Ultra-Aire MD33 User manual

The Ultra-Aire MD33 is a built-in dehumidication solution that can be
conveniently installed inside standard wall framing. The Ultra-Aire MD33
provides the ultimate in comfort, health and property protection.
TS-927 6/18 Rev E
P/N: 4035900 Serial No.: Install Date:
Sold by:
HVAC Installer: Please Leave Manual for Homeowner
Installation Instructions
INSTALLATION BY AN HVAC PROFESSIONAL IS RECOMMENDED
98H
Patent Pending
D Therma-Stor, LLC

Safety Instructions ...................................................................... 3
Specifications .............................................................................. 5
Optional Accessories................................................................... 6
Dehumidifier Set Up .................................................................... 6
Drain Installation Recommendations........................................... 7
Electrical Requirements .............................................................. 7
Dehumidifier Installation ............................................................. 8
Maintenance.............................................................................. 12
Air Flow...................................................................................... 12
Controls ..................................................................................... 13
Service....................................................................................... 15
Warranty .................................................................................... 17
TABLE OF CONTENTS
Therma-Stor is committed to manufacturing quality products. To maintain
our standards, product specications may change without notice.
4201 Lien Road, Madison, WI 53704
[phone]
www.Thermastor.com
© 2017 Therma-Stor LLC

3
www.InWallDehumidier.com | [phone] Ultra-Aire MD33 Installation Instructions
SAFETY INSTRUCTIONS
WARNING!
THIS SYMBOL MEANS IMPORTANT INSTRUCTIONS. FAILURE TO HEED THEM
CAN RESULT IN SERIOUS INJURY OR DEATH.
READ THE INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
CAREFULLY BEFORE INSTALLING AND OPERATING THIS DEVICE. PROPER
ADHERENCE TO THESE INSTRUCTIONS IS ESSENTIAL TO OBTAIN MAXIMUM
BENEFIT FROM THIS DEHUMIDIFIER.
CAUTION!
THIS SYMBOL MEANS IMPORTANT INSTRUCTIONS. FAILURE TO HEED THEM
CAN RESULT IN INJURY OR MATERIAL PROPERTY DAMAGE.
Registrations
The Ultra-Aire MD33 conforms to unied standard UL 60335-2-40 and CSA Standard C22.2.60335-2-40.
CAUTION!
READ ALL INSTRUCTIONS BEFORE BEGINNING INSTALLATION.
ALWAYS USE CAUTION AND WEAR CUT RESISTANT GLOVES WHEN HANDLING SHEET
METAL.
ALL STATE AND NATIONAL ELECTRICAL AND PLUMBING CODES MUST BE ADHERED TO
FOR PROPER UNIT OPERATION AND WARRANTY COMPLIANCE.
IMPROPER INSTALLATION MAY CAUSE PROPERTY DAMAGE OR INJURY.
INSTALLATION, SERVICE, AND MAINTENANCE MUST BE PERFORMED BY A QUALIFIED
SERVICE TECHNICIAN.
DEHUMIDIFIER IS HEAVY. HANDLE WITH CARE AND FOLLOW INSTALLATION INSTRUCTIONS.
DO NOT USE IN POOL APPLICATIONS, OR WARRANTY WILL BE VOID.
THIS APPLIANCE IS INTENDED FOR USE AT ELEVATIONS BELOW 4000 M (13,000 FT).
THIS APPLIANCE IS NOT INTENDED FOR USE BY PERSONS (INCLUDING CHILDREN) WITH
REDUCED PHYSICAL, SENSORY OR MENTAL CAPABILITIES, OR LACK OF EXPERIENCE
OR KNOWLEDGE, UNLESS THEY HAVE BEEN GIVEN SUPERVISION OR INSTRUCTION
CONCERNING THE USE OF THE APPLIANCE BY A PERSON RESPONSIBLE FOR THEIR
SAFETY. CHILDREN SHOULD BE SUPERVISED TO ENSURE THAT THEY DO NOT PLAY WITH
THE APPLIANCE.
WARNING!
120 VOLTS MAY CAUSE SERIOUS INJURY FROM ELECTRIC SHOCK. TURN
OFF CIRCUIT BREAKER BEFORE STARTING INSTALLATION OR SERVICING,
AND LEAVE CIRCUIT BREAKER OFF UNTIL INSTALLATION OR SERVICE IS
COMPLETED.

