Technical data

27
Flue System for Individually Flued Single Boilers Only
The table below provides a guide to the maximum flue length allowed for
each boiler using 100 mm diameter components on non condensing boilers.
Purewell VariHeat High Efficiency Non Condensing Boilers
Boiler Model
Flue
Diameter
(mm)
Maximum
Flue Length
(m)
Equivalent Length (m)
90° Elbow 45° Elbow
PV 65he 100 19 1.5 1.3
PV 85he 100 12 1.5 1.3
PV 105he 100 8 1.5 1.3
PV 125he 100 4 1.5 1.3
The table below provides a guide to the maximum flue length allowed for
each boiler using 150 mm diameter components, connected to the boiler
primary flue which is 100 mm diameter, on non condensing boilers
Purewell VariHeat High Efficiency Non Condensing Boilers
Boiler Model
Flue
Diameter
(mm)
Maximum
Flue Length
(m)
Equivalent Length (m)
90° Elbow 45° Elbow
PV 65he 150 149 2.2 2.0
PV 85he 150 88 2.2 2.0
PV 105he 150 69 2.3 2.0
PV 125he 150 47 2.3 2.0
The table below provides a guide to the maximum flue length allowed for
each boiler using 150 mm diameter components on condensing boilers.
Purewell VariHeat High Efficiency Condensing Boilers
Boiler Model
Flue
Diameter
(mm)
Maximum
Flue Length
(m)
Equivalent Length (m)
90° Elbow 45° Elbow
PV 70c 150 131 2.1 1.6
PV 95c 150 114 2.2 1.7
PV 110c 150 114 2.2 1.7
PV 140c 150 79 2.3 1.8
PV 180c 150 57 2.3 1.8
Open Flue
Purewell VariHeat boilers are designed
for Type B23 open flue systems.
Type B - An appliance intended to be
connected to a flue that evacuates the
products of combustion to the outside
of the room containing the appliance.
The combustion air is drawn directly
from the room.
Type B2 - A type B appliance without
a draught diverter
Type B23 A type B2 appliance
incorporating a fan upstream of the
combustion chamber/heat exchanger.
For details of the full range of classifications
refer to BSI publication PD CR 1749:2001.
Equivalent Length Components
For single, or individually flued multiple
boilers, it is possible to select components
from the Hamworthy Masterflue MF range
of components, and design a flue system
that has an overall length within
the specified limits.
The maximum flue length is the sum
of all the vertical and horizontal sections
(A + B + C) plus the equivalent lengths
of all the 90 degree and 45 degree elbows.
The tables opposite provide details
of the flue system maximum lengths,
and the equivalent lengths for the elbows.
Flue System for Multiple Boilers
Multiple boilers may be installed using a
common flue header. For multiple boiler flue
applications or where an existing flue system
is to be used, please consult with our flue
technical team for further advice.
Tel: [phone]
Email: [e-mail]
Flue Guide
Purewell VariHeat Boilers
NOTES
1. The figures shown in these tables are calculated for Hamworthy Masterflue MF components. As the flue coupled to these
boilers will be pressurised and the flue gases wet, leading to running condensation within the flue, it is important that the flue
components used are fully sealed and resistant to the aggression of condensate. Masterflue MF components are manufactured
from acid resistant stainless steel and incorporate a tri-lip seal at the joints to provide leak free performance.
2. 45° And 90° bends are based on Hamworthy Masterflue MF slow radius components. Alternative bends and components
will have differing performance characteristics leading to a final performance that does not match the details in the chart.
3. If the flue system intended is not covered by the details in the charts then contact Hamworthy Heating for advice.
Using different sizes and diameters will effect the equivalent length of flue that may be used.