Kamco CF30 User manual

The Power Flushing
Knowledge Base
Frequently asked questions,
and their answers

Adding corrosion inhibitor Page 15
Aluminium heat exchangers-FX2 Page 6
Articially softened water Page 16
Best chemical for old systems Page 7
Bleeding radiators after a ush Page 14
Blocked cold feed pipe-check? Page 6
Blocked radiator & piping tips Page 14
Boiler noises Page 4
Checking system water is clean Page 15
Clearow tank overowing? Page 13
Cold feed & expansion tank Page 3
Combi boiler won’t re Page 8
CombiMag Dual power ush heater Page 8
Corrosion inhibitor-level checking Page 7
Damaging a heating system?? Page 17
Deposit inside copper pipe? Page 6
Discharging very hot water Page 9
Double panel radiators Page 4
Expansion vessel Page 3
Extension hoses Page 5
Filling loop, do not use Page 16
Firing the boiler during a power ush Page 7
Flushing radiators after removal Page 5
Gas Safe Registration Page 3
Gravity hot water systems Page 10
Guaranteed cleanliness? Page 17
How long does a power ush take? Page 3
How long will a power ush last? Page 17
Imperial size pipework Page 5
Individual radiator dumping Page 14
Individual radiator ushing Page 14
Inhibitor used with soft water Page 16
Location of ushing pump Page 5
Microbore systems Page 9/10
Mixing different inhibitors Page 7
No ow in one direction Page 13
Over pressurising a system? Page 6
Plastic piping, barrier type Page 11
Plastic piping, non-barrier Page 11
Poor mains water ow rate Page 14
PowerFlush FX2-leaving in system? Page 6
PowerFlush FX2-Neutralising Page 6
Primatic single feed cylinders Page 10
Push t connections Page 5
RadHammer vibrator Page 4
Radiators staying cool at top Page 13
Radiators staying hot at the top Page 13
Reducing time for a power ush Page 15
Septic tanks & power ushing Page 12
Servicing Kamco pumps Page 16
Single pipe systems Page 10
Systems to avoid ushing Page 11
Temperature limitation Page 9
Thermal store cylinders Page 5
Thermostatic radiator valves Page 6
Things NOT to do Page 15
Underoor heating Page 11
Underoor heating, bacterial growth Page 11
Vibrating radiators Page 4
Volume of a heating system Page 4
INDEX

General questions; planning, and ‘before you
start’.
Q. How long does it take to power ush a system
thoroughly?
A. It will vary from house to house, but generally about
5+ hours for a three bed house with a vented system,
but less me for a sealed / combinaon boiler system,
because you don’t have to cap o the cold feed and
expansion piping.
You can save more me by using a CP2 pump head
adaptor to get connected faster, and also by ltering the
water as you go with a CombiMag power ush lter.
Q. How big a heang system can you use a Clearow
pump on?
A. Obviously this will depend on what model Clearow
you have. If you have a CF30 Classic, then you can tackle
systems up to 20 radiators with the right technique.
Follow the normal procedures for systems up to 12
radiators, but tackle larger systems in secons. For
example, with a twenty radiator system, close o ten
radiators totally, and ush the rest of the house normally.
Once done, close down all the ushed radiators, and
repeat the procedure on the rest of the system.
The CF40 Evoluon has a signicantly higher ow rate,
and so up to 25 radiators is a reasonable prospect, and
larger if you secon the system.
If you regularly work on larger systems, you’ll really
appreciate the extra performance of a CF90 Quantum2,
which will get more debris from any given system (even a
small microbore one!)
Q. Do you need to drain down the system before you
start?
A. No. You only need to run some water out of a
vented system to lower the water level in the feed and
expansion tank, so that you can cap it o.
Q. Can you power ush a sealed system?
A. You certainly can - in fact you can ONLY power ush a
sealed system. Why do we say that? because any system
that you power ush must be sealed (even if that is for
the duraon of the power ush only in the case of a
vented system).
That is why you must ‘cap o’ the cold feed and
expansion pipes of systems that AREN’T already sealed,
to prevent the high ow of water of a good power
ushing pump from forcing water up into the f&e tank
and overwhelming the tank overow. Naturally you
remove the temporary caps aer you’ve ushed the
system.
Obviously you don’t have a vent or cold feed pipe to cap
o with a sealed system, and so the power ush won’t
take so long. When you break into the sealed system
wherever you have chosen to connect your power
ushing pump, you’ll lose the normal system operang
pressure, and will have to re-pressurise the system with
the lling loop aer you’ve nished the ush.
Q. If I power ush a sealed system, which has a
pressure/expansion vessel, do I need to take any special
precauons or disconnect it?
A. No, not if you are using Kamco ushing chemicals.
They will not cause any problems with the diaphragm of
an expansion vessel.
Q. Do you need to be Gas Safe registered to power ush
heang systems?
A. You don’t have to be Gas Safe registered to power
ush a heang system. As long as you are NOT working
on the gas train, then you don’t need approval, BUT be
Frequently asked quesons about the use of Clearow power ushing pumps
Page 3

