Carel MC User manual

Connected Solutions
MC
NO POWER
& SIGNAL
CABLES
TOGETHER
READ CAREFULLY IN THE TEXT!
Duct / Air Handler Atomizing
Humidication System
(Modulating)
User manual

3
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
IMPORTANT WARNINGS:
This product is compliant with the European directives and other standards
specied on the EC declaration of conformity. The customer is responsible for
suitably verifying any use of the product that implies application of standards
relating to any special environments and/or processes (e.g. heavy industry,
medical environments, maritime environments, railway environments, etc.)
other than those specied by Carel.
The humidiers manufactured by CAREL are advanced products, whose operation
is specied in the technical documentation supplied with the product that can
be downloaded, even prior to purchase, from the website www.carel.com. Every
product made by CAREL, in relation to its advanced level of technology, requires
a qualication/ conguration / setup phase in order to best full your specic
application. If the humidier is not installed correctly as described in the user manual,
it may, as indicated in the manual, can cause the nal product to malfunction, of
which CAREL cannot be held responsible.The client (builder, developer or installer of
the nal equipment) assumes all responsibility and risk relating to the conguration
of the product in order to achieve the expected results in relation to the specic
nal installation and/or equipping. In this case, subject to specic agreements,
CAREL acts as a consultant for the success of the installation / start-up / use of the
machine, but in no case does it accept liability for proper operation of the humidier
and of the nal plant, should the warnings and recommendations in this manual or
in any other technical documentation of the product not be followed. In particular,
in addition to the obligation to observe the above mentioned warnings and
recommendations for proper use of the product, we recommend paying attention
to the following warnings:
DANGER ELECTRIC SHOCK: The humidier includes live electrical parts.
Disconnect the power supply before accessing internal parts, in case of
maintenance and during installation.
DANGER WATER LEAKS: The humidier automatically and constantly lls and/
drains quantities of water. Malfunctions in the connections or humidier may
cause leaks.
DANGER OF BURNS: The humidier contains hot parts and delivers steam at
100 °C / 212 °F.
• The product is designed exclusively to humidify rooms either directly or
through distribution systems (ducts).
• Installation, operation and maintenance must be performed by qualied
personnel, aware of the necessary precautions and able to perform the
required operations correctly.
• All operations on the product must be carried out according to the instructions
given in this manual and on the labels applied to the product. Any uses or
modications unauthorized by the manufacturer are considered improper.
CAREL denies all responsibility for such unauthorized uses.
• Do not attempt to open the humidier in any way other than the ones
described in the manual.
• Follow the regulations in force in the place where the humidier is installed.
• Keep the humidier out of the reach of children and pets.
• Do not install and use the product near objects that can be damaged by contact
with water (or condensate). CAREL denies all responsibility for direct or indirect
damage as a result of loss of water from the humidier.
• Do not use corrosive chemicals, aggressive solvents or detergents to clean the
internal or external parts of the humidier, unless specically indicated in the
user’s manual.
CAREL adopts a continuous development policy. Therefore, CAREL reserves the
right to carry out modications and improvements to any product described
in this document without prior notice. The technical data in the manual can
undergo modications without forewarning.The liability of CAREL in relation to its
own product is governed by CAREL general contract conditions published on the
website www.carel.com and/or by specic agreements with clients; in particular,
within the limits set by the applicable law, in no way will CAREL, its employees or
its branch oces/aliates be responsible for any lack of earnings or sales, loss of
data and information, cost of replacement goods or services, damage to objects
or persons, work interruptions, or any direct, indirect, accidental, patrimonial,
coverage, punitive, special or consequential damage in any way caused, be
they contractual, out-of-contract, or due to negligence or other responsibility
originating from the installation, use or inability of use of the product, even if
CAREL or its branch oces/aliates have been warned of the possible damage.
ATTENTION
NO POWER
& SIGNAL
CABLES
TOGETHER
READ CAREFULLY IN THE TEXT!
Separate the probe cables and the digital input cables as much as possible
from the inductive load and power cables to prevent possible electro-magnetic
interference.
Never introduce power cables and signal cables (including those of electric control
board) into the same cable troughs.
The installation of the product must absolutely include the grounding connection,
using the special yellow-green terminal on the terminal block. Do not use the
neutral as grounding connection.
DISPOSAL
The humidier consists of metal parts and plastic parts. With reference to the
European Parliament and Council Directive 2002/96/EC issued on 27 January 2003
and the related national implementation legislation, please note that:
1. WEEE cannot be disposed of as municipal waste, said waste must be collected
separately;
2. the public or private waste collection systems dened by local legislation
must be used. Moreover, the equipment can be returned to the distributor at
the end of its working life when buying new equipment;
3. the equipment may contain hazardous substances: the improper use or
incorrect disposal of such may have negative eects on human health and
on the environment;
4. the symbol (crossed-out wheeley bin) shown on the product or on the
packaging and on the instruction sheet indicates that the equipment has
been introduced onto the market after 13 August 2005 and that it must be
disposed of separately;
5. in the event of illegal disposal of electrical and electronic waste, the penalties
are specied by local waste disposal legislation.
Warranty for materials: 2 years (from the manufacture date, excluding
consumables).
Certication: the quality and safety of CAREL products are guaranteed by CAREL’s
ISO 9001 certied design and production system, as well as marking.

