Low water cutoff
If this water heater is installed above radiation level, a low
water cutoff device must be installed at the time of installation.
An electronic low water cutoff is available as a factory supplied
option on all models. The low water cutoff should be inspected
every 6 months. A fault message,
Flow Sw/LWCO
will be
indicated in the Operator Interface on a low water condition
as sensed by the low water cutoff.
Relief valve
This unit is supplied with a safety relief valve(s) sized in
accordance with ASME Boiler and Pressure Vessel Code,
Section IV (“Rules of Construction of Heating Boilers”). The
relief valve(s) is installed in the vertical position and mounted
in the hot water outlet. No valve is to be placed between
the relief valve and the unit. To prevent water damage, the
discharge from the relief valve shall be piped to a suitable floor
drain for disposal when relief occurs. No reducing couplings
or other restrictions shall be installed in the discharge line. The
discharge line shall allow complete drainage of the valve and
line. Relief valves should be manually operated at least once a
year.
CAUTION
Avoid contact with hot discharge water.
Water heater installations
Piping of the water heater system
The drawings in this section show typical water heater piping
installations, see FIG.’s 9-1 through 9-4. 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 appliance 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 appliance 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 pressure relief
valve must be piped to a suitable floor drain. See the
Relief Valve
section on this page.
Water connections
All water heaters have 2 1/2 inch copper pipe inlet and outlet
connections. Installed piping to and from the appliance must
be a minimum of 2 1/2 inch diameter.
CAUTION
Field installed reducing bushings must not
be used.
Any reduction in pipe size may decrease flow resulting in high
water temperatures, water heater 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 water heater and also
ensure that flow through the water heater does not exceed the
maximum recommended flow rate of 75 GPM for Models 500
- 1000 and 90 GPM for Models 1500 - 2000 for a water heater
equipped with a copper heat exchanger.
Water heater circulator requirements
This is a low mass, high efficiency hot 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. Pipe diameter and length are critical to ensure proper
flow through the water heater. A Temperature Rise Chart
(Table 4D on page 34) is provided to assist in proper pump
selection. 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 at full rate.
Example:
The water heater inlet temperature is 160°F (71.1°C)
and the water heater outlet temperature is 180°F (82.2°C). This
means that there is a 20°F (11.1°C) temperature rise across the
water heater. The water heater temperature rise is visible in the
Operator Interface on the water heater’s front control panel.
32
4
Water connections
Installation & Operation Manual
*Please note that these illustrations are
meant to show system piping concept only,
the installer is responsible for all equipment
and detailing required by local codes.
NOTICE
