been looking to purchase a copy of this text. recently bought a used wood boiler and building an addition. is the revised edition worth the extra money. what benefit is the disk? i've been told john sigenthalers book is a necessity for a poor carpenter trying to be a boilerman. the price difference between the two is a few fittings and a valve. thanks for the reply.
	
		
			
		
		
	
				
			
	
	