careful if you use the CP2 adapter on some combinaon
boilers.
Obviously you have to take the boiler case o to t the
CP2 adapter on to the pump body located within the
boiler casing. If the boiler case is ‘sealed’, i.e. it is part of
the combuson air inlet system, then you do need to be
Gas Safe registered ##.
If the case is only decorave, then you don’t.
## In this case, and you are not Gas Safe registered,
you’d probably connect the Clearow pump across the
tails of one radiator, aer having rst removed it.
Q. How do I know how much water is in a system,
parcularly larger ones, so that I can add the correct
amount of ushing chemical?
A. It’s always tricky to esmate the amount of water in a
larger system (and no-one ever can tell you from exisng
records), and so the industry ‘rule of thumb’ guide is to
mulply the boiler output, expressed in kW, by 12, and
that gives an approximate gure, in litres.
For smaller systems, then assume that 10 radiators (or
radiator panels) is close to 100 litres. More modern
systems frequently contain less water, but it’s always
beer to add too much chemical than too lile.
Q. Will power ushing cure boiler noises?
A. Boiler noises are oen caused by scale or debris
accumulang on heat transfer surfaces, thus prevenng
the water from carrying away heat from the metal
surface. This means that the metal runs hoer than
design temperature and may even exceed 100 degrees C.
The layer of scale / debris is never even, and there will
be areas where the water contacts metal above 100
degrees. At this temperature water ashes into steam,
increasing its volume by almost 1500 mes. The steam
bubbles then move away from the high temperature
zone and collapse and it is the sound of the implosion
of the steam bubble that you hear. This phenomenon
is most likely to occur when the boiler rst res and is
working hard.
It is a reasonable assumpon that if you can remove the
debris / scale (and you usually can when power ushing)
that you will remove the problem.
Having said that, we know that boilers with cast iron
heat exchangers can acquire corrosion pits as they age,
generally if the water treatment has been inadequate. In
these areas, where the heat exchanger metal is reduced
in thickness, the heat ux can be higher than the
designer intended, and there can sll be boiler noises no
maer how clean the heat transfer surface may be aer
a power ush.
Q. What about double panel radiators - won’t the
water take the course of least resistance and just clear
one panel?
A. Yes, it will. However, whilst carrying out the individual
radiator ush, gently tap the front panel with a rubber
mallet, where the brackets aach to the rear panel.
There will always be at least four points of connecon, at
the ends, top and boom. This vibrates debris loose with
surprisingly good eect.
An even beer method
is to use a Radhammer
vibrator device, also
supplied by Kamco. This
device clicks into the
chuck of an SDS drill
which has been set to
‘hammer only’. The high frequency vibraon will loosen
debris that will not respond to other cleansing methods.
Q. Is it a good idea to tap radiators whilst carrying out a
power ush?
A. Yes. Many engineers tap every radiator along
the lower edge with a mallet as they open it up for
the individual radiator ush, to vibrate loose any
compacted sludge trapped in the boom seam. The
Kamco RadHammer is even more eecve, and a brief
applicaon of the RadHammer aer you have what is
apparently already got clear water running through a
radiator can give surprising results!
Page 4

Q. Can I use a radiator valve change kit (= tapered
rubber bung kit), used when changing radiators, to
make the system a closed circuit for the power ush?
A. No. The tapered bung inserted in the cold feed pipe
will be forced out, and the expansion tank will ll up and
overow.
Q. Can I use plasc or metal push t caps, such as
“Speedt” ngs, to make the system a closed circuit?
A. Yes, but check the push t cap ‘O’ ring for wear
regularly, and replace it if in doubt.
Q. What do I do if the expansion pipe on an old system
is imperial size copper piping?
A. Why not extend the pipe slightly, using a compression
ng with a special imperial size olive, enabling you to
add a short length of metric piping? Then use a push t
end cap as usual.
Q. If I connect my Clearow pump into the system
across the tails of one (removed) radiator, what
happens to that radiator? How should I clean it?
A. You’ll need to ush this separately with a hose pipe
(so pick a small radiator!).
Alternavely, some engineers will adapt the outer end
of their dump hose to t onto one side of this removed
radiator, with another adapted tube leading from the
other side of the radiator to the drain.
This way, every me you dump, you’re pung a good
ow of water through the radiator. By the me you’ve
nished the power ush, the radiator should be very
clean.
Q. I want to keep my pump outside the house. Can I use
extension hoses?
A. Yes you can, and we can supply any length extensions
that you may wish, but we oen supply an extra set of 5
metre ow and return hoses, and send them out with a
3/4” - 3/4” male nipple in one end of each hose.
This means that when you need to extend ow and
return hoses, you simply couple the new extension
hoses onto your exisng ow and return hoses, and if
you somemes need a longer dump hose, rather than
longer ow and return hoses, the 2 x 5 metre lengths can
be coupled together and added on to the exisng dump
hose. This gives exibility without the need for a van full
of hose.
Cauon: longer hoses mean greater friconal losses, and
so we suggest a maximum overall length of 12 metres
per hose.
Q. Can you power ush a heang system with a thermal
store type cylinder?
A. Yes. Our advice is to isolate the thermal store cylinder
and ush the radiator and boiler circuits separately.
There are two reasons for this:
1. One cylinder manufacturer (Gledhill, though others
may take a dierent view), advises that their cylinders
shouldn’t be connected on the posive side of a pump
that may provide more than one bar pressure.
Although that level of pressure on the cylinder is unlikely
to be present anyway, we advise a cauous approach.
2. If you do include the thermal store in the power
ushing circuit, then instead of pumping approximately
100 or less litres of water around, you’ll be pumping
around almost three mes that, and so the vital overall
ow rate will be much less than half – so not a good idea
Page 5