5
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Content
1. INTRODUCTION 7
2. INSTALLATION 8
2.1 Instructions...................................................................................................................................................................8
2.2 Primary Control Cabinet Wiring....................................................................................................................16
2.3 Secondary Control Cabinet Wiring.............................................................................................................16
3. OPERATING THE MC CONTROLS 22
3.1 INTERFACE BUTTON COMMANDS...............................................................................................................22
3.2 Initial Power up....................................................................................................................................................... 23
3.3 System Status...........................................................................................................................................................23
3.4 User Settings.............................................................................................................................................................24
3.5 Current Alarms ........................................................................................................................................................24
3.6 Run Hours................................................................................................................................................................... 27
3.7 Service Setting ........................................................................................................................................................28
3.8 Factory Settings......................................................................................................................................................30
3.9 Factory Defaults (Caution) ...............................................................................................................................33
3.10 Date/Time Setting.................................................................................................................................................33
3.11 Manual Control.......................................................................................................................................................33
3.12 Alarm History ...........................................................................................................................................................33
3.13 Communications...................................................................................................................................................33
4. MAINTENANCE 35
5. TROUBLESHOOTING 36
6. PARTS OF ATOMIZING HEADS 40
7. CONTROL CABINET PARTS 41
8. WIRING DIAGRAMS 43
8.1 Duct Main / DDC ..................................................................................................................................................43
8.2 Secondary ................................................................................................................................................................. 44
9. TECHNICAL SPECIFICATIONS 45
LIMITED WARRANTY
All products manufactured by Carel USA, LLC are warranted to the original purchaser to be free from defects in materials and workmanship
in the course of normal and reasonable use for a period of 2 years from the date of installation or 2 years and 1 month from the date
of shipment (The OEM controls warranty is 2 years from date of manufacture), whichever comes rst, so long as the product has been
installed and operated in accordance with all appropriate manuals and wiring diagrams, and started up by a qualied Carel USA technician.
Any product or part that is found to be defective will, at the option of Carel USA, LLC be replaced or repaired. Carel USA, LLC reserves
the right to inspect any part or installation before replacing or repairing defective parts. After startup of the product, labor for repairs or
replacement of parts is not covered by this warranty. Products not included in this warranty are NTC and PTC probes, transformers (TRA
series), and routinely replaceable parts such as steam cylinders and gaskets. Carel USA, LLC assumes no liability for consequential or
inconsequential damage, or damage due to negligence or improper use. Under the terms of this warranty, the original purchaser may
have certain legal rights and other rights, which may vary from state to state. The Warranty will not be considered valid if a product is
damaged due to negligence, mishandling or misapplication, or if the product label is missing. Carel USA will attempt to repair or replace
the products within two (2) months of the receipt of the returned goods.

