The tankless will give you 25-30% reduction in the cost of hot water over a standard tank gas water heater. And, in most parts of the country, gas is less than electricity.

With rebates and tax credits, the package can be attractive.

Something that you would have to figure into the cost of a standard gas tank heater is the cost of a flue (or a powervent unit A powervent water heater will cost about the same as a tankless.)

The unit you have linked to has a BTU rating of 190,000 and costs about $800. I think a comparable tankless unit would be the Rheem units. They have a unit that falls on either side of the unit that you linked to. Their 53 is 142,000 BTU and is $670, the 74 is almost 200,000 BTU and is $890. I have the Rheem 42 and have been happy with it. Other than that, I would buy the one that is the best size for your situation.

In order to know what size tankless unit to buy, you need to know water temp in the winter and the total GPM that you need to supply at one time. (a shower is about 2.5 a bathroom faucet is about 1 gpm, Kitchen sink 1.5 gpm, tub is 3-4 gpm, standard washing machine is 2-4 gpm)

There is a slight delay in getting hot water with a tankless. It generally adds a few seconds on to your wait for hot water. It's usually not a big deal, but you should be aware of it.

I think that you would do fine with a gas tankless water heater. If it is sized properly, the unit that you linked to should be fine.

Here is a link that might be useful: Rheeem gas tankless

GPM at most usage points is relative to how wide-open is the faucet. I've never run my shower at full-open, it's not necessary, about 1.5 GPM does me fine. I have my washer's tap turned down to 2 GPM.

Putting a tankless unit outdoors is only practical in a climate that doesn't experience freezing temperatures in winter. I don't think New Jersey fits that description.

I do love my tankless heater, but retrofitting one in an existing home is quite the expensive proposition when you have to pay to have it done. Usually, the payback time for the price difference between a traditional tank heater and a tankless is in the decades. Utility rebates and tax credits certainly impact that, but get a realistic bid from a plumber for the whole job, not just the water heater. It's the venting and installation of a proper sized gas line that is the expensive part. The product itself is cheap when compared to that.

The OP indicates that she is in Florida, Zone 9.
Should be fine with the outdoor mount. Winter water temps shouldn't be too extreme either.

I agree that they should price it installed, however, it looks like the vent is taken care of and gas line doesn't seem to be a big deal since she is installing it now. (OP should be sure to mention the tankless heater to the gas co. before the service goes in)

My retrofit on a 90 year old house was smooth and easy. I did do it myself, but if I had paid for it, it wouldn't have been terrible. I was able to vent through the wall and the gas line was about 20 ft total. They sold a vent kit that provided everything for a basic through the wall venting.
To bring my existing heater up to code, I would have had to install a flue inside the masonry chimney or go with a powervent.

The OP doesn't have an existing vent. She would have to pay for a vent through the roof or pay for a powervent water heater to go through the wall. The powervent water heaters cost as much as the Tankless.

Thanks all of you for responding. I am in FL so I don't think temperature will be a big issue. The utility company will bring the gas from the street to the house for free as long as I hook up at least two appliances (no problem!). There is a $550 rebate for a gas heater (either kind), $100 rebate for range, and $100 for dryer. Then, it's my understanding there is also a $300 federal tax credit for the tankless heater.

I got one estimate so far at just over $1M for all the house piping with vent (not including he actual water heater). There is a program where the price of the water heater gets put on the bill and I can pay $25 for that each month (for five years - lol!) or just pay the whole thing outright. There is some electricity to hook up but my electrician thinks that will be a piece of cake.

I am getting another estimate. After talking to the second contractor, I am actually now thinking of putting the tankless in the attic. I have to get a vent up there regardless of whether I get the Lowboy or the Tankless - it's just that the tankless vent is more expensive. I have no idea how a Lowboy will be able to get lifted into my attic or how the old one is getting out (at least in one piece!). I am moving away from the Tankless outdoors because of the "unsightly" pipe that needs to go from the meter up the side of the house into my attic.

I am usually skeptical about such newfangled (just joking) things, but when I lived in Europe, everybody had this kind of tankless heater and there were no problems(and that was 40 years ago!). We are trying think green and I think this is definitely in that category.

