Cleaning/Flushing Stainless Steel Plate Heat Exchangers

Would like to know the correct procedure for flushing and cleaning stainless steel plate heat exchangers.

We have a WP24-14 plate GEA plate heat exchanger, operating now for 5 years as a condenser on a heatpump. Recently it has been noticed that head pressure has been increasing. It is suspected that a film of scale/scum have formed on the heat exchangers plate surfaces ( water side), this is inhibiting the heat transfer to the water. Water flow rate through the condenser is ok.

Have been told Citric Acid or Formic acid can be used to clean and flush stainless Steel plate heat exchangers.

Would appreciate any information on this topic.

Came across this, may be useful...

http://www.kamco.co.uk/GuidanceNotes...Exchangers.pdf

Excellent post Brian_UK

Citric Acid will work, and will dissolve scale. Using a strong acid ( sulphuric or hydrochloric) is not recommended, especially HCl, as this will cause severe chloride corrosion inside the heat exchanger, especially in joints and where plates meet. I generally use Absorbic acid, as it is, for me, readily available, and makes a good descaler, especially as I have aluminium plate heat exchangers that tend to corrode internally with plain water. If the water output is in any way going to be used directly by humans ( washing or showering) then rinsing after descaling is a good idea..