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16
F. CONNECT TANKLESS HEATER PIPING AS
SHOWN IN FIGURE 10. See Table 1 for Tankless
Heater Rating.
WARNING
Install automatic mixing valve at tankless heater
outlet to avoid risk of burns or scalding due to
excessively hot water at xtures. Adjust and
maintain the mixing valve in accordance with
the manufacturer's instructions. Do not operate
tankless heater without mixing valve.
THE FOLLOWING GUIDELINES SHOULD BE
FOLLOWED WHEN PIPING THE TANKLESS HEATER:
1. FLOW REGULATION — If ow 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 ow regulator matching the heater
rating should be installed in the cold water line to
the heater. The ow regulator should preferably be
located below the inlet to the heater and a minimum
of 3’ away from the inlet so that the regulator is not
subjected to excess temperatures that may occur
during “off” periods when it is possible for heat
to be conducted back through the supply line. The
ow regulator also limits the ow of supply water
regardless of inlet pressure variations in the range of
20 to 125 psi.
2. TEMPERING OF HOT WATER — Installation of
an automatic mixing valve will lengthen the delivery
of the available hot water by mixing some cold
water with the hot. This prevents the possibility
of scalding hot water at the xtures. In addition,
savings of hot water will be achieved since the user
will not waste as much hot water while seeking a
water temperature. 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. The mixing valve
should be “trapped” by installing it below the cold
water inlet to heater to prevent lime formation in the
valve. Refer to Figure 10.
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 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 benecial to the
tankless heater but to piping and xtures plus the
many other benets derived from soft water.