Aprilaire 1750, 1770 User Manual

Thermostatic Expansion Valve (TXV) is a precision device

Model 1750

Model 1770

used to modulate the flow of refrigerant entering the evaporator coil at the same rate as the refrigerant being boiled off in the evaporator coil. The TXV also provides the necessary pressure drop within the system to separate the high and low pressure sides of the system. This separation allows the low pressure refrigerant to absorb heat.

The cabinet of the Model 1750/1770 is fully insulated with a

1" insulation that is designed to reduce unit operating sound levels, prevent condensation from forming on the exterior of the unit, and prevent the possibility of heat gain when the unit is located in higher temperature locations, such as mechanical rooms or above ceilings.

The evaporator coil features a unique lanced fin and

double row tube design, giving the Model 1750/1770 better surface contact with the moisture-laden air. The R-22 refrigerant within the coil provides the maximum temperature differential required for the air to reach dewpoint sooner, removing more moisture. These features provide the unit with a 60% SHR rating at 80˚F and 60% RH.

The Model 1750/1770 can be controlled two ways; by using

the control that is integrated into the cabinet of the unit, or by using a separate Model 70 control mounted in the occupied space. When the integral control is utilized, it is designed as a “set it and forget it control”, the only interaction required is through a “more” or “less” dry adjustment knob located on the inlet side of the unit. When the Model 70 control is utilized, it becomes the sensor, determines unit operation, and display the space RH%.

Inlet and Discharge connections are designed for 8"

insulated, flexible duct or can be ducted with standard 8" round or spiral duct.

The unit is equipped with a safety disconnect switch that

will completely shut the power off during any service or maintenance.

The internal blower is a direct drive forward curved blower

designed to deliver the air flow required for air “sampling” and distribution. The unit is designed to deliver the proper amount of air quietly and efficiently.

SPECIFICATION SHEET

DEHUMIDIFIER

MODEL 1750/1770

MODEL 1750 PERFORMANCE

AT INLET AIR CONDITIONS AND 275 CFM

MODEL 1770 PERFORMANCE

AT INLET AIR CONDITIONS AND 500 CFM

PRODUCT SPECIFICATIONS

MODEL 1750/1770 DEHUMIDIFIER

Low Dewpoint Control Level ("MORE DRY" or 7 bars on display) 40°F High Dewpoint Control Level ("LESS DRY" or 1 bar on display) 65°F Temperature Sensor Range 40°F to 100°F Relative Humidity Sensor Range 30% to 100% Temperature Storage Range -30°F to 120°F Relative Humidity Storage Conditions 0% to 100% Supply Voltage (DC from Model 1700/1720 Control Board) 12 VDC

PRINCIPLE OF OPERATION

The Aprilaire Model 1750/1770 is designed to dehumidify the air coming into the unit by passing the incoming air over a cooling coil to drop the air temperature and dewpoint of the air.

oisture is removed from the air and drained out of the unit to a

M common floor or waste drain. The air is then reheated in the condenser coil and exits the unit.

It dehumidifies until a preset dewpoint setpoint is reached, then shuts off until periodic sampling determines a need for operation.

The Model 1750 can be installed in two types of configurations: “Whole-Building” or “Localized/Spot”.

Typical “Whole-Building” Operation:

In the “Whole-Building used to dehumidify the entire building. In this application, the Model 1750/1770 must be wired to the HVAC equipment blower.

In this configuration, the unit can be installed two ways:

1. Pulling air from the occupied space, through the dehumidifier and discharging it into the supply duct/plenum of the HVAC system.

2. In a bypass method, pulling air from the return, through the dehumidifier and discharging it into the supply duct/plenum of the HVAC system.

In order to check the dewpoint of the incoming air, the 1750/1770 must “sample” the air. To do this, the 1750/1770 will turn on with the first HVAC equipment blower call in each selectable cycle (time) period. In the event that the blower is on continuously or during occupied times, the dehumidifier will sample at the first available opportunity within the cycle period. If no HVAC equipment blower call occurs during the cycle period, the 1750/1770 will activate it’s internal blower 3 minutes prior to the end of the cycle to enable it to sample the air. If the incoming air is above the desired set point, the dehumidifier compressor will turn on. If the HVAC equipment blower call ends prior to the dehumidification set point becoming satisfied, the 1750/1770 will continue to run and operate until the set point is met. The unit can be set to “sample” the air every 30 minutes, 1 hour, 2 hours, or 3 hours.

Typical “Localized/Spot” Operation:

In the “Localized/Spot

In this configuration, the unit can be installed two ways:

1. Pulling air from the occupied space, through the dehumidifier, and discharging it directly back into the occupied space. This is typically done using wall grilles or ceiling diffusers.

2. Pulling air from the occupied space, through the dehumidifier, and discharging it into the supply duct serving the same occupied space that the air was pulled from. This allows the warmer, dehumidified air to mix with cooler supply air from the HVAC System when the HVAC system air conditioning is on.

If the Model 1750/1770 is wired to the HVAC equipment blower, the operation is the same as the typical “Whole-Building” operation.

If the Model 1750/1770 is operated independently of the HVAC equipment blower, the unit will use its internal blower to both sample the air and provide the air flow necessary to distribute the air into the space.

” configuration, the Model 1750/1770 is

” configuration, the Model 1750/1770 is used to dehumidify a specific room or location within the building.

PRODUCT SPECIFICATIONS

ODEL 70

M OCCUPIED SPACE CONTROL

• On/Off buttons

• Displays set point indication bars and measured RH in the area

• Senses dewpoint in the occupied space

• Adjustable to achieve “more” or “less” dry conditions

Form No. 4251 05.09

RESEARCH PRODUCTS RESERVES THE RIGHT TO CHANGE SPECIFICATIONS WITHOUT NOTICE.

PO Box 1467 • Madison, WI 53701-1467 • Phone 800/334-6011 • Fax 608/257-4357 • www.aprilairecontractor.com

Printed in USA