I am putting some new firebrick in my harman boiler i bought used and the front two are tight i already cleaned the surface really well. My question is what is the expansion rate of the fire brick and is this going to put stress on the boiler. I wonder if i should take a 1/8 inch off them to give them a little room to grow.
	
		
			
		
		
	
				
			 
	 
	 
 
		