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Difference Between Chemical Power Flushing and Descaling

'POWER FLUSHING', 'JET FLUSHING' & 'HARD FLUSHING' are all expressions used (in the heating trade over many years) to denote the process by which heating systems are forcibly cleansed using water at high velocity, but low pressure, so that no physical damage is caused to the system. The objective of Powerflushing is to restore systems with circulation and boiler noise problems (caused by sludge and corrosion deposits) to optimum operation. Power flushing removes these deposits and the problems that they cause. Chemical Powerflushing is advised prior to the installation of a replacement heating boiler. Manufacturers insist that existing heat emitters i.e. radiator coils are powerflushed otherwise warranties of equipment may become void.

Descaling is used in hard water areas, the use of water in heating and cooling systems invariably results in a build up of limescale (hard water) deposits within the system, usually in the highest temperature zones. The resultant scale not only restricts water flow, but acts a very effective insulant, reducing heat transfer efficiency, and increasing running costs. Heavy scale deposits can also lead to localised overheating of heat transfer surfaces, resulting in premature failure of heating appliances. In all areas, rust and corrosion may take place in heating and cooling systems, leading to a build up of corrosion deposits, and a reduction in efficiency.

Process of Power Flushing

The power flushing pump is simply connected into the heating system, either across standard circulator pump couplings, across the tails of one radiator, or wherever most practicable. The powerful flow, combined with instantaneous flow reverser device, will dislodge and mobilise deposits and corrosion which resist traditional system cleaning methods.

Once the corrosion and sludge deposits have been loosened and mobilised, fresh clean water is forced through the heating system, pushing the contaminated water out through a full bore dump valve to waste. During the process, radiators are individually flushed, without removing or disconnecting them from the system, by directing the full output of the pump through each radiator separately.

At the end of the flushing process, the system contains fresh clean water and reinstatement of the system to normal operation takes only a few minutes

System flushing will not remedy design or mechanical faults, which should be rectified, but in many cases it will cure the problems caused by these.

Click on the picture on the right to see Power Flushing in process

Process of Descaling

The tank is filled sufficiently with descaling solution to ensure that the pump rotor housing is submerged during use.

Then the outer ends of the flow and return hoses are securely screwed to the plant or equipment to be descaled, using BSP threaded adaptors & PTFE tape if necessary. Connect the power cable to a suitable earthed power supply (220 or 110 volt [50 cps], according to model). As the pump will be used in a damp location, it is recommended that a residual current circuit breaker plug top be used.

Once the pump is switched on the liquid level is checked to ensure that it does not fall below the level of the rotor housing as some of the contents of the tank enter the equipment being descaled, particularly when the overall capacity of the system being descaled is greater than the tank capacity of the pump.

During use, the tank cap should rest on top of the screwed stem, but should not be screwed on by more than a quarter turn, to allow for the passage and elimination of the gas evolved during descaling. It is important that the foam level does not exceed the maximum filling level.

The built-in flow reverser makes it possible to attack scale from both directions. During descaling periodically the flow reverser handle is moved from one stop to the other. This reduces descaling time considerably, and is more effective in flushing out any solid matter, which will accumulate on the circumference of the base of the tank. By attacking scale from both sides it is possible to clean piping which is almost totally obstructed.

Scale removal can be considered complete when bubbles no longer form in the return pipe, and the solution is still acidic.

Facts about Chemical Power Flushing

• Cures flow and circulation problems
• Cleans the whole system including underfloor pipework
• Removes aggressive water; treatment prevents further corrosion.
• Cures or prevents boiler noise
• Restores heat output to radiators

Facts about Descaling

• Scale forming salts are present in all domestic water
• Limescale is 400 times less conductive of heat than copper
• Limescale will form on all direct heated surfaces i.e. water heaters, combi boilers etc
• The harder the water, the more limescale will form
• If there is a high volume of hot water being generated, scale will form even if area does not suffer from hard water i.e. hotels

More Information on Power Flushing from Kamco