Tank Water Heater vs. Tankless Water Heater

14 years ago

Recently, while doing my "bi-decade" home inspection of all parts big and small of the house, I ran across our 17yr old hot water tank (A.O. Smith 40/G NG). There seemed to be some weird funkiness to the tank and it got me to think that I should replace it. After doing some research, I found that maybe I should have replaced that thing about 7yrs ago (which partially explains my cold showers ... the other part belongs to my wife ... anyway).

So, more research. I didn't find any tank water heaters that qualified for the 30% Energy Star initiative (best I found was .70EF). What I did find, which surprised me, were plenty of tankless that did qualify for the credit. More research...and narrowed it down to a brand called Navien and model NR-210A.

So, calling my local plumber(s), I wanted job quotes for: 1) install / replace tank water heater with one of the .70EF models ... and ... 2) install / replace to Tankless Navien. Here's where it gets ugly.

1) house was built in 1993, fist owner. Since it was built in 1993, the codes were different. For me to install a new tank HWH would require the company to install a square cement wall around the unit and deepen the ditch (it's in a "half" crawl space with 6' height). The existing unit is 48" and newer units are taller. BLUF: to replace with a .7EF HWH, 12yr warranty, do the install with construction will cost me about 3k and no 30% Fed Credit.

I've had 3 companies come out and they won't touch it without the modifications. My 3k quote was the low quote (I won't even suggest what the others were). From all the research I did, the Nevien consistently hit the top of the charts as it relates to EF and warranty (my 2 criteria). I provided each company with my research. I got responses from my research: from dumbfounded - never heard of companies like Navian or Noritz or Paloma ... to stunned happy surprise that a consumer did research. My research was done not on company market fluff, but the governments Energy Star program. As of right now, there are ZERO tank HWH's that qualify for the credit.

2) for 3.3k, I get a new Navien NR-210A (bells/whistles), .98EF and installation of circulation T's at the long runs on external circulation, 15/5yrs warranty ... and the 30% Fed Credit. To me it was no brainer. More efficiency, less cost overall after credit.

My math:

Standard tank: 3000.00

Tax Credit: 0.00

TOTAL: 3000.00

Tankless: 3300.00

Fed Tax Credit: 990.00

State Rebate: 199.00

TOTAL: 2111.00

Delta: 889.00 savings going tankless, + reduced gas costs.

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Comments (4)

brickeyee
14 years ago
"Standard tank: 3000.00 "

That is an outrageously expensive water heater.

