Specifications
14
Check and if necessary torque coil plate nuts to 25 ft.-
lb. max (Do Not Over Torque) before filling system and
again after the boiler has been up to operating temperature
for several hours.
Tankless heater ratings in the FD boiler are based on
continuous draw, temperature rise of 100°F (40-140°F) and
boiler water temperature of 200°F. Some of the items
effecting the coil performance are as follows:
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1. Install Flow Regulator
If flow through the heater is greater than its rating,
the supply of adequate hot water may not be able to
keep up with the demand. For this reason a FLOW
REGULATOR matching the heater rating should be
installed in the cold water line to the heater. Refer
to figure below for piping recommendations. Locate
the flow regulator below the inlet (cold water side)
of the heater and a minimum of 36” away from the
inlet so that the regulator is not subjected to excess
temperatures during “off” periods when it is possible
for heat to be conducted back through the supply
line. The flow regulator will limit the flow of supply
water regardless of inlet pressure variations ranging
from 20 to 125 psi.
2. Install Water Temperature Mixing Valve
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a. Adjust and maintain the mixing valve in
accordance with manufacturers instructions.
b. Installation of a mixing valve will lengthen the
delivery of the available hot water by mixing
some cold water with the hot. In addition,
savings of hot water will be achieved since the
user will not waste as much hot water while
seeking desired water temperature.
c. Higher temperature hot water required by
dishwashers and automatic washers is possible by
piping the hot water from the heater prior to
entering the mixing valve.
d. The mixing valve should be “trapped” by
installing it below the cold water inlet to heater to
prevent lime formation in the valve.
TANKLESS HEATER PERFORMANCE
Schematic Tankless Heater Piping
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3. Flushing of Heater
All water contains some sediment which settles on
the inside of the coil. Consequently, the heater
should be periodically backwashed. This is
accomplished by installing hose bibs (as illustrated
below) and allowing water at city pressure to run
into hose bib A, through the heater, and out hose bib
B until the discharge is clear. The tees in which the
hose bibs are located should be the same size as
heater connections to minimize pressure drop.
4. Hard Water
A water analysis is necessary to determine the
hardness of your potable water. This is applicable to
some city water and particularly to well water. An
appropriate water softener should be installed based
on the analysis and dealer’s recommendation. This is
not only beneficial to the tankless heater but to
piping and fixtures plus the many other benefits
derived from soft water.