Danfoss QT Data sheet

Data sheet

Thermostatic actuator QT

- return temperature control with AB-QM valves

Description		QT is a self-acting thermostatic actuator
		designed to be used as return temperature
		control thermostat in one-pipe heating systems.
		QT is dedicated to be used with AB-QM
		automatic balancing & control valve.
		AB-QM together with QT is a complete
		one-pipe solution: AB-QT.
		Main data:
		• Setting range: 35-50 °C, 45-60 °C, 65-85 °C
		• Designed for AB-QM DN 10-32
		• Easy-to-install external surface sensor

Benefits	•	Reduces actual riser flow to match heat
		demand
	• Improved room temperature control
	• Reduced overheating of the building
	•	Reduced heating cost

Ordering	QT thermostatic actuator
	Setting range	fit to	Code No.
	(°C)	AB-QM
	45 … 60	DN 10-20	003Z0382
		DN 25-32	003Z0383
	35 … 50	DN 10-20	003Z0384
		DN 25-32	003Z0385
	65 … 85	DN 10-20	003Z0386
		DN 25-32	003Z0387

Accessories

Type	Code No.
Pocket for submersible sensor	003Z0391
Adapter kit QT (DN 10-20)	003Z0392
Adapter kit QT (DN 25-32)	003Z0393
Sensor pocket kit	003Z0394
QT flow setting tag	003Z0395

AB-QM valves

	DN	Qmax.	Ext. thread	Code No.	AB-QM	Ext. thread	Code No.
		(l/h)	(ISO 228/1)			(ISO 228/1)
	10 LF	150	G ½ A	003Z1261		G ½ A	003Z1251
	10	275		003Z1211			003Z1201
	15 LF	275	G ¾ A	003Z1262		G ¾ A	003Z1252
	15	450		003Z1212			003Z1202
	20	900	G 1 A	003Z1213		G 1 A	003Z1203
	25	1.700	G 1¼ A	003Z1214		G 1¼ A	003Z1204
	32	3.200	G 1½ A	003Z1215		G 1½ A	003Z1205

© Danfoss | 2018.07

VD.C6.U4.02 | 1

Data sheet	Thermostatic actuator QT

Applications
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

Technical data

General data

Setting range				35 … 50		45 … 60		65 … 85
Temperature tolerance			°C		±3
P-band 1)					5 1)/8 2)
Max adm temperature at sensor					90
Capillary tube length			m		0.6
Materials
Housing						CuZn36Pb2As (CW 602N)
Cone and diaphragm support						MPPE (Noryl)
Main spindle						(CW 614N) Zn39Pb3
Sensor cap					Polypropylene (Borealis HF 700-SA)
Temperature sensor						Copper, mat. No. 2.0090
Adapter		DN 10-20			CuZn39Pb3 (CW 614N), coated with Cu Zn8B
		DN 25-32				CuZn39Pb3 (CW 614N)
Nut		DN 10-20			CuZn39Pb3 (CW 614N), coated with Cu Zn8B
		DN 25-32				CuZn39Pb3 (CW 614N)

1)with AB-QM DN 10-20, at 50 % flow setting

2)with AB-QM DN 25-32, at 50 % flow setting

		QT setting 0 (min) QT setting 6 (max)				QT setting 0 (min) QT setting 6 (max)
AB-QM				AB-QM
50% setting				50% setting

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
	system (Fig.1) AB-QM is to be installed after the
	last radiator in the riser.
	In horizontal based heating system (Fig.2) AB-QM
	can be mounted also elsewhere in the loop, as
	long as the temperature sensor can be mounted
	after the last radiator in that loop.
	QT should be mounted on the AB-QM by hand.
	Maximum allowed torque is 5 Nm.
	It is recommended to insulate the sensor if the
	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.

				rfor	man
			tpe			c
		s
	e					e
	B
	Sensor holder
	Fastener
Thermo paste	Hot water supply
Fig. 6	Fig. 7
© Danfoss | 2018.07						VD.C6.U4.02 | 3