Just noticed that there's condensation on the ceiling and part of the wall near a water heater that's inside the house in the laundry room. I believe it's coming from the water heater because I can see some condensation going up the wall from the water heater closet. The weird thing about this is that there is NO condensation inside the water heater closet or on the water heater itself. I notice it after taking a shower, so the water heater turns on. My question is how can I verify that the water heater is the problem? If that's the problem why is it happening and how can I fix it?