Section 4: Installation Page 15
UNDERFLOOR:
• Flow temperature 50°C
• Return temperature 40°C
• Di erential 10°C
In underfl oor systems, it is essential that the return temperature
must be maintained at or above 40°C to prevent internal corrosion
of the boiler water jacket.
Refer to Section 2.4 for the size and type of the connections and
Section 5 for the position of the connections.
OPEN VENTED SYSTEMS:
! NOTE !
The presence of ‘pumping over’ in an open vented heating
system connected to the Grant boiler will invalidate the
product guarantee.
Open vented systems must be correctly designed and installed.
The open safety vent pipe must be positioned to prevent ‘pumping
over’ (i.e. the discharge of water from the open safety vent pipe
into the feed and expansion cistern under the pressure created by
the circulator). For detailed information on the correct design of
open vented heating systems, and the correct location of the open
safety vent pipe, refer to the CIBSE Domestic Heating Design
Guide and OFTEC Technical Book 4 (Installation).
4.5 PIPEWORK MATERIALS
The Grant boiler is compatible with both copper and plastic
pipe. Where plastic pipe is used it must be of the oxygen barrier
type and be the correct class (to BS 7291-1) for the application
concerned.
On either sealed or open-vented systems; where plastic pipe is
used a minimum of ONE metre of copper pipe (or as per pipe
manufacturers instructions) MUST be connected between both
the boiler fl ow and return connections and the plastic pipe.
! NOTE !
Do not connect plastic pipe directly to the boiler.
Grant does not accept any responsibility for any damage,
however caused, to plastic piping or fi ttings.
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 7291-1.
! WARNING !
When plastic pipe is used, the system MUST incorporate
a low 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 IRL
(product code: ZPRESSSWITCHBRASS).
UNDERFLOOR PIPEWORK
Plastic pipe may be used on underfl oor fl oor systems where the
plastic pipe is fi tted after the thermostatic mixing valve. Copper
tube must be used for at least the fi rst metre of fl ow and return
primary pipework between the boiler and the underfl oor mixing/
blending valves.
4.6 CONNECTIONS
4.6.1 FLOW AND RETURN CONNECTIONS
Refer to Section 5.
4.6.2 CONDENSATE CONNECTION
The condensate trap is supplied loose in the burner box and
needs to be fi tted as shown in Figure 6-2.
Refer to Section 6 for details of the condensate disposal pipework.
4.6.3 DRAIN COCK
A drain cock is supplied in the accessories pack and should be
fi tted at the bottom on the front of the boiler to allow the boiler to
be drained.
To enable draining of the system, a suitable drain cock must be
fi tted at the lowest point of the heating system.
4.7 PREPARATION FOR INSTALLATION
1. Grant Boiler House models are supplied in two separate
cartons; one containing the boiler and the other containing
the burner and condensate drain trap. The dual thermostat
(15/26 & 26/36 & 36/46Kw models) is also included with the
burner.
The dual thermostat is factory fi tted on the 46/70 models.
The fl ow pipe and compression fi ttings are supplied with the
Vortex 26/36 & 36/46kW, the Eurofl ame has 1” BSP fl ow and
return fi ttings.
2. Carefully remove the packaging from the boiler and unpack
the carton containing the remaining items.
4.8 INSTALLING THE BOILER
1. Having decided upon the position of the boiler and type of
fl ue, prepare the wall as described in Section 9. Ensure
that the fl ue terminal position complies with the necessary
clearances.
2. Make the water connections as described in Section 5. If
access will be restricted, make any connections to the boiler
before placing it in its fi nal position. Refer to Section 7 if the
boiler is to be used on a sealed system.
! NOTE !
If using a balanced fl ue system - install the balanced fl ue
system before connecting the heating system pipework to
the boiler. Once the fl ue system is fi tted then complete the
water connections and fi ll the heating system.
3. Ensure the requirements are met for the disposal of
condensate as described in Section 6.
4. Connect the power supply as described in Section 8.
5. Connect the fl ue and ensure there is an adequate air supply
as described in Section 9.
4.9 FILLING THE HEATING SYSTEM
Refer to Section 7.2 (Filling the Sealed System)
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