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  • Description
  • Characteristics
  • Downloads
  • Dimensions
  • Wiring plan
  • Additional diagrams
  • Legend

The mixing unit USWK is designed for smooth heat medium flow control in ventilation systems equipped with water heaters or coolers for supply air temperature regulation. The mixing unit controls heat medium flow supplied to the water heat exchanger and in such a way maintains the supply air temperature. The mixing unit USWK is compatible with NKV water heaters, duct coolers OKW as well as all water heat exchangers (both heaters and coolers) integrated into air handling units.


Design of the mixing unit USWK is shown in fig. 1. The circulation pump (1) of the mixing unit ensures ongoing heat medium circulation through the water heat exchanger. The heat medium regulating three-way valve (3) with electric actuator (2) is installed before the circulation pump to mix the water supplied from the heating (cooling) system with the return water supplied through the recirculation pipe (4).

The three-way valve is designed to provide the mixing ratio of two water streams and thus to control the heat medium temperature supplied to the water heat exchanger. The three-way valve actuator is controlled by 0-10 V output signal from the ventilation control system.


The mixing set is connected directly to the water heat exchanger and water mains through rigid and/or flexible pipes.

In case of flexible pipe connection, fix the mixing unit firmly to the wall or another rigid surface with clapms. While installing the mixing set keep the motor horizontal position to disable any distortions and mechanical loads from the connected pipelines to USWK unit. While connecting the mixing set to water mains make sure of no loads and distortions that may damage the unit structure and provoke USWK airtightness breach. While connecting the pipelines ensure their quick detachment for scheduledf servicing and maintenance operations.


All electric connections are allowed by qualified electricians with valid permit for electric operations. Before connecting the pump make sure to have grounded it. Make steps to prevent contact with power cables.


The pump motor bearings are greased by the pumped medium. The single-phase pumps do not require extra overload protection and the three-phase pumps must be provided with external overload protection. The maximum allowable heat medium pressure in the unit is 10 bar.


3-way valve  
Δpv100 — pressure loss at fully opened valve;
V100 — rated water flow at Δpv100.

Parameter USWK 3/4-4
Measurement unit
Three-way valve Kvs Three-way valve Kvs 4 -
Connecting diameter Connecting diameter 3/4" mm
Circulating pump Circulating pump

DAB VA65/180

Three-way valve regulation mode Three-way valve regulation mode

Smooth 0…10 V

Three-way valve with electric actuator Three-way valve with electric actuator

Belimo R317

Three-way valve actuator Three-way valve actuator

Belimo LR24A-SR

Connection Connection Резьбовое -
Three-way valve nominal diameter Three-way valve nominal diameter DN 20 -
Maximum capacity Maximum capacity 2.3 m³/h
Maximum developed head Maximum developed head 57 -
Pumped medium temperature Pumped medium temperature -10 +110 °С
Maximum glycol content in pumped medium Maximum glycol content in pumped medium 30 -
Number of pump speeds Number of pump speeds 3 -
Phase Phase 1 -
Maximum pump power Maximum pump power 78 W
Pump voltage Pump voltage 230 V
Weight 4.1 kg
Files archieve
User's manual "USWK" (pdf 110.73Kb)
Instruction on mounting and operation "USWK" (pdf 1.52Mb)
Brochure "USWK" (pdf 434.17Kb)
Download high quality image "USWK" (psd 924.04Kb)
Download image "USWK" for your website (png 216.8Kb)
Parameter Value Measurement unit
B 150 mm
H 290 mm
H1 180 mm
L 460 mm
Wiring plan
Wiring plan


Т1 and Т2 - supply and return pipeline;
Р1 and Р2 - manometers for supply and return pipelines in the water mains;
1 - USWK (mixing set);
2 - Water heater;
3 - Three-way valve with actuator;
4 - Circulation pump;
5 - Shutoff valve;
6 - Supply and return pipeline from water mains to the water heater;
7 - Non-return valve;
8 - Balancing valve;
9 - Coarse filter.

Additional diagrams
Additional diagrams

To select the mixing set according to the nomographic chart, calculate the required heat medium flow through the water heat exchanger and water pressure drop (water head). These parameters are calculated according to the heating/cooling diagrams specifically for each water heat exchanger stated specifically herein.

Series   Connecting diameter   3-way valve, Кvs
  3/4''; 1''; 1 1/4''; 1 1/2''; 2''   4; 6; 10; 16; 25; 40
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