Product Overview

Data sheet AVDO
Automatic By-pass Valve
VD55K622 © Danfoss 04/10
AVDO self-acting constant fl ow controls are used
to maintain a minimum fl ow rate (e.g. through
a low water content gas boiler) or to control
diff erential pressure in a heating system.
The closing of radiator or zone valves due to
reduced heating demand may result in low
fl ow and increased system diff erential pressure
(potentially dead heating pumps). AVDO valves
open with a falling system load and allow fl ow
through a bypass line whenever the diff erential
pressure through the valve exceeds set point;
ensuring a minimum fl ow rate or a system
diff erential pressure at minimum system load.
AVDO:
Opens on rising diff erential pressure.•
Setting diff erential pressure range of 0.725 - •
7.25 psi (0.05-0.5 bar).
Designed for 145 psi (10 bar), max. 248°F •
(120°C).
Operates without impulse tubes.•
Can be supplied with NPT or solder tail •
pieces.
Application
Ordering
Technical data
1
Application Examples:
The placement of the AVDO can be piped between the supply and return or parallel to the circulator as
seen in the fi gures below.
Setting range 0.725 - 7.25 psi (0.05 - 0.5 bar)
Max. diff erential pressure 7.25 psi (0.5 bar)
Operation pressure 145 psi (10 bar)
Max. fl ow temperature 248°F (120°C)
Max. leakage when closed 0.22 gpm (0.05 m
3
/h)
Figure 1:
Low water content gas boiler
where a min. fl ow is required
through the boiler.
Figure 2:
Manifold with zoned
multiple loops
Figure 3:
Diff erential bypass control
across a pump being used on a
constant circulating system.
Code Numbers Type Description Size/Connection
AVDO 15
Straight Valve Body
1/2” Union Solder
1/2” Union Male, NPT
003L602001
003L602002
AVDO 20
3/4” Union Solder
3/4” Union Male, NPT
003L602501
003L602502
AVDO 25 1/2” Union Solder 003L603002