Water heater replacement . One or both?

[trueballer]

House with two 50 gallon gas water heaters connected in series. 11 years old. One of the water heaters has a tiny leak at the bottom. Plumber suggests getting it replaced After ruling out fixable causes like drain valve, TP valve, etc. Should I replace both or just replace one and buy some more time with the other one? Obviously, the plumber wants me to replace both.

[bd7]

Well, what would be the cost of doing one vs two? I have two unrelated water heaters (for different areas of the house) and I replaced them both because I got a deal on a 'contractor 2-pack' at Lowes. b/t/w, what does 'in series' mean?

[Watty]

Where they are located and how much damage they would do if they fail is a major consideration.

There are old threads with lots of opinions about when you should replace water heaters that you can look up but I don't recall there being any consensus.

Personally I replace mine when they are maybe 10 to 12 year old at a time that is convenient to me even if they are not failing. Not being in a hurry lets me get several prices and I think I also get a better price when I tell them that I am flexible about when they install it so they can do it as a fill in job when they are in the area.

I don't recall exactly and prices might have gone up but I think my last water heater cost about $1,200. That is only about $100 per year so I am a bit decadent and don't try to squeeze every last year out of it.

I would go on and replace both of them and I would replace both if them even if one was not leaking, but that is just me.

House with two 50 gallon gas water heaters connected in series.

I am not a water heater guru or anything but that is an odd setup.

It might be worth looking into installing a tankless water heater instead if you have a lot of hot water needs

[RetiredAL]

House with two 50 gallon gas water heaters connected in series. 11 years old. One of the water heaters has a tiny leak at the bottom. Plumber suggests getting it replaced After ruling out fixable causes like drain valve, TP valve, etc. Should I replace both or just replace one and buy some more time with the other one? Obviously, the plumber wants me to replace both.

If the 2nd one is leaking change them both. If it's the 1st, well it's doing 90% of the work and the 2nd just 10%, hence the 2nd won't have a ton of scale in it to create hot spots which tend to be the source of tank leaks. That's assuming at the tanks are someplace (like in the garage) where leaking would not be catastrophic.

[privateer79]

to throw some more chaos into the mix:
how about you fix the leaky one, and inspect/replace the sacrificial anode on the non-leaking one? (maybe look at the anode on the failed one too?)

(I didn't even sleep at a holiday inn last night, but I've swapped out a water heater or two)

[EZ James]

Deleted

[EZ James]

Are you sure that the heaters are arranged in series or in parallel ?

I have experience with water accumulating under a WH for a few days then go on for 11 years with no further leaks. Never determined with certainty the source.

Do you really need two 50 gallon tanks? Could you get by with one?

I both tanks are the same model, in parallel and have been in use for the same amount of time I'd expect the non-leaker to fail soon so would opt for replacement of both. This assumes that one is actually leaking and not just appearing to leak due to some other cause like condensate, rain flowing down the exhaust stack or something else.

If they are in series they are operating at different temperatures and will not degrade at the same rate and the preceding does not apply.

[Goal33]

If they’re in series… then bypass the leaking one, uninstall it, and just keep using the one that’s working. Do you need 100 gallons of hot water?

[Valuethinker]

House with two 50 gallon gas water heaters connected in series. 11 years old. One of the water heaters has a tiny leak at the bottom. Plumber suggests getting it replaced After ruling out fixable causes like drain valve, TP valve, etc. Should I replace both or just replace one and buy some more time with the other one? Obviously, the plumber wants me to replace both.

Unless the money is really tight, I would probably replace both at once. The difficulty and hassle of getting a contractor out is sufficient to make me not want to do it again (for at least 10 years).

[hoofaman]

What about replacing both with a single tankless water heater? Is that a viable option in your situation?

[desiboy]

Like OP, I have two water heaters in series. I turned off gas to the first (water inlet) many years ago since we don't need that much hot water. And replaced just the second (hot water out to the house) a few years ago. I figured the first will last quite long as it's not actively heating and serving more as a caching tank!

[trueballer]

Are you sure that the heaters are arranged in series or in parallel ?

I have experience with water accumulating under a WH for a few days then go on for 11 years with no further leaks. Never determined with certainty the source.

Do you really need two 50 gallon tanks? Could you get by with one?

