[Steam-engine] relief valves

[CopperheadMarine at aol.com]

Jeff Smith
 
  Always remember, you can cut off air to a wood fire to control it,  but a 
coal fire will have you hunting another set of grates if you don't keep  air 
flowing trough them.
 
  If you have plenty of water and a safe area to do so you can blow  down and 
add water to cool. You can rake an open hole in the center of the  grates or 
at the flue sheet to admit cool air but someone will have to prove to  me that 
this doesn't stress the boiler and get the flues leaking before I would  do 
it to any of mine except in an emergency. I agree that the best solution is  to 
plan properly.
 
 
Chas F