7
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
1. INTRODUCTION
The MC system requires clean compressed air and water to
operate eciently and with minimal maintenance.
1.1 Requirements
• Compressed Air Requirements: 0.15 CFM per pound
of water per hour is required. DO NOT UNDERSIZE AIR
COMPRESSORS. The system cabinets should be fed with 100
psi of compressed air. Internal regulators are used to reduce
it to the required discharge pressure to the atomizing heads
(30 psi at manifold ends). Compressor after cooler, moisture
separator and trap, and 0.1 micron coalescing lter are the
minimum requirements. Oil from compressed air will cause
excessive maintenance on the atomizing heads. Size air
piping to avoid excessive pressure drops.
• Water Requirements: The system requires 5 psi of clean
water at the atomizing manifolds. 20 psi to the cabinet is
the recommended minimum. If water lines are old, steel,
or galvanized, then a water lter is required prior to the
control cabinet. NEVER use steel or galvanized pipe within
the system.
1.2 How the MC Works
The MC atomizing system is built around the exclusive atomizing
nozzle design developed by Carel LLC over 10 years ago. This
nozzle has many exclusive features:
• All stainless steel construction
• Special piston lubricant that avoids liberation of ions
• Most ecient design of air use versus droplet size
• Simple design with extremely low maintenance
The MC atomizing head uses what is called “Supersonic Vacuum
Implosion” technology. This technology produces small droplets
using minimal compressed air with relatively low pressures (30
psi air, 5 psi water). Air and water regulators and solenoid valves in
the control cabinet control the pressures and ow to the nozzles.
On a call for humidity, the air valve is opened and air ows to
the nozzles. When the air pressure rises high enough, it will
push back the pistons in the atomizing nozzles, pulling back the
cleaning needle and opening the water seat, allowing water to
then ow out of the nozzles and be atomized. The nozzles are
failsafe in that if the air pressure is too low, the pistons will remain
closed and prevent water ow. The tip of the cleaning needle
is also used as a secondary modulation valve giving the MC its
exclusive 100:1 modulating turn down.
In operation, compressed air exits the front of the nozzle
through a precision metered orice which surrounds the
water orice. As the air exits at supersonic speed, it produces
a high vacuum around the water orice. Water is drawn into
the vacuum and super compressed. The water is then instantly
accelerated to supersonic speed and decompressed, tearing
it into tiny droplets and also distorting the droplets wildly.
This distortion causes microingestion of the surrounding
atmospheric air, enhancing the speed at which the droplets
then evaporate. Modulating the compressed air supply to the
heads causes the pistons to move, modulating the water ow.

