Electric shock from pellet stove
I'd really stop testing this by shocking yourself.  (!)
If it happens repeatedly it's usually not static.  
If it happens more when you're on water, probably not static.  


You can use a non contact voltage tester (NCVT) to see if the stove frame is energized:  



Just don't trust it too much, and test it on an outlet every time you use it to make sure it's working.  

I'd use the NCVT to verify that the frame of the stove is energized, unplug the stove (carefully!) and test again.  

If it's hot plugged in but OK unplugged, I'd call whoever installed or services the stove, otherwise call an electrician.