I am not actually using the hot ater tank to warm the water. I have just had a Ranai (sp?) on demand hot water heater installed and we left the old tank (only 4 years old) as a "holding" tank before the on-demand heater. This way there will be abit of storage and the water should be slightly higher in temp than when coming directly out of the ground.
I just wanted to descale the tank becasue there seems to be "gunk" in it becasue it was off for approx. six months, and the water seems to be hard as it is.
Any ideas or confirmation about taking out the pressure resease valve and dumping it in that way would be helpful.