BrianFtxNew Member Hi all, DIY guy here. Two Gas water heaters installed right next to each other at same height (one in a closet, the other just outside the closet). One was replaced this past summer (New), the other is 15yo old (Old) started leaking last night, then the entire drain valve completely broke off the tank. I'm not sure how they are plumbed, and not sure what is safe to do here. The New heater has a shut off on only one line (I'm assuming in inlet line). The Old heater has shut off valves on both lines. Currently I have turned off the gas to both heaters, and both lines on the Old heater are shut off. The Old tank is empty. Both lines on the New tank are open. With this set up, I still get water coming from hot water tap, it's just no longer hot. My question is this: can I restore gas/heat to the New heater and have hot water supply for the house while the Old heater is completely shut off & turned off? My thought is that, if they were plumbed in series, then shutting both valves on the Old heater as I have done would stop water from coming out of tap when hot side tap turned on. Unless the New tank is the second tank in the series and it is somehow drawing water from the new tank outlet despite the fact that there is no new supply coming into it. Seems like shutting both valves on either tank would stop hot water from making it to a tap's hot side. So since I have water (even though it is cool water since all gas is off) coming out when I open hot tap, is that proof that these are plumbed in parallel?? This leads me to believe they are parallel, which hopefully means I can relight pilot and restore gas/heat to the new heater while the old heater is completely shut off, allowing me to have hot water until the Old tank is replaced. Does this make sense? Thanks for any thoughts/advice!!