PDF User Manual

1

0529EN  

April 2015

M

ixing

 

valves

T

hree

-

way

 

mixing

 

valve

 

wiTh

 

bonneT

r298

ISO

14001

0032A/3

OHSAS

18001

0064L/1

ISO

9001

0006/7

F.C.

F.O.

3

4

0,5

1

2

1000

800

600

500

400

300

200

100

Q [l/h]

∆p [mm H

2

O]

80 90

70

60

50

40

30

20

10

10

20

30

40

50

60

70

80

90

100

200

300

400

500

600

700

800

900

1000

Opening

Shutter

Kv

(direct + by-pass)

Primary side  

flow rate Qp

By-pass  

flow rate Qbp

F.C.

3,25

0 %

100 %

0,5 mm

3,48

11 %

89 %

1 mm

3,79

18 %

82 %

2 mm

3,78

29 %

71 %

3 mm

3,12

44 %

56 %

4 mm

2,35

74 %

26 %

F.O.

1,78

100 %

0 %

Table 1

Operation

R298 + handwheel for manual operation

The three-way R298 mixing valve is equipped with a handwheel to allow for 
manual operation, which are carried out via a simple clockwise rotation for 
the valve opening and anticlockwise for closure.
Total opening of the bonnet, and therefore of the primary side supply, is 
obtained by screwing down the handwheel, while unscrewing it fully frees 
the thread for the drive motor connection.

bypass

Direct

SYSTEM SIDE

BOILER ROOM

SIDE

SYSTEM SIDE

BOILER ROOM

SIDE

clockwise

rotation 

anticlockwise

rotation

SYSTEM SIDE

BOILER ROOM

SIDE

SYSTEM SIDE

BOILER ROOM

SIDE

clockwise

rotation 

anticlockwise

rotation

R298 + K281 actuator for automatic operation

The handwheel can be replaced with a K281 actuator for automatic mixing 
adjustment, in combination with electronic thermoregulation. The K281 
actuator is mounted manually, by screwing the brass ring nut in a clockwise 
direction until it stops. This does not require the use of any tools.

bypass

Direct

SYSTEM SIDE

BOILER ROOM

SIDE

SYSTEM SIDE

BOILER ROOM

SIDE

SYSTEM SIDE

BOILER ROOM

SIDE

SYSTEM SIDE

BOILER ROOM

SIDE

Description

The R298 mixing valve allows for the interception and mixing of heating fluid 
in radiant heating and cooling systems for floors or ceilings and in medium-
size radiator heating systems that require precise control of water delivery 
temperature. The R298 valve is equipped with a handwheel for manual 
operation, or alternatively, it can be coupled to a K274 actuator for automatic 
control.

Versions and product codes

Product code

Connections

Actuator connection Center distance [mm]

R298Y001

1 1/2” M x 1 1/2” F

M28 x 1,5 mm

120

R298Y027

1 1/2” M x 1 1/2” F

M30 x 1,5 mm

Completion codes

• Actuators 

K281

 or 

K282

Accessories

• 

P19Y001

: ring nut M30x1,5 mm for adapting valve R298 M28x1,5 mm 

threading.
• 

P19Y002

: ring nut M28x1,5 mm for adapting valve R298 M30x1,5 mm 

threading.

Technical data

• Heating fluid: water for air-conditioning systems
• Max. working temperature: 90 °C
• Max. working pressure: 10 bar
• Maximum differential pressure: 1,2 bar
• Center distance: 120 mm
• Connections: 1 1/2” flat seat
• Mixing: by bonnet DN20, which is normally closed on the primary side

Materials

• Body, bonnet and nut in brass CW617N - UNI EN12165
• EPDM sealing rings

Losses of pressure

In Table 1, values in Kv and mixing percentage ratios (between the by-pass 
"QBP" flow rate and the primary side "Qp") corresponding to the various 
opening positions are displayed.

SYSTEM SIDE

BOILER ROOM

SIDE

Qp

Qbp

R298

2

0529EN  

April 2015

M

ixing

 

valves

T

hree

-

way

 

mixing

 

valve

 

wiTh

 

bonneT

r298

ISO

14001

0032A/3

OHSAS

18001

0064L/1

ISO

9001

0006/7

Installation

• The R298 valve must be installed according to the direction of flow as 
indicated by the arrow present on the valve body. 

• The R298 valve must be installed on the delivery side. The circulator on the 
secondary circuit must be installed downstream from the mixing valve.

System

terminals

R298

Circulator

• The R298 valve can be installed in a vertical position with the actuator to the 
right or left, or in a horizontal position with the actuator above.
Horizontal downward facing installation of the valve is not permitted.

Dimensions

G

A

L

I

B

B

G

K

K

J

J

D

E

F

Product 

code

G

B

A 

[mm]

I

 [mm]

L 

[mm]

D 

[mm]

E 

[mm]

F 

[mm]

K 

[mm]

J

 [mm]

R298Y001

1 1/2” 

M

1 1/2”F 59

120

209

28

50

104

41

53

R298Y027

M

N

Product code

M

[mm]

N

[mm]

R298Y001/K298Y027 +

K281X002/K282X002

113

255

R298Y001/K298Y027 +

K281X012/K281X022

115

265

Product specifications

R298

Three-way mixing valve with bonnet, with 1 1/2” flat seat connections and by-
pass. Body, bonnet and nut in brass UNI EN 12165 CW617N. Handwheel with 
protection and manual operation functions. Max. working temperature 90 °C. 
Max. working pressure 10 bar. Center distance of 120 mm. Can be motorized 
by installing the K281 or K282 series actuator.

Additional information

For additional information please check the website: www.giacomini.com or contact the technical service:  

'

 +39 0322 923372      

6

 +39 0322 923255      

*

 consulenza.prodotti@giacomini.com

This pamphlet is merely for information purposes. Giacomini S.p.A. retains the right to make modifications for technical or commercial reasons, without prior notice, to the items described in 
this pamphlet. The information described in this technical pamphlet does not exempt the user from following carefully the existing regulations and norms on good workmanship. 
Giacomini S.p.A. Via per Alzo, 39 - 28017 San Maurizio d’Opaglio (NO) Italy