4Ultra-Aire MD33 Installation Instructions www.InWallDehumidier.com | [phone]
SAFETY INSTRUCTIONS
AVERTISSEMENT!
CE SYMBOLE DÉSIGNE DES INSTRUCTIONS IMPORTANTES. LE NON-RESPECT DE
CES INSTRUCTIONS PEUT ENTRAINER DE GRAVES BLESSURES, VOIRE LA MORT.
LISEZ ATTENTIVEMENT LES INSTRUCTIONS SUR LE FONCTIONNEMENT ET L’ENTRETIEN
RELIÉS À L’UTILISATION DE CETTE UNITÉ AVANT D’EN EFFECTUER L’INSTALLATION ET
L’UTILISATION. LE RESPECT DE CES INSTRUCTIONS EST PRIMORDIAL AFIN DE TIRER LE
MAXIMUM DE BÉNÉFICES DE VOTRE DÉSHUMIDIFICATEUR.
MISE EN GARDE!
CE SYMBOLE DÉSIGNE DES INSTRUCTIONS IMPORTANTES. LE NON-RESPECT
DE CES INSTRUCTIONS PEUT ENTRAINER DE GRAVES BLESSURES OU DES
DOMMAGES MATÉRIELS.
ENREGISTREMENTS
LE Ultra-Aire MD33 EST FIDÈLE À LA NORME UNIFIÉE UL 60335-2-40 AINSI QU’À LA NORME
C22.2.60335-2-40.
MISE EN GARDE!
LISEZ LES CONSIGNES EN ENTIER AVANT DE COMMENCER L’INSTALLATION.
SOYEZ TOUJOURS VIGILANT ET PORTEZ DES GANTS RÉSISTANT AUX COUPURES LORSQUE
VOUS MANIPULEZ DES FEUILLES DE MÉTAL.
TOUS LES CODES DE L’ÉLECTRICITÉ NATIONALE ET D’ÉTAT DOIVENT ÊTRE RESPECTÉS POUR
UNE UTILISATION ADÉQUATE DE CETTE UNITÉ ET UNE VALIDITÉ DE LA GARANTIE.
UNE INSTALLATION NON CONFORME PEUT CAUSER DES DOMMAGES MATÉRIELS OU DES
BLESSURES.
TOUTE INSTALLATION, TOUT ENTRETIEN ET TOUTE RÉPARATION DOIVENT ÊTRE EFFECTUÉS
PAR UN TECHNICIEN D’ENTRETIEN QUALIFIÉ.
LE DÉSHUMIDIFICATEUR EST LOURD. MANIPULER AVEC SOIN ET SUIVRE LES INSTRUCTIONS
D’INSTALLATION.
ÉVITEZ D’UTILISER POUR LE FONCTIONNEMENT D’UNE PISCINE OU LA GARANTIE SERA
ANNULÉE.
CET APPAREIL EST PRÉVU POUR UNE UTILISATION EN ALTITUDE À PLUS DE 4000 M (13000 PI).
CET APPAREIL NE DOIT PAS ÊTRE UTILISÉ PAR DES PERSONNES DONT LES CAPACITÉS
PHYSIQUES, SENSORIELLES OU MENTALES SONT LIMITÉES (Y COMPRIS LES ENFANTS) OU DES
PERSONNES SANS EXPÉRIENCE NI CONNAISSANCES PERTINENTES POUR L’UTILISATION DE
L’APPAREIL À MOINS D’AVOIR ÉTÉ FORMÉES SUR L’UTILISATION DE L’APPAREIL PAR UNE
PERSONNE RESPONSABLE DE LEUR SÉCURITÉ. LES ENFANTS DEVRAIENT ÊTRE SUPERVISÉS
AFIN D’ÉVITER QU’ILS NE JOUENT AVEC L’APPAREIL.
AVERTISSEMENT!
UNE DÉCHARGE ÉLECTRIQUE DE 120 VOLTS PEUT CAUSER DES BLESSURES
SÉRIEUSES. FERMEZ LE DISJONCTEUR AVANT DE COMMENCER L’INSTALLATION
OU L’ENTRETIEN ET LAISSEZ LE DISJONCTEUR EN POSITION FERMÉE JUSQU’À
CE QUE L’INSTALLATION OU L’ENTRETIEN SOIT COMPLÉTÉ(E).

