Element: Prevents airflow blockage by shutting off the compressor.

Effects of High Humidity

Growth of mold, bacteria, and fungus can occur.
Condensation forms on cold surfaces.
Hygroscopic materials can swell due to excess moisture.

Humidity Control Devices

Humidistat: Control device that responds to humidity levels.
Float Switch: Shuts off the compressor to prevent condensation overflow.
Desiccants: Chemicals used to absorb moisture from conditioned air.

Humidifier Operation

When a humidifier adds moisture to pre-heated air, the temperature decreases slightly.
Air Changes Per Hour (ACH) describes the complete air volume replacement in one hour.
A solenoid valve in a humidifier operates when the furnace and blower are running.

Types of Humidifiers

Vaporizing Humidifier: Uses its own heat source to create steam.
Impeller Humidifier: Utilizes a spinning disk to fling water against a diffuser for atomization.
Nozzle-Type Humidifier: Forces water through an orifice to produce a fine mist.
Plate Humidifiers: Designed for low-capacity applications only.
Rotating Disk Humidifier: Features spinning disks with shallow grooves to atomize water.
Rotating Drum Humidifier: Contains a water pan and a drum with an absorbent sleeve.
Under Duct Humidifier: Installed through the bottom of ductwork for central humidification.

Water Quality

Demineralized Water: Treated to remove minerals.
Soft Water: Low mineral content, natural water like rainwater.
Medium Hard Water: Untreated water with 5 to 15 grains/gal. of mineral content.
Softened Water: Ion exchange replaces minerals with sodium salts.
Very Hard Water: Contains over 15 grains/gal. of mineral content.

Humidity and Comfort

Ideal indoor relative humidity for human comfort is between 30% and 50%.
Portable humidifiers are recommended for humidifying single rooms.

Additional Considerations

Overflow outlet of whole house humidifiers must be at least 1" above open drain to prevent siphoning back into the potable water supply.
Dehumidifiers function by maintaining coil temperatures below the dew point to remove moisture.

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Description

Explore key terms related to humidity and its management through humidifiers in this chapter 35 quiz. Understand concepts like relative humidity, atomizing humidifiers, and evaporative humidifiers. Test your knowledge and enhance your understanding of how these systems work.