heat exchanger cleaning

My Universal M25xp has been running warmer than normal this summer. It is approximately 17 years old with just over 1000 hrs on it. Removed the heat exchanger. It still has the original paint, so I don't think it has ever been removed before.

I've ben told that a 50/50 mix of Muriatic acid and water will clean/loosen the scale build up. How long should I leave the heat exhanger in this bath? Since the acid should only attack the scale I would thing multiple dunkings and cleaning may be necessary. Anybody done this before?

Any suggestions for other/better methods of cleaning?

 

May be what you do with car radiators would help. When scale builds up it builds up in layers like fish scales and is smooth in the direction of flow.

Reverse flushing ie. forcing water through in the reverse direction gets underneath the scale and lifts it off.

A mixture of compressed air and water helps as long as you don't over pressurise the system and blow it up. A "Y" junction with water from a hose and air from a compressor blowing through shold move it.

Don't forget to check your pumps.

 

I have used muriatic acid effectively to clean a heat exchanger. I closed the ports and filled the heat exchanger with a 20% solution. It foamed and bubbled a lot for a few minutes. When the bubbling was finished, I flushed well with fresh water. Vinegar will work too, but it takes much longer. If I use vinegar, I leave the heat exchanger filled with it over night.

Mike