Glow-worm Micron 70FF - Manual (Page 9)

9 2000225229C
3 Water Systems
3.7 Open Vented Fully Pumped Heating and
Domestic Hot Water
The connections for the system MUST be as shown in diagrams
3.1 and 3.2.
Plastic pipes should not be connected directly to the boiler. An
intermediate metallic pipe of 1m in length should be fitted
between the boiler and the plastic pipe system. Plastic pipes
should be type S to BS7291.
3.8 Inhibitor
Attention is drawn to the current issue of BS5449 and BS7593
on the use of inhibitors in central heating systems.
When installing in an existing system take special care to drain
the entire system, including radiators, then thoroughly cleaning
out before installing the boiler whether or not adding an inhibitor.
3.9 Sealed Water Systems
The installation should comply with the appropriate requirements
of the current issue of BS4814, BS5449, BS6759, BS6798 and
BS7074 Part 1 and 2.
3.10 Safety Valve
A safety valve must be fitted to a sealed water system.
It shall be preset, nonadjustable with a lift pressure of 3bar,
incorporating seating of a resilient material, a test device and a
connection for drain.
The drain from the safety valve must be routed clear of any
electrical fittings and positioned so that any discharge can be
seen.
3.11 Expansion Vessel - Sealed Systems only
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, unless laid down differently by the manufacturer.
The expansion vessel volume depends upon the total water
system volume and the initial system design pressure. For any
system an accurate calculation of the vessel size is given in the
current issue of BS7074 Part 1.
Example: For an initial system design pressure of 0.7bar the
minimum total vessel volume required is 0.063xTotal System
volume.
NOTE: A higher initial design pressure requires a larger volume
expansion vessel.
Guidance on vessel sizing is also given in the current issue of
BS5449 and BS7074 Part 1, for IE refer to the current edition of
I.S.813 "Domestic Gas Installation".
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.
The water content of the boiler is given in Data Table 1.
3.12 Pressure Gauge - Sealed Systems only
A pressure gauge with a set pointer and covering at least the
range of 0 to 4bar (0 to 60lb/in
2 ) shall be permanently fitted to
the system in a position where it can be seen when filling the
system.
3.13 Domestic Hot Water Cylinder
SINGLE FEED INDIRECT CYLINDERS ARE NOT SUITABLE.
The domestic hot water cylinder must be of the indirect coil type.
It must be suitable for working at a gauge pressure of 0.35bar
above the safety valve setting.
3.14 Domestic Hot Water System - Unvented
Where a storage system will not have a vent to atmosphere the
installation must comply with Building Regulations and local
Diagram 3.2
PUMPED RETURN PUMPED FLOW
6770
28mm
PIPE
22mm
PIPE
28mm
PIPE
22mm
PIPE
Water Company Bye-laws, see also the current issue of BS6700.
If fitting into an existing system the local authority must also be
advised.
3.15 Filling a Sealed Water System
Provision for filling the system at low level must be made.
The installation should comply with the appropriate requirements
of the current issue of BS 5449.
3.16 Water Makeup
Provision must be made for replacing water lost from the
system. A make up vessel mounted above the highest point of
the system and connected through a non-return valve to the
system on the return side of either the hot water cylinder or
heating system.