Response by Control Type—Advanced Microprocessor Controls

Hot Water/Steam Heat

The valve begins to open when the requirement for heating is 33% and is proportionally adjusted until the valve is full open at 100% heat requirement.

5.2Humidity Control

5.2.1Dehumidification/Humidification Required, in Percent (%)

The humidity control program for the Advanced Microprocessor is based on a calculated % require- ment for dehumidification/ humidification. This % requirement is determined by the particular type of control algorithm selected by the user.

5.2.2Control Types Proportional Control

The % requirement is determined only by the difference between the return air humidity and the humidity setpoint. As the return air humidity rises above the humidity setpoint, the % dehumidifica- tion required increases proportionally from 0 to 100% over a humidity band equal to the humidity sensitivity setting. The converse is true for % humidification requirement.

PID Control

If PID Control is selected, humidity is controlled in the proportional mode with the sensitivity band being determined by the humidity sensitivity setpoint.

Intelligent Control

If Intelligent Control is selected, the return air humidity is controlled at or near the humidity set- point. The % dehumidification/humidification required is calculated based on a set of logical “rules” that simulate the actions of an expert human operator (see Intelligent Control on page 35).

5.2.3Dehumidification Operation

One-Stage Dehumidification, Compressorized Direct Expansion (DX) Systems

If single compressor dehumidification is selected, a compressor is activated when the humidity control calculates a requirement of 100%; the compressor is deactivated when the requirement falls below 50%.

Two-Stage Dehumidification, Compressorized Direct Expansion (DX) Systems

The first stage of dehumidification activates when the humidity control calculates a requirement for dehumidification of 50%. The first stage of dehumidification is deactivated when the dehumidification requirement drops below 25%. The second stage of dehumidification is activated when the require- ment for dehumidification rises to 100% and deactivated when the requirement falls below 75%. If the compressors have unloading capability (four-step cooling), then the compressors are activated in the fully loaded condition for each stage of dehumidification.

Normal or Delayed Reheat (for Two-Stage Dehumidification Only)

If the return air temperature falls enough to require more than the total available reheat capacity, then one (1) stage of dehumidification is disabled and the reheats are activated. If the return air tem- perature falls enough to require twice the total reheat capacity (200%), both stages of dehumidifica- tion are disabled. One stage of dehumidification will be re-enabled at 66% call for heating. Both stages of dehumidification are re-enabled at 33% call.

If delayed reheat is selected and both compressors are activated for dehumidification, the reheats are disabled until only one compressor is required.

If normal reheat control is selected, then the reheats are not disabled during dehumidification, even if both compressors are operating. Refer to section 3.4.2 - Setup System Selection and 4.8.4 - DIP Switches regarding wiring required for this option.

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Emerson DH, VH, DE, VE manual Humidity Control, Hot Water/Steam Heat, Dehumidification/Humidification Required, in Percent %
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VE, DH, VH, DE specifications

Emerson is a well-known brand in the field of automation solutions, offering a range of products that cater to various industries. Among its diverse portfolio, Emerson’s products like DE (Digital Electronics), VH (Variable Frequency Drives), DH (Distributed Control Systems), and VE (Valve Positioners) stand out for their advanced features, cutting-edge technologies, and unique characteristics.

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