Data sheet
Thermostatic actuator QT
- return temperature control with AB-QM valves
Description |
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QT is a self-acting thermostatic actuator |
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designed to be used as return temperature |
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control thermostat in one-pipe heating systems. |
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QT is dedicated to be used with AB-QM |
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automatic balancing & control valve. |
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AB-QM together with QT is a complete |
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one-pipe solution: AB-QT. |
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Main data: |
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• Setting range: 35-50 °C, 45-60 °C, 65-85 °C |
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• Designed for AB-QM DN 10-32 |
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• Easy-to-install external surface sensor |
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Benefits |
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Reduces actual riser flow to match heat |
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demand |
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• Improved room temperature control |
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• Reduced overheating of the building |
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Reduced heating cost |
Ordering |
QT thermostatic actuator |
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Setting range |
fit to |
Code No. |
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(°C) |
AB-QM |
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45 … 60 |
DN 10-20 |
003Z0382 |
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DN 25-32 |
003Z0383 |
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35 … 50 |
DN 10-20 |
003Z0384 |
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DN 25-32 |
003Z0385 |
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65 … 85 |
DN 10-20 |
003Z0386 |
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DN 25-32 |
003Z0387 |
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Accessories
Type |
Code No. |
Pocket for submersible sensor |
003Z0391 |
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Adapter kit QT (DN 10-20) |
003Z0392 |
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Adapter kit QT (DN 25-32) |
003Z0393 |
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Sensor pocket kit |
003Z0394 |
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QT flow setting tag |
003Z0395 |
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AB-QM valves
DN |
Qmax. |
Ext. thread |
Code No. |
AB-QM |
Ext. thread |
Code No. |
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(l/h) |
(ISO 228/1) |
(ISO 228/1) |
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10 LF |
150 |
G ½ A |
003Z1261 |
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G ½ A |
003Z1251 |
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10 |
275 |
003Z1211 |
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003Z1201 |
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15 LF |
275 |
G ¾ A |
003Z1262 |
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G ¾ A |
003Z1252 |
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15 |
450 |
003Z1212 |
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003Z1202 |
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20 |
900 |
G 1 A |
003Z1213 |
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G 1 A |
003Z1203 |
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25 |
1.700 |
G 1¼ A |
003Z1214 |
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G 1¼ A |
003Z1204 |
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32 |
3.200 |
G 1½ A |
003Z1215 |
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G 1½ A |
003Z1205 |
© Danfoss | 2018.07 |
VD.C6.U4.02 | 1 |
Data sheet |
Thermostatic actuator QT |
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Applications |
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Fig. 1 |
Fig. 2 |
Fig. 3 |
QT is designed to be used in combination with AB-QM in one-pipe heating systems. AB-QM together with QT converts one-pipe heating system into energy efficient variable flow system, where flow in the risers is dynamically adjusted to match the load in the riser by control of return water temperature.
In one-pipe systems flow in the riser is always present. TRV on the radiator controls room temperature by controlling flow through radiator. However, by reducing flow through the radiator, water flow is not reduced but diverted to a by-pass and thus total water flow in the riser remains permanent. Therefore at partial loads water temperature in the pipe is increasing.
As a result the riser itself with the by-pass pipe continues to heat the room. This can cause overheating of the room.
After the building is renovated the heating system becomes oversized since the heat losses of the building decrease. As a result overheating issue increases even more.
AB-QM mounted in the riser provides a robust solution that offers reliable balance of one-pipe heating system at all system conditions. As a result, every riser gets design flow – and never more than that. Each riser becomes independent part of installation.
In addition, QT as a self-acting return temperature thermostat installed on AB-QM provides flow control through the temperature of return water in the riser. By this water flow in the riser is dynamically controlled to match the actual load in the riser. This results in improved room temperature control and greatly reduced overheating of the building. Thus one-pipe systems become energy efficient variable flow systems, similar as Two-pipe systems are.
Typical applications are:
-one-pipe vertical riser based heating system (Fig. 1)
-one-pipe horizontal loop based heating system (Fig. 2)
-two-pipe vertical riser based heating system without TRV’s, such as staircase or bathroom risers (Fig. 3)
2 | VD.C6.U4.02 |
© Danfoss | 2018.07 |
Data sheet |
Thermostatic actuator QT |
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Technical data
General data
Setting range |
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35 … 50 |
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45 … 60 |
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65 … 85 |
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Temperature tolerance |
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°C |
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±3 |
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P-band 1) |
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5 1)/8 2) |
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Max adm temperature at sensor |
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90 |
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Capillary tube length |
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m |
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0.6 |
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Materials |
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Housing |
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CuZn36Pb2As (CW 602N) |
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Cone and diaphragm support |
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MPPE (Noryl) |
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Main spindle |
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(CW 614N) Zn39Pb3 |
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Sensor cap |
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Polypropylene (Borealis HF 700-SA) |
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Temperature sensor |
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Copper, mat. No. 2.0090 |
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Adapter |
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DN 10-20 |
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CuZn39Pb3 (CW 614N), coated with Cu Zn8B |
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DN 25-32 |
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CuZn39Pb3 (CW 614N) |
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Nut |
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DN 10-20 |
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CuZn39Pb3 (CW 614N), coated with Cu Zn8B |
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DN 25-32 |
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CuZn39Pb3 (CW 614N) |
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1)with AB-QM DN 10-20, at 50 % flow setting
2)with AB-QM DN 25-32, at 50 % flow setting
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QT setting 0 (min) QT setting 6 (max) |
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QT setting 0 (min) QT setting 6 (max) |
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AB-QM |
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AB-QM |
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50% setting |
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50% setting |
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P band |
P band |
P band |
P band |
Fig. 4 Functional graph for QT on AB-QM DN 10-20 |
Fig. 5 Functional graph for QT on AB-QM DN 25-32 |
Mounting |
When used in vertical based one-pipe heating |
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system (Fig.1) AB-QM is to be installed after the |
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last radiator in the riser. |
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In horizontal based heating system (Fig.2) AB-QM |
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can be mounted also elsewhere in the loop, as |
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long as the temperature sensor can be mounted |
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after the last radiator in that loop. |
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QT should be mounted on the AB-QM by hand. |
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Maximum allowed torque is 5 Nm. |
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It is recommended to insulate the sensor if the |
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thermostat is installed in a very cold place (< 5 °C). |
Installation of the sensor
For proper heat transfer between a heating water pipe and the thermostat sensor, it is very important to apply thermo paste (included in the box) on the surfaces in contact.
Sensor itself can be mounted in any direction. For best performance of QT it is recommended to install sensor facing up (Fig. 7). It can be mounted either above or below sensor head.
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rfor |
man |
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tpe |
c |
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s |
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e |
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e |
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B |
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Sensor holder |
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Fastener |
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Thermo paste |
Hot water supply |
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Fig. 6 |
Fig. 7 |
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© Danfoss | 2018.07 |
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VD.C6.U4.02 | 3 |