Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I built my Jensen 51 replica in 2006 and the boiler has been kept full of distilled water at all times. 

Since distilled has to be purchased and this boiler uses about half a gallon to fill, I am loath to drain it/waste it after each run.  In 16 years and over 400 hours of operation, there is no apparent corrosion or buildup of any type based on peering thru the front boiler glass portholes with a flashlight.  The 51R boiler is pretty stout, this approach may not be appropriate for thinner walled boilers, but it works for me.

Rog