Damage limitation
Andrew Murray, senior manager at Kilfrost’s speciality fl uids division examines
the impact of heat transfer fl uids on the longevity of systems and the benefi ts of
inhibited glycols
he popularity of heat pumps is
on the rise. But if sourced or used
incorrectly, heat transfer fl uid - a
key component - can have major
fi nancial implications despite
the low initial cost to the customer. This is
because the life span and reliability of any
heating system depends on the quality of the
heat transfer fl uid used.
T
Corrosion concerns
Although UK numbers of GSHP installations
are relatively small, they have been increasing.
Installations across both residential and
commercial buildings have increased from
2,000 to 21,000 per year over the period 2006-
11. It is expected that annual installations
of heat pumps will reach 49,000 per year by
2015.
Heat transfer fl uids are a vital part of the
GSHP process. Corrosion of these pumps can
lead to many problems; the most signifi cant
being damage that may result in fl uid leakage.
Corrosion within systems can also increase
the need for maintenance and expensive
repairs.
Many heat transfer fl uids are glycol-
based. Glycols themselves are not particularly
corrosive in concentrate form. However, when
they are diluted with water to achieve the
Suppliers and installers of
systems face signifi cant
reputational and fi nancial
risk if the fl uid they are
installing results in system
damage
required frost protection, system corrosion
becomes a real problem for the installer and
ultimately the end user. Bacterial growth and
scaling within the system can also become an
issue as a result of hard and/or inferior water.
So, what can be done to prevent rust within
systems and to increase their longevity?
Using a high-quality product and mixing
it with poor quality water makes little sense.
Mixing an inhibited glycol-based heat
transfer fl uid with water of a suffi cient quality
enables the system to last longer by reducing
corrosion, bacteria and scaling. This saves
both time and money for the customer by
limiting the need for maintenance and repairs.
Suppliers and installers of systems
therefore face signifi cant reputational and
fi nancial risk if the fl uid they are installing
results in system damage. An effi cient
inhibited heat transfer fl uid gives the installer
and the customer greater peace of mind.
As a result, all of Kilfrost’s Thermatrans
inhibited heat transfer fl uids are specifi cally
designed to deliver higher resistance to
degradation, scale, bacterial growth and
corrosion. They also provide freeze protection,
cleaner circuits, effi cient heat transfer
and long term cost benefi ts to system
maintenance.
Challenges due to lack of standards
As the industry recognises the challenges of
system corrosion, an international standard,
known as the ASTM D1384 corrosion test
standard is playing an increasingly important
role.
This involves immersing metals
commonly used in heat transfer systems, such
as aluminium, iron, steel and copper in an
inhibited glycol/water mixture and analysing
them in laboratory conditions for signs of
corrosion.
The test demonstrates the ability of the
Down the tube: Choosing the right heat transfer
fl uid can have enormous fi nancial implications
for heat pump systems despite its low capital
outlay, says Kilfrost
fl uid to protect suffi ciently against corrosion
and therefore gives the end user greater
confi dence. Any fl uid can claim to contain
corrosion inhibitors but without the presence
of a test standard, the extent of protection is
impossible to gauge accurately.
Despite its existence, there is still a
lack of understanding of this standard in the
industry and while it provides a valuable
indication as to the quality of the heat transfer
fl uid, it remains voluntary. There is therefore
a need for greater education on the impact of
specifying poor quality heat transfer fl uids and
the benefi ts that inhibited glycol-based fl uids
can bring to both the end user and installer.
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