Aprilaire 800 owner manual Introduction, Principles of Operation, Sequence of Operation

INTRODUCTION

Thank you for your recent Aprilaire® humidifier purchase. We appreciate your business and are pleased to add your name to our growing list of customers. You have invested in the highest quality equipment available. Aprilaire manufactures whole-house indoor air quality products and is a recognized leader in the heating and air conditioning industry.

Your humidifier will require periodic maintenance to assure continued consistent performance.. See page 14..

Now, please take a few minutes and read this booklet. This will familiarize you with the benefits you will receive from the equipment you just purchased and help you understand the routine maintenance that will be required.

Be sure to register your humidifier warranty online at: www.aprilaire.com/warranty..

Genuine Aprilaire Replacement Model 80 Steam Canisters are available from your installing contractor or from most other heating and air conditioning contractors in your area. Use the dealer locator on our web site (www.aprilaire.com) or look in the Yellow Pages under Humidifying Apparatus or Heating & Air Conditioning Contractors.

PRINCIPLES OF OPERATION

The Aprilaire® Model 800 Canister Steam Humidifier delivers humidity in the form of steam to the conditioned space via the HVAC system duct or optional Aprilaire Model 850 Fan Pack. The humidifier generates steam by energizing two electrodes that extend into a canister of water. Current flowing between the electrodes causes the water to boil, creating steam. Water is introduced to the humidifier through a fill valve to a fill cup located in the top of the cabinet. The fill cup serves as an overflow reservoir and provides an air gap between the humidifier and water source. The steam canister is filled from the bottom. The canister is seated in a drain cup assembly which includes a drain valve. The drain and fill valves work together to maintain water level in the canister to deliver the rated steam capacity based on the electrical conductivity of the water and to temper drain water. See Figure 1 for representation of fill and drain system and canister..

Steam is delivered into the airstream through a dispersion tube mounted in the HVAC system ductwork. Openings in the dispersion tube are fitted with “tubelets” which extend into the center of the tube. The design of the dispersion tube and tubelets distribute steam over a wide area in the duct and direct any condensed moisture back into the steam hose.

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Figure 1 – Fill and Drain System and Canister
	Steam
	Outlet
Fill Cup
	Overflow
		High Water
		Level Sensor
		Electrodes
Flow Control
Orifice
		Canister
Inlet	Fill
Fill Valve		Drain Valve
		Drain Cup
	Supply
	Water
	Drain
		90-1522

SEQUENCE OF OPERATION

When the Automatic Digital Humidifier Control (ADHC) detects humidity below the set point, and provided the humidifier is turned on and the HVAC system blower is operating, the internal controller in the humidifier energizes the electrodes and measures the current flowing through the water between them. The controller adjusts water level in the canister via a fill valve and a drain valve to maintain a constant current. The operating water level in the canister depends on the mineral content of the water which determines conductivity.

The ADHC has the ability to turn on the HVAC system blower if the homeowner or installer chooses to utilize that feature. See ADHC installation manual..

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