5
2
Section Introduction
1. Description
The Mira Enhance single impeller centrifugal pump is designed to receive a single
gravity feed from a mixing valve and provide a pressurized supply to a fixed shower
head or shower handset. (Refer to Figures 2 and 3). The pump is not suitable for an
installation in the system layouts shown in Figures 4 and 5.
The pump is more effective when pushing water along a pipe rather than pulling. Thus
the pump is best positioned as close to the hot water or blend water source as possible
to reduce cavitation (air bubbles) in the pipes. The greater the static (inlet) water
pressure on the pump the better it will operate. Thus positioning a pump at high level
is not advantageous, and may result in inferior performance.
Due consideration should be made to the pump position as any noise generated may
be amplified by installation conditions such as reverberant panels etc. The pump motor
is air cooled and it is important that the flow of air around the motor is not impeded. The
pump should be sited in a frost free area and inlet/outlet pipework layouts which can
create significant airlocks are best avoided.
ATTENTION: Pipework on the outlet side of the pump that could be prone to airlocks
can be fitted with a float-type automatic air vent (bottle vent) at the highest point as
shown in Figure 3. This will ensure that air released in the hot water during the pumping
and heating process can be vented.
The stored hot and cold water volumes should be sufficient for the required duty.
Typical minimum flow rates are 10 l/min for a pulsating handset or overhead shower.
The manufacturer’s data for the outlet fittings should be consulted.
Thank you for purchasing a quality Mira product. To enjoy the full potential of your new
product, please take time to read this guide thoroughly, having done so, keep it safe
for future reference.
2. Operation
The pump would normally start automatically when the mixing valve is set to open. The
contacts of the flow switch at the pump outlet close when the flow rate in the outlet pipe
is more than 1.4 l/min. When this occurs the electrical circuit to the motor is completed
and the pump operates. The opposite action occurs when the mixing valve is set to
shut.
A vertical distance of 300 mm between the water discharge point through the shower
outlet and the base of the cistern would typically achieve the flow rate required.
However, long pipe runs or restrictive terminal fittings will increase the gravity head
required to produce the required flow.
