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General Description.
The ‘EP’ range of units are designed to pressurise sealed heating or chilled water systems, making
up for losses due to leakage, etc.
The units comprise a small mains break tank incorporating type ‘A’ air gap, supplied with water via a
ball valve, together with one (EP 1) or two (EP 2) regenerative type pressure pumps, all enclosed in a
purpose built sheet steel enclosure.
The control of the system is by the use of a close differential pressure switch, with a small pre-
charged pressure vessel and a flow-regulating valve.
As the pressure in the system falls below the preset fill pressure, the pressure switch will enabled
duty pump.
The pump will then deliver water to the system, via the flow-regulating valve, thereby raising the
pressure until the cut-out pressure is reached the pump will stop.
The duty pump will auto-rotate per operation in an attempt to achieve even wear on the pumps.
Should the duty pump fail to produce pressure, the standby pump (EP 2 units) will start as the
pressure falls further.
If the pressure, within the system, goes beyond preset design limits, then the system pressure alarm
switches will become activated, illuminating the ‘High Pressure’ or ‘Low Pressure’ lamp on the unit,
and operating a volt free contact (which is usually connected to shut down the burner / chiller).
EP units are available in an enhanced level, if required, incorporating additional control features and
alarms.
Expansion Vessels, which do not form part of the ‘EP’ units, are supplied either individually, or as
part of a complete packaged unit.
They are designed to accept the expanded water from the system, either as the system temperature
rises, in the case of a heating system, or as the system returns to ambient temperature after chilling,
in case of a chilled water system.
This water is held within the vessel, until the system pressure drops, when the expanded water is
forced back into the system by gas pre-charge.
The pressure vessel incorporates a flexible internal diaphragm, which prevents contact between the
gas and water, thus eliminating the need for frequent recharging.
