4.2
Pump selection and pump aquastat
Fig. 12 shows the head loss through the boiler at
various flow rates for the Vitogas 50 boilers.
The minimum return water temperature is 120°F
(48.8°C). The maximum temperature rise between
return and supply is 68°F (37.7°C).
4.3
Initial system fill
Treatment for boiler feed water should be considered in
areas of known problems, such as high mineral content
and hardness. In areas where freezing might occur, an
antifreeze may be added to the system water to protect
the system. Please adhere to the specifications given
by the antifreeze manufacturer. Never use silicate
based automotive antifreeze.
Please observe that an antifreeze/water mixture may
require a backflow preventer within the automatic water
feed and influence components such as diaphragm
expansion tanks, radiation, etc. A 40% antifreeze
content will give freeze-up protection to approximately
-10°F (-23.3°C). Do not use antifreeze other than
specifically made for hot water heating systems. System
also may contain components which might be
negatively affected by antifreeze. Check total system
frequently when filled with antifreeze.
A pressure reducing valve (or “fill” valve) is required to
reduce the incoming water pressure. The total of the fill
pressure, pump head, and any small pressure rise from
thermal expansion of the water must be less than the
boiler pressure relief valve setting. An expansion tank
must be connected to the system close to the suction
side of the circulating pump to prevent pressure
increase resulting from thermal expansion of the system
water.
Fig. 11
Standard Vitogas 50, RS boiler piping connections
RS boiler with right hand water piping, left hand gas piping
(Boiler shown with access panel removed)
75
90
6
0
40
85
3.6
flC
100
flF
55
12
0
70
2.0
0.4
8
0
flC
Flow direction must
be as shown
Return
Supply
Low water
cut-off
probe or
float type
Min. 2˝ above
supply pipe
centerline
Gas
pipe
Sensing well
for aquastat
capillaries
Power
120V
60 Hz
Lubricated
plug valve
Vitotronic control
Drip leg
with cap
6
˝
150
Mount relief
valve, air vent
and pressure
gauge to
tapping on left
hand side
Mount drain valve
to lower tapping
Pilot burner
mounting side
2˝
2˝
2˝
Fig. 12
Head loss through boiler
0
10
20
30
40
50
60
70
80
90
100
USG/min
0
38
76
114
152
190
228
266
304
342
380
ltr./min
FLOW
7.0
28
6.5
26
6.0
24
5.5
22
5.0
20
4.5
18
4.0
16
3.5
14
3.0
12
2.5
10
2.0
8
1.5
6
1.0
4
0.5
2
0
0
HEAD LOSS
kPa
in W.C.
R
S8
RS
11
RS
14
9