8
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
2. INSTALLATION
2.1 Instructions
Step 1: Installation Rules
The following general rules need to be applied to any MC
installation. Carel will not take responsibility for any system
installed that does not follow these rules and warranty may be
voided.
1. All atomizing heads on a system must be at the same
elevation. Due to the low water pressure involved, a deviation
in elevation of heads of more than 3 inches may be enough to
cause the lower heads to spray heavy while the higher heads
don’t spray at all.
2. Keep minimum pressure drops in the air and water
piping. Always use minimum 1/2” I.D. water lines. Use minimum
1/2” I.D. air lines up to 200 lbs/hr in capacity and/or when the
total system layout is less than 100 feet. Use minimum 3/4” I.D.
air lines when the system capacity is over 200 lbs/hr and/or they
total system layout is more than 100 feet. Avoid excessive use of
sharp 90° elbows - neatness is secondary to function. NOTE: It is
the installer’s responsibility to insure that the air and water lines
are sized to provide proper pressure and volume to the cabinet
and then to the atomizing heads.
3. Avoid vertical bends in air and water system piping.
These could trap dirt, water or air and prevent proper blowout of
the lines during maintenance.
4. Heads should be mounted above the air and water
lines. This insures that sediment and debris will not ow into the
atomizing heads to cause maintenance.
5. Position atomizing heads to avoid direct discharge onto
obstructions. As a rule of thumb, the atomizing heads discharge
a plume of mist up to 15 feet long and to 4 feet in diameter.
Anything in this plume has the potential to get wet.
6. Position the heads to allow access for maintenance.
Position over aisles or along walls where access is easy, rather
than over equipment and racks.
7. For optimal performance, the control cabinet should be
located at least 3 feet below the elevation of the atomizing heads.
This is to allow a column of water pressure against the water
regulator contained in the control cabinet to allow controllability.
8. Size the compressor properly. 0.15 CFM (0.12 SCFM) per
pound of water per hour is required. DO NOT UNDERSIZE AIR
COMPRESSORS. The system cabinets should be fed with 100 psi
of compressed air. Internal regulators are used to reduce it to the
required discharge pressure to the atomizing heads (30 psi at
manifold ends).
*DO NOT install the cabinet more than 3 feet above the manifold
it is controlling.
9. Compressed air must be clean and without oil.
Compressor after cooler, moisture separator and trap, and 0.1
micron coalescing lter are the minimum requirements. Oil
from compressed air will cause excessive maintenance on the
atomizing heads, causing a premature buildup of mineral around
the water nozzle tip and in the front air orice of the atomizing
heads, blocking air ow and causing a heavy spray.
10. Insure proper water supply. 20 psi to the cabinet is
the recommended minimum. If water lines are old, steel, or
galvanized, then a water lter is required prior to the control
cabinet. NEVER use steel or galvanized pipe within the system.

9
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Step 2: Plan system layout
(Assistance is available from CAREL USA)
The MC atomizing heads discharge a plume of mist that will
reach 15 feet long and 3 feet in diameter in still air. In air handlers,
air passing over the heads will turn and carry the droplets, so it
is usually advantageous to have the atomizing heads discharge
somewhat perpendicular to the air ow. The following graphic
illustrates that the lightest droplets turn rst and the heaviest
droplets last, usually arriving at about the same evaporation
distance downstream. The TURNING RADIUS table shows how
high the air handler must be to avoid impingement.
This graphic also shows the mix of droplets contained in the
atomized mist at various levels of modulation. Accordingly, the
evaporation distance reduces as the heads modulate down.
The basic rules of atomizing head positioning are:
• Discharge perpendicular to the air stream when the air
handler or duct height will allow.
• Discharge perpendicular to, or in the direction of the air
ow, never against it.
• In VAV systems, angle the heads toward the top of the
downstream cooling coil.
• Locate as far upstream from any cooling coil or mist
eliminator as possible. Rules of thumb: 36” to coil or eliminator,
20 feet in straight ducts with no coils or eliminators.
NOTE: The installer is responsible for the nal position of the
atomizing manifolds (even if drawings are provided by Carel
USA). Accordingly, atomizing manifolds may need to be moved
by the installer after startup in order to avoid stratied air and
dead or turbulent areas of the duct or air handler.

10
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Typical air handler installation with one manifold
(elevation view):
As you can see, the atomizing manifold is located after the preheat
(or heating) coil and prior to the cooling coil. The manifold is
placed at the bottom of the air handler, as far away from the
cooling coil as possible, and angled to discharge toward the top
edge of the cooling coil. This angled discharge also allows for VAV
operation when air ow may reduce.
In typical duct applications, the manifold is
arranged in the middle of the duct with the heads
discharging in the direction of air ow.
Duct size must be a minimum of 18” high and wide
enough to allow 2” between heads minimum and
9” at either side.
Evaporation distance is about 20 feet to any elbows,
take-os or obstructions.

11
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
If there is no room between the preheat and cooling coils,
then the system could be located after the cooling coil if a mist
eliminator is used:
Likewise, in a duct system that does not have enough straight
duct run for evaporation, a mist eliminator can be employed.
However, there are rules for mist eliminator use:
• Face velocity through the eliminator must not exceed 750 fpm.
• Air ow through the eliminator must be laminar.

