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VENTILATION
The ventilation requirements of these boilers are dependent
on the type of flue system used, and their heat input. All vents
must be permanent with no means of closing, and positioned
to avoid accidental obstructions by blocking or flooding.
Detail reference should be made to BS. 6644 for inputs
between 70kW and 1.8MW (net). In IE refer to the current
edition of I.S.820.
The following notes are for general guidance only:
Dust contamination in the combustion air may cause blockage
of the burner slots. It is recommended direct connection of
the air intake via ducting to clean outside air be used.
However, if combustion air is to be drawn directly from the
boiler room, the air inlet guard MUST be used.
IMPORTANT NOTE.
If combustion air is drawn from within the boiler room,
ensure no dust or airborne debris can be ingested into
the appliance. Dusty concrete flooring should be sealed
to reduce the presence of dust.
The temperature within a boiler room shall not exceed 25°C
within 100 mm of the floor, 32°C at mid height and 40°C with-
in 100 mm of the ceiling.
OPEN VENTED SYSTEM REQUIREMENTS
Detail reference should be made to the appropriate standards
listed on page 8.
The information and guidance given below is not intended to
override any requirements of the above publications or the
requirements of the local authority, gas or water undertakings.
The vertical distance between the pump and feed/expansion
cistern MUST comply with the pump manufacturer's minimum
requirements, to avoid cavitation. Should these conditions not
apply either lower the pump position or raise the cistern above
the minimum requirement specified by Ferroli Ltd
The isolation valves should be fitted as close to the pump as
possible.
The information provided is based on the following assump-
tions:
An independent open vent/safety pipe connection is made
immediately after the system flow pipe connection.
An independent cold feed/expansion pipe connection is made
immediately after the open vent/safety pipe connection.
The maximum flow rate through the boiler is based on a tem-
perature difference of 11°C at full boiler output.
The boiler is at the highest point of circulation in the system.
Systems designed to rise above the boiler flow tappings will
automatically require a minimum static head higher than that
shown.
The position of the open vent/safety pipe above the expansion
cistern water level is given as a guide only. The final position
will depend upon the particular characteristics of the system.
Pumping over of water into the expansion cistern must be
avoided.
Both open vent/safety pipe and cold feed/expansion pipes
must be of adequate diameter to suit the output of the boil-
er. Refer to Tables below and BS 6644:2005.
Open Flued Installations
If ventilation is to be provided by means of permanent high and
low vents communicating direct with outside air, then reference
can be made to the sizes below. For other ventilation options
refer to BS. 6644. In IE refer to the current edition of I.S.820.
Required area (cm2) per kW of total rated input (net)
Low level (inlet)
High level (outlet)
Note: Where a boiler installation is to operate in summer months
(e.g. DHW) additional ventilation requirements are stated, if
operating for more than 50% of time (refer to BS6644).
Room Sealed Installations
A minimum of 2cm2 free area per kW of net heat input at both
high and low level is required for boiler rooms. For enclosures
refer to BS6644.
With a cold feed head of <8m, the pump must
be fitted on the return to the boiler.
This diagram does not show safety valves, wa-
ter flow switches, etc. necessary for the safe
operation of the system.
Open Vent Pipe Sizes
Rated output
Minimum bore
kW
61 to 150
151 to 300
Steel pipe sizes complying with medium or heavy quality or BS 1387.
Cold Feed Pipe Sizes
Rated output
Minimum bore
kW
61 to 150
151 to 300
Steel pipe sizes complying with medium or heavy quality or BS 1387.
Boiler Room
Enclosure
4
10
2
5
Nominal Size (DN)
mm
in
32
1 1/4
38
1 1/2
Nominal Size (DN)
mm
in
25
1
32
1 3/4
13
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