if you want to clean a heang system.
3. Another way to power ush a heang system with a
thermal store, again without including the cylinder and
contents in the power ush, is to loop the cylinder out,
so that the power ush pump is only connected in once,
and the boiler and radiator circuits are ushed just as for
a more convenonal heang system.
See the following diagram for how to do this:
Things that might concern you
Q. Can you over pressurise a system, causing joints to
leak?
A. No. All Kamco Clearow pumps are centrifugal type
pumps. What water they can’t push through a system
will simply re-circulate in the tank. Maximum pressure
is less than two bars. It is the ow rate through a system
that is important when power ushing.
Q. Any problems with thermostac valves (TRVs)?
A. Generally, no, even with older TRV’s which should
only be ed on the water inlet side of a radiator. Some
thermostac valves may sck down, or act as non return
valves, so set them on ‘MAX’, and remove the valve
heads. Push down on the sprung pin a few mes to
ensure that valve is fully open.
Things to check before you start
Q. The locaon where the cold feed and expansion
pipes join a vented system is oen a problem area with
a lot of compacted debris. Can you tell if the cold feed
pipe is blocked, without cung into the pipe work?
A. Not conclusively, but try holding a small magnet
against the outside of the copper pipe.
Copper isn’t magnec, and so if you feel the magnet
being pulled onto the pipe, that tells you that there’s a
lot of magnec iron oxide based debris in there. If it’s
completely blocked you will
have to cut the pipe work
secon out. Start cung!
Q. Is there is another way to check if a cold feed pipe is
blocked?
A. When starng to set up for a power ush, you’ll
normally cap o the cold feed and expansion pipes
before anything else. Don’t!
Just cap the expansion pipe only and leave the cold feed
‘open’. Now get your power ushing pump connected in
downstairs, with the isolang valves closed (as is normal
unl you are ready to start the power ush). Open the
isolang valves without switching the pump on.
Because the pump isn’t running, theorecally, water
should start draining from the system into your pump
tank, under gravity.
If that doesn’t happen, the reason will be a blocked cold
feed pipe. Cut it out!
Chemicals to use
Q. Can I use Powerush FX2 liquid on a system with
aluminium radiators, or an aluminium heat exchanger
such as found on condensing boilers?
A. No. We recommend that systems which include
aluminium are treated with HYPER-FLUSH, ideally several
days beforehand. You could then power ush the system
with water alone, but for the best result we recommend
that you use another pack of Hyper-Flush Concentrate as
you carry out the power ush.
Q. Why can’t I leave PowerFlush FX2 in a system, or pre-
treat a system with FX2?
A. We advise against leaving PowerFlush FX2 in
systems for a period of me BECAUSE it is a very
powerful ushing chemical. A contribung factor to its
performance is that it has a low pH, i.e. it is acidic.
It does contain special inhibitors in the formulaon to
prevent corrosion of the system during the power ush,
and these inhibitors are very eecve.
However, if you le PowerFlush FX2 in a system for
too long, then these special organic inhibitors would
gradually break down, and become less eecve, and
some corrosion could take place.
This is not a problem during the course of a power ush,
and if FX2 were le in a reasonably sound heang system
Page 6

over night, we would not have any undue concerns,
as long as it was carefully ushed out and Neutralising
Crystals circulated through the system as is usual aer
using PowerFlush FX2.
Q. Do I really need to carry out the neutralising step
aer 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 compleng the power ush, hence the
neutralising step.
The PowerFlush FX2 formulaon does include specic
organic corrosion inhibitors that protect the metals of
the heang system from aack during the Powerush.
However, if FX2 is le in the system, then with me and
temperature these parcular types of inhibitor break
down. Without their protecon, 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 ushing chemicals
out with the fresh water ow, they oen 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
precauon in case there is a small amount of the FX2 sll
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 ush a very old
(30 years) heang system?
A. If you do decide to power ush 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 applicaon (and not
PowerFlush FX2), because Hyper-Flush is a pH neutral
product and is therefore less likely to be problemac
than more aggressive chemicals. However, a 30 year old
system has seen a lot of acon, and we would suggest
that the system be monitored carefully (= watched!)
during the ush, whatever chemical you use. Aer 30
years there are probably radiators on the verge of failure,
with only a veneer of debris prevenng leakage from
deep pits in corroded areas, and so your watchword is
cauon.
Q. How oen 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 heang
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 opmum
level is 100 parts per million for Systemsafe-DM.
Other manufacturers’ inhibitors may not use as much
molybdate.
There are many dierent formulaons, as most good
and proven inhibitors will be a blend of up to a dozen
components – some other inhibitors are oen 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 scker supplied with
the inhibitor is le aached 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 abilies 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 protecon, but the ideal
situaon would be to drain down and only use one
inhibitor in your system (a Buildcert approved one), to
keep a system clean and long lasng.
Q. I oen work on solid fuel red 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 operang at higher temperatures and it
Page 7

performs well at the normal 0.5% dosage rate.
Firing the boiler during a power ush
Q. What about ring the boiler whilst carrying out a
power ush?
A. By all means re the boiler if you can – most chemical
reacons will proceed faster with some heat, and
also, when you come to put the full ow through each
radiator in turn, it’s useful to be able to feel whether
the radiators are heang up across the whole area, or
whether they have cold areas / panels. If they do, then
you can give that radiator extra aenon.
A CLEARFLOW pump will handle water temperatures
above 70oC. We suggest ring the boiler for up to een
minutes, but there’s no need to leave the boiler ring
connuously.
If you do re the boiler, remember that when you switch
it o, the heat exchanger is sll very hot, and connues
transferring heat to the water circulang through it, and
to the Clearow pump. If you can’t keep your hand on
the pump tank, switch the boiler o.
If the boiler is non funconal, or being replaced, then
you won’t be able to re it anyway. If you’re using a
powerful chemical such as Powerush FX2, you’ll sll get
a good result even if you can’t re the
boiler.
The alternave is to use a Kamco
CombiMag Dual Digital combined
power ushing magnet and heater,
with a 3kW electric heater. This is
inserted in one of the ow or return
hoses.
Q. I have a combinaon boiler system to power ush
but the boiler won’t re - what can I do?
A. Persuading a combinaon boiler to re can be dicult
because the low pressure limit switch senses a lack of
pressure, and prevents the boiler from ring.
1. Remember that when your power ushing pump is
connected into the heang, the maximum pressure you
will nd is at the output of the pump impellor, or in more
praccal terms, where your inlet hose connects into the
system. From that point on the pressure is falling away
throughout the system unl the point where the return
hoses drops the water back into your power ushing
pump tank, where the pressure is again zero.
If you’re using a Kamco CP2 adapter to get connected
into the heang system, your power ushing pump will
be close to the boiler. Consequently if you set the ow
reverser handle so that the water ow is immediately
into the boiler rather than heading out into the radiator
circuit, you’ll be pung 1 bar+ pressure into the boiler
and a combinaon boiler should re up.
If you’re not sure of the ow direcon, just try with the
ow reverser lever in either direcon.
Note: the current Kamco CF40 Evoluon and CF90
Quantum were ‘tweaked’ when we designed them to
give extra pressure to help in this situaon.
2. If the above doesn’t work, try parally closing the
Clearow valve on the return side of your pump. By
reducing the cross seconal area, you will automacally
increase the pressure. Flow rate will be decreased, and
so only leave the valve parally closed whilst ring the
boiler. Once you have the water warm, shut o the boiler
and fully open the Clearow valve for the normal high
ow rate needed for eecve power ushing.
3. Here’s another suggeson.
If you’re ushing a combinaon boiler system that has
been in use for a while (not a new boiler), and you have
connected your power ushing pump into the system
across the copper tails of a radiator, this should work.
You could make up a temporary valved manifold and
loop out the power ushing pump by closing the two
valves in the ow and return hoses and opening the
valve in the bypass between the hoses.
You now have a temporarily completely closed circuit,
and so re-pressurise this the normal way, and then re
up the boiler unl you have the system water good and
hot. When you’ve got it up to temperature, shut o the
boiler and use the valved manifold to put your power
Page 8

