GSW 61009 REV. C (09-03) - Manual (Page 15)

VI) COMBO HEATING
When using this water heater in the application of a combi-
nation space and potable water heating system, be sure to
follow instructions provided with the water heater and the
manual shipped with the air handler.
NOTE the following warnings:
1. The piping and components connected to the water
heater for the space heating applications shall be suit-
able for use with potable water. The system should be
installed with new, non-ferrous piping. Do not use pip-
ing, pumps, valves, fittings, solder, gluing and pipe
sealant that are not completely compatible with potable
water.
2. A water heater which will be used to supply potable
water must not be connected to any heating system or
components previously used with a non-potable water
heating appliance. Do not use: piping that has been
treated; broiler seal chromates; or other chemicals.
3. Do not use this heater as a replacement for an existing
boiler installation.
4. Do not introduce toxic chemicals such as those used for
boiler treatment, into the potable water used for space
heating.
5. If the space heating water system requires water with
temperatures in excess of 60°C (140°F), a mixing valve
or other means must be installed in the potable hot
water supply to temper the water and reduce scald haz-
ard potential.
6. If the heater is installed with a back-flow preventer on
the incoming water line or in a closed system, a
diaphragm-type expansion tank must be installed in the
system to prevent weeping due to expansion (see
Figure 2B).
7. Proper sizing of the water heater for the given space
and potable heating application is essential to ensure
adequate heating capacity. The sizing and installation of
such combination system must be performed by quali-
fied personnel and be in accordance with public utility
requirements and/or Codes having jurisdiction.
The sizing of the water heater should be based on the
design heat loss of the structure to be heated plus the
potable water requirements.
IT IS IMPORTANT THAT THE WATER HEATER USED BE
OVERSIZED TO ALLOW ADEQUATE HEATING AND
POTABLE WATER HEATING CAPACITY.
– 15 –
HOT
WATER
TO
HOUSE
COLD TO
WATER HEATER
CHECK VALVE CIRC. PUMP
DIRECT
VENT
WATER
HEATER AIR HANDLER
RADIATOR OR RADIANT FLOOR PIPING ARE
VIABLE ALTERNATIVES TO AIR HANDLER.
Figure 5