Navien NPE-240A Installation Manual page 20

The following is a typical water piping example for NPE-180A/
●
210A/ 240A models.
Union
Full port
Gas Valve
Gas Supply
Hot Water Supply
Recirculation Line
[NPE-180A/ 210A/ 240A]
NPE-180S/210S/240S
●
Union
Full port
Gas Valve
Gas Supply
Condensate Drain
Cold Water
Supply
[NPE-180S/ 210S/ 240S]
20 Installing the Water Heater
3.4.1 Using the Water Heater for Combination
Water Heating and Space Heating
When using the water heater for both water (potable) heating and
space heating, follow these guidelines:
Ensure that all piping and components connected the water
●
heater are suitable for potable water applications.
Do not introduce toxic chemicals, such as boiler treatments, into
●
the potable water.
On Combi applications, circulators suitable for DHW applications
●
must be used.
Do not connect the water heater to any heating systems or
●
components that have been previously used with non-potable
Pressure
water heaters.
Relief Valve
If the system requires varying temperatures for water—for
●
example, hotter water for space heating than for other
Shuto Valve uses—install a mixing valve to temper the water and reduce the
potential for scalding.
Do not use the water heater for space heating only.
●
Make sure circulator ow rate through the Water Heater does
Condensate Drain
●
not exceed 4 GPM.
Cold Water
Supply
3.4.2 Selecting a Recirculation Mode ("A" model
Expansion only)
Tank
On all "A" model Navien water heaters, you can choose from
two pre-heating modes: internal recirculation mode or external
recirculation mode. To select a recirculation mode, you must set
the DIP switches on the front panel, and set the position of the
2-way valve inside the water heater. By default, the DIP switches
are set to OFF.
When you use a recirculation mode, there will be some minor
ciency loss, as a result of the water heater maintaining a steady
temperature within the circulation loop. Although in many cases,
higher gas usage will be made up for by lower water usage.
The recirculation feature of the "A" models has three performance
advantages:
Elimination of any minimum ow rate requirement.
●
Elimination of any hot/cold/hot stacking—the "cold water
●
sandwich
Quicker hot water delivery t
Pressure
●
wasted.
Relief Valve
Shut Valve Note
Hot Water
Supply
ect.
xtures, which results in less water
When using external recirculation mode with the
built-in pump, observe the following maximum
recirculation pipe lengths includin
is recommended):
-1/2" Copper Pipe- 100' (30m) of equivalent length
-3/4" Copper Pipe- 500' (150m) of equivalent length
Lengths in excess of these limits will require an
external recirculation pump.
ttings (3/4" pipe