Technical information

18. Hydraulic Requirements

The boilers are intended to be used in
conjunction with FULLY PUMPED, SEALED
systems subject to the requirements below.
They are NOT SUITABLE for use on gravity
circulation systems. The boiler must NOT
be used for direct hot water supply.
Underfloor Systems

Despite the low boiler flow
temperatures feature, in the event of control
and/or mechanical failure or incorrect
adjustment, to prevent damage to the
installation or associated pipe work ALL low
temperature under floor installations require
an obligatory mixing valve installing as part
of the system controls or a high limit
thermostat set at 60
o
C to interrupt the
demand for heat signal from the underfloor
heating controls.
EC25S Combi Types
In hard water areas suitable protection
should be provided to prevent the build up
of deposits in the primary hot water heat
exchanger. The appliance guarantee does
not extend to failure as a result of lime scale
or other contamination.
The central heating system should be in
accordance with the recommendations
given in BS. 6798 and BS. 5449.

Hot water cylinders must be double
feed indirect and to aid efficiency and fast
recovery times (all appliances are hot water
priority) should be of the high recovery type.
Recommended minimum coil capacity
25kW.
The boiler must be capable of being
adequately vented of air. Drain taps MUST
be located in accessible positions, which
permit the draining of the whole system -
including the boiler and hot water storage
vessel. Drain taps should be at least 1/2
inch BSP nominal size and be in
accordance with BS. 2879.
In

order to facilitate servicing of the
unit, full flow isolating valves must be fitted
to all water and gas connections, (these
valves can be supplied by eco hometec as
an optional extra if required).
18.1 Expansion Vessel
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An expansion vessel must be
fitted to all systems.
Table 13 Expansion Vessel Req.
*Vessel Charge & Initial System Pressure
*VC&ISP 0.5 bar 1.0 bar 1.5 bar
Factor 0.08 bar 0.11 bar 0.16 bar
EXAMPLE 1.
Central heating system filled to 1 bar.
Total system water content 60 litres
Multiply 60 (water content litres) x 0.11
(factor from chart) = 6.6 litres.
Vessel required 6.6 litres.
Vessel supplied 10 litres.
Vessel adequate.
EXAMPLE 2.
Central heating system filled to 1 bar.
Total system water content 150 litres
Multiply 150 (water content litres) x 0.11
(factor from chart) = 16.5 litres.
Vessel required 16.5 litres.
Vessel supplied 10 litres.
Vessel inadequate.
Additional vessel 6.5 litres required.
When system content unknown or difficult to
determine the following table can assist with
calculating water content.
Table 14 System Contents
Approx. Litres per kW
New Radiators 9
Old Radiators 13
U/Floor
Heating
22
Expansion vessels should be connected to
the system at a point close to the pump inlet
in order to maintain positive pressure
throughout the system.
Page 30
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(
UK
)
LTD
.