Viessmann Vitodens 222-F B2TB, Application Manual

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Product Information
Storage Tank Loading System (STLS)
"
!
Large DHW Loads (>3.5 GPM)
When a 222-F is required to satisfy a large dump load, the STLS has
the ability to extract stored energy from the onboard tank to meet
the desired load. Consider a bath tub that requires a flow rate of 4.4
GPM(1). Since the DHW circulator(2) is preset to 3.4gpm, the addi-
tional 1 gpm of cold water will enter into the tank(3). As the 3.4g of
hot water enters the tank, it immediately enters the DHW outlet(4).
Since this 3.4g is not enough to satisfy the demand, 1gpm is taken
from the tank to meet this target outlet flow rate. This allows for a
ten minute draw rate of over 60USG.