2
A4. Breaker
Make sure that the power supply to the unit
is disconnected before performing any work
on the unit to avoid the possibility of shock
injury or damage to the equipment.
The unit is to be protected by a time delay fuse or HACR
(heating, air conditioner, refrigerator) breaker. By taking
an amp reading at the unit AC voltage supply line, you can
determine if the breaker is tripping prematurely. Place a
clamp-on type ammeter around the black wire between the
unit and breaker. Turn ON the unit and record the amp
draw. If the breaker trips before the rated amperage, re-
place the breaker.
MODELS
CIRCUIT PROTECTION
T.D. Fuse HACR Breaker
39125 (Basement)
15 amp
15 amp
39325 (Basement)
20 amp
20 amp
39224 (Basement)- Circuit 1
15 amp
15 amp
- Circuit 2
15 amp
15 amp
39424 (Basement)- Circuit 1
15 amp
15 amp
- Circuit 2
15 amp
15 amp
All Rooftop Units
20 amp
20 amp
59528.601
15 amp
15 amp
59529.601
15 amp
15 amp
59530.601
15 amp
15 amp
A5. Air Box
Improperly installed, the air box can be a source of cooling
problems. The air box must be sealed to the ceiling tem-
plate to prevent the mixing of discharge and return air. This
will cause short cycling or frost formation on the inside coil
On heat pumps, recirculation can cause the high side pres-
sure to build, tripping the overload and/or breaker. In some
instances, the ceiling template is bent when the anchor bolts
are overtightened, causing gaps between the air box and
the ceiling template. These gaps can be sealed with alu-
minum tape or a closed cell foam weather strip. The duct
connecting the air conditioner or heat pump must be air
tight. Use aluminum tape to seal the joints. The thermo-
stat sensing bulb must be properly located to control tem-
perature. If the sensing bulb is left curled against the side
of the electric box or used as a ground connection, im-
proper operation will occur. Relocate the sensing bulb in
its proper place as indicated in the Installation and Operat-
ing Instructions. Check the air filters and clean.
Section A - Installation, cont’d.
A6. Ducting
A6a. Rooftop Units
Sizing and Design
The installer of this air conditioner system must design the
air distribution system for his particular application. Sev-
eral requirements for this system MUST be met for the air
conditioner to operate properly. These requirements are
as follows:
Roof cavity thickness must be between 2.00" and 5.50".
This distance is measured between roof and ceiling sur-
face.
The total cross-sectional discharge area of the outlet ducts
from the plenum area under the air conditioner must be as
follows:
1. 579 & 600 Series
17.5 sq. in.
2. 591, 595 & 630 Series
21.0 sq. in.
Duct Sizing Requirements as Follows:
Min.
Max.
Duct Depth (591/595/630 Series)
1-1/2" 2-1/4"
(579/600 Series)
1-1/4" 2-1/4"
Duct Width
7"
— —
Total Duct Length
12 ft.
36 ft.
Duct Length (short run)
1/3 Total Length
Register Requirements as follows:
Min.
Max.
Distance from Duct End
5"
8"
Distance from End of Elbow
15"
— —
Distance between Registers
24"
— —
Total Number Required/AC
4
8
Number Required per Run/AC
2
— —
Free Area per Register
14 sq. in.— —
The duct material must meet or exceed any agency or RVIA
Standard that may be in existence at the time the RV is
produced.
It is the responsibility of the installer of this
system to ensure the ductwork will not col-
lapse or bend during or after the installation.
All discharge air ducts must be properly insulated to pre-
vent condensation from forming on their surfaces or adja-
cent surfaces during operation of the air conditioner or heat
pump. This insulation must be R-7 minimum.
Note:
The Dometic Corporation will not be held liable for
roof, structural or ceiling damage due to improperly insu-
lated or sealed ductwork.
Return air opening must have 40 sq. in. minimum free area
including the filter.
Return air to the air conditioner must be filtered to prevent
dirt accumulation on air conditioner cooling surface.
A6a. Roof Top Units
Manual
Compliments
of
Northwest
RV
Supply
Printed
From
http://www.nwrvsupply.com