12
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
When the duct velocity exceeds 750 fpm, an expanded
transitional section may be used to reduce duct velocity to an
acceptable level (less than 750 fpm).
In very large systems, multiple manifolds may be used to meet
capacity. The following sketch is a typical layout, but in these
cases Carel USA should work up the nal layout.

13
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Step 3: Mounting the atomzing manifolds
The atomizing manifolds are supplied preassembled to match
the width of the air handler or duct. At the feed end, they are to
be terminated with compression to threaded ttings, and at the
other end they are to be terminated with compression plugs and
a gauge assembly on the air line:
In systems over 250 lbs/hr capacity, the manifold is fed to the
center and terminated on both ends, one end with an air gauge
assembly:
The atomizing manifold(s) should be mounted in the air handler
or duct per the instructions in Step 2 or per installation drawings
provided by the manufacturer.

14
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Support the manifold by the duct edges and by pieces of vertical
uni-strut (not supplied), so that the manifold is held level with
the atomizing heads discharging as per Step 2 or the installation
drawings and without sagging.
If manifolds are longer than 8 feet, they will be in two or more
pieces. Use the compression unions supplied to join them
together as shown at right.

15
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Step 4: Mounting the cabinet
The control cabinet should be mounted to a solid surface at a convenient height. However, the cabinet
should not be located more than 3 feet above the atomizing heads. Optimum installation is with the
control cabinet level at least 3 feet below the atomizing heads.
Air and water inlet connections are on the left side of the cabinet, outlet connections on the right, so
leave clearance for these.
Cabinet must be mounted level and indoors. Minimum temperature = 40°F, maximum temperature and
humidity
= 120°F and 85%RH noncondensing.
Dimensions and mounting holes for the cabinets are as follows.
Step 5: Connect air and water
The air and water ball valves shown at right are supplied loose with the cabinet. Solder a piece of
1/2” copper tube (no longer then 2’) to the 1/2” ball valve (supplied). Slip tube in top hole and 5/8”
compression tting then tighten. Cement a piece of 1/2’schedule 80 PVC pipe (no longer then 2’) to the
1/2”union PVC ball valve (supplied). Slip pipe in bottom hole and cement to the union tting in cabinet.
On the inlet side (left), the top connection is for air, bottom one is for water. On the outlet side (right) the
middle connection is the drain.
Use 1/2” water lines to feed the cabinet and from the cabinet to the atomizing manifold.
Use 1/2” air lines when the system is under 200 lbs/hr and the
piping distance is less than 100 feet. Use 3/4” air lines when the system is over 200 lbs/hr and/or the
piping distance is longer than 100 feet. If the piping has excessive elbows and is more than 100 feet,
then use 1” air lines.

16
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
NOTE: Use two (2) wrenches on all ttings to prevent twisting
of the ttings inside the cabinet, which can cause them to leak.
NOTE: It is the installer’s responsibility to size the air and water
lines to minimize the pressure drop and provide 100 psi air and
20 psi water minimum to the cabinet in sucient volume for
system operation.
Step 6: Connect electric power
• In the top of the cabinet are the electrical connections. Connect
110 VAC to terminals 1 and 2 and the ground wire to the green
and yellow ground terminal. Cabinet requires a 5 Amp service.
• The terminals have knife blade disconnects. The power
transformer has an internal circuit breaker.
A
B C
APower Transformer
B Power terminals with knife switches
C Control wiring terminals
Step 7: Mount and wire sensors and safeties
• The control humidity sensor is located in the return plenum or
in the room.
• The hi-limit humidity sensor is located downstream of the
atomizing heads, after the cooling coil or mist eliminator in
air handlers and at least 20 feet downstream of the atomizing
heads in ducts. Locate so live mist does not impact the sensor.
• The airow switch can be located anywhere on the duct or air
handler where it can properly sense the pressure change when
the fan is running versus when it is o. This switch is adjustable
for proper air pressure sensing.

