Danfoss AVQ, AVQT Controllers

Introduction

This document provides instructions for the installation, operation, and maintenance of Danfoss AVQ and AVQT controllers.

Illustrations of valve models: AVQ (PN16) with DN 15-32, AVQ (PN25) with DN 15-50, AVQT (PN25) with DN 15-50, and AVT/AVQT (PN25) with DN 32-50. Each illustration shows the valve body and actuator, with associated DN and Δρ values (e.g., Δρ = 0.2 bar).

Safety Notes

⚠️ WARNING: Prior to assembly and commissioning, it is absolutely necessary to carefully read and observe these instructions to avoid injury to persons and damage to the devices.

Necessary assembly, start-up, and maintenance work must be performed only by qualified, trained, and authorized personnel.

Prior to assembly and maintenance work on the controller, the system must be:

• Depressurized
• Cooled down
• Emptied
• Cleaned

Please comply with the instructions of the system manufacturer or system operator.

Definition of Application

The controller is used for flow (and temperature at AVQT) control of water and water-glycol mixtures for heating, district heating, and cooling systems. The technical parameters on the product labels determine the use.

Assembly

Admissible Installation Positions

For medium temperatures up to 100 °C: The valve can be installed in any position.

For medium temperatures above 100 °C: Installation is permitted only in horizontal pipelines with the actuator oriented downwards.

Diagram showing admissible installation positions for the valve. For medium temperatures up to 100°C, installation is permitted in any position. For medium temperatures above 100°C, installation is only permitted in horizontal pipelines with the actuator oriented downwards.

Installation Location and Installation Scheme

Installation schematics for AVQ(T) controllers. Diagram ① shows return mounting, indicating the valve connected to the return line. Diagram ② shows flow mounting, indicating the valve connected to the flow line.

Valve Installation

1. Clean the pipeline system prior to assembly.
2. The installation of a strainer upstream of the controller is strongly recommended .
3. Install the valve. Observe the flow direction indicated on the product label or on the valve . The valve with mounted weld-on taipieces may only be spot-welded to the pipeline. The weld-on taipieces may be welded only without the valve and seals! If these instructions are not observed, high welding temperatures may destroy the seals. Flanges in the pipeline must be in parallel position and sealing surfaces must be clean and without any damage. Tighten screws in flanges crosswise in 3 steps up to the maximum torque (50 Nm).
4. Caution: Mechanical loads of the valve body by the pipelines are not permitted.

Diagram of valve installation, including a strainer, flow direction arrow, and flange tightening. A table lists DN, L, PN, kvs, and dp values.

Mounting of Temperature Actuator (AVQT Controllers Only)

Place the temperature actuator AVT at the diaphragm and tighten the union nut with wrench SW 36. Torque: 35 Nm.

Other details: Refer to instructions for the temperature actuator AVT.

Diagram illustrating temperature actuator mounting.

Insulation

For medium temperatures up to 100 °C, the pressure actuator may also be insulated.

Diagram showing insulation for the pressure actuator for medium temperatures up to 100°C.

Dimensions and Weights

1) Conical external thread according to EN 10226-1

2) Flanges PN 25, according to EN 1092-2

General Dimensions (Threaded Connections)

Diagrams of AVQ (PN16), AVQ (PN25), and AVQT (PN25) valve models with dimension lines.

Dimensions for AVQ (PN 16)

Dimensions for AVQ (PN 25)

Note: Other flange dimensions - see table for tailpieces.

Dimensions for AVQT (PN 25)

Dimensions for AVT/AVQT (PN 25)

Note: Other flange dimensions - see table for tailpieces.

Detailed technical drawings of AVQ, AVQT, and AVT/AVQT valve models with dimension lines corresponding to various DN sizes. Tables provide precise dimension values.

Start-up

Filling the System, First Start-up

System schematic for start-up. Shows open valves in the system, with slow opening of shut-off devices in the flow pipeline and then in the return pipeline.

1. Open valves in the system.
2. Slowly open shut-off devices in the flow pipeline.
3. Slowly open shut-off devices in the return pipeline.

Leak and Pressure Tests

⚠️ WARNING: Before pressure test, open the adjustable flow restrictor by turning it to the left (counter clockwise).

Pressure must be gradually increased at the +/- connection.

Non-compliance may cause damages at the actuator or the valve. A pressure test of the entire system must be carried out in accordance with manufacturer's instructions.

The maximum test pressure is: 1.5 x PN (PN - see product label).

Schematics for leak and pressure tests and putting the system out of operation. The leak test diagram shows the adjustable flow restrictor and the +/- connection for pressure measurement. The shut-down diagram shows slow closing of shut-off devices in flow and return pipelines.

Putting out of Operation

1. Slowly close shut-off devices in the flow pipeline.
2. Slowly close shut-off devices in the return pipeline.

Settings

Flow Rate Setting

The flow rate is adjusted by means of the setting of the adjustable flow restrictor . There are two possibilities:

1. Adjustment with the flow adjusting curves.
2. Adjustment with heat meter, see page 15.

Pre-condition (minimum differential pressure over the valve): At the maximum flow rate, the pressure difference Δp across the control valve must be at least: Δp_min = 0.5 bar.

Schematic illustrating flow rate setting using the adjustable flow restrictor. It shows the restrictor and indicates the minimum required differential pressure (Δp) across the control valve.

Adjustment with Flow Adjusting Curves

The system does not need to be active for adjustment.

