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Drawing Number:
Drawing Date:
H-2-RO
September 07, 2008
NOTE: This drawing is not intended to describe a complete system and is not a replacement for a pro-
fessional engineering drawing. It is intended only as a guide and does not imply compliance with local
building code requirements. Confer with local building officials before installation. The Contractor or
engineer is to determine the necessary components and configuration of the particular system to be in-
stalled. It is the responsibility of the engineer or contractor to ensure that the installation is in accordance
with all local building codes.
27
On-Demand
Equipment List QTY
On-Demand 2
Water Heaters
Domestic Hot Water - Circulation Systems
2 On-Demand Water Heater
Optional Piping Installation
Electronic Connection *
* Refer to On-Demand Accessories
and Model Applicability for
electronic connection details.
GasSupplyLine
On-Demand
Water Heater
Primary
On-Demand
WaterHeater
Sub 1
(Optional)
2-10 Gallon
Storage Tank
(Toeliminate cold water
sandwiche
ect caused by
frequentOn/O
operation)
Expansion Tank
Minimum 3/4 “ Cold
Water Supply Line
Minimum 3/4 “ Hot
Water Supply Line
Building Outlets
For this application:
Pump should be controlled by an Aquastat,
Timer or Combination Aquastat and Timer.
Pump to be sized to maintain circulation
loop temperature.
A minimum of 3 GPM flow is recommended
for the circulation system.
The pump should be sized to overcome the
pressure loss through the on demand water
heater, optional storage tank, and supply
and return plumbing in the circulation loop.
Reference the section Pump Sizing for
Circulation.
Pump to be of bronze or stainless construc-
tion.
Aquastat Connection
Key
Pressure Relief Valve
Check Valve
3/4" Union
3/4" Ball Valve
Boiler Drain Valve
Solenoid Valve
S
Pressure Regulator
Circulating Pump
Mixing Valve