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Drawing Number:
Drawing Date:
H-2-RP
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.
26
On-Demand
Equipment List QTY
On-Demand 2
Water Heaters
Domestic Hot Water - Circulation Systems
2 On-Demand Water Heaters with Gas or Electric Tank
Preferred Piping Installation
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.
The pump should be sized to overcome the
pressure loss through the tank water heater,
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.
Expansion Tank
Minimum 3/4 “ Cold
Water Supply Line
Minimum 3/4 “ Hot
Water Supply Line
Building Supply
Gas SupplyLine
On-Demand
WaterHeater
Primary
On-Demand
WaterHeater
Sub1
Gas or Electric
Tank Water
Heater
Important:
Install return line to the hot
supply line as close as possible
to the on demand water heater.
Electronic Connection *
* Refer to On-Demand Accessories
and Model Applicability for
electronic connection details.
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