H120 –H150 Hot Water Boilers
page 10
3.8 HEATING PIPE SIZE & LAYOUT
•
The flow & return connection sizes of 1”BSP on the boiler are not necessarily the correct
pipe sizes for the heating system. It is important that the pipe sizes are correctly calculated
before installation.
•
Hurlcon recommend a two pipe system with the pipes sized according to the flow
requirements and length of runs with a maximum water velocity of 1.5 M/s.
•
Reference The Institute of Plumbing Australia. - “SELECTION & SIZING OF COPPER
TUBES FOR PIPING SYSTEMS”.
Nominal flow capacities
Model
Output
Flow rates
DT
pd
min Pipe dia
F & R length
120
24 kW
0.38 l/s
15
°C
8 kPa
20 mm
6.0 m
150
35 kW
0.53 l/s
15
°C
14 kPa
25 mm
4.5 m
Notes
1.
An automatic heating bypass valve should be fitted to maintain adequate flow rate through the
boiler when thermostatic valves are fitted and or when the majority of radiators are required to be
turned off for long periods of time.
2.
Any pipe work that is in an unheated area such as under the floor or in the ceiling space should be
suitably insulated to prevent heat loss and possible freezing of the pipes.
3.
The pipe work should be graded to facilitate the elimination of air at the highest point and the
draining of the system at the lowest point. Provide air bleeds and drains at these points.
3.9 SIZING OF PRESSURE VESSEL
If the total water capacity of the heating
system is greater than 60 litres then an
additional pressure vessel should be fitted.
An approximate figure can be calculated
from the following table. An additional
tank can be fitted at a convenient location
on the system if required.
Item
Capacity
litres
per
Therma rad Radiators
0.70
kW
Thermaboard single
0.22
metre
Thermaboard double
0.44
metre
Copper tube 25 mm
0.44
metre
Copper tube 20 mm
0.23
metre
Copper tube 15 mm
0.10
metre
Typical two pipe system
Hydronic Boiler
Return
Radiator/Heat emitter
Flow
Flow
Flow
Bypass valve