5
www.InWallDehumidier.com | [phone] Ultra-Aire MD33 Installation Instructions
SPECIFICATIONS
Part Number: 4035900
Blower: 155 CFM @ 0.0" WG
Power: 324 Watts @ 80°F and 60% RH
120 Volt, hard-wired - electrical can be routed
through bottom or out the back of the cabinet
Automatic Restart: Ye s
Current Draw: 2.8 Amps
Operating Range: 49°F - 95°F
Sized For: Up to 1,200 Square Feet
Water Removal at 80°F and 60% RH
Capacity: 33 Pints/day
Eciency: 4.25 Pints/kWh
Controls: Digital dehumidistat control internally
mounted behind tamper-proof cover
Air Filter: 1/2" Washable - mounted behind diuser
Dehumidistat: Digital, tamper-proof, oat switch input
Cabinet: Galvanized Steel
Decibels: 46 dBA
Drain Connection: 3/4" O.D.
Drain Hose: 10' gravity fed (3/4" I.D.) hose - can be routed
through bottom or out the back of the cabinet
Refrigerant Type: R134A
Refrigerant Amount: 10 oz.
Coils: Electrophoretic coated coils - prevents
corrosion and extends life of the unit
Utility Connections: Accessible from front for blind installation
Dimensions (listed in inches):
Width: 14 "
Height: 30"
Depth: 5 "
Unit Weight: 39 lbs.
Shipping Weight: 57 lbs.
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6Ultra-Aire MD33 Installation Instructions www.InWallDehumidier.com | [phone]
OPTIONAL ACCESSORIES
4037766 Surface Mount Kit
Available for masonry CMU or installations where the unit cannot be recessed into the wall.
4037767 2x4 Wall Mounting Bezel Kit
Available for 2x4 wall installations where the unit cannot be allowed to penetrate the opposite side wall.
4037768 Rear Panel Kit
Available for 2x4 wall installations where the unit will penetrate through the other side of the wall into an
unconditioned space.
4037714 Washable Filter
4039155 Washable Filter, 6-Pack
Important Precautions
• If used near a water source, be certain that there is no chance the unit could get splashed. Connecting the
unit to a dedicated circuit with Ground Fault Circuit Protection is recommended. Electrical wires must be
properly grounded, and with the capability to be disconnected to provide for service.
• The device is designed to be installed indoors in a space that is protected from rain and ooding.
• Tamper proof fasteners provide access to the front of the device for operation, maintenance and service.
• Avoid directing discharge air at occupants.
• DO NOT place sides, top or bottom of cabinet in direct contact with structural building members or
unwanted noise may result. Unit is designed to be suspended by side mounting anges only.
• Drain hose must be routed with downward slope from unit drain connection to appropriate location. Consult
local building codes for acceptable condensate drain connections.
Location Considerations
• Install the unit on or inside of an interior wall and with direct connection to building electrical service.
A 15 Amp circuit must be provided. Install the unit in a location that is near a power supply.
• Electrical and plumbing rough-in must be provided to installation location, adhering to any applicable local
codes.
• Install the unit such that discharge air is directed away from thermostats and not installed inside of a wall
cavity that contains a thermostat.
• Install the unit in an area that is not near the A/C return or below a supply vent.
• The unit generates condensate. Install the unit with nearby access to a drain or determine if there will be a
need for a condensate pump.
• The unit will t within 16" O.C. stud walls. If walls are more or less than 16", consideration must be given to
providing additional support.
• Rough opening must be a minimum of 2" o the oor, 6" from the ceiling, and 10" from an inside corner.
• Check that there are no hidden wires or pipes inside the wall where unit is to be installed. Contact a certied
electrician or plumber before removing any wires or pipes inside the wall.
DEHUMIDIFIER SET UP

