When my husband was alive, the two of us managed very well with one water heater and that included wahing machine and dishwasher. I shudder to think what you pay for keeping water constantly hot in 2 water heaters. Your utility bills must be sky
high.

Look into tankless water heaters. The cost might be about the same (may be a little higher) but you'll save $$ on your water heating costs and you can ditch the recirculator, unless you have baseboard water heat. You'll never run out of hot water and you won't have to keep 100 gallons hot. I have something similar to your set up but my two units run different sides of the house. I will replace with one tankless when the time comes.

Rheem and Rinnai make good tankless products.

Not to be contrary, but I loved loved loved my tankless hotwater heater. It was electric and the complicated venting wasn't necessary. And it gave me back 9 square feet. Best of all, it'll never burst and flood your house.

It is different, but this time, different can be really good. I will buy tankless all over again when I own instead of renting. Always. No draw backs.

What's the downside to tankless? Our house is two rooms deep and long.

They make both electric and gas tankless water heaters. Your plumber should be familiar with them.

There are tons of water heater brands out there. I think for the better brands, you're looking at several hundred dollars a pop. I have top of the line Bradford White heaters and it would be cheaper to replace them with one tankless.

My brother has tankless and he lives outside Chicago. His gas bill went down after installing it.

Check out how little room it takes up! So cool!

Looks slick, rob333! We don't have a space problem -- full basement that's 'just a basement' (unfinished). IS there a downside, other than that electrical rates are going up while nautural gas rates are dropping? Do they wear out fast? Will they overheat if you take a long shower?

We'd have to have an electrician come in to install tankless, right? (I doubt the plumber is going to tout this -- whenever he GETS here.)

Our kitchen, laundry and a half-bath are at the east end of the house. Our MBR and guest rooms are on the west end.

Chisue, I cannot imagine you ever needing 2 - 50 gallon WH's.
I had 1 for many years and never had a problem with 2 adults and 1 teenager. (2100 sq ft, 2 full baths)
A couple years ago I had to get a new one, and the plumber talked me into a 30 (something) gallon.

I have only had a problem once with running out of hot water. I wanted to take a long hot bath and decided when I got in it wasn't hot enough...so I drained most of it and re-filled. Then SO went upstairs to get a shower and he ran out.
It heats back up very quickly.

I don't know why you would need two hot water heaters for two people in that size house. My house is 4000 sqft and we have one hot water heater and two people. We are never short of hot water unless we run several things at once like the dishwasher and washing machine or shower.
MY Oklahoma house had a small short under counter hot water tank in the kitchen in the corner cabinet beside the dishwasher and the main hot water heater for the rest of the house.

We did have a plumbing company come give estimates which was thousands of dollars. Then we went to Lowes and talked to their plumbing department and got a better lifetime warranty hot water heater and their plumbing company installed it for about half of the price the other company had quoted. We were extremely pleased with the price and the professionals that they sent out. We did have to have a permit pulled from the city for changing the hot water heater, be sure you check that in your city, and everything passed he said it was a very good job.
I had no idea that a permit had to be pulled but the city said any time you touch electrical, plumbing, or gas it must be permitted and inspected for code. And a badly installed hot water heater can be extremely dangerous, it can flood, it can blow up like a bomb and if gas it can kill you with carbon monoxide if not properly vented.

Check Lowes..

I wish I had thankless but they are really expensive. They are really a great way to go in an RV, lots of companies using them.

The only issue with tankless and the distance is you may have to run the water a little longer to get hot water out of the tap. I'm guessing you may have that issue today so it won't be so bad.

You don't need an electrician, per se. the plumber would be the first guy to call. There may be some electrical work involved but it should be minimal if you install a natural gas tankless.

Be sure to check that your Rheem doesn't have a lifetime warranty because many of the better quality name brands are. If you just have to change the elements or the sacrificial rod inside the tank you you may have to pay for parts.
Definitely worth checking out your warranty.

Tankless water heaters are typically more expensive to buy, more expensive to install, more expensive to operate, and may need annual maintenance (to the tune of several hundred $$ per year if your water is even moderately hard). I've attached a photo of an install (just a random one I found by googling) that's gives you a sense of what a more typical setup looks like. In addition to a pressure release line, it usually will have lines and connections to allow the circular pump-through of descaling chemicals required for periodic maintenance.

To have a tankless unit that will supply enough throughput (gallons per minute) to allow more than one connection to run at a time may require something that burns more BTUs than your home furnace. With a water circ system, I think you'd find it very expensive to operate.

I faced the same question and with my plumber's advice decided to stick to gas tank models because it's cheaper. I also have two but not connected in parallel, they serve different ends of the house. Maybe it would work for you to go with one 75 gal unit. The box stores don't sell better quality products, personally I was happy to go with my plumber's recommendation (even if more expensive) to know that he stands behind his installs.

Good luck.

The Plumber Has Arrived!

We've decided to have him change the piping to isolate two tanks (of any size). We will use the one still-functioning Rheem 50-gallon tank -- and the recirculating pump. He will take out the failed tank. We're only gambling an extra service call when this tank fails, and we can see how it goes with one 50-gallon tank.

It was 22F here yesterday and the day before; we'd need a high-BTU tankless unit with a pump -- and maybe a timer. There would be additional installation expense. There is ongoing descaling expense. Maybe it we were young and had time to amortize it...

The tank heaters are 'a known quantity'. They have minimal heat loss in the basement, near the furnace. We already enjoy instant hot water at every tap in the house with the circulator pump. We are used to LOTS of hot water; my jet tub fills in three minutes.

Thank you all so much for helping me prepare good questions before the plumber arrived.

Looking forward to a long, HOT shower tonight! (That's not going to be a jinx, is it?)