Replace tandem 50-gallon water heaters with one 75 or just keep one?

At 13 years old, those power-vented units are allready living on borrowed time. Taking the $475 deal to pull the leaker and run the "good" one is definatly the smartest move for your wallet right now, but you have to treat it as a temporary fix. Power-vent blowers and sensors usually start failing around the 10-12 year mark anyway, and since they're the same age, that second tank is likely right behind its twin in terms of internal corrosion.

A single 50-gallon tank is actualy plenty for a family of four if you aren't running the dishwasher, laundry, and multiple showers simultaneously. People get upsold on 75-gallon tanks all the time, but unless you have a high-flow rain shower head or you're actually filling that soaker tub, it's mostly just wasted energy keeping that much water hot. Jumping to a 75-gallon unit for $3,500 seems like a massive price hike for capacity you probably won't even notice.

If you take the $475 option, I'd suggest taking the $3,000 you're saving and putting it aside. When that second 50-gallon finally gives up—and it will—you'll be in a much better position to decide if you want a fresh 50-gallon or maybe even a **tankless unit**. Since you already have power-vented units, you're already set up with the PVC venting, wich makes a future tankless conversion much easier than if you had old-school atmospheric venting. One thing you can do once the leaking one is gone is to check the **anode rod** on the remaining unit. If it's completely eaten away, you know that tank is on its last legs. But for under 500 bucks to buy yourself another year or two of hot water? That's a solid plan. Just keep the area clear around that floor drain so you don't have a mess when the second one eventually decides to let go.

I’ve been reading about those anode rods too, but are they actually easy to swap out? I saw a video where the guy had to use a massive impact wrench beacuse it was rusted shut. If the tank is allready 13 years old, is there a risk of cracking something if I try to force it?

Also, does having two tanks help with how fast the hot water reaches the faucet? I’d hate to save the money now but end up waiting five minutes for the shower to get warm because I removed half the capacity.

Two tanks won't get you hot water faster at the tap—that's all about pipe distance and wether you have a recirc line. More tanks just means more 'runway' for long showers. I'd honestly skip the anode rod on a 13-year-old tank. If it's seized, you're more likely to twist the tank or break the nipple than save it at this point. Just ride it out. If that power-vent motor starts making a high-pitched whine or a grinding noise, don't waste $400 on a new blower assembly for an old tank. That's the universe telling you it's time for a fresh 50-gallon.