17
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
2.2 Primary Control Cabinet Wiring
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
G
NC
ALARM
NO ALARM
NO COMPRESSOR / WATER TREATMENT ENABLE
WATER TREATMENT FAILURE NC
24 Vac
NC
COMPRESSOR FAILURE
- OUTSIDE AIR AND/OR SUPPLY
+ OUTSIDE AIR
- CONTROL SIGNAL
- CONTROL SIGNAL
+CONTROL SIGNAL
CAREL NTC SENSOR
AS*H100000
+Vdc (+G)
M
OUT H CONTROL HUMIDITY SENSOR
REMOTE ON/OFF
NEUTRAL
110 vAC
110 Vac
GROUND
VGO - SOLENOID - TO TERMINAL 5 STAGE 4 (SECONDARY CABINET)
M - TO TERMINAL 4 STAGE 4 (SECONDARY CABINET)
Y (0-10 Vdc) TO TERMINAL 3 STAGE 4 (SECONDARY CABINET)
VGO - SOLENOID- TO TERMINAL 5 STAGE 3 (SECONDARY CABINET)
M - TO TERMINAL 4 STAGE 3 (SECONDARY CABINET)
Y (0-10 Vdc - TO TERMINAL 3 STAGE 3 (SECONDARY CABINET)
VGO - SOLENOID - TO TERMINAL 5 STAGE 2 (SECONDARY CABINET)
M - TO TERMINAL 4 STAGE 2 (SECONDARY CABINET)
Y (0-10 Vdc) - TO TERMINAL 3 STAGE 2 (SECONDARY CABINET)
+ SUPPLY AIR
OUT H ASDH100000 HIGH-LIMIT HUMIDITY SENSOR
24 Vac
AIRFLOW SWITCH NC
NC
Terminal 29-32 are connected to a SPDT relay.
Terminals 30 and 32 are the common of the
relays.
Compressor/water treatment enable is a SPST
relay.
Water treatment and compressor failure
alarms need to come from a dry contact.
24 Vac provided by the MC cabinet (#16)
CAREL NTC sensors do not have polarity.
DDC input control signal
Airow switch and remote on/o inputs
need to come from dry contacts.
24 Vac provided by the MC cabinet (#4)
2.3 Secondary Control Cabinet Wiring
Wire all power and controls according to local and national electrical codes. Wire the control cabinets according to the wiring diagrams
supplied with the cabinets themselves. Wiring diagrams in this manual are for reference only.
5
4
3
2
1
G
Y (0-10 Vdc) FROM PRIMARY CABINET
NEUTRAL
110 vAC
110 Vac
GROUND
M FROM PRIMARY CABINET
VGO FROM PRIMARY CABINET
SEE PRIMARY CONTROL CABINET WIRING
ABOVE

18
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
PC-301 Air Proving Switch
Mounting the PC-301 air ow switch:
Mount the airow switch in the supply or return duct using the
screws supplied. Mount the device so that the diaphragm is in a
vertical position as shown at right.
If the airow switch is to be mounted on the return duct
(vacuum), then mount it in a vertical position by the small plate.
Drill a 7/16”hole in the side of the duct and connect the supplied
tubing to the low pressure tap on the airow switch and then
run it through the drilled hole in the duct. Put no more than 2”of
tubing into the duct. Caulk around the tubing where it enters the
duct. The high pressure tap is left open to atmosphere.
If the airow switch is to be mounted to the supply duct
(pressure), then drill a 7/16 hole in the side of the duct, apply
caulking to the large plate, and mount the device with the large
plate to the duct and the high pressure tap/tubing mated to the
hole. The low pressure tap is left open to atmosphere.
Mounting Diagram
Maximum Electrical Switch Ratings
Vac Full Load
Amps
Locked Rotor
Amps
Pilot Duty
(VA)
Non-Inductive
Amps
24V - - 60 10
120V 6.25 37.5 300 10
240V 3.1 18.6 300 10
277V 2.7 16.2 300 10
Wiring Diagram
NOTE: There is an adjustment screw located under the metal
cover. This must be adjusted to insure that the air ow switch
turns on during air ow and o when air ow ceases.

