Flue System; Condense Drain; Design Waste Gas Volume And Temperature; Maximum Length Of Flue Duct - Hamworthy Sherborne Series Installation, Commissioning And Service Manual

6.0 FLUE SYSTEM

Detailed recommendations for flue systems are given in
BS 6644, BS 5440, IGE/UP/10.
All flue discharges for plant exceeding 150kW output
must comply with the Third edition of the 1956 Clean Air
Act Memorandum.
The following notes are intended to give general
guidance only.
6.1 Flue System General Requirements
The Hamworthy Sherborne boiler is designed for use
with the following flue systems supplied by Hamworthy -
see Figures 6.1.1, 6.1.2, 6.1.3 & 6.1.4:
80/125mm concentric room sealed, balanced flue system
for rear through the wall discharge.
100/150mm concentric, room sealed, balanced flue
system for remote discharge, horizontal or vertical –
maximum length 7m.
100mm separate air and flue ducts, room sealed,
balanced flue system for remote discharge – maximum
length 10m.
100mm flue duct, for connection to an open flue
(chimney) system – maximum length 10m.
Flue systems should be designed with reference to BS
5440 part 1, IGE/UP/10 and Third Edition of the 1956
Clean Air Act Memorandum.
Flue installations can be configured to suit a number of
applications, see Figures 6.1.1, 6.1.2, 6.1.3 & 6.1.4: but
must comply with one of the following options:
Room Sealed.
Type C13: Horizontal balanced flue. – Fig 6.1.1.
Type C33: Vertical balanced flue. – Fig 6.1.2.
Type C53: Separate intake and discharge ducts
terminating in different pressure zones. – Fig 6.1.3.
Open Flue.
Type B23: Intake from ventilated plant room and
discharge via horizontal/vertical flue. – Fig 6.1.4.
WARNING
The Sherborne boiler
Condensing boiler and in certain conditions
'pluming' will be visible from the flue terminal.
Should pluming be a concern, the flue system
design should discharge at high level.
Care should be taken to ensure that the flue is installed
such that any condensation is continuously drained back
to the boiler or any resultant low points in the flue system.
Horizontal flue runs should be kept to a minimum and
must be inclined at 2° upwards in the direction of the
exhaust gas flow. All joints should be such that any
condensation is directed back down the slope.

6.2 Condense Drain

The boiler is provided with a condense drain suitable for
connection to 22mm plastic waste pipe (not supplied),
which must be connected to a tundish (not supplied).
Discharge piping from a tundish should be of a synthetic
material due to the mild acidity of the condensate (pH 3-
HAMWORTHY HEATING LTD
is a High Efficiency/
5), with all discharge piping having a minimum fall of
30mm/m away from the boiler. Consideration should be
given to possible freezing of condense water traps and
pipework. This must be avoided at all times by routing
pipework within the building, where possible.

6.3 Design Waste Gas Volume and Temperature

Where the boiler(s) discharge into an open flue system, it
is recommended that the volume and temperature of the
waste gases used for design of the flue system are as
shown in Figure 2.2.

6.4 Maximum Length of Flue Duct.

For single boiler installations the maximum allowable
linear equivalent length of straight smooth bore tube for
both (air supply and flue discharge) twin duct, and
concentric systems is approximately 10m and 7m
respectively. This dimension relates to the distance
between the boiler and the discharge terminal. The table
below nominates the equivalent length of flue tube.
Components can be combined in any order provided that
the total equivalent length of flue does not exceed the
maximum. Note: if the maximum stated lengths of flue
are exceeded the boiler will not achieve maximum
output.
Figure 6.4 Flue Resistance
Equivalent tube lengths.
Component
Straight tube ø100mm per m
45° bend ø100mm
90° bend ø100mm
Concentric straight tube ø80/125mm per m
Concentric straight tube ø100/150mm per m
Concentric 45° bend ø100/150mm
Concentric 90° bend ø100/150mm

6.5 Disconnection

Each boiler is fitted with a telescopic appliance
connector, enabling the boiler to be disconnected from
the flue system.
NOTE! The flue system must be self supporting and
not present a risk to people in or around the building.
See Section 13: SERVICING for further information.

6.6 Flue Discharge

The flue system must ensure safe and efficient
operation of the boiler to which it is attached, protect the
combustion process from wind effects and disperse the
products of combustion to the external air.
The flue must terminate in a freely exposed position and
be so situated as to prevent the products of combustion
7
SHERBORNE
Length
m
1
2.25
4.10
1
1
1.30
2.20
500001103/E