ushing pump into circuit again.
4. This p has been given to us by several of our
customers now, and we can’t guarantee that it will work
on every combinaon boiler. With some boilers it is
possible to fool the pressure sensor that stops the boiler
ring, by linking out the low pressure switch. You’ll need
to take all the normal precauons when working with
electricity (switch o rst!), pull the wires o the water
pressure sensor (two) & link them together.
The boiler manufacturer technical department may be
able to conrm the success of the link out.
(Don’t forget to restore the correct wiring aer the
power ush).
Other hot water issues
Q. Is it OK to dump very hot water from a heang
system down a drain or sewer?
A. There is a Public Health Act Regulaon of 1936, which
states that water should not be discharged down a public
sewer at a temperature greater than 43oC, but in reality
this is unlikely to be a problem when power ushing.
However, do consider the risk of cracking a toilet pan
if you discharge very hot water into it when power
ushing.
Q. Why shouldn’t I use a CLEARFLOW pump with
scalding hot water?
A. A Clearow pump may need to be used with very
strong chemicals, such as neat hydrochloric acid, when
being used for descaling. To enable this, all weed parts
are either plasc, or are sleeved in plasc, and this
imposes a temperature limitaon.
At high temperatures the clear plasc ow and return
hoses will become very exible and may kink, so don’t
put scalding water through them. High temperature
resistant hoses can be ed to a Clearow pump – but
this type of plasc is not transparent, and you’d lose the
advantage of being able to monitor water cleanliness by
viewing the water as it travels through the pipes.
Remember that working with scalding water above 65oC
poses risks to you!
Q. What do I do if I arrive at a house where the heang
has been working, and the water temperature is above
70oC? Do I have to wait for the water to cool down?
A. No. Once you have connected the Clearow power
ushing pump into the system, and connected all hoses,
immediately set the valves into the dump mode (dump
valve open), and then switch on. Run and dump for a
couple of minutes, allowing cold water in to the system,
before reverng to the normal ushing procedure.
Tricky systems to power ush!
Q. Can you power ush a microbore system?
A. Yes, but connecon of the Clearow pump should
be on to the circulator pump ngs, and not on to a
radiator, otherwise the small bore tubing will drascally
reduce the ow rate, and the system power ush will
be less successful than normal. We advise using 5 litres
of FX2 (instead of the usual 2.5 litres), to ensure the
parcles of debris are dispersed in as ne a form as
possible.
If you can’t clear a radiator on a microbore system, it
may be that a plug of sludge is blocking the narrow
diameter pipework leading back to the manifold. If you
have a Kamco Systemsure IK6 injector, the following can
be worth trying to restore ow to the radiator.
Switch o and isolate the Clearow pump. Close both
valves on the problem radiator. Aach the injector unit
to the air bleed screw ng, and pump up the pressure
Page 9

as high as possible.
Quickly open one radiator valve, and the air will oen
dislodge and move the semi-solid sludge along the pipe.
Close the radiator valve, pump up the injector again, and
open the other radiator valve. Finally, direct the full ow
of the Clearow through the radiator, with both valves
open.
Q. Can you power ush a microbore system with
double entry radiator valves?
A. Yes, but we
suggest that
you double the
amount of FX2
to 5 litres. If
the distributor /
spreader tube
(which directs
the incoming
water towards the far side of the radiator) has broken
away, so that the entrance and exit are eecvely only
15-20mm apart, any ushing eect on that radiator will
be minimal. Conversion to opposing inlet and outlet
valves is a beer long term proposion.
Q. Can you power ush a single pipe system?
A. If the radiators on a single pipe system have severe
deposit build-ups, or cold panels, then the power ush is
not likely to be successful. BS7593:2006 advises against
power ushing a single pipe system. If you do take on
such a system, improve the chances of success by pre-
treang with two packs of HYPERFLUSH, and operate
the ow reverser more oen than usual whilst ushing
individual radiators.
Q.
Can the CLEARFLOW be used on a system which has a
Primac type single feed cylinder?
A. It is necessary to disconnect or loop out the Primac
cylinder otherwise the high ow rate of the Clearow
pump will dislodge the air bubble in the cylinder, leading
to mixing of radiator and tap water.
The Primac cylinder was usually gravity fed, with
separate pumped ow and return piping to the radiators.
Consequently, connecng your Clearow onto the ow
and return piping to the Primac will not enable you to
power ush the radiator circuit.
This would have to be power ushed separately, ideally
by connecng across the system circulator pump
connecons.
N.B. Remember that Water Bye-laws prohibit the use
of corrosion inhibitors (other than potable ones!) in
systems with a Primac cylinder, because of the risk of
contaminang the domesc water supply.
Q. How do you recognise a Primac cylinder?
A. The system itself should give you a clue. You won’t
nd a feed and expansion tank, nor an expansion
vessel anywhere else. Check the cylinder pipe
connecons closely. Convenonal cylinders have
male BSP connecons on the cylinder for pipework
to be connected to, whilst Primacs have female BSP
connecons going into the cylinder. If you’re lucky, you’ll
see the word ‘Primac’ stamped into the cylinder near
the top.
Q. If the system is a gravity hot water system, with a
separate non-pumped hot water circuit leading away
from the boiler, won’t that reduce the ow rate of
water through the radiators when carrying out the
individual radiator ush?
A. If you use the circulator pump adapter leads to
connect across the circulator pump connecons, or
connect onto radiator tails, you shouldn’t lose much of
the ow through the large diameter pipework of the
gravity hot water circuit. The boiler heat exchanger will
act as a large diameter by-pass.
Page 10

