What kind of advice are you looking for?

Replacing tank with tankless isn't a direct swap-out. Tankless must instantaneously heat the water from cold supply to hot output as fast as the water passes through the unit. They have much larger gas burners than a traditional tank heater, which requires a larger gas supply line to feed it. I don't find a Rinnai EN180EN model on a search. Is it a special model provided to your gas utility partnered with Rinnai? There is an RE180eN model. It has a 180,000 BTU burner.

As Ramona1976 advises, question your gas people on whether ALL of the required updates that may be required to your home are included in the stated cost. A regular 120v electric outlet is also required at the unit to operate the electronics. Recurring flushing is advised to keep the unit clear of accumulated mineral deposits if there isn't a whole-house water softener. Is that service cost covered? Every one to two years is recommended depending on the water and usage conditions.

This is simply a marketing ploy by the utility to sell you something. That’s all. So if a tank-style hot-water heater has served you well up till now, I see no reason to switch to tankless just ’cause. We switched to tankless years ago because it fit our needs much better. Even though we had two water heaters, we had a full house and four bathrooms in constant use so we ran out of hot water a lot. And now with two tankless units we don’t! No reason to spend twice the money (I’ve no idea what a regular tank-style heater costs, but I'm guessing it’s under $1,000) if you don't have to, especially if you’re on a reduced income!

Dena talk with your plumber as to what replacing your hot water heater would cost.

You live alone. I'm assuming you're not taking hot showers while running the dishwasher and washing machine all at the same time? I'm guessing replacing the tank would run you about 1/2 the cost of switching to tankless.

We put in a tankless for space reasons, but the installation was expensive. The gas line also required an upgrade. If you have been satisfied with your current tank then save your money & just replace it.

“Also, a 15 year old tanked installation will need ancillary work to bring it up to code, for any new tank install.“

As usual, nonsense from ”Verbo,” the imposter “pro.”

If the quoted number covers all the costs of installation, it is a decent deal for a tankless hot water heater. The water heater is around $850 and the new gas pipe and venting probably brings the cost to $1000. Scheduled installation at your convenience and 4 years of financing is around $850.  Even if you decide not to switch, you might want to replace your existing unit soon as scheduled work is cheaper and more convenient than waiting until you are trying to find immediate installation when the current one leaks. If your current water heater was only a couple years old, replacement wouldn't be a great deal but yours is old enough I would be concerned.

Yes, it would likely be cheaper to buy a tank and get it installed but you would have to check the going price for a professional installation. In my area, a handyman charges $350 to $400 plus materials to deliver and install a new hot water heater. The guys who just did my furnace work said they get $500 to $600 plus the cost of the unit. Energy costs won't be getting any cheaper in years to come and for low volume users, energy cost is estimated to be about a third cheaper than a tank model. If you can save $5/month, that is $240 over the 4 years of payments. In addition, tankless model save space so if you need extra storage, a tankless unit would free up quite a bit of space. In some houses, the new storage space would be worth the cost before discussing energy costs.

If I were in your situation I would stick with the tank heater. We have a propane Rinnai tankless. It does need descaling periodicially. We do not have hard water so we can get away with doing it every 2 years. We do it ourselves. We have also had problems with bugs getting into the fan in the unit. One little bug stuck in the fan blade caused cold water in the middle of a shower and the tankless throwing error codes. The first time it happened we had no clue what the problem was. Had to call someone out. First guy was incompetent and said it was just a blip in the gas. Finally got someone out that knew what they were doing. It was a small bee stuck between one of the fan blades. Have lived here 5 years and it has happened 3 times now. After the first time we just take care of it ourselves. Ours is indoors so we have a vent and that is how the bugs get in. Not sure if this would be a problem with an outdoor tankless. Just some things to think about.

I have personally owned a tankless for 27 years. I have saved over 15K over that time from a traditional tanked. That includes the approximately 2-3K savings for each of the new installation of 2 new tanked water heaters, as a typical lifespan for a tanked is 12-15 years. With correct maintenance, a tankless is easily a 40 year heater. I know of one that is 47 years old.

Tankless acquisition and installation costs is typically double the costs of traditional tanked. Typical permitted tanked aquisition and installation costs in my area are around $2200 for a tanked, and around $3600 for tankless. Yes, the permitting costs, plus new earthquake strapping and elevation requirements, as well as the plumbed route to a drain for the T&P catch basin typically does increase the costs for an install. It is not just a change from one to another, tank for tank. Same with the change to a tankless from a tanked. It isn’t plug and play. There is additional work required to do that, which is why it’s typically double the costs of a tanked install.

I work with plumbers regulary for these installs, as part of bathroom renovations and updates. Going tankless is an especially desirable update for those with new baths who don’t want to run out of hot water when showering, or don’t want to worry about insufficient capacity to fill a soaking tub. It is worth it for 90% of the people considering it for replacing an older gas water heater. It is never worth it for electric tankless.