172-65627M-09 (SQ10) 18 Oct 2021
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A. Cold water inlet, hot water outlet
The cold water inlet and hot water outlet of the unit are connected to the inlet/
outlet of the heat exchanger. Make sure to follow the installation procedures
regardless of the instructions provided. These are the minimum precautions
to prevent this unit from being damaged or malfunctioning.
(1) Make sure to install valves (preferably full
bore gate valves) near the cold water inlet
and hot water outlet, giving consideration
to maintenance of the unit.
(2) Install a safety valve (relief valve) (not
included with the unit) on the hot water
outlet piping (to prevent damage to the
unit due to the pressure rise which may
occur under abnormal conditions).
(The pressure for the safety valve (relief
valve) should be set at 0.9 MPaG or less. Also, if there is equipment
with a lower pressure tolerance than the unit, make sure to select the
appropriate valve for that equipment.)
(3) When the water temperature is set to a high temperature, do not use
PVC or lead piping intended for water supply as there is a possibility
that the inlet piping may become hot even if the water temperature on
the inlet side is low.
(4) Install hot water outlet piping with a pipe rise. (Make sure that the tip of
the unit
’s temperature sensor is fully immersed in water.)
(5) There is no valve for drainage in the unit. Make sure to install a valve
for drainage to ensure ease of maintenance.
(6) A flow switch (for sensing the flow rate) is installed at the cold water
inlet. To prevent the switch from operating erroneously, straight piping
500 mm or longer should be installed before the cold water inlet.
The procedures below should also be followed according to the type of hot
water supply piping used by the system.
A-(1):
For single-pass system hot water piping
In single-pass systems, the cold water supplied to the unit is heated and
supplied to the point of use, and is not returned to the unit by recirculation
etc.
a)
After stopping hot water use, heat expansion occurs due to water being
heated by the residual heat in the heat exchanger. Install a check valve
on the cold water inlet piping to prevent hot water backflow due to heat
expansion.
After closing the valve or tap at the point of use, or stopping hot water
use, the pressure inside the piping will increase if heat expansion
occurs and there is no pressure relief port. If there is no way to relieve
the pressure, this may lead to damage to piping or the unit, therefore a
pressure relief device such as a safety valve should be installed
between the unit and the point of use.
The rapid opening and closing of ball valves can cause water hammer
to occur, potentially damaging the unit. Take measures to prevent
rapid valve operation.
SQ
Safety Valve
(Relief Valve)
Inlet Valve
Outlet Valve
