Product Overview

250 series
Automatic air vent for solar heating systems. 1/2” Male NPT connections. Brass body and cover. Chrome plated. Float
in high resistance polymer. Seals in high resistance elastomer. Medium: water and glycol solutions. Maximum percentage
of glycol: 50%. Working temperature range: -20 to 360ºF. Maximum working pressure: 150 psi. Maximum discharge
pressure: 75 psi.
Code NA29284
Shut-off valve for automatic air vent for solar heating systems. 1/2” F NPT x 1/2” M NPT connections. Chrome plated brass
body and ball. Seals in high resistance elastomer. Medium: water and glycol solutions. Maximum percentage of glycol:
50%. Working temperature range: -20 to 360ºF. Maximum working pressure: 150 psi.
SPECIFICATION SUMMARIES
Operating principle
The accumulation of air bubbles in
the valve body causes the float to
drop so the air vent valve opens.
This phenomenon occurs, and
consequently, the valve functions
correctly, as long as the water
pressure remains below the
maximum discharge pressure.
Installation
250 series automatic air
vents must be installed in
a vertical position, typically
on the top of the solar
heating system panels and at points in the circuit where air bubbles
gather that need to be discharged.
They must always be installed in combination with a shut-off valve.
This is necessary since the vent valves must be shut off after use to
remove the air during the filling and starting up phase of the system.
Hydraulic characteristics
Discharge capacity when the system is being filled
Construction details
Resistance to temperature
The high performance level of this series of automatic air vent
valves, required in solar heating systems, is ensured by using materials
that are highly resistant to temperature. The materials allow the vent
function with glycol water temperatures up to 360ºF (180°C).
Application diagram
T
max
= 180°C / 360 °F
P max = 10 bar / 150 psi
T
max
= 180°C / 360 °F
Pmax = 10 bar / 150 psi
T
max
= 180
°
C / 360
°F
Pmax
= 10 bar / 150 psi
T
max
= 180°C / 360 °F
Pmax = 10 bar / 150 psi
T
max
= 180°
C / 360
°
F
P
max
= 10 bar / 150 psi
Maintenance
The 250 series automatic air vent is made to
allow checking of the internal mechanism.
Access to the moving parts that govern the air
vent is attained by simply removing the top
cover.
A shut-off valve must be installed before the
250 series device to allow shut off to simplify
any maintenance work and for shutting off after
the filling phase.
T
max
= 180°C / 360°F
P max = 10 bar / 150 psi
T max = 180° C / 360 °F
P
max
= 10 bar / 150 psi
3.5 4
.5
4.5 3.5
2.5
2
.5
1.5 1
.5
0.5
0
70 60 50 40
30
20
10
0
(bar) (psi)
)s/lN( )MFCS(
1
0.1
0
0.5
0.9
0.8
0.7
0.6
0.4
0.3
0.2
1.2
1.1
0
2.5
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25