1. Unscrew cover , loosen counter nut .
2. Screw (clockwise) the adjustable flow restrictor in up to its stop. The valve is closed, no flow.
3. Select the flow adjusting curve in the diagram (see next page). Required flow rate.
4. Unscrew (counter-clockwise) the adjustable flow restrictor by the determined number of revolutions .
5. Adjustment is completed. Continue with step 3, page 15.

Note: The setting may be verified with the help of a heat meter if the system is in operation, see next section.

Illustrations demonstrating the adjustment of the flow restrictor. Step 1 shows unscrewing the cover and loosening the counter nut. Step 2 shows screwing the restrictor clockwise until it stops. Step 3 refers to flow adjusting curves. Step 4 shows unscrewing the restrictor counter-clockwise by a specified number of revolutions. Step 5 indicates completion.

Flow Adjusting Curves

Graphs plotting flow rate (m³/h) against revolutions for various DN sizes (DN 15, DN 20, DN 25, DN 32, DN 40/50) and Kvs values (e.g., kvs 4.0, kvs 2.5, kvs 1.6 for DN 15).

Adjustment with Heat Meter

Pre-condition: The system must be in operation. All units in the system or a bypass must be completely open.

1. Unscrew cover , loosen counter nut .
2. Observe the heat meter indicator. Turning to the left (counter-clockwise) increases the flow rate. Turning to the right (clockwise) reduces the flow rate.
3. After the adjustment has been completed: Tighten counter nut .
4. Screw the cover in and tighten.
5. Cover may be sealed.

Temperature Setting (relevant only at AVQT controllers): See instruction for temperature actuator AVT.

System schematic for adjustment with a heat meter. Shows the system in operation with all units open. Illustrations show unscrewing the cover, loosening the counter nut, observing the heat meter, and turning the restrictor left (increase flow) or right (decrease flow). Final steps show tightening the counter nut, screwing on the cover, and optional sealing.

Technical Specifications and Dimensions

Dimensions and Weights

1) Conical external thread according to EN 10226-1

2) Flanges PN 25, according to EN 1092-2

General Dimensions (Threaded Connections)

Dimensions for AVQ (PN 16)

Dimensions for AVQ (PN 25)

Dimensions for AVQT (PN 25)

Dimensions for AVT/AVQT (PN 25)

Note: Other flange dimensions - see table for tailpieces.

Operation

Start-up

Follow the system manufacturer's or operator's instructions.

Filling the System, First Start-up

System schematic for start-up. Shows open valves in the system, with slow opening of shut-off devices in the flow pipeline and then in the return pipeline.

1. Open valves in the system.
2. Slowly open shut-off devices in the flow pipeline.
3. Slowly open shut-off devices in the return pipeline.

Leak and Pressure Tests

⚠️ WARNING: Before pressure test, open the adjustable flow restrictor by turning it to the left (counter clockwise).

Pressure must be gradually increased at the +/- connection.

Non-compliance may cause damages at the actuator or the valve. A pressure test of the entire system must be carried out in accordance with manufacturer's instructions.

The maximum test pressure is: 1.5 x PN (PN - see product label).

Putting out of Operation

1. Slowly close shut-off devices in the flow pipeline.
2. Slowly close shut-off devices in the return pipeline.

Settings

Flow Rate Setting

The flow rate is adjusted by means of the setting of the adjustable flow restrictor . There are two possibilities:

1. Adjustment with the flow adjusting curves.
2. Adjustment with heat meter, see page 15.

Pre-condition (minimum differential pressure over the valve): At the maximum flow rate, the pressure difference Δp across the control valve must be at least: Δp_min = 0.5 bar.

Schematic illustrating flow rate setting using the adjustable flow restrictor. It shows the restrictor and indicates the minimum required differential pressure (Δp) across the control valve.

Adjustment with Flow Adjusting Curves

The system does not need to be active for adjustment.

1. Unscrew cover , loosen counter nut .
2. Screw (clockwise) the adjustable flow restrictor in up to its stop. The valve is closed, no flow.
3. Select the flow adjusting curve in the diagram (see next page). Required flow rate.
4. Unscrew (counter-clockwise) the adjustable flow restrictor by the determined number of revolutions .
5. Adjustment is completed. Continue with step 3, page 15.

Note: The setting may be verified with the help of a heat meter if the system is in operation, see next section.

Illustrations demonstrating the adjustment of the flow restrictor. Step 1 shows unscrewing the cover and loosening the counter nut. Step 2 shows screwing the restrictor clockwise until it stops. Step 3 refers to flow adjusting curves. Step 4 shows unscrewing the restrictor counter-clockwise by a specified number of revolutions. Step 5 indicates completion.

Flow Adjusting Curves

Graphs plotting flow rate (m³/h) against revolutions for various DN sizes (DN 15, DN 20, DN 25, DN 32, DN 40/50) and Kvs values (e.g., kvs 4.0, kvs 2.5, kvs 1.6 for DN 15).

Adjustment with Heat Meter

Pre-condition: The system must be in operation. All units in the system or a bypass must be completely open.

1. Unscrew cover , loosen counter nut .
2. Observe the heat meter indicator. Turning to the left (counter-clockwise) increases the flow rate. Turning to the right (clockwise) reduces the flow rate.
3. After the adjustment has been completed: Tighten counter nut .
4. Screw the cover in and tighten.
5. Cover may be sealed.

Temperature Setting (relevant only at AVQT controllers): See instruction for temperature actuator AVT.