Issues with Descaling FE200 Hot Water coil due to Hard Water

I installed one of these in about 1988 and it has worked well although I did remove the hot water output mixer valve after a while.

Then with thermostatic valves on showers it was fine.

Recently we have found that the heat exchanger for the mains pressure hot water has not performed well so have been trying, with limited success to find a way to descale it.

From the internet searches done it would seem there was once available a machine called a VORTEX DECALOMAT 3 Descaling Unit (See The Gledhill Manual Page 22/23) that looks llike it was was a good design for the task of descaling the heat exchanger.  Now days all I see offered are the machines designed for cleaning out a whole heating system and these seem a bit OTT. (See Fernox Training Video on UTube)  This in fact seems to be the situation reported in this post from 2010 

The use of inhibitors and issues with descaling etc. was not covered so well in my original manual.

If anyone has any knowledge, suggestions or questions please email to Email: fe200@smalle.uk Especially news of an appropriaye method for descaling the coil without needing a full scale flushing machine.

We have tried dragging descaler through the coil with a vacuum with limited success and the next thing to try is connecting in the descaler from a source higher up. The problem is that the coils inside the tank are arranged like this in pic below and it is hard to get the fluid in to fill the coils.  This was done with the mains water off and the input and outputs to the coil disconnected.

My Original FE200 Manual.pdf.

Later Full Gledhill Boilermate Manual

Gledhill Manuals Download Page.

David Torrens April 25th 2017