prv valve has been replaced (this is the 3rd one) on a 3 year old gas hot water heater yet the prv continues to dribble from time to time. the systems does have an expansion tank and i've been told that this may have filled with water. is that possible? can it be repaired or does it need to be replaced? if repair is possible is it a "home handyman" job or one for a professional?
it is possible that you have excess preasure on the supply to the heater. I had your problem and found that the regulator was bad. use a preasure gauge (available at home centers for @ $5.00) on the drain valve of the hot water tank. the preasure should be less that 75 pounds. I personally set the preasure in my house and rental houses to 55-60 pounds.