Would a water heater with stagnant water (being filled up but never used) wear out its anode rod at the same pace as a water heater that’s constantly being used (having the tank replenished with fresh water while depleting the old water in the tank)?
Hi, It’s a somewhat trick question because of variables involved, but perhaps I can help a little. Two things that speed up anode consumption are heat and more conductive water. If the tank is just sitting stagnant, not being used, I’d expect it wouldn’t be heated much. Anode consumption will be slower in cooler water. About stagnant water vs fresh water coming in, that’s harder to guess at in part because of bacteria. If water is constantly flushing through, bacteria cannot really flourish, but sitting unused, there is little to prevent bacteria from multiplying. Anaerobic bacteria feed off the hydrogen gas produced by the action of the anode, so given time, you could get a nice little swamp going on in the tank, which will likely speed up anode consumption. A powered anode might be the right solution to that problem as it protects the tank without generating hydrogen gas. Also, if you’re just storing the tank, maybe draining it and getting it quite dry inside will prevent rust internally as it waits to be used again.