However, this will not clean the gravity hot water
pipework. Some engineers will re-locate the Clearow
pump and connect it across the cold feed and expansion
piping to force water through the gravity hot water
circuit.
If there is one radiator on the gravity hot water circuit, as
is somemes the case, or a towel rail, you may be able to
connect your Clearow across the tails.
In and ideal world, you would disconnect the gravity hot
water pipework at the boiler, and then power ush the
hot water circuit separately – but this is far from easy in
a back boiler red gravity hot water system.
Q. Can you ush a very old system which has
passivated steel or stainless steel piping, such as
Truweld or Gecol?
A. Yes, you can, but we advise extreme cauon, and you
should always point out to the householder that you
cannot guarantee that there will not be any leaks. These
pipes were ‘stop-gap’ materials used during a period
(late sixes/early sevenes) when there was a copper
shortage, and were not expected to have a very long life.
The passivated steel tube (similar dimensions to 15mm
copper tube) was fabricated from sheet steel, folded
over, seam welded and galvanised. Thirty years later
it has generally corroded internally such that it is on
borrowed me. Some engineers refer to this steel
pipe work as “Birmingham” tube, as one source was a
GKN company in the West Midlands. Look for tube of
an aluminium / silver colour, and connected with so
soldered copper joints – and avoid it. Another clue is that
it is magnec – copper and stainless steel aren’t.
The stainless steel tube supplied at that me was of a
low quality and is prone to ping corrosion, and again is
on borrowed me.
If in doubt, do not power ush the system. If you accept
the job, use HyperFlush instead of PowerFlush FX2 – and
always ask the householder to sign a disclaimer!
Q. Are there any other systems I should treat with
cauon?
A. Look out for low quality ‘Type Z’ 15mm copper
tubing of connental original, also supplied at the me
of copper shortages. It was prone to ping, and had a
very thin wall thickness, such that it could not be bent.
You can recognise it because the manufacturers kindly
printed a red line along it. Another clue will be the lack
of any bends (only joints) in the copper piping.
Q. Can you power ush systems with old plasc piping
(PEX), which didn’t have the ‘barrier’ included?
A. You can ush such systems exactly as for any other
system, BUT you’ll probably nd they are very heavily
sludged. Most plasc piping now includes a barrier
layer, to stop air diusing through the wall of the pipe,
and only ‘barrier’ type pipe should be used for heang
systems.
The water in pipe without a barrier layer will always
be more oxygenated (=more conducive to corrosion)
and therefore systems with the non barrier pipe can be
expected to corrode faster even with a good corrosion
inhibitor present. The inhibitor level should be checked
every six months rather than annually.
Unless the system is re-piped it is probable that it will
need to be power ushed every few years, and it is
prudent to warn the householder that this is the case.
Other systems?
Q. Can you power ush a system with plasc piping,
such as Hep2O?
A. Yes you can. PowerFlush FX2 liquid and HyperFlush
can be used on plasc pipework systems, and will not
damage either the pipework, or the ‘O’ ring materials.
Q. Can you power ush under oor heang systems?
A. Yes you can. Underoor heang systems are piped in
plasc tubing, and either FX2 liquid or HyperFlush can be
used on these systems, and will not damage either the
pipework, or the ‘O’ ring materials.
Page 11

Q. How do I go about ushing underoor system?
Where do I connect my Clearow pump?
A. The rst queson we usually ask is “Are you sure
the system needs ushing?”, If the whole house has
underoor heang, with no radiators or towel rails,
where might the debris have come from?
Oen heang circuits are mixed systems, perhaps with
radiators upstairs where it is most dicult to convert to
underoor heang, and with underoor heang plasc
pipework downstairs, and it is corrosion debris from the
upstairs radiators that is accumulang in the under oor
circuits.
Underoor circuits usually have a separate circulaon
pump. We advise that rst the downstairs underoor
circuit is isolated and the rest of the heang system then
ushed convenonally. Once water there is fresh and
clear, isolate the upstairs circuits, and use a Kamco CP2
pump head adapter to connect on to the underoor
heang system circulator pump. Flush each underoor
loop one at a me using the individual ow control
valves on each circuit, just as you would if you were
ushing radiators.
N.B. We HAVE encountered systems which are totally
underoor heang and which have ow problems as
a result of debris. Generally this is organic, bacterial
maer which has occurred as a result of degradaon of
glycol based anfreeze type products in the water. The
temperature of underoor circuits needs to be much
lower than convenonal central heang circuits (in
order to prevent householders ‘tap dancing’ on very hot
oors), and this lower temperature is very conducive to
bacterial growth.
Q. If I have an underoor heang system with bacterial
growth, how can I remove it, and prevent future
problems?
A. You need a specialist cleaner to break down and
remove bacterial maer in heang systems. Kamco
Systemsafe-Bio is the product to use. Circulate it through
the heang system for at least 4 hours if using the system
circulator pump, or up to 24 hours if the system is heavily
fouled. You can reduce this me by 75% if using a power
ushing pump.
Once the system is clean, add further Systemsafe-Bio at
a dosage rate of 0.25% to prevent future contaminaon,
together with the correct dosage rate of Systemsafe-DM
corrosion and scale inhibitor.
Q. How can you work out how much water is present
in an underoor system, and how much chemical is
needed?
A. If the system installer le notes on how much pipe
was used under the oor, you could calculate it - but
that’s unlikely. However, there is a rule of thumb guide
with underoor heang that if you mulply the boiler
output (in kW) by 23, you’ll have a fair guide to the
water content in litres. Thereaer, calculate how much
PowerFlush FX2 would be needed by mulplying the
system water volume by 2.5%, or mulply by 0.5% if you
are using HyperFlush.
For countryfolk
Q. Can I power ush a system in a house which does not
have mains drainage, but only a sepc tank?
A. You can power ush
the heang system
of such a dwelling,
but it requires care
and consideraon
beforehand. The only
alternave to a power
ush would be a
complete and costly system re-build.
Also remember that a power ush uses several hundreds
of litres of water, depending on the size of the system,
and it would be a good precauon if the householder has
the sepc tank serviced/ emped in advance of the date
of the power ush.
The main consideraon is what chemical to use, if any,
and how to safely dispose of it and of the waste water
generated during a power ush.
Page 12

