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CF90 Quantum2
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Professor Power-Flush's 'Tips & Wrinkles'

Professor Power FlushWe've been building and supplying power flushing pumps for 20 years - but we're still learning new things, and we thought to share them with you.


You've probably got tips of your own, so if you'd like to share them with us then please click the link at the bottom of this page.


Click the links below to learn more about:


  • The puzzling situation when water in your pump tank threatens to overflow whilst you are flushing, yet you don't have the mains water inlet valve open. What's happening?
  • Is there something wrong with your power flushing pump? The answer is usually NO.

    This situation often occurs when, for whatever reason (perhaps a zone valve jammed by hard scale broken loose from elsewhere in the system, or a complete blockage in part of the system, or even a sticking non-return valve), your power flushing pump is running but is not actually able to push any water into the system, and so is not emptying its tank. At the same time system water on the return side drains down under gravity, gradually increasing the water level in your tank.

    The solution is not always obvious, but you need to check for any possible reason why the system is choking off pump flow.

  • Open vented systems
  • We all know that the point where the cold feed and expansion pipes join a system is often a problem area with a lot of compacted debris. If it’s completely choked you may as well cut the pipe work section out.

    But how do you know without cutting into it?

    The answer is to hold a small magnet against the outside of the copper pipe. Copper isn't magnetic, so if you feel the magnet being pulled onto the pipe, that tells you that there's a lot of magnetic iron oxide based debris in there. Start cutting!

  • There is another way to check if a cold feed pipe is blocked
  • When setting up for a power flush, you'll normally cap off the cold feed and expansion pipes before anything else. DON'T!

    Just cap the expansion pipe and leave the cold feed 'open'. Now get your power flushing pump connected in downstairs, with the isolating valves closed (as is normal, until you are ready to start the power flush).

    Now open the isolating valves without switching the pump on. Because the pump isn’t running, theoretically, water should start draining from the system into your pump tank, under gravity.

    If that doesn't happen, you have found a blocked cold feed! Cut it out!

  • Severely choked radiators
  • If during a power flush you struggle to clear a severely choked radiator, try this:-

    With the full pump flow 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 agitation in the radiator which will create the optimum condition for mobilising debris (click picture below).

    Then switch off 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 flushing 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 better chance of removing it (click picture below).

  • Baxi say don't power flush a Solo 2. Why is that?
  • Baxi had a kettling problem with heat exchangers in early models. They later supplied a rubber 'kebab' in the heat exchanger, the function of which was to cause turbulence to prevent localised boiling. However, power flushing can dislodge the 'kebab' such that it blocks the exit, so if you need to tackle such a system you’ll have to isolate the boiler.

  • Most chemical reactions proceed faster with heat, and therefore it is industry practice, if possible, to fire the system boiler during a power flush, before adding the flushing chemical. However, persuading a combination boiler to fire can be difficult because the low pressure limit switch senses a lack of pressure, and prevents the boiler from firing. What can be done to get the boiler to fire up?
  • Remember that when your power flushing pump is connected into the heating system, the maximum pressure you will find is at the output of the pump impellor, or in more practical terms, where your inlet hose connects into the system. From that point on the pressure is falling away throughout the system until the point where the return hose drops the water back into your power flushing pump tank, where the pressure is again zero.

    If you're using a Kamco CP2 adaptor to get connected into the heating system your power flushing pump must be very close to the boiler. Consequently, if you set the flow reverser handle so that the water flow is immediately into the boiler, rather than heading out into the radiator circuit, you'll be putting 1 bar+ pressure into the boiler and a combination boiler should fire up.

    If you're not sure of the flow direction, just try with the flow reverser lever in either direction.

    Note: the new Kamco CF40 Evolution and CF90 Quantum2 were 'tweaked' when we designed them to give extra pressure to help in this situation.

    If the above doesn't work...

    ...try partially closing the Clearflow valve on the return side of your pump. By reducing the cross sectional area you will automatically increase the pressure. Flow rate will be decreased, so only leave the valve partially closed whilst firing the boiler. Once you have the water warm, shut off the boiler and fully open the Clearflow valve for the normal high flow rate needed for effective power flushing.

    Here's another suggestion;

    If you're flushing a combination boiler system that has been in use for a while (i.e. not a new boiler), and you have connected your power flushing pump into the system across the copper tails of a radiator, this should work:

    You could make up a temporary valved manifold (see picture below) and loop out the power flushing pump by closing the two valves in the flow 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, then fire up the boiler until you have the system water good and hot. When you've got it up to temperature, shut off the boiler and use the valved manifold to put your power flushing pump into circuit again.

    And finally;

    This tip has been given to us by several of our customers, but we can’t guarantee that it will work on every boiler. You might consider fooling the pressure sensor that stops the boiler firing, by linking out the low pressure switch. You’ll need to take all the normal precautions when working with electricity (i.e. switch off first!), pull the wires off the water pressure sensor (two) & link them together.

    The boiler manufacturer technical department may be able to confirm the success of the link out. (Don’t forget to restore the correct wiring after the power flush).



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