over night, we would not have any undue concerns,
as long as it was carefully flushed out and Neutralising
Crystals circulated through the system as is usual after
using PowerFlush FX2.
Q. Do I really need to carry out the neutralising step
after using PowerFlush FX2?
A. PowerFlush FX2 is based on phosphoric and citric
acids. It is the low pH that gives it its “bite”, but of course
it is necessary to ensure that the system water is back
to pH 7 before completing the power flush, hence the
neutralising step.
The PowerFlush FX2 formulation does include specific
organic corrosion inhibitors that protect the metals of
the heating system from attack during the Powerflush.
However, if FX2 is left in the system, then with time and
temperature these particular types of inhibitor break
down. Without their protection, there would be some
corrosion in the system. The likelihood is then that some
while later the householder will call you and complain
that they have to repeatedly bleed the radiators.
When engineers force debris and flushing chemicals
out with the fresh water flow, they often believe that
they have got all the acidic residue out – and they
MIGHT be right – and the pH of a sample could be 7.
The neutralising step (use of Neutralising Crystals) is a
precaution in case there is a small amount of the FX2 still
present in a nook or dead end pipe in the system.
However, to get the maximum amount of debris out of a
system, then PowerFlush FX2 is the way to go.
Q. What’s the best chemical to use to flush a very old
(30 years) heating system?
A. If you do decide to power flush a very old system, then
it’s important to carry out a survey beforehand - and you
might change your mind subsequently!
We suggest Hyper-Flush for this application (and not
PowerFlush FX2), because Hyper-Flush is a pH neutral
product and is therefore less likely to be problematic
than more aggressive chemicals. However, a 30 year old
system has seen a lot of action, and we would suggest
that the system be monitored carefully (= watched!)
during the flush, whatever chemical you use. After 30
years there are probably radiators on the verge of failure,
with only a veneer of debris preventing leakage from
deep pits in corroded areas, and so your watchword is
caution.
Q. How often should I check the corrosion inhibitor
level, and how do I do it?
A. Whilst annual checking of inhibitor level is an excellent
idea, actually doing this presents a problem to all heating
engineers – you have to know what brand inhibitor is IN
the system.
There is currently no test kit that will test
for the presence of all inhibitors. The only
safe thing is to drain down and start again if
the brand inhibitor in a system is unknown.
Kamco supply a test kit for SystemSafe-DM
inhibitors, but it is important to note that
this test kit will only give the correct answer when used
on a system containing Systemsafe DM.
The test is used to check the level of
molybdate in the treated water,. When
Systemsafe is dosed at the ideal rate
(impossible to guarantee in a real system of
unknown volume of course), the optimum
level is 100 parts per million for Systemsafe-DM.
Other manufacturers’ inhibitors may not use as much
molybdate.
There are many different formulations, as most good
and proven inhibitors will be a blend of up to a dozen
components – some other inhibitors are often very
basic, and very dilute - but they wouldn’t pass the NSF/
Buildcert inhibitor standard as Systemsafe DM does.
It is important that the adhesive sticker supplied with
the inhibitor is left attached to the system / boiler so
that you know what inhibitor is in the system - and when
it was added.
Q. Is it OK to mix inhibitors?
A. It’s unlikely that mixing two inhibitors will do any
harm, however most inhibitors are NOT all the same, as
many people think. They are complex blends chosen for
the abilities of individual components, but it’s probably
true to say some elements will be common.
There’s a good chance that mixing two inhibitors will
provide some degree of protection, but the ideal
situation would be to drain down and only use one
inhibitor in your system (a Buildcert approved one), to
keep a system clean and long lasting.
Q. I often work on solid fuel fired boilers, which run at
a higher temperature. Do I need to use a higher dosage
rate of Systemsafe-DM?
A. No, Systemsafe-DM is also used on commercial
systems operating at higher temperatures and it
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