What ushing chemical should you use?
The possibilies are:
1. ‘NONE’, accepng that you won’t be able to carry out
a very ecient power ush but you won’t have to worry
about the eects of any chemical on the bacteria in the
sepc tank.
2. Use PowerFlush FX2, carrying out the normal
ushing procedure as usual unl you have put the full
ow through each radiator in turn. Instead of then
commencing to dump on each radiator in turn, carefully
start adding Neutralising Crystals into the power ushing
tank to neutralise all the acidity before you begin to
dump on each radiator. Check the pH regularly unl the
water is back up to a pH of 7.
What about the contaminated waste water, containing
quanes of iron oxides?
You can minimise the amount
of corrosion debris going down
the drain by using a Combimag
power ushing lter (two would
be beer!), and we strongly
recommend that any power ush on
a sepc tank dwelling should use a
CombiMag.
If the householder has concerns about the debris
entering the sepc tank, then consider taking a 200 litre
barrel on site, and using that to take the waste water
away to where it can be disposed of down a foul water
drain.
It’s very probable that the total amount of water used
during the power ush will exceed 200 litres, and so
to minimise the amount of water to be taken o site,
consider only pumping into the barrel the rst minutes
worth of dumped water from each radiator, as you
commence the ‘dump on each radiator’ procedure.
This obviously will be the most contaminated water.
Something puzzling is happening here!
Q. What happens if there is no apparent ow through
the CLEARFLOW unit when the ow reverser handle
is in one parcular direcon when I’m working on the
upstairs radiators?
A. If the system is a gravity hot water system, there is
probably an an gravity / non return valve in the radiator
circuit. If the non return valve is accessible, either loop it
out, or remove the plunger so that it doesn’t prevent the
ow of water in one direcon. If you can’t nd the non
return valve (which is very probable), the ow reverser
lever must be le in one direcon.
Q. I’ve connected my Clearow into a heang system,
made it into a sealed system, opened the isolang
valves, and switched on. The pump appears to be
working ne, but the water level in the Clearow tank
is overowing without the mains water inlet valve even
being open. What’s happening? Is there something
wrong with the Clearow pump?
A. The answer is usually NO.
A1. This situaon oen occurs when for whatever reason
(perhaps a zone valve jammed by hard scale broken
loose from elsewhere in system, or complete blockage
in part of system, or even a scking non-return / check
valve) your power ushing pump is running / rotang but
is not actually able to pump the water from its tank out
into the system i.e. no water is actually leaving the tank.
However, some system water will drain back down into
the tank through the ‘return’ hose under gravity, and so
the water level starts to rise.
(This occurs most oen in a gravity hot water system,
or one that has at some me been converted from such
a system.) The soluon is not always obvious, but you
need to check for any possible reason why the system is
choking o pump ow.
If you can’t locate the problem, you’ll have to point the
ow reverser lever in the opposite direcon, and leave it
there.
A2. It’s less likely, but if it is a sealed system, there may
be an automac pressurisaon unit (somemes known
as an autoller) connected to the system, to maintain
the required pressure.
Switch it o, or it will be connually introducing more
water into the system to try to top up the pressure, and
as a side eect forcing water against the direcon of ow
you need for a successful power ush.
Q. On some systems, when I am dumping the water
from the system, and I have used the boiler to heat the
water during the power ush, I noce that the radiators
are cold at the boom, and warm at the top. What’s
happening?
A. A Clearow pump circulates the water through a
system much faster than the standard system pump, and
it is the cool fresh water speeding straight across the
base of the radiator that you can feel.
Page 13