I'm sorry, there are a couple of things that aren't clear from your last post:

You said that you got a quote of "$1M"(!?!) Surely you don't mean $1 million!

I don't know the particulars of your installation, but the least expensive way to vent a tankless (besides the outdoor model) is to vent through the sidewall of the house. The vent is then very short and inexpensive. Probably the most expensive way to vent a tankless is through the roof because it is a long vent.

If the house doesn't have a basement, often the tankless heater can be mounted on a garage wall and then vent through the wall. Where is the current heater located?

"I am moving away from the Tankless outdoors because of the "unsightly" pipe that needs to go from the meter up the side of the house into my attic." -- I don't understand this... Why wouldn't the gas line go in the wall along with the rest of the plumbing?

No water heater is maintenance free -- for that reason, I would think that putting the heater in the attic may not be the best solution. Dust, temp extremes and potential damage from leaking are also considerations. You may also run into code issues.

As you have suggested, this technology isn't new, it has been used in Europe and Japan for a while. In fact, most of these units come from Japanese manufactures.

The only brand that I'm aware of that has had significant issues is Bosch. Based on feedback, I wouldn't recommend that brand. They have a unique design that has been problematic.

jake, thanks for taking the time to answer me!

lol! Sorry about the typo - I meant $1K!

It is a one story house with no basement. My current electric water heater is in the attic and if I decide to go with a gas lowboy that will be in the attic too.

Re my comment about the unsightly pipe running up the side of the house to the attic: I was confused about this too. My main water pipe from the street is on the east side of the house - the gas line will come in on the west side of the house. So (if I am understanding correctly) what they will do is extend the water pipe (currently hooked to the electric water heater in the attic) across the attic and down to the tankless unit on the west side of the house and then back up again along with the gas pipe. Does this make sense? I admit I am having trouble understanding how the water part of this works.

Re venting: If I locate the tankless unit in the attic, I doubt I could vent to the side of the house - that would require about 15 feet of pipe to get to a side wall when the roof is, oh, so close. I wonder if the vent can be elbowed toward the back part of the roof and not the street side of the roof. I don't want to see the vent from the street!

I doubt if there are any code issues about putting the water heater in the attic - all this would be done with city permits. About the water heater being in the attic - well I currently have a 40 gallon electric water heater in the attic in addition to my air conditioning unit being up there too! Scary, right? A tall person can stand up in the attic so it's not that bad to work up there.

My DH was wondering if the water heater could be installed in the laundry closet on the main floor of the house right above the washer and dryer. That would solve a lot of problems, wouldn't it?

I am starting to lose steam on this project. I can live with the electric water heater and the electric dryer. But, I just want to be able to boil water properly which I can't seem to do on my electric stove! I swear a propane tank outside near the kitchen could solve that problem quite easily!

Don't get discouraged, it will be fine.

You can go through the roof or sidewall. If the roof is closer, great. The thing that affects price the most is the length of the vent pipe. A long vent pipe gets expensive. If it will go in the attic, fine. You probably want a drain pan under it anyway.

It could go in the laundry room. The room should be vented to allow for combustion air (you need it for the dryer also). I'm guessing it already has louvered doors or similar. The only downside is that the heater can make some noise. If that's not acceptable, stay with the attic idea.

You will like a gas stove. What kind are you getting?

I forgot about the noise that the heater would make. Kind of like a whooshing, furnace like sound, right?

We are now leaning towards putting the unit in the attic. I am going to call the Fire Department today to find out if they have any objections or advice about the tankless WH in the attic. I obviously want it to be as safe as possible.

Re the stove: I am planning to get a KitchenAid Architect II series stove with convection. We had a KitchenAid in the past and I was very happy with it.

There is a sound of relays when it kicks on and then the fan.
It's not bad in the basement or garage, but not good if near a living space.

I did look through the manual on the Rheem for anything mentioning max environmental temps, not installing it in an attic, etc. and didn't see anything. Any other issues regarding installation in the attic would be local plumbing codes. Your plumber should know that information.

The stove sounds great. You will like it.