Have a VRV with a 26 gallon tank. I drain the tank by running the water pump, including the water heater. I also open the drain plug. In addition to making sure it is level or even tilted slightly toward the drain plug. I obviously am leaving some amount of water in the tank because it smells bad after a few months. I solve it easy enough with a bleach mixture. But I would like to figure out a way to completely remove the water. I've heard of pumping pressure into the tank. Any ideas?