WATER TREATMENT AND
“Investing in flushing and water treatment
procedures greatly improves the efficiency
and longevity of a heating system, which are
all great benefits to shout about”
To flush or not to flush: that is
the water treatment question
Martyn Bridges, director of technical communication and product management at Worcester
Bosch, explains why water treatment is so important and how neglecting to flush out a boiler
can wreak havoc on a heating system.
While it is stated in Part L of
the Building Regulations
that installers are required
to thoroughly cleanse the
heating system connected to a new boiler,
not every installation will be flushed.
Neglecting water treatment could be
due to lack of awareness or because of cost
but, put simply, the legal requirement is
to not only flush a property’s system when
installing a new boiler, but to inhibit the
It isn’t just about the legalities though.
Investing in flushing and water treatment
procedures greatly improves the efficiency
and longevity of a heating system, which
are all great benefits to shout about when
discussing with your customers about the
importance of treatment.
Just because a system is new doesn’t make
it exempt from potential water quality
issues. For instance, research conducted
by an approved BuildCert CIAS testing
laboratory, has shown that even a new
system will show visible magnetite within
just one to two days of installation. Over
time, this can then block radiators,
reducing the heat transfer from the
system into the property, forcing the
boiler to work harder.
What’s more, refined components
and smaller water passages mean that
it does not take a great amount of
sediment from an unclean heating
system to clog up or restrict the
waterways in a modern condensing
As a result, the importance of
performing a full system cleanse to keep
an appliance running as efficiently as
possible shouldn’t be underestimated.
It is also worth bearing in mind that
many new boilers are installed within
existing heating systems which were
previously open vent.
An open vent system with an open feed
and expansion arrangement is more likely
to allow oxygen ingress than a sealed
primary system. Therefore, in cases where
a system is being or has been changed
from an open vented system to a combi
boiler, it is likely that there will be more
contamination to deal with.
DEALING WITH DEBRIS
As a general guide to cleanse a dirty
system, installers can either use a power
flush until the contamination has been
removed or, if it’s a lightly contaminated
system, a gravity flush may suffice.
When power flushing, the system should
be flushed at least once prior to cleansing,
without turning on the boiler, in order to
remove any loose debris.
Afterwards, a cleansing agent should be
added and circulated within the system at
the normal operating temperature. The
longer the agent is left to work, the more
beneficial the cleaning process.
This is especially the case if sludge
deposits are present, so in this instance
a 48-hour cleansing process should be
considered. It is important to then drain
the system a few times to thoroughly
ensure that no agent remains.
Once a flush has been completed,
adding a corrosion inhibitor in
accordance with BS7593 will complete the
A corrosion inhibitor essentially
prevents the hard work you have already
done to cleanse the system from going to
waste by preventing the formation of scale,
corrosion and microbiological growths.
A FILTER BIT MORE?
For even more protection, specifying
a system filter provides a long-lasting
solution to preventing contaminants
forming in a system.
Worcester’s Greenstar System Filter, for
example, contains a powerful internal
magnet to capture debris often found
within dirty system water such as iron
oxide and magnetite. Meanwhile, a
separate internal mechanism harnesses
non-magnetic contaminant such as flux
Ultimately, what is a relatively low-cost
accessory, can have a huge impact
on the boiler’s lifespan. If this wasn’t
enough, the Greenstar System Filter
could also help to save up to six per
cent on household heating bills – so it is
really worth talking to your customers
about the long-term benefits of
investing in protecting the system.
Worcester is dedicated to providing
a robust training programme, which
includes a dedicated water treatment
We’d urge as many installers as
possible to consider taking this course
so that they can be confident in
recommending the best water treatment
ENQUIRY NUMBER 109
Water treatment is so important to the overall performance of
the boiler with the benefits to the quality of water clear for any
homeowner to see
42 Heating & Plumbing Monthly | JUNE 2018 | www.hpmmag.com