Domestic Hot Water - 50 Litre Tank - Potterton Puma Flowsure+ Installation & Service Instructions Manual

Installation Requirements - Page 11
HOW TO USE FIG. 6.
Starting with the required SYSTEM HEATING LOAD, draw a
vertical line downwards so that it intersects the chosen
SYSTEM DESIGN TEMPERATURE DROP line, normally this
would be 11°C (20°F) although up to 17°C (30°F) can be used
without increasing radiator sizes. From this intersection point
draw a horizontal line so that it intersects the PUMP CURVE.
From this intersection draw a vertical line upwards.
The AVAILABLE PUMP HEAD can now be read from the
horizontal scale, and the corresponding FLOW RATE from the
vertical scale in the centre of the chart.
The system must be designed so that its hydraulic resistance
does not exceed the available head unless an additional
circulating pump is fitted. More available head can be
achieved by choosing a greater temperature difference.
If the designed flow rate through the boiler is less than 11.5
l/min, the boiler could be noisy and ultimately overheat. See
note on system by-pass in Section 1.5.
Central Heating Range Rate.
For most installations the boiler will automatically adjust the
central heating output to match your heating system
requirement.
Systems which have very low water content and a low heating
requirement may benefit by reducing the maximum boiler
output. This is achieved by rotation of the range rate
Part No. 27/20334
adjuster, located on the electronic modulation control board
(see Fig. 26).
The boiler central heating output can be adjusted between the
maximum and minimum values stated on the data badge.
Operation of this adjuster will not affect the maximum boiler
output when domestic hot water is being drawn off.

1.10 Domestic Hot Water - 50 Litre Tank

The 50 litre tank is a secondary store which is designed to be
kept heated to meet instantaneous hot water demands that
require intermittently higher flow rates.
At a flow rate of approximately 12 litres/min, hot water will be
delivered for around 4 minutes at a 50°C rise reducing
thereafter. The tank will fully recover after a few minutes to
again deliver 12 litres/min at a 50°C rise.
Domestic hot water always takes priority over central heating.
If domestic hot water is drawn off while the central heating is
operating the boiler will automatically transfer the boiler output
to the domestic hot water supply.
A secondary water expansion vessel is supplied with the tank
and must be connected to the appropriate tapping on the
controls assembly.
Installation Requirements 11