User Guide
On-Demand Rack System • 9
INSTALLATIONINSTALLATION
RACK #3 RACK #1RACK #2
COLD HEADER COLD HEADER
Hot Water
Outlet
,
K
d
,
K
d
HOT HEADERHOT HEADER
,
K
d
Cold
Water
Inlet
Expansion
Tan k
Gas
Supply
'
^
'
^
'
^
GAS HEADER
'
^
'
^
K
>
K
>
K
>
^ŚƵƚKī
/ƐŽůĂƟŽŶ
Val ve
Check
Val ve
Union
Pressure
Relief
Val ve
GAS HEADER
NOTES:
1. HEADERS MUST BE SIZED FOR TOTAL CAPACITY. WATER LINES SHOULD BE GREATER THAN 2 INCHES.
2. GAS SUPPLY HEADER MUST BE SIZED BY CURRENT METHODS PERSUANT TO NFPA 54 AND TO SUPPLY TOTAL
MAXIMUM INPUT FOR ALL WATER HEATERS.
3. IF THE APPLICATION CALLS FOR RECIRCULATION, INSTALL THE RECIRCULATION PUMP AS SHOWN ABOVE.
THE RECIRCULATION PUMP SHOULD BE SIZED TO PROVIDE 2 TO 4 GPM PER ACTIVATED HEATER. THE PUMP
SHOULD BE CONTROLLED WITH AN AQUASTAT. REFER TO THE WATER HEATER’S SPECIFICATION SHEET FOR
PRESSURE DROP INFORMATION.
4. CHECK VALVE SHOWN AT INLET IS ONLY NEEDED IF A RECIRCULATION LINE IS INSTALLED.
INSTALLATION MUST FOLLOW ALL APPLICABLE CODE REQUIREMENTS.
ZĞĐŝƌĐƵůĂƟŽŶ
Pump
Pump
Check Valve
2
2
1
1
1
1
3
4
HCGAS HCGAS HCGASHCGAS HCGAS HCGASHCGAS HCGAS HCGAS
Figure 5: Piping schematic for more than six (6) water heaters. This schematic illustrates a reverse return setup.
Each rack system can comprise up to six water heaters. Note that the multi-unit controller can control
up to 20 water heaters.