NC1991-DVC-NG Install Manual

17
Hot water piping
• Do not use lead, PVC, iron or any piping which
has been treated with chromates, boiler seal or
other chemicals.
• The longer the piping, the greater the heat loss.
Try to make the piping as short as possible.
• Use mixing valves with low water resistance.
Use shower heads with low pressure loss.
• If necessary, use a pump or other means to
ensure that the supply water pressure to the
inlet of the heater does not fall below 29 PSI
when the maximum amount of water is being
demanded. Also install a pressure meter on
the inlet. If this is not done, local boiling will
occur inside the water heater causing abnormal
sounds and decreasing the durability of the heat
exchanger.
Freeze Prevention
• Freezing is prevented within the device automatically unless the outside temperature without wind
is below -30°F (-35°C).
* When combustion air is supplied from the indoors, the room temperature must be greater than 32°F (0°C)
to prevent freezing and the room inside must not have negative pressure.
• If this model is installed in an area where the outside temperature can approach freezing conditions
of -30°F (-35°C) or below, then additional freeze protection measures must be used. For temporary
freeze protection measures, refer to the Owner's Guide.
• The freeze prevention heaters will not prevent the plumbing external to the unit from freezing.
Protect this plumbing with insulation, heat tape or electric heaters, solenoids, or pipe covers.
• In order for the freeze prevention heaters to operate, the water heater must have power at all times.
Supply water piping
• Do not use PVC, iron, or any piping which has been
treated with chromates, boiler seal or other chemicals.
• Mount a check valve and a shut off valve (near the inlet).
• In order for the client to use the water heater
comfortably, 98.1 to 491 kPa (14 to 70 PSI) of
pressure is needed from the water supply.
Be sure to check the water pressure. If the
water pressure is low, the water heater cannot
perform to its full capability, and may become a
source of trouble for the client.
Drain piping
• Expansion water may drop from the
pressure relief valve and wet the oor.
* Pressure relief valve (1)
Install a drain hose (accessory) to remove the
water. Prevent the drain hose from becoming
pinched.
* Pressure relief valve (2)
If necessary, provide drain piping or use a
drain hose to remove the water.
Pressure relief valve (1)
Pressure relief valve (2)