19
SPACE HEATING AND POTABLE WATER SYSTEM
Your water heater is equipped with additional side taps for use in
space heating applications. See Features and Components on
Page 11 for locations. If this water heater is to be used to supply
both space heating and potable (drinking) water, the instructions
listed below must be followed:
•
Be sure to follow the manual(s) shipped with the air handler
or other type heating system.
•
This water heater cannot be used in space heating applications
only.
•
This water heater is not to be used as a replacement for an
existing boiler installation.
•
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 heating system requires water temperatures in
excess of 120°F, a mixing valve must be installed per the
manufacturer’s instructions in the potable hot water supply to
limit the risk of scald injury. See Mixing Valves on Page 18.
•
Pumps, valves, piping and fittings must be compatible with
potable water.
•
A properly installed flow control valve is required to prevent
thermosiphoning. Thermosiphoning is the result of a continuous
flow of water through the air handler circuit during the off cycle.
Weeping (blow off) of the temperature-pressure relief valve (T &
P relief valve) or higher than normal water temperatures are the
first signs of thermosiphoning.
•
The hot water line from the water heater should be vertical past
any mixing valve or supply line to the heating system to remove
air bubbles from the system. Do not connect the water heater to
any system or components previously used with non-potable water
heating appliances when used to supply potable water.
STORAGE TANK INSTALLATION
When installing the water heater with a storage tank, see Figure
55 on page 60 in Piping Diagrams for suggestions.
NOTE:
If tank temperature is set above 120°F and water is supplied
for domestic use (hand washing, showering, etc.) a mixing valve
should be installed in the hot water line to domestic fixtures.
Installation must conform to local code requirements. If a check
valve is installed in the cold water supply line, an expansion tank
must be installed between the check valve and the water heater’s
cold water inlet. Set storage tank temperature five degrees lower
than the water heater’s temperature setting. Using the plug valve,
adjust the flow in the recirculating line to five gallons per minute.
SOLAR INSTALLATION
If this water heater is used as a solar storage 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 (48.9°C). A mixing
valve must be installed in the water supply line to limit the supply
temperature to 120°F (48.9°C).
NOTE:
Solar water heating systems can often supply water with
temperatures exceeding 180°F (82.2°C) and may result in water
heater malfunction.
CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements or such
conditions as high line pressure, among others, have installed
devices such as pressure reducing valves, check valves, and back
flow preventers. Devices such as these cause the water system to
be a closed system.
THERMAL EXPANSION
As water is heated, it expands (thermal expansion). In a closed
system the volume of water will grow when it is heated. As the
volume of water grows there will be a corresponding increase in
water pressure due to thermal expansion. Thermal expansion can
cause premature tank failure (leakage). This type of failure is not
covered under the limited warranty. Thermal expansion can also
cause intermittent temperature-pressure relief valve operation:
water discharged from the valve due to excessive pressure build
up. This condition is not covered under the limited warranty. The
temperature-pressure relief valve is not intended for the constant
relief of thermal expansion.
A properly sized thermal expansion tank should be installed
on all closed systems to control the harmful effects of thermal
expansion. Contact a local plumbing service agency to have a
thermal expansion tank installed.
NOTE:
To protect against untimely corrosion of hot and cold
water fittings, it is strongly recommended that di-electric unions
or couplings be installed on this water heater (see Figure 9) when
connected to copper pipe.
Sweat
Fittings
Sweat
Fittings
Temperature-
Pressure
Relief Valve
Union
Union
Cold
Water
Inlet
Shutoff
Valve
Hot
Water
Outlet
Figure 9