Bosch GWH C 920 ES - Cascading Unit Applications

Bosch applications manual | 06.2009BOSCH THERMOTECHNOLOGY CORPORATION
Bosch applications manual
| 23
8.1 Cascading unit applications
A cascading application should be considered if the potential hot
water demand exceeds the capacity of one GWH 715 ES, GWH C
800 ES, or GWH C 920 ES/ESC. The cascading set up supports
variable fl ow inputs and is designed for large homes and commercial
applications. Cascading, unlike parallel applications, maintains the
activation fl ow rate of a single appliance.
8.1.1 GWH 715 ES, GWH C 800 ES, GWH C 920 ES/ESC cascading
with domestic hot water recirculation
Cascading allows up to four appliances to be connected. One of the
appliances will serve as the controlling Master appliance and will
attempt to meet the hot water demand. If the hot water demand is
beyond the capacity of the Master appliance, a signal is sent to one
or more of the Slave appliances to begin operation.
cold
hot
hot
cold
Electric
buffer Tank
tankless link
cold
hot
inlet
outlet
Symbols
Service
valve
Pressure
relief
valve
Flow
direction
Tankless
link
Potable
water
expansion
tank
Note:
Drawing is not to scale.
cold
hot
cold
hot
tankless link
tankless link
Bosch GWH 715 ES, Bosch GWH C 800 ES, or Bosch GWH C 920 ES/ESC
Timer
Bronze or
stainless
steel
circulator
Domestic hot water
recirculation return line
Flow
check
valve
System parameters:
• For applications with 200ft of pipe or more.
• The plumbing must be connected in the reverse return method
with a minimum number of elbows to aid in balancing
pressures between the appliances.
• Locate appliances close together for improved performance.
- Maximum distance between appliances: 36”.
- Minimum distance between appliances: 1”.
• Minimum pipe diameter: ¾” (2 appliances or less).
• Minimum pipe diameter: 1” (3 appliances or more).
• Minimum water pressure: 50 psi.
• Insulate pipes to prevent heat loss.
See Chapter 5.1 for recirculation pump parameters