19
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
DPWC/DPWT- DPDC Wall – Duct Temperature/Humidity Sensors
Model Description
Humidity: Thin lm capacitor
Linear 0-1 Vdc or 4-20 mAdc from 10 to 90%RH
Accuracy: +- 3%RH from 20 to 90%RH
calibrated at 55%RH and 25°C (77°F)
+- 5%RH above 90%RH and below 20%RH
Response time: 60 seconds
Power: 12 to 24 Vac/dc or +12 to –12 Vdc
Housing: Wall: ABS with glass ber ll
Certications: Calibrated to NIST traceable humidity/
temperature standard, CE Approved
Humidity (0-1 VDC or 4-20 mADC)
DPWC111000 Wall Humidity sensor (replaces ASWH100000 and SHWOOP)
DPDC110000 Duct Humidity sensor (replaces ASDH100000 and SSDOMH00/1)
Temperature & Humidity (NTC temp, 0-1 VDC or 4-20 mADC humidity)
DPWC111000 Wall Temp/hum sensor (replaces SWNTCTH0/1, STHONTC0/1 and
ASWC111000)
DPWC110000 Wall Temp/hum sensor (replaces STHOAP AND ASWC110000)
Temperature & Humidity (0-1 VDC or 4-20 mADC temp & humidity)
DPDC111000 Duct temp/hum sensor (replaces SDNTCTH0/1 AND ASDC111000)
DPDC110000 Duct temp/hum sensor (replaces SSDOMHT0/1 AND ASDC110000)
IMPORTANT: If you are going to control the MC system from a DDC
system (and therefore Carel is not supplying any sensors, it is vitally
important that the preheat, cooling, and reheat systems are all integrated
to compensate for and take advantage of the evaporative cooling
eect of the atomizing system. If the following control sequence is not
followed, CAREL cannot be held responsible for improper evaporation
of the mist generated.

20
ENG
MC DUCT +03U400025 - rel. 4 - 20201201
Recommended Sequence of Operation for DDC Controls
1. There should be a control air humidity sensor located
either in the return air duct or in the room being humidied.There
should be a supply air humidity sensor located downstream of
the humidier system, mist eliminators, or cooling coil (after the
fan is acceptable) to sense humidity from the system.
2. The control software should allow a set point for the
control air humidity, which will be set to the desired level of
relative humidity in the controlled space. The control software
should also allow a set point for the supply air humidity, which
will be set to a high limit setting of about 90%RH with a wide
band of about 10%.
3. On a fall in control air relative humidity and supply air
relative humidity below their controller set points, the control
logic should bring the system atomizing heads into operation
and modulate them from 0-100% of capacity according to the
lowest demand, either from the control air sensor or from the
supply air sensor.
4. On approaching either the control air humidity set
point or the supply air humidity set point, the control logic
should cause the system atomizing heads to decrease their
output proportionally from 100-0% again according to the
lowest demand, either from the control air sensor or from the
supply air sensor. In eect this is a low signal selector routine.
5. On reaching either set point, the atomizing heads
should be turned o by giving the MC system the lowest control
signal.
6. In addition to the humidity sensors, there should also
be temperature sensors located downstream of the preheat coil,
and downstream of the humidier mist eliminators. The software
should permit a preheat temperature set point, and a cooling
coil set point.
7. A preheat set point should be set and will modulate
the preheat coil according to the preheat temperature sensor to
maintain the preheat set point. A cooling coil set point should
be set to maintain the supply air temperature by modulating the
cooling coil.
8. During operation of the atomizing humidiers, the
supply air temperature will drop due to evaporative cooling.
As the supply air temperature drops, the cooling coil should be
modulated toward closed. When the cooling coil is closed and
the supply air temperature continues to drop below the supply
air temperature set point, the preheat coil should be modulated
toward open to maintain the supply air temperature set point
and compensate for the evaporative cooling of the humidier.
This action supercedes the preheat control based on the preheat
sensor.
9. If reheat is used, then the supply air temperature set
point should reset to the point where it controls the coldest zone
without needing its reheat. It is pointless to overcool the supply
air and then force massive amounts of reheat. Do not activate
reheat unless preheat is at 100%.