1)Turn off boiler and/or the immersion heater.
2)Tie up the ball valve or isolate mains water supply to the cold water storage tank.
3)Open all hot water taps and drain the entire system. Close taps.
4)Fernox DS-3 should first be dissolved in warm water, at the maximum concentration of 1 kg per 10 litres of water, (minimum concentration is 250 g per 10 litres of water).
5) i)Connect a funnel to a suitable length of rubber or plastic tubing. The tubing should fit into (or onto) the cylinder feed connection on the inside of the cold water storage tank and the strong acid solution then introduced via the funnel, or:-
ii)Where the cold water storage tank serves the hot water cylinder only and no other appliance or outlet, the DS-3 solution can be introduced directly into the tank.
6)Refill the water system until the water level in the cold water storage tank is just covering the cylinder feed connection. This is to prevent over dilution of the acid solution of minimising the total amount of the water in the system.
7)Turn on the boiler and/or immersion heater and heat the acid solution in the hot water cylinder to a moderate temperature (50-60oC / 120-140oF) and keep at this temperature for a minimum of 4 hours (max 12 hours).
8)Open all hot water taps briefly every 10-15 minutes, allowing ’ - 1 pint of acid solution to run into a plastic container. This is because the acid solution will be neutralised by lime deposits within the pipework and slowly drawing off a small amount of solution will replace spent de-scaler within the pipes. Avoid contact with enamel baths and sinks etc.
9)Finally, turn off the boiler and immersion heater, and drain the hot water system completely. BALE OUT any residual water from the cold water storage tank as this may contain some DS-3 below the feedpipe connection.
10)When disposing of spent DS-3 solution it is best neutralised with Fernox Superconcentrate System Neutraliser.
11)Release the ball valve of the cold water storage tank and thoroughly rinse the entire hot water supply system, opening all hot water taps - Also rinse the cold water system (where applicable) as some acid may have entered via the cold water storage tank.