7
www.InWallDehumidier.com | [phone] Ultra-Aire MD33 Installation Instructions
A 10' long power cord is included for installations where a plug in connection is permitted in accordance with
the National Electrical Code and local codes and ordinances. A dedicated 15A circuit and GFCI receptacle
are recommended. Electrical connections inside the device are made with the included wire nuts. Route the
cord through the appropriate knockout and secure with the non-metallic cable clamp.
If not using the included 10' power cord,
ensure that the electrical connection and
wire size are adequate and in conformance
with the National Electrical Code,
ANSI/NFPA 70 – latest edition and all local
codes and ordinances. Use exible,
armored, or non-metallic sheathed, copper
wire with grounding conductor. Use the
included non-metallic cable clamp as required.
• The Ultra-Aire MD33 requires 120-volt,
60 Hz, AC-only, 15 amp, fused and
grounded electrical supply.
• A visible circuit breaker or disconnect
switch near the unit is required for
maintenance and service.
• A dedicated circuit is recommended.
• Use of a UL listed or CSA approved
strain relief is required.
ELECTRICAL REQUIREMENTS
Wiring Schematic
DRAIN INSTALLATION CONSIDERATIONS
Consult local building codes for condensate drain restriction and additional requirements. The Ultra-Aire
MD33 is provided with 10' of 3/4" I.D. drain hose. Verify drain hose length is appropriate for application.
The hose must be connected to the drain port and routed down the wall cavity and into the air conditioning
condensate drain or other acceptable drainage.
• For gravity drainage, the bottom of the unit must be at, or above the drain height.
• Avoid any entrapment of stagnant water within the hose.
• Consider 1/4" drop for every foot of drain hose.
• Codes may dictate that a drain trap is necessary before or near to the main building drain.
Be sure to install the metal cover over the top of the hose. This prevents air from entering the unit through
the wall cavity.

8Ultra-Aire MD33 Installation Instructions www.InWallDehumidier.com | [phone]
DEHUMIDIFIER INSTALLATION
Tools Required:
• Phillips Screwdriver
• 1/4" Hex Nut Screwdriver
• Level
• Square or Ruler
• Stud Finder
• Wire Stripper
• Drywall Saw
• Side Cutters or Carpenters Knife
• Tape Measure
• Pen or Pencil
Other Materials To Consider:
• Electrical wire (depends on
installation and distance of
wiring requirements)
• Additional hose length or PVC
pipe (depends on drain location)
• Materials to repair drywall
(depends on installation)
• Condensate Pump Kit
(depends on drain location)
• GFCI Outlet (if using supplied
power cord)
Step 1. Remove the shipping bracket by carefully
cutting the two zip ties with side cutters or shears.
Remove the four screws from the shipping bracket
using a 1/4" hex nut screwdriver.
Step 2. Remove electrical box cover from the unit by
removing the two screws on the cover using a 1/4" hex
nut screwdriver.
WARNING!
SHUT OFF BREAKER / POWER BEFORE BEGINNING INSTALLATION.
1.
2.
Electrical
Box
Shipping
Bracket
AVERTISSEMENT!
FERMEZ LE DISJONCTEUR/ALIMENTATION AVANT DE COMMENCER L’INSTALLATION.
Items Included in Box:
• Ultra-Aire MD33 Dehumidier
• Diuser Cover with Filter
• Ultra-Aire MD33 Installation Instructions
• Drain Hose (10')
• Power Cord (10')
• Hose Clamp
• Grommet for Drain Hose
• Non-Metallic Cable Clamp
• Bag A: #10 Wood Screws (5)
• Bag B: #8 Sheet Metal Screws (5)
• Bag C: Tamper Resistant Screws for
Diuser Cover (5) and 1/4" Hex T-15
Torx Security Bit
• Bag D: Phillips Screws for Diuser
Cover (5)
The Ultra-Aire MD33 can be installed in a variety of applications:
• 2x6 16" O.C. Stud Wall Installation
• 2x4 16" O.C. Stud Wall Installation
- If penetrating both walls and the opposite side is a mechanical room, no additional accessories are needed.
- If back wall is functional space, installation requires Front Mounted Bezel Kit (PN 4037767).
- If the other side of the wall goes into an unconditioned space, it may require the Rear Panel Kit (PN 4037768)
to add a layer of insulation to prevent condensation.
• Surface Mount Installation
- Surface Mount Kit (PN 4037766) required for installation.