I both tanks are the same model, in parallel and have been in use for the same amount of time I'd expect the non-leaker to fail soon so would opt for replacement of both. This assumes that one is actually leaking and not just appearing to leak due to some other cause like condensate, rain flowing down the exhaust stack or something else.

If they are in series they are operating at different temperatures and will not degrade at the same rate and the preceding does not apply.

I think it is a leak rather than just condensate. I noticed water about 10 days ago, wiped it off, didn’t see any for two days, but then saw some again. Since then, I have been wiping water under the tank a little bit every day or every other day. Same spot at the base of the tank. I don’t think condensate would do that. I can also tell that there is water inside the outer shell of the tank.

Cost is 1800 for one versus, 3600 for two. 5500 square-foot house with five bathrooms. Probably need both.

I have been told that they are connected in series, but I’m not sure and I could certainly be wrong about that.

[lazydavid]

I would replace both, and have them re-piped to be in parallel with independent ball valves on both the inlet and outlet (4 valves total). That way you can take one out of service without giving up hot water.

We did essentially that at our house, though we didn't replace both the first time because one of them was only a year or two old. But it was great when that one needed repairs a few years later, no issue waiting a week for warranty parts to arrive. And when it eventually failed 2 years ago, I could take the old one out myself and wait until it was convenient (read:cheaper) for my plumber to come install the new one.

[lthenderson]

If they are the same model bought at the same time, I would replace both. But if they were bought at different times or different models, I would just replace the one.

[Sandtrap]

To OP:
also have a 5000+ sf hm. + 4 baths etc.

Question:

What about simplifying your system with just 1 water heater at 80 to 100+ gallons?

j

[ralph124cf]

Well, what would be the cost of doing one vs two? I have two unrelated water heaters (for different areas of the house) and I replaced them both because I got a deal on a 'contractor 2-pack' at Lowes. b/t/w, what does 'in series' mean?

"In Series" means that the water first goes into one heater, passes thru that one, and then into the next one, then to the house. Typically, the first heater brings up the water to a lower temperature, like 85-95 degrees, and then the final heater brings the temperature up to the users desired hot water temperature.

[mikep]

Look into a heat pump water heater with the 30% tax credit and if any local utility rebates. You could keep the 2nd one on gas so you never have to run the heat pump one in full electric mode. Also, rebates/tax credits are usually limited to one water heater per address.

[flarf]

Cost is 1800 for one versus, 3600 for two. 5500 square-foot house with five bathrooms. Probably need both.

Number of bathrooms and square footage of the house don't really answer the question of how much hot water you need. How many people are living there? Do they take showers or baths? Do you have low-flow shower heads?

[snic]

Cost is 1800 for one versus, 3600 for two. 5500 square-foot house with five bathrooms. Probably need both.

Number of bathrooms and square footage of the house don't really answer the question of how much hot water you need. How many people are living there? Do they take showers or baths? Do you have low-flow shower heads?

This. My house is almost as large and there was an 80 gallon tank and a 40 gallon tank in series. But I knew from our previous house, which had only a 50 gallon tank, that my family would be fine with that. So when the 40 gallon broke, I just had it removed.

OP, are you sure the other tank is similarly old? It might be much younger. They have manufacture dates on them.

Finally, if you're going to spend $3600 to replace them, you might be able to install a tankless continuous hot water system for about that much or slightly more, which would save some energy. They do seem to require more maintenance than tank heaters, though. Another alternative would be to replace both tanks with a single 80 or 100 gallon tank, assuming you really need one that large. That would be cheaper than replacing both with two tanks.

[wilked]

I would replace both, and have them re-piped to be in parallel with independent ball valves on both the inlet and outlet (4 valves total). That way you can take one out of service without giving up hot water.

We did essentially that at our house, though we didn't replace both the first time because one of them was only a year or two old. But it was great when that one needed repairs a few years later, no issue waiting a week for warranty parts to arrive. And when it eventually failed 2 years ago, I could take the old one out myself and wait until it was convenient (read:cheaper) for my plumber to come install the new one.

This

Piped in parallel is superior than piped in series

I would also ask for tankless to be quoted.

I didn't see it answered - how old are the water heaters? Are they gas-fired or electric?

Did your plumber enquire into your interest in heat pump water heaters? A lot of states are giving big rebates for these. What state are you in?