Pump; Flow Rate; Water Treatment - Biasi RIVA OV M110.18SM/OV User Manual And Installation Instructions

3.9 Ventilation Requirements
A safety valve need not be fitted to an open
vented system. (See 3.16 for sealed systems)
3.10

Pump

The pump should be fitted on the flow pipe
the boiler and have isolating valves each side.
A variable duty pump should be set to give a
temperature difference of no greater than 20°C
between the flow and return, with the boiler
controls set at "MAX", which is approximately
80°C to give a flow rate as shown in table 1.
See figure 6 for pressure loss of the boiler.
High resistance microbore systems may require
a higher duty pump.
3.11

Flow Rate

If it is necessary to alter the flow rate, the system
can be fitted with a lockable balancing valve in
the main flow or return pipes shown as valve "A"
in figure 7. The flow rate through the boiler must
not be allowed to fall below that given in table 1.
Table 1. Flow Rate
MINIMUM FLOW
200 l/h
This is equal to 20°C differential at minimum
heat input.
3.12

Water Treatment

WATER TREATMENT,
FLUSHING THE HEATING SYSTEM
NOTE: British Standard BS7593: 2006
the importance of cleansing and flushing of the
system to ensure it continues to run efficiently
with the minimum of maintenance necessary.
Biasi UK Ltd fully supports this professional
approach and recommends that the system is
cleansed with an effective chemical cleanser and
protected long term with a suitable inhibitor. Such
products are available from Fernox and Sentinal.
3.13 Open Vented Water System
The boiler must be supplied
water supply taken from a feed and expansion
cistern situated at a maximum height of 27
metres (90ft) above the boiler.
The cold feed must be 15mm minimum size.
The vent must rise continuously and be
unrestricted.
14
from
RATE
CLEANSING AND
stresses
from an unrestricted
It is important that the relative positions of the
pump, cold feed and open vent are as shown in
figure 9.
3.14 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE NOT
SUITABLE
The domestic hot water cylinder must be of the
double feed fully indirect coil type.
3.15 Sealed Water Systems
The installation must comply with the
requirements of the current issue of BS4814,
BS5449, BS6759, BS6798 and BS7074 Part 1
and 2.
See figure 7 for a suggested layout.
3.16 Safety Valve Sealed System
A safety valve must be fitted to a sealed system.
It shall be preset, non-adjustable with a lift
pressure of 3 bar, incorporating seating of a
resilient material, a test device and a connection
for drain.
The drain from the safety valve must be routed
outside the building, must not discharge above
an entrance or window or any type of public
access area, be clear of any electrical fittings and
positioned so that any discharge can be seen.
3.17 Expansion Vessel
A diaphragm type expansion vessel, conforming
to the current issue of BS4814 (see also BS7074
Part 1 and 2) must be connected at a point close
to the inlet side of the circulating pump, see the
diagrammatic layout, figure 7 unless laid down
differently by the manufacturer.
The expansion vessel volume depends on the
total water system volume and the initial system
design pressure. For any system an accurate
calculation of vessel size is given in the current
issue of BS5449 and BS7074 Part 1.
Example: For an initial design pressure of 0.7 bar,
the minimum total vessel volume required is
0.063 x Total System Volume.
Note: A higher initial design pressure requires a
larger volume expansion vessel.
The charge pressure must not be less than the
static head of the system, that is, the height of
the highest point of the system above the
expansion vessel.
appropriate