Thanks. I guess if you are ever away for several hours/days, you could get a few degrees temp drop. So, a back up isn't a bad idea there. 
But, how many degrees and over what period are we talking before it's a major issue? 
If I understand correctly, it's more of a sudden temp jump that's an issue. 
		
	
		
		
		
		
		
	
		
		
	
	
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