Classic
LXRS, RS
-
Propane Installation
9
INSTALLATION
Note.
The pump
manufacturers minimum
requirements must be
complied with.
All dimensions in mm (in.)
Note.
Gravity horizontal pipes should be ABOVE ceiling level and as SHORT as
possible. A MINIMUM inclination of 25 mm per 3 m run (1" per 10') is required to avoid
air locks. If these conditions cannot be met, pumped primaries MUST be used.
NB:
Imperial dimensions are approximate
The above graph assumes 8 elbows in the gravity circuit. For each elbow in excess of
8, (R) must be reduced by 300 mm (12 in.) or (H) increased by 100 mm (4 in.)
6
OPEN VENT SYSTEM REQUIREMENTS -
Fully pumped
The system should be vented directly off the boiler flow pipe, as close to
the boiler as possible. The cold feed entry should be inverted and MUST
be positioned between the pump and the vent, and not more than 150mm
(6") away from the vent connection.
There should be a minimum height - 450mm (18") of open vent above the
cistern water level. If this is impossible refer below.
The vertical distance between the highest point of the system and the
feed/expansion cistern water level MUST not be less than 450mm (18").
The pump MUST be fitted on the flow side of the boiler.
A suitable pump is a domestic circulator capable of providing an 11°C
(20°F) temperature differential (e.g. Grundfos UPS 15/50 or equivalent).
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
Caradon Plumbing Ltd.
Note.
A cold water feed must be available back to the boiler when all
automatic valves are in the closed position (refer to BS. 6798) and, when
close coupled, the feed must not be in a vertical leg.
System
return
Connections
to boiler
Inverted cold
feed entry
System
flow to
pump
150 (6")
Max
15mm
Cold
feed
450 (18")
Mimimum
450 (18")
Mimimum
22mm
Open vent
Feed / expansion
cistern
Water
level
(cold)
INST
ALLA
TION
7
LOW HEAD INSTALLATIONS
The
Classic
range of boilers can be installed in low
head situations by fitting a 'surge arrester' in the
expansion pipe, as shown.
The following conditions MUST be observed:
1.
The surge arrester must be at least 42mm in
diameter x 150mm long, thus ensuring a MINIMUM
air gap and a MINIMUM depth of water below the
static water level (cold) of 75mm.
2.
The static water level (cold) must be at least
200mm above the top of the horizontal flow pipe,
fitted as shown. The vent connection MUST NOT be
made immediately off the top of the boiler, as
venting is made less efficient.
3.
The maximum practical length of 15mm cold feed
pipe should be used in order to reduce the effective
volume of system water expanding into the feed/
expansion cistern to a minimum.
Minimum Requirements
Surge
arrester
75 (3)
Min.
450
(18)
Min.
200
(8)
Min.
Highest
point of
flow or
return
150
(6)
Max
Max. practical
length
To pump
Cold
water
level
Feed / expansion
cistern
75 (3) Min.
Flow
Return
22 (3/4)
Open vent
8 REQUIREMENTS FOR CORRECT GRAVITY HOT WATER PERFORMANCE
