Rheem RTG-53X Installation Instructions Download Page 1

Tankless Water Heater Recess Box 

Installation Instructions

The purpose of this manual is to provide the installer with 

the basic instructions necessary to properly install the recess 

box. This manual assumes that the installer has basic car-

pentry skills and plumbing knowledge. Local codes may 

apply to this installation; all local building, electrical,  and 

plumbing codes should be followed.

It is very important that all persons who are expected to 

install, operate or adjust this recess box and/or water heater, 

read these instructions along with those instructions pro-

vided with the tankless water heater.

Recognize this symbol as an indication of Important 

Safety Information!

Refer to the Use and Care Manual provided with your 

tankless water heater for the proper installation proce-

dures and conditions.

!

Only these models of Outdoor Tankless Water Heaters 

will fit or function in this recess box;

RTG-53X  

 

RUTG-53X   

RMTG-53X 

 

PTG-53X 

 

PH-20ROF 

 

   

 

 

WARNING! 

Gasoline, as well as other flammable materials and liquids (adhesives, solvents, 

paint thinners etc.), and the vapors they produce are extremely dangerous. DO NOT handle, use or store 

gasoline or other flammable or combustible materials anywhere near or in the vicinity of a water heater 

or any other appliance. Be sure to read and follow the labels on the water heater, as well as the warning 

printed in this manual. Failure to do so can result in property damage, bodily injury or death.

!

1

Location

 - 

This water heater recess box is for OUT-

DOOR installation ONLY, and is intended for use only 

with the water heater models listed above. Do not attempt 

to install a water heater of another brand or model in this 

recess box.

Do not attempt to modify this recess box. Doing so will 

alter the intended design, potentially causing an unsafe 

operating condition.

Consult the Use and Care Manual provided with your tank-

less water heater for installation instructions regarding a 

suitable location for the water heater. All guidelines regard-

ing clearances and distances from overhangs, windows and 

doors, and air inlets into the home must be followed. 

 

Recess Box Clearances

 - This recess box is de-

signed to be installed with a Zero (0) clearance to combus-

tibles. For service and proper operation,  24” (61 cm) of 

clearance is required in front of the recess box.

 

Freeze Protection

 

- To help prevent water lines from 

freezing do not locate water heater on the side of a build-

ing with prevailing winter winds. Refer to the Use and 

Care Manual provided with your water heater for addi-

tional information. 

AP14133 (12/06)

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