User Guide

ManualsBrandsComfort-Aire ManualsComfort Aire Mini-Split Systems46,800 BTU HZ Series Geothermal DMX2 Vertical Heat Pump

Design Guide - HZH/HZV Series

ClimaDry

II Modulating Reheat

Comfort-Aire/Century’s patented ClimaDry

Dehumidication is an innovative means of providing

modulating reheat without the complication of refrigeration

controls. ClimaDry

II is hot gas generated reheat, which

utilizes one of the biggest advantages of a Water-Source

Heat Pump (WSHP), the transfer of energy through the

water piping system. ClimaDry

II simply diverts condenser

water through a water-to-air coil that is placed after the

evaporator coil. If condenser water is not warm enough, the

internal “run-around” loop increases the water temperature

with each pass through the condenser coil (see gure 1,

below).

ClimaDry

II Benets

ClimaDry

II is like no other reheat option on the market.

Proportional reheat is controlled to the desired leaving

air temperature setpoint (factory setpoint of 72°F, 22°C),

no matter what the water loop temperature is. Since

dehumidication operation will occur under less than full

load cooling conditions a good percentage of the time,

it is important to have a reheat function that provides

100% reheat in the spring and fall when the water loop is

cool. Supply air temperature is eld adjustable to +/- 3°F

[+/- 1.7°C] for even greater exibility with the optional

potentiometer. It is recommended that the ClimaDry

supply air temperature be set to match the space cooling

setpoint so that ClimaDry

does not impact room

temperature. Competitors without ClimaDry

II typically

use an on/off (non-modulating) refrigeration based reheat

circuit, typically referred to as “Hot gas reheat” (HGR).

HGR needs higher condensing temperatures to work well,

typically 85°F [29°C] entering water temperature (EWT).

With HGR, cooler water temperatures produce cooler

supply air temperatures, which could overcool the space,

requiring additional space heating from another source or

a special auto-change-over relay to allow the unit to switch

back and forth between reheat and heating. Rarely does

HGR provide 100% reheat, like ClimaDry

II. ClimaDry

has a simple and easy to troubleshoot refrigerant circuit.

No switching valves or hard to diagnose leaky check valves

are utilized. No unusual refrigerant pressures occur during

the reheat mode. The ClimaDry

II refrigerant circuit is like

every other Comfort-Aire/Century unit (without reheat),

so everything the technician already knows applies to

troubleshooting the ClimaDry

II refrigeration circuit. Plus,

the water loop portion of the ClimaDry

II option is easy to

understand and diagnose.

ClimaDry

II Applications

ClimaDry

II can be applied to a number of common

applications, such as:

• Classrooms.

• Condominiums.

• Apartments.

• Computer rooms.

• Spaces with high latent loads like auditoriums, theaters,

convention centers, etc.

• Most applications where humidity is a problem.

(Note: ClimaDry

is not for use in high fraction

outdoor air applications or in applications with

corrosive atmospheres, such as pool rooms.)

Figure 1: ClimaDry

II Schematic

COAX

Note:

All components shown

are internal to the heat

pump unit.

(TO WATER LOOP)

(FROM WATER LOOP)

MODULATING

MIXING

VALVE

ENTERING

AIR

INTERNAL

PUMP

EVAPORATOR

COIL

LEAVING

AIR

REHEAT

COIL

REFRIGERANT OUT

(COOLING)

REFRIGERANT IN

(COOLING)

WATER IN

WATER OUT

ClimaDry

II - Benets and Application