Did they gold plat the inside of the tank for corrosion protection?
0
greenerremods
14 years ago
If it didn't include delivery and 2 years of free gas, tell'm to take a hike.
0
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Be careful with the first hour ratings. On a 100 gal tank you will get about 70-75 gallons of hot on that first load. You then get the balance of the first hr rating over that first hr. For the kind of lay-out you suggest I think you should split the house up into two systems and try to centralize each tank to its load. That minimized pipe losses with the recirc, and yours will be substantial. The very best recirc system is the Metlund Design system. It complies best with all the new Title 24 regs. You will need 3/4" insulation on your hot piping. Again T24. Be very careful with the pex sizing. I re-piped with Uponor and the brass fitting here in the Foothills of N CA. There is a bushing affect on the fittings. The ID of 1/2" is 3/8, 3/4=9/16 and 1" is 13/16. It does make a difference. I have a couple faucets I was surprised how poor the pressure is on my current well 40-60 psi set-up. I had intended to go to a constant pressure well pump but now will definitely do so. Everything is good about the 50 psi range. Not so at 40# I am a fan of tankless. I represented a major manuf of tankless for 20 yrs. As far as your suggested products I will only suggest that you avoid Bosch. They, imho, do not have the right technology. Your first step regardless of what you do for equipment is a thorough water test. Manuf of tankless have to list annual cleanings for maintenance, but I had one unit for 12 years and never touched it. It was a pre-production model and I had to replace it prior to selling the house. I cut it in half and it was as clean as a whistle. Many of your plumbing questions and answers begin with the compete water test. Tankless (2) could handle your loads until you bring the tubs into play. They represent a massive load, even for your Vertex's. To handle your tub flows you should have two units on each side of the house. The thing about the tankless is they will each make your 7 or so gpm 24 hrs per day, but 135/7=about a 18-20 min fill. Will you wait that long for your bath. I have a bath fill controller on my tub. I set it at 104 and 35 gal (the vol of my tub) and it will deliver 35 gal of 104* water and shut off the hot and beep to tell me my bath is ready. Pretty cool actually. Your shower should be okay with one tankless, but your shower head(s) must fall within the flow capacity of the water heater. I can go on and on with this topic. Get your water tested and report back. That should be step one regardless of what your are doing.
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There is a LOT of disinformation on these forums about on-demand tankless units, ESPECIALLY the electric units. First, energy cost savings is NOT a reason in itself to make the switch. No reason alone is sufficient. It is the total package, in light of your particular lifestyle, that will dictate the pro-con outcome of the decision making process. First, tankless units save space -- a lot of it, especially electric units that do not need to be vented. In Texas we have no basements, so that can be an important issue. Second, an electric unit is unlikely to blow up, unlike anything using natural gas. Third, there is an endless supply of hot water, which in a successive-morning-shower household like mine, is a really important issue. And finally, yes there is some documented comp fuel savings (electric tankless over electric tanks, or gas over gas), that is really offset by the added initial cost of the unit plus upgraded electrical service or gas supply line sizing. Moreover, there ARE full-house electric units out there that provide plenty of water, unless you plan on taking two showers simultaneously while also doing your laundry and running the dishwasher! And if that's your bag, you can run 2 or more electicals together. Or get a really big gas unit. Bottom line, nearly every nay-sayer of tankless units ignore the pros and focus on a single con - cost, cost, cost. Well, we all don't drive a Ford Focus for a reason. Some of us enjoy our Buicks, Porsches or Camrys even though another car would get us from point A to point B cheaper while using less fuel etc etc etc. Full disclosure: I have a Steibel Eltron Tempra 36 whole-house electric unit. Love it. My electric bill went up nary at all.
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impliedconsent
Original Author
14 years ago
Most of the cost was not the tank, but the construction they would have to do to get it to code. I'm not clear on exactly what the spec's of the code are; however, it involved creating a 4" minimum width, 4sided-concrete wall. They said because of the height of the 6' crawl space, they would have to dig a ditch deeper (certain spec) to comply with vent angles, etc...

I'm not a plumber, but 3 separate companies wouldn't touch a normal tank install without doing the modifications. Tankless: mount, hook-up, done. (I have a 1" gas main into the house, made it easier).
Vith
9 years ago
last modified: 9 years ago
Guys if you read the post, the reason the tank water
heater was so expensive was due to the construction required to get his
house up to code. I personally like my tank heater.

If your changing from a tank to tankless there is alot of work to do.
Moving water lines, moving gas lines (possibly upgrading gas line size
too) and running a new intake/exhaust if using gas, upgrading the main
service amps if using electric.

Some things to consider

Tank Heater

Pros
1. Costs less to replace in the future
2. Easier to maintain (Tank water heaters are easy to flush out
  every year)
3. Easier to install (dont have to upgrade gas line or main service amps)
4. Gas water heater will still operate in power outage (electric will still have some hot water to use for a while till power kicks back on).
Cons
1. Not as efficient as tankless
2. No Tax Credits
3. Hot water limited by FHR (first hour rating)
Tankless Heater

Pros
1. Unlimited hot water
2. More efficient
3. Saves space
Cons
1. Will cost more in the future to replace (there is no guarantee the tankless will last longer
  than a tank version, the heat exchanger can go bad and that is the most
  expensive part of the tankless) ,
2. Harder to maintain (you need to try to clean
  those tankless heaters out every year with a descaler so they stay
  working efficiently)
3. Harder to install (upgrade gas line or main service amps)
4. Tankless heaters have a limited throughoutput. While it is unlimited hot water, it can only supply so many gallons of hot water at a time
5. Will not operate in a power outage. A tankless water heater is controlled by electronics whether the heater is gas or electric does not matter.
6. Requires minimum gallons per minute from city water supply, some people have not been able to install due to that problem.
7. Consumer reports note that users complain of inconsistant water temperatures. http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm
Another good site to look at: http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/tankless-water-heaters.html

Tank Water Heater vs. Tankless Water Heater

Comments (4)

brickeyee

greenerremods

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Tank Water Heater vs. Tankless Water Heater

Comments (4)

brickeyee

greenerremods

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Vith

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