Baxi Geoflo, Operation, Installation & Maintenance Instructions

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© Baxi Heating UK Ltd 2006
Purge Pumps
It is possible that difficulty may be experienced removing air out
of the ground arrays, especially out of the top of each of the
“Slinky®” loops which consist of a large number of 1 metre
diameter loops of 1” bore pipe. This can also occur with vertical
(ie. drilled) arrays. All procedures for removing air from
slinkies® applies equally to removing air from underfloor
heating systems. Most underfloor heating manifolds have
fill/purge connections, and the same pump and procedure can
be used for underfloor as for slinkies®.
Why not just use mains water ?
A normal rising cold water main in a building has insufficient
flow to force out this air - typical flow rates from a cold tap are
around 10 to 30 litres per minute, which is less than half that
required. Also mains water is “aerated”.
Why can’t I use an existing pump that I have ?
To remove the air from Slinky® ground arrays, a suitable pump
will be required. The longest slinky® trench is 50 metres, which
will contain a total of about 300 metres of pipe. To achieve the
minimum velocity through the slinky® pipes to remove the air,
a minimum pump power in excess of 1 kW is required. If you
are considering using an existing pump and it does not absorb
at least 1 kW then it will not be suitable. In addition, the pump
needs to have high-flow (at least 60 litres per minute) against a
pressure of at least 1 bar. To achieve this, a “multi-stage” type
of pump is needed, which is different to “normal” types of
water pump.
Where can I get hold of a suitable purge pump ?
We recommend the Clarke CPE130SS, part no. 051010379
from www.machinemart.co.uk or telephone 0845 450 2855.
The pump comes ready to take a 1” BSP fitting. A plumbers
merchant can supply a 2 x 1” BSP male iron to 28 mm
compression. This will enable the pump to be connected to the
slinky® manifold using 28 mm “Speedfit” or similar pipe and
elbows.
Any other tips ?
Before it will work, the pump itself needs to be purged of air by
removing the fill plug, and filling with water, along with both
connecting pipes. Fill the ground arrays with water as far as
possible, and pressurise them with mains water using the cold-
feed on the heat pump. Opening the valve between the slinky®
manifold and the water pump will force water through the
pump, into the dustbin, purging air out of the pump on the way.
It usually takes around 2 to 3 minutes of pumping for water to
go all the way through one slinky® and back to the dustbin. As
the Clarke CPE130SS will achieve up to 5 bar pressure against a
closed valve it is essential that the connections to the pump and
manifold are robust.
Clarke CPE130SS
Purge Pump