34
Sealed Systems
If plastic pipe is to be used, the installer
must check with the plastic pipe
manufacturer that the pipe to be used
is suitable for the temperature and
pressures concerned.
Plastic pipe must be Class S to BS
7291 - Part 1:2010.
Underfloor Pipework
Plastic pipe may be used on underfloor
floor systems where the plastic pipe is
fitted after the thermostatic mixing valve.
Copper tube must be used for at least
the first metre of flow and return primary
pipework between the boiler and the
underfloor mixing/blending valves.
4.8 Pipe Connections
Flow and return connections:
The flow and return connection are at
the rear of the boiler (see Section 2.4)
and the sizes are as follows:
Spira 5-18 Flow 1” BSP Female
Return 1” BSP Female
Spira 6-26 Flow 1” BSP Female
Return 1” BSP Female
Spira 9-36 Flow 1” ¼ BSP Female
Return 1” ¼ BSP Female
Drain Cock:
Fit the ½” drain cock to the bottom
rear ½” BSP connection. Fit the
automatic air vent assembly into the
½” connection on the rear of the boiler
(this is to vent the secondary unit only),
the flow pipe from the boiler must be
vented.
Condensate Connection:
The 1¼” BSP female condensate outlet
connection is located at the rear of the
boiler. Refer to Section 5 for details on
condensate connection and disposal
pipework.
4.9 Wash System
The Grant Spira boiler is supplied
with an automatic cleaning system to
wash any ash build up from the tubes
of the condensing (secondary) heat
exchanger.
This factory fitted wash system consists
of two spray jets, mounted on the
underside of the heat exchanger
access cover. They are connected by a
manifold pipe located on the upper side
of the cover. Refer to Figure 4-1.
This manifold is fed with mains cold
water via a solenoid valve located at the
rear of the boiler.
This solenoid valve is supplied loose
in the boiler components kit and must
be fixed to the back panel of the boiler
using the two self-tapping screws
provided. Refer to Figure 4-2.
The valve is connected to the wash
system manifold via flexible hose,
supplied already fitted within the boiler
casing. Connect one end of the hose to
the outlet of the solenoid valve and the
other to the inlet connection of the wash
system manifold.
Connect the mains water supply to the
15mm compression inlet connection of
the isolating/check valve, mounted on
the solenoid valve inlet.
On either sealed or open-vented
systems; where plastic pipe is used
a minimum of ONE metre of copper
pipe MUST be connected between
both the boiler flow and return
connections and the plastic pipe.
DO NOT CONNECT PLASTIC PIPE
DIRECTLY TO THE BOILER. Grant
UK do not accept any responsibility
for any damage, however caused, to
plastic piping or fittings.
!
WARNING
The system MUST incorporate a
low-level pressure switch to shut
off power to the boiler if the system
pressure drops below 0.2 bar. A
suitable low pressure switch kit is
available to purchase from Grant
UK (product code MPCBS62). refer
to Figure 8-11 for the electrical
connection details on this switch.
!
WARNING
!
NOTE
A minimum water inlet water
pressure of 100 kPa (1 bar) is
required to maintain an adequate
supply for cleaning purposes. The
maximum inlet water pressure is
800 kPa (8 bar).
!
NOTE
In hard water areas an anti-scale
device should be fitted on the cold
water supply to the wash system
to prevent scale build-up in the
manifold pipe and jets.
Figure 4-1: Spray jets (manifold
omitted)
Figure 4-2: Solenoid valve self-tapping
screws (wiring omitted)
4.10 Fan Box and Flue Starter
Fit the fan box to the flanged flue outlet
on the back of the boiler so that the flue
starter outlet is at the top.
Remove the nuts and washers from the
four studs around the flanged flue outlet
of the boiler. Refer to Figure 4-3.
Remove the access panel from the rear
face of the fan box.
With the neoprene gasket in place
on the fan box, locate the four studs
through the corresponding holes in the
gasket/fan box. Two of the studs pass
through the flange at the base of the fan
box. The other two are inside the fan
box and are reached via the rear access
opening.
Secure the fan box in position using
the four nuts and washers previously
removed.
When tightening these nuts, ensure that
the fan box/flue starter section is vertical
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