10
EVOMAX
-
Installation & Servicing
GENERAL
WATER CIRCULATION SYSTEM
The system pump MUST be connected to the boiler, see below.
The boiler must NOT be used for direct hot water supply. The hot
water storage cylinder MUST be of the indirect type.
Single feed, indirect cylinders are not recommended and MUST
NOT be used on sealed systems.
The appliances are NOT suitable for gravity central heating nor
are they suitable for the provision of gravity domestic hot water.
The hot water cylinder and ancillary pipework, not forming part of
the useful heating surface, should be lagged to prevent heat loss
and any possible freezing - particularly where pipes run through
roof spaces and ventilated underfloor spaces.
The boiler must be vented.
Draining taps MUST be located in accessible positions, which
permit the draining of the whole system - including the boiler
and hot water storage vessel. They should be at least 1/2” BSP
nominal size and be in accordance with BS. 2879.
The central heating system should be in accordance with the
relevant standards listed on page 8.
Due to the compact nature of the boiler the heat stored within the
castings at the point of shutdown of the burner must be dissipated
into the water circuit in order to avoid overheating. In order to
allow pump operation after burner shutdown the boiler control box
incorporates a 4 minute pump overrun facility. In order to make use
of this, the pump must be supplied from the terminals inside the
boiler. Note: for pumps requiring a current greater than 1.3 amps
inductive, they must be connected via a relay.
When sizing pumps, reference should be made to the table below
which show the boiler resistance against flow rates, to achieve the
required temperature differential.
Flow rates for common systems using either 11ºC, 15ºC or 20ºC
temperature differentials and hydraulic resistances are given in
the table below.
Flowrate (l/min)
Hydraulic Resist
-
ance (mbar)
11ºC 15ºC 20ºC 11ºC 15ºC 20ºC
Evomax 30/30P
39.1
28.7
21.5
425
225
127
Evomax 40/40P
52.1
38.2
28.7
875
405
225
Evomax 60/60P
78.2
57.3
43.0
435
180
83
Evomax 80/80P 104.2 76.4
57.3
750
420
180
Evomax 100
*
95.6
71.7
*
315
134
Evomax 120
*
*
86.0
*
*
218
Evomax 150
*
*
107.5
*
*
230
* Not recommended due to excessive flowrates which may cause
erosion of the casting.
Note
.
• With the boiler firing at maximum rate, the temperature
differential should not be less than figures quoted in table
above. High flow rates required for lower temperature
differentials could lead to errosion of the heat exchanger water
ways.
• With the boiler firing at minimum rate, the temperature
differential should not be greater than 35
o
C. Lower flow rates
generating higher temperature differentials will lead to lock out
of the boiler.
• The lower the return temperature to the boiler, the higher the
efficiency.
In installations where all radiators have been provided with
thermostatic radiator valves, it is essential that water circulation
through the boiler is guaranteed. This can be best achieved
by means of a differential pressure valve, which is installed in a
bypass between the flow and return pipes. The bypass should
be fitted at least 6m from the boiler, and should use a minimum
size of 28mm pipe. The bypass should be capable of allowing
a minimum flow rate to achieve a temperature differential of no
greater than 35
o
C at minimum rate.