Installation Guide
Residen al Standard Gas Water Heater Use and Care Guide • 13
GETTING STARTED
Residen al Standard Gas Water Heater Use and Care Guide • 13
GETTING STARTED
Space Hea ng
Some water heater models are equipped 
with inlet/outlet connec ons for use with 
space hea ng applica ons. If this water 
heater is to be used to supply both space 
hea ng and domes c potable (drinking) 
water, the instruc ons listed below must 
be followed.
•   This water heater is suitable for 
combina on water (potable) hea ng 
and space hea ng and not suitable for 
space hea ng applica ons only.
•   Be sure to follow the manual(s) 
shipped with the air handler system.
•   This water heater is not to be used as 
a replacement for an exis ng boiler 
installa on.
•   Do not use with piping that has been 
treated with chromates, boiler seal or 
other chemicals and do not add any 
chemicals to the water heater piping.
•   If the space hea ng system requires 
water temperatures in excess of 120°F, 
install a Thermosta c Mixing Valve 
in the domes c (potable) hot water 
supply at each point-of-use to limit the 
risk of scald injury. Install the mixing 
valve per its manufacturer’s instruc-
 ons.
•   Pumps, valves, piping, and fi  ngs 
must be compa ble with potable 
water.
•   A properly installed fl ow control valve 
is required to prevent thermosiphon-
ing. Thermosiphoning is the result of a 
con nuous fl ow of water through the 
air handler circuit during the off  cycle. 
•   The domes c hot water line from the 
water heater should be ver cal past 
any mixing valve or supply line to the 
air handler to remove air bubbles from 
the system. Otherwise, these bubbles 
will be trapped in the air handler heat 
exchanger coil, reducing effi ciency.
•   Do not connect the water heater to 
any system or components previously 
used with non-potable water heat-
ing appliances when used to supply 
potable water.
Solar Installa on
If this water heater is used as a solar stor-
age heater or as a backup for the solar 
system, the water supply temperatures 
to the water heater tank may be in excess 
of 120°F. A Thermosta c Mixing Valve or 
other temperature limi ng valve must be 
installed in the water supply line to limit 
the supply temperature to 120°F. The unit 
must be set to Standard Mode (See Operat-
ing Modes in Opera on sec on on page 
24).
NOTICE: Solar water hea ng systems can 
o en supply water with temperatures 
exceeding 180°F and may result in water 
heater malfunc on. 
Figure 11 - Combustion Space Heating and Potable Water (Typical Installation)
IN 
REMOVE A
MUST BE VERTICAL TO
IR BUBBLES
E
OUT 
COIL
AIR
HANDLER 
TO
AIR
HANDLER
SHUT-OFF
VALVE 
*
EXPANSION TANK
VACUUM 
RELIEF
VALVE
COLD WATER INLET
VA
FLOW CONTROL 
LV
 PUMP 
* 
SHUT-OFF
CHECK VALVE 
†
(1/8” HOLE 
DRILLED IN CLAPPER)
VALVE
CHECK 
 VALVE 
†
TEMP/
PRESSURE
RELIEF
VALVE
TEMPERED WATER
TO FIXTURES
(MUST MEET TEMPS LISTED 
IN MASS. CODE 248 CMR 
†
)
MIXING VALVE
(MUST BE INSTALLED BELOW 
TOP OF WATER HEATER
AS PER MANUFACTURER’S 
RECOMMENDATIONS)
UNION
UNION
HOT 
WATER
OUT
*
  MASSACHUSETTS INSTALLATION REQUIREMENTS: 
  1.) CONNECT ELECTRONICALLY-CONTROLLED TIMER TO AN ALL-BRONZE PUMP. PUMP MUST ACTIVATE EVERY 6 HOURS 
  FOR 60 SECONDS. TURN PUMP TIMER OFF BEFORE CLOSING PIPING LOOP SHUT-OFF VALVE. 
  2.) ALL WATER PIPING MUST BE INSTALLED AND INSULATED IN ACCORDANCE WITH MASSACHUSETTS CODE (248 CMR 
  & 780 CMR). 
  3.) PIPING LOOP BETWEEN WATER HEATER AND AIR HANDLER MUST BE INSTALLED IN COMPLIANCE WITH 248 CMR. 
†  REQUIRED FOR MASSACHUSETTS.
‡  PIPING FROM THE TOP OF THE WATER HEATER WITH TEES IS ACCEPTABLE.
WATER HEATER ACCEPTED 
BY THE BOARD FOR 
INSTALLATION IN 
MASSACHUSETTS. 
†
TYPICAL MIXING VALVE INSTALLATION 
COMBINATION SPACE HEATING / POTABLE WATER HEATING SYSTEM
SEE 
NOTE ‡
100’-0” MAXIMUM DISTANCE 
FROM WATER HEATER 
TO FAN COIL AND BACK 
(DEVELOPED LENGTH) NOT 
INCLUDING COIL IN HEATING UNIT.
†