Eventually the warmer water will be swept from the
radiator, but you can speed it up by introducing some air
into the top, of the radiator to force the water level down,
using a Kamco Systemsure injector.
Q. On some systems, aer I have red the boiler to heat
the system once I have added the ushing chemical, I
noce that the radiators are hot at the boom, but sll
cold at the top. Why?
A. The reason is the same as for the previous queson.
A Clearow pump circulates the water through a system
much faster than the standard system pump, and the
heated water is speeding across the base of the radiator
rather than circulang throughout the whole radiator.
Given me the heat will spread up the radiator, but try
reversing the ow a few mes to speed up the process.
Cutting corners?
Q. Is it necessary to bleed radiators aer a power ush?
A. Yes. However, the amount of air in the radiators is
usually small. If you keep the water level in the Clearow
tank at least 15 cm (6”) above the minimum, you’ll
minimise the air to be bled from radiators.
Q. Is it really necessary to carry out the individual
radiator ushing procedure?
A. Yes. You can prove it for yourself by ushing a system
without pung the full ow through each radiator in
turn, and then dumping unl the waste water is clear.
Now put the full ow through each radiator in turn, and
watch the water discolour again as more debris is brought
into suspension.
Q. Do I need to carry out a separate dumping procedure
on each radiator?
A. Yes, but don’t do so immediately aer adding the
ushing chemical. If you do, you’ll be dumping your
ushing chemical straight down the drain, and will have
to keep adding more as you work your way around the
house.
Whilst we think that this is an excellent idea from a
chemical suppliers’ point of view, it isn’t generally
necessary, as loosened debris takes many hours to sele
or compact, and will have been purged from the system
long before this could happen.
Put the full ow, with chemical treatment, through
each individual radiator in turn. Only then, commence
dumping, working your way round the house, ensuring
the full ow through each radiator individually as you
dump, by closing o all other radiators.
Operational problems
Q. What do I do if the mains water supply is very poor,
and can’t replenish the CLEARFLOW tank fast enough
whilst dumping? Should I part close the dump valve?
A. Don’t parally close the dump valve if the water level
in the tank keeps falling. Wait unl the water level is
about 12 cm from the boom, close the dump valve and
re-open the isolang valve on that side (i.e. re-establish
circulaon through the system).
However, leave the water inlet tap OPEN, and allow the
tank to ll unl the level is close to maximum.
As soon as the water level reaches maximum, again switch
into dumping mode, unl the water level falls to 12 cm
from the boom, and then repeat the exercise unl dump
water nally runs clear.
This method ensures that the water is always moving
vigorously throughout the system, ensuring that debris is
kept moving, in suspension.
Q. What can I do if I am working on a radiator with such
a severe build-up of corrosion debris that I am struggling
to clear it all?
A. Dicult radiators such as this will oen respond to
use of the Radhammer vibrator device, also supplied by
Page 14

Kamco. This device ts into the
chuck of an SDS drill which has
been set to ‘hammer only’, and
is applied rmly to problem
areas of the radiator. The high
frequency vibraon will loosen
debris that will not respond to other cleansing methods.
Q. I’ve tried everything with a severely choked radiator
- full ow, heated the water, vibrated with a
RadHammer and sll there’s a cold area. What else can
I do?
A. Try this:- With the full pump ow on the problem
radiator, use a Kamco Systemsure IK6 chemical injector
to blast air into the top of the radiator using an IK6 air
bleed valve adaptor.
You’ll get a huge amount of turbulent agitaon in the
radiator which will create the opmum condion for
mobilising debris. Then switch o your pump and
immediately inject more air into the radiator, to depress
the water level to about half way down the radiator.
Switch on your power ushing pump again. The air in the
top of the radiator will prevent any water from passing
along the top channel, and the full force of the water
will slam into the usual debris build up area along the
base of the radiator, giving you a much beer chance of
removing it.
How can I check that I’ve thoroughly cleaned
the system?
Q. Is there a beer way than a simple visual
inspecon to ensure that the system water is
really clean?
A. Yes. A simple way to check that the water
is chemically as clean as mains tap water is to
take a sample both of tap water, and of the
water exing from the dump hose, and to take
measurements with a Total Dissolved Solids
(TDS) electronic meter. The dump water reading should
be as close to the mains water reading as possible, and
ideally within 5-10% of the reading obtained for tap
water.
Another method is to use a turbidity tube to give
a reading of suspended parculate maer in the
dump water. The turbidity tube is a long clear tube,
with a marker on the base. Turbidity is determined
by the degree of obscuraon of the marker when
looking along the length of the tube containing
system water.
What NOT to do
Q. Can the CLEARFLOW pump be set up and le
unaended whilst I carry out another job elsewhere?
A. No, it is unwise to leave any powered equipment
unsupervised in a domesc environment, with runs of
hose and power cable which could be in close proximity
to householders, children, and pets.
Should there be an electricity power cut, the Clearow
would stop pumping, and water would drain down into
the tank through the return hose, causing it to overow.
You will be using powerful ushing chemicals, and as
for all chemical products, they should be treated with
respect and kept away from children.
Q. Are there any possible problems when dumping
water into a toilet pan?
A. Yes, and the most likely one is the dump hose sliding
out of the toilet pan when you start dumping, and
ooding the bathroom, so trap it in place with the toilet
seat before you start work. Beer sll, use a piece
of cord to e the dump hose to the seat hinge. Also,
consider whether the porcelain might be stained by the
discoloured dump water.
Saving time
Q. How can I reduce the me taken to power ush a
heang system?
A. In order to clean a system eecvely you must carry
out the full procedure, including pung the full ow
through all radiators and secons of the heang system.
However, you can reduce the overall procedure me if
you use an inline magnec power ushing lter, such as
the Kamco CombiMag lter.
Page 15

