Hamworthy 563216020, Инструкция по установке, наладке и обслуживанию, Страница: 30 / 34

HAMWORTHY HEATING LTD
25
CHESIL-ELECTRONIC 500001181/K
Figure A3 - Heating System Calculation Sheet
1. System Parameters
System Water Content - Vs = litres
System Anti-freeze Content - ra = %
Maximum System Working Pressure - P
w
= bar
Maximum Static Head -
P
h
= metres
If the system volume is not known then the following rule of thumb can be applied:
System water content = Boiler power (KW) X 10
2. Expansion Vessel Volume Calculation, Vv-
(ra + 81.5) x Vs ( + 81.5 ) x
Vv = = Vv = litres
921 921
If the system is to be set up using the factory preset alarm levels for the Chesil unit then no other
calculations are necessary. The factory preset levels are:
Cold Fill Pressure Switching Level, P
f
= 1.8 bar
Hi Pressure Alarm Level, P
hi
= 3.6 bar
Lo Pressure Alarm Level, P
lo
= 1.3 bar
The safety valve lift pressure should be set 0.35 bar above the Hi pressure alarm level.
3. Cold Fill Pressure Switch Setting Calculation, P
f
-
P
h
P
f
= + 0.2 = + 0.2 P
f
= bar
10.2 10.2
4. Safety Valve Lift Pressure Calculation, P
s
-
Actual fitted expansion vessel volume, V
va
- V
va
= litres
Actual fitted expansion vessel acceptance factor, a
va
-
V
v
x 0.35 x 0.35
a
va
= = a
va
=
V
va
Actual working pressure, P
wa
-
P
f
+ a
va
+
P
wa
= = P
wa
= bar
1 - a
va
1 -
Note! If P
wa
> P
w
then increase expansion vessel volume, V
va
and recalculate from step start of step 3
P
s
= P
wa
+ 0.7 = + 0.7 P
s
= bar
5. Calculation of Expansion Vessel Acceptance Factor at Safety Valve Lift Pressure, a
s
-
P
s
- P
f
-
a
s
= = a
s
=
P
s
+ 1 + 1
Note! If a
s
> 0.5 then increase expansion vessel volume, V
va
and recalculate from step start of step 3
6. Lo Pressure Alarm Setting Calculation, P
sl
-
P
sl
= P
f
- 0.3 = - 0.3 P
sl
= bar
7. Hi Pressure Alarm Setting Calculation, P
si -
P
sh
= P
wa
- 0.35 = - 0.35 P
sh
= bar
Example
Vs = 2000 litres
ra = 10%
P
w
= 8 bar
P
h
= 22 m
( 10+81.5) x 2000
Vv = = 199
921
22
P
f
= + 0.2 = 2.35
10.2
V
va
= 300
a
va
= 0.23
2.35 + 0.23
P
wa
= = 3.35
1 - 0.23
P
s
= 3.35 + 0.7 = 4.05
4.05 - 2.35
a
s
= = 0.34
4.05 + 1
P
sl
= 2.05
P
wa
= 3.0