Glow-worm SS 115, Instructions For Use Manual, Page: 9 / 24

4 Installation
4.3 Pipework – Central Heating Circuit
The central heating pipework between the boiler and the
Glow-worm cylinder should be installed using copper tube of
minimum size 22 mm.
If the distance between the boiler and the Glow-worm cylinder
is excessive, a larger pipe diameter may be necessary. It will
be necessary to install a circulating pump in this pipework if
your Glow-worm wall mounted boiler does not contain a built-
in circulating pump.
4.4 Discharge Pipework
The outlet connections of both the temperature and pressure
relief valve and expansion relief valve should be connected in
15 mm copper tube to the tundish supplied.
The tundish should be installed vertically, as close to the
Glow-worm cylinder as possible and within 600 mm of the
temperature and pressure relief outlet. It must be positioned
away from any electrical components and installed in the
same space as the Glow-worm cylinder, so that it is visible to
the user.
The D1 discharge pipe from the T&S Valve/Expansion Valve
can be tee'd upstream of the tundish, see diagram 4.5. The
discharge pipework must be installed using minimum 22 mm
copper pipework from the 1 inch BSP female connection on
the tundish to a safe and visible discharge point. There must
be a vertical section of pipe at least 300 mm long, below the
tundish before any bends or elbows in the pipework. Increase
the diameter of the pipework if the total resistance of the
discharge pipework exceeds the figures shown in the table
below:
The installation of the discharge pipework must be in
accordance with G3, see diagram 4.1.
600mm
maximum
28 mm discharge pipe with 4 elbows and 7 m length from
tundish to discharge point.
Resistance for 4 elbows
at 1.0 m each = 4.0 m
Resistance of discharge pipe = 7.0 m
Total Resistance = 11.0 m
The total resistance of the discharge pipework is less
than the maximum allowed for 28 mm pipework (18 m)
therefore the discharge pipework size is acceptable.
Under fault conditions, the discharge warning pipe can emit
water at near boiling temperature. Ensure the discharge pipe
terminates at a safe position where there is no risk of contact
with hot water by persons in or about the building (safe and
visible).
Example
:­
22 mm discharge pipe having 4 elbows and a
length of 7 m from the tundish to the discharge point:
Resistance for 4 elbows
at 0.8 m each = 3.2 m
Resistance of discharge pipe = 7.0 m
Total Resistance = 10.2 m
The total resistance of the discharge pipework is greater
than the maximum allowed for 22 mm pipework (9 m).
Therefore calculate the next largest size.
22 mm up to 9 m 0.8 m
28 mm up to 18 mm 1.0 m
35 mm up to 27 mm 1.4 m
Minimum size
of discharge
pipework from
Tundish
Maximum total
resistance allowed expressed
as a length
of straight pipe
(i.e. no elbows or bends)
Resistance
created by each
elbow or bend
Diagram 4.2
12529
12530
Diagram 4.1
High level termination
Typical discharge pipe arrangement
9