9
www.InWallDehumidier.com | [phone] Ultra-Aire MD33 Installation Instructions
DEHUMIDIFIER INSTALLATION
Inside of Wall
Drain
Hose
Electrical
Wiring
14 1/2"
30 1/4
14"
14"
Steps 5 - 8
Step 4. The drain hose can exit through the back,
side, or bottom of the unit. Once the location is
determined, remove the appropriate knock out.
If exiting through the bottom, remove the access
cover to facilitate routing of the drain line.
Save access cover for reinstallation after drain
line is routed.
Step 5. After installation location has been determined,
use a stud nder, locate and mark stud walls.
Step 6. Using measuring tape and pencil, measure
14 1/2" across and 30 1/4" down and draw a line.
Step 7. Using a square or ruler, score the lines
and cut with drywall saw.
Depending on installation, both walls may need to
be cut through.
4.
Step 3. There are three electrical knock outs, one on
the back and two on the bottom of the unit. Remove
appropriate knock out and install non-metallic cable
clamp with clamp screws inside of unit oriented so
they are accessible for tightening later.
If using included power cord, insert cord through non-
metallic cable clamp so that a minimum of ½” insulation
jacket is inside of cabinet before tightening non-metallic
cable clamp screws. Make electrical connections using
included wire nuts.
3.
Step 8. If not using included power cord, route the
electrical wire from the circuit breaker or disconnect
switch through the wall cavity and extend out of the
opening by 14" to 20".
Use the 10' drain hose provided or the appropriate
length of hose to come through the wall cavity
or back of the unit and extend out of the opening
by 14" inches.
If cutting through both walls, electrical wiring
and drain hose may be routed dierently. Use
appropriate routing for your installation.
WARNING!
SHUT OFF BREAKER / POWER
BEFORE BEGINNING INSTALLATION.

10 Ultra-Aire MD33 Installation Instructions www.InWallDehumidier.com | [phone]
Step 10. Once electrical and drain hose are routed
through the unit, set the unit into the wall.
Step 9. Lift the unit and place it near the wall opening to route
electrical wires through appropriate knock out and drain hose
through hole.
If access cover was not removed, insert grommet into knock out
hole and snap into place before routing drain hose through.
It is recommended to have two people to lift the unit. Place
one hand under the drain pan to support the unit during this step.
Wall
MD33
14 1/2"
Side View
Drain Hose
and Electrical
Steps 9 - 10
DEHUMIDIFIER INSTALLATION
Step 11. Insert the dehumidier into the center of the opening,
allowing for a minimum of 1/8" clearance from framing on both
sides. Additional insulation or sound dampening material (not
provided) may be required if the dehumidier cabinet contacts
the studs, especially in applications involving metal studs.
Fasten the unit to the framing by inserting four of the #10
(wood) or #8 (sheet metal) screws into the slotted holes.
Top and bottom blocking is not necessary for securing the
dehumidier. Any existing blocking, headers or framing
should not intrude into the rough opening and be a minimum
of 1/2" away from the cabinet.
The cabinet is designed to create 1/2" clearance to the back
wall when installed inside a standard 2x6 stud space with
1/2" minimum drywall sheathing.
For alternate installations, maintain 1/2" clearance to back
of wall of dehumidifier cabinet.
11.
Before securing the unit into place, make sure it is level. Level
or slightly forward is acceptable, but never backwards.
15 1/2"
15"
0˚ 1˚-2˚ 1˚
OK OK NOT
OK
Front
Front
Front
CAUTION!
THE UNIT IS NOT SECURED YET.