Product specifications

7.6.Connecting the central heating circuit.
The 22mm diameter connections for the central
heating circuit flow and return pipes are located on
the underside of the appliance. (Fig 14). The flow
pipe (A) is colour coded red and the return pipe (B)
is colour coded blue.
Figure 14: Boiler flow & return connections.
Locate and fit the separately supplied automatic air
vent to the boiler's top right corner (Fig 15). Once
fitted, loosen the automatic air vent's cover cap.
Figure 15: Automatic air vent
Before connection to the central heating system, the
system must be thoroughly flushed in accordance
with the guidance given in BS7593.
The system must comply with the requirements of
BS5449, and to avoid corrosion and leaks, be
airtight, closed and connected in accordance with
Benchmark procedure.
When connecting the boiler to a heating system
containing plastic pipework the following must be
noted:-
Important Note!
Th
e Atmos Multi is suitable for use on a
sealed heating system only. It must not be
connected to an open vented heating system.

In a floor heating system, the plastic
hoses/pipes used must either meet BS7291 having a
class 'S' rating or DIN 4726/4729 having an air
permeability less than 0·1 g/m³ at 40ºC.

In a radiator system, the plastic hoses/pipes
used must either meet BS7291 having a class 'S'
rating or DIN 4726/4729 having an air permeability
less than 0·1 g/m³ at 85ºC in a twenty four hour
period.
Connection of the Atmos Multi to a heating system
containing non-diffusion barrier oxygen permeable
plastic pipe or class 'H' plastic pipe will invalidate
the boilers guarantee.
It is important that there is a by-pass on the central
heating circuit to ensure that the system water is
able to flow through the boiler's heat exchanger at
all times. This may be achieved by leaving at least
one radiator permanently open. Alternatively, a
pressure differential regulator valve (Fig16) that
provides an automatic system bypass is available
from Atmos Heating Systems.
Figure 16: Pressure differential regulator valve
Note: Set the pressure differential regulator valve
(supplied by Atmos) to 0.2
For the optional Pre-Assembled Pipework kit, the
bypass is included and should be set to 0.1
ATMOS MULTI Mk 2 version 2008
Page 22