Ruud RP13, Installation Instructions Manual

12

INSTALLATION

Replacement Units 

To prevent failure of a new unit, the existing line set 

must be correctly sized and cleaned or replaced. 

Care must be exercised that the expansion device 

is not plugged. For new and replacement units, a 

liquid line filter drier must be installed and refrigerant 

tubing must be properly sized. Test the oil for acid. If 

positive, a suction line filter drier is mandatory.

IMPORTANT:

 When replacing an 

R-22 unit with an R-410A unit, either replace 

the line set or ensure that residual mineral oil is 

drained from existing lines including oil trapped in 

low spots.

Indoor Coil

CAUTION:

Only use evaporators 

approved for use on R-410A systems that are 

specifically matched with the outdoor unit per 

the manufacturer’s specification sheets. Use 

of existing R-22 evaporators can introduce 

mineral oil to the R-410A refrigerant, forming two 

different liquids and decreasing oil return to the 

compressor. This can result in compressor failure.

REFER TO INDOOR COIL MANUFACTURER’S 
INSTALLATION INSTRUCTIONS.

IMPORTANT:

 The manufacturer is not 

responsible for the performance and operation of 

a mismatched system or for a match listed with 

another manufacturer’s coil.

NOTICE:

 All outdoor units must be 

installed with a matched TXV indoor coil. Refer to 

manufacturer’s outdoor unit specification sheet for 

approved indoor coils.

The thermostatic expansion valve in the 

matching coil is specifically designed to operate 

with R-410A. 

DO NOT use an R-22 TXV or 

evaporator. The existing evaporator must 
be replaced with the factory-specified TXV 
evaporator specifically designed for R-410A.

Location

Do not install the indoor coil in the return duct 

system of a gas or oil furnace. Provide a service 

inlet to the coil for inspection and cleaning. Keep 

the coil pitched toward the drain connection.

CAUTION:

When coil is installed 

over a finished ceiling and/or living area, it is 

required that a secondary condensate pan be 

installed under entire unit. Failure to do so can 

result in property damage.

Interconnecting Tubing

The purpose of this section is to specify the 

best construction/sizing practices for installing 

interconnection tubing between the indoor and 

outdoor unit. 

Refrigerant Level Adjustment

All units are factory-charged with R-410A 

refrigerant to cover 15 feet of standard size 

interconnecting liquid and vapor lines with a 

required field installed filter drier. Adjustment of 

charge may be necessary even if the application 

has exactly 15 feet of line set due to other 

installation variables such as pressure drop, 

vertical lift, and indoor coil size. For different 

lengths, adjust the charge as indicated below.

• 1/4" ± .3 oz./foot [6.4 mm ± 8.5 g/.30 m]
• 5/16" ± .4 oz./foot [7.9 mm ± 11.3 g/.30 m]
• 3/8" ± .6 oz./foot [9.5 mm ± 17.0 g/.30 m]
• 1/2" ± 1.2 oz./foot [12.7 mm ± 34.0 g/.30 m]
• 6 oz. required factory supplied field-installed

•

 filter drier.

Charge Adjustment = (Line Set (oz./ft.) x Total
Length) – Factory Charge for Line Set

Example: A three ton heat pump unit with factory 
installed 3/8” liquid service valve requires 75 ft. of 
line set with a liquid line diameter of 1/2”.

Factory Charge for Line Set = 15 ft. x .6 oz. = 9 oz.
Charge Adjustment = (1.2 oz. x 75 ft.) – 9 oz. =
+ 81 oz.

Tubing