This is installed between the heang system and the
power ushing pump, and extracts magnete (the major
corrosion constuent) from the circulang water, which
consequently clears much faster, reducing the me taken
to obtain clear fresh water throughout the system. The
volume of water required to power ush a system is also
signicantly reduced.
Miscellaneous
Q. Can you use the pump to add corrosion inhibitor to a
system?
A. Yes, it’s a good way to get corrosion inhibitor
rapidly into a system and thoroughly dispersed. Before
disconnecng the Clearow pump, lower the water level
in the tank to just above the minimum level, close the
dump valve, and add the inhibitor into the Clearow tank.
Allow circulaon through the system for ten minutes
before nally disconnecng.
Part L: 2006 of the Building Regulaons now require that
a system is treated with corrosion inhibitor. Benchmark
members specify the use of an inhibitor which has
passed the NSF/Buildcert performance standard. Suitable
inhibitors, such as Kamco Systemsafe-DM, will display the
Buildcert logo, so check for this to ensure that you use an
inhibitor that has been performance tested.
Q. When ushing a system with a combinaon boiler
ed with a lling loop, do I need to connect a water
supply hose to the orange Clearow water inlet valve?
Can’t I just run water in through the lling loop during
dumping?
A. No. It is important that fresh water is fed into the
system via the Clearow tank. Introducing the water
through a lling loop elsewhere will destroy the high
velocity mono-direconal ow and hence the eciency
of the whole power ushing process.
Q. I’m working on a house with a water soener
installed on the water supply. Is there any problem if I
ll the system with arcially soened water aer the
power ush? Can Systemsafe-DM inhibitor be used?
A. Systemsafe-DM can be used for systems containing
arcially soened water, and will give a signicant
degree of protecon.
However, you should be aware that by using arcially
soened water you are risking a higher level of corrosion.
Arcially soened water is inherently more corrosive
than either hard or naturally so water, for good sound
chemical reasons, hence ANY inhibitor will have to work
harder, and ping of aluminium is always a possibility.
Any new water soener installaon complying with
guidelines will have a by-pass. We suggest that you by-
pass the water soener whilst lling the system, then
re-open the by-pass and enjoy the benets of arcially
soened water elsewhere in the house. Prudent boiler
manufacturers take the view that if you can use water
that is less aggressive, then you should.
Background informaon:
BEAMA Water Treatment is a trade associaon to which
the market leading inhibitor manufacturer members
(including Kamco) belong, and BEAMA members advise
customers and installers in the supply chain against using
soened water in the primary side of heang systems.
Although a good corrosion inhibitor can minimise
corrosion problems, BEAMA stascs show that 74%
of sampled systems have inadequate/no inhibitor or
are under-dosed, and such systems when lled with
arcially soened water are at considerable risk.
Q. Baxi say don’t power ush a Solo 2- why is that?
A. Baxi had a keling problem with heat exchangers in
Page 16

early models. They later supplied a rubber ‘kebab’ in
the heat exchanger, the funcon of which was to cause
turbulence to prevent localised boiling, BUT power
ushing can dislodge the kebab such that it blocks the
exit, and so if you need to tackle such a system, you’ll
have to isolate the boiler.
Servicing
Q. Where can I get my Kamco pump serviced?
A. At Kamco. We have a service department at our St
Albans works where we build the pumps. We have all
spares in stock, and can service any pump that we’ve
sold since 1986.
We don’t have service engineers on the road as the
volume of repairs doesn’t warrant that. We carry out
repairs at St Albans, and ensure that we turn them
around fast.
Upon receipt of a pump we strip and performance check
it, and then call you to advise what we think needs
doing, and the cost.
It is unlikely that a repair will take more than two hours
labour. The cost of parts needs to be added, but unless
something drasc has happened to a pump, the cost of a
repair is always far less than the cost of replacing it.
We only need the pump on its tank to be returned (no
hoses required) and we advise that the pump be very
well packed, parcularly around and ABOVE the motor
/ handle to prevent parcels carriers from destroying the
pump.
If you don’t use a parcels carrier service yourself, then
we can arrange for TNT to upli it and return it to our
works. They send a specic vehicle out to do the upli,
and charge £25 for this. On the upside, they are quick
and quite ecient. If you would like a Kamco pump
serviced, either send it to the service department at our
works address, or, if you prefer, pack the pump and then
call us to arrange collecon.
Will power ushing damage the system?
Q. Will power ushing cause damage to a heang
system?
A. It is rare for a heang system to experience leaks
aer the power ushing process. However, experienced
heang engineers will probably explain the following to
householders:-
Sludge and debris are present as a result of corrosion
over a long period of me.
The power ushing process will cure most circulaon
problems, but cannot undo the corrosion and gradual
decay of heang system components that has led to the
need to power ush the system.
Occasionally some systems may have radiators with
localised deep corrosion pits, with only a scab of rust
prevenng the system water from leaking out. The
vigorous ow rate required to mobilise sludge and
deposits may dislodge such a scab, leading to a leak from
the radiator during the ushing process.
The advanced stage of corrosion required for such a
situaon means that the leak would occur imminently
even without a power ush. If it should be brought
forward slightly by the ushing process, then it is beer
that it occurs whilst a heang engineer is present to
remedy the problem, rather than for it to arise over a
weekend or whilst the house is unoccupied.
Kamco power ushing chemicals are comprehensively
inhibited, so that they do not aect the metals from
which heang systems are constructed.
They are formulated so that they loosen and dissolve the
corrosion products that cause boiler noise and circulaon
problems, enabling the power ushing process to power
them out of the heang system.
It is important aer the ushing process to add a good
quality inhibitor such as SYSTEMSAFE-DM to the heang
system to prevent future decay. Part L: 2006 regulaons
now make the addion of a chemical corrosion inhibitor
mandatory.
Page 17

Guaranteed cleanliness?
Q. Can you guarantee to get a system clean with a
power ush?
A. Although an engineer may power ush a system unl
the water exing the dump hose is clear, and will usually
carry out tests to check this, it is not uncommon for
a system with relavely clear water to sll have some
compacted debris in the lower parts of the system /
radiators. This may later break loose and discolour the
water, although it is rare that it is in sucient quanty to
cause problems.
Engineers occasionally nd a layer of very hard black
iron oxide corrosion debris (magnete) in the form of
scale on the internal surfaces of pipe work, and which has
developed over many years. Somemes this hard scale
will not be removed by a power ush, but fortunately the
same adhesive nature that makes it dicult to remove
also tends to keep it bonded to the pipe where it does no
harm.
How long will a power ush last?
Q. Once I have a power ushed a house, will it require
ushing again aer a few years?
A. We would not expect a well designed system without
obvious problems to require a further powerush in less
than ve years, and generally for much longer than that
if the system has been properly treated with a Buildcert
approved inhibitor. However, there are too many
variables and unknowns for us to give specic advice.