Installation and operating instruction
Gas condensing unit WTC-GB 15-B Compact and WTC-GB 25-B Compact
12 Technical documentation
83309302 1/2018-05 La
153-196
12.4 Circulation pump
The following operating modes of the internal pump of the condensing unit are
possible [ch. 6.6.2.2]:
Load proportional
With this type of control, the pump capacity is assigned to the burner capacity re-
quired (pump capacity
≙
WTC capacity).
De-couple control
With de-couple control, the pump modulates between de-couple sensor and flow
sensor depending on the differential temperature.
The de-couple control be adapted to the conditions of the system via parameter
2.2.12 Inertia pump internal
.
Proportional pressure stage 1 … 3
With proportional pressure control, the differential pressure at the pump is regu-
lated depending on the volumetric flow. The lift height reduces with decreasing
volumetric flow.
This control version is recommended for systems with high pressure loss changes.
Constant pressure control regulates the differential pressure at the pump to a con-
stant value. The lift height is kept constant regardless of the volumetric flow.
This control version is recommended for systems with low pressure loss changes
(e. g. underfloor heating).
Proportional pressure auto adaption
Automatic change-over between the proportional pressure stages (characteristic
curves).
With proportional pressure control, the differential pressure at the pump is regu-
lated depending on the volumetric flow. The lift height reduces with decreasing
volumetric flow.
This control version is recommended for systems with high pressure loss changes.
Constant pressure auto adaption
Automatic change-over between the constant pressure stages (characteristic
curves).
Constant pressure control regulates the differential pressure at the pump to a con-
stant value. The lift height is kept constant regardless of the volumetric flow.
This control version is recommended for systems with low pressure loss changes
(e. g. underfloor heating).