Installation & Operation Manual
36
Water heater installations
Piping of the water heater system
Before beginning the installation, consult local codes for specific
plumbing requirements. The installation should provide unions
and valves at the inlet and outlet of the water heater so it can be
isolated for service. An air separation device must be supplied
in the installation piping to eliminate trapped air in the system.
Locate a system air vent at the highest point in the system. The
system must also have a properly sized expansion tank installed.
Typically, an air charged diaphragm-type expansion tank is
used. The expansion tank must be installed close to the water
heater and on the suction side of the system pump to ensure
proper operation.
CAUTION
The water heater system should not be
operated at less than 12 PSIG.
Hot water piping must be supported by suitable hangers or floor
stands,
NOT
by the water heater. Copper pipe systems will be
subject to considerable expansion and contraction. Rigid pipe
hangers could allow the pipe to slide in the hanger resulting in
noise transmitted into the system. Padding is recommended on
rigid hangers installed with a copper system. The water heater
pressure relief valve must be piped to a suitable floor drain.
Any reduction in pipe size may decrease flow resulting in
high water temperatures, noise, flashing to steam, and non-
warrantable heat exchanger damage.
It is important to guarantee that adequate flow is provided to
properly dissipate heat from the unit and also ensure that flow
through the unit does not exceed the maximum recommended
flow rate of 55 GPM for Models 400 - 750 and 90 GPM for
Models 1000 - 2100 for a water heater equipped with a copper
heat exchanger.
Circulator pump requirements
This is a low mass, high efficiency water heater which must
have adequate flow for quiet, efficient operation. Pump
selection is critical to achieve proper operation. A pump
should be selected to achieve proper system design water
temperature rise. Two heat exchanger head-loss charts (FIG.’s
4-3 and 4-4) are provided to assist in proper pump selection. A
System Temperature Rise Chart (Table 4B on page 37) is also
provided. This table provides GPM and water heater head-loss
at various temperature rises for each model based on Btu/hr
input. Temperature rise is the difference in water heater inlet
temperature and water heater outlet temperature while the
water heater is firing.
4
Water connections
Water connections
Models 400 - 750 have 2" NPT inlet and outlet connections
and Models 1000 - 2100 have 2 1/2" NPT inlet and outlet
connections.
CAUTION
Field installed reducing bushings must not
be used.
Models 1000 - 2100
PRESSURE DROP
IN FEET
HEAD
FLOW IN GALLONS PER MINUTE
Figure 4-3_Presssure Drop Chart - Models 400 - 750
Figure 4-4_Pressure Drop Chart - Models 1000 - 2100
Circulator pump specifications
1. Maximum operating pressure for the pump must exceed
system operating pressure.
2. Maximum water temperature should not exceed the
nameplate
rating.
3. A properly sized expansion tank must be installed near the
water
heater.
Example:
The water heater inlet temperature is 140°F (60°C)
and the water heater outlet temperature is 160°F (71.1°C). This
means that there is a 20°F (11.1°C) temperature rise across the
water heater.
Circulator pump operation
The water heater pump must run when the unit is firing.
Separate supply circuits can be provided or the two circuits
(pump and controls) can be combined for connection to one
circuit, properly sized for both.
Pump delay operation
A pump delay operation feature is provided. The water heater’s
circulating pump will cycle on at each call for heat, before the
unit fires and will continue to run as long as the call for heat is
active. After the call for heat, the unit will shut down and the
pump will continue to run for a period of time to remove the
residual heat from the heat exchanger.
