Armed Polite Society

Please login or register.

Login with username, password and session length
Advanced search  

News:

R.I.P. Scout26

Pages: [1] 2

Author Topic: Opinions on tankless water heaters  (Read 565 times)

MillCreek

  • friend
  • Senior Member
  • ***
  • Posts: 16,789
  • APS Risk Manager
Opinions on tankless water heaters
« on: January 28, 2021, 03:50:01 PM »

It has been a while since the last discussion of tankless vs. tank water heaters.  Perhaps the technology is so mature that nothing changes.  We are five years into our Rheem gas water heater and I am pondering when it comes time to replace: tankless vs. a new tank.  It would be propane powered.  I have never owned a tankless water heater and have little idea of the pros and cons.  I ask the Collective to edumacate me.
_____________
Regards,
MillCreek
Snohomish County, WA  USA


Quote from: Angel Eyes on August 09, 2018, 01:56:15 AM
You are one lousy risk manager.

Nick1911

  • Administrator
  • Senior Member
  • *****
  • Posts: 7,493
Re: Opinions on tankless water heaters
« Reply #1 on: January 28, 2021, 03:53:36 PM »

Only 5 years in?  Come ask in 2030 or so.  =)

I've installed a few for customers.  I don't think I'm ready to put one in my house, it's a lot of complexity - a lot that can go wrong which my old gas water heater doesn't have.

Installing them can be a pain, high efficient gas models require access to everything - hot and cold water lines, drain, 120v power, natural gas, and a new flue + combustion air intake venting.

Brad Johnson

  • friend
  • Senior Member
  • ***
  • Posts: 15,705
  • Witty, charming, handsome, and completely insane.
Re: Opinions on tankless water heaters
« Reply #2 on: January 28, 2021, 04:18:04 PM »

Pro: They're great if you need endless hot water or don't have space for a traditional water heater. You don't have the standby losses of keeping water hot when there's no demand.
Cons: Depending on energy type, size, and mfg, they can be horrifically energy inefficient compared to modern water heaters in terms of BTU per degree per gallon. (i.e. - Some are pretty decent. Some suk bawls.) They also must be flushed regularly, usually yearly, to combat scale buildup. Finally, they can ultimately be more expensive to purchase compared to a traditional water heater because and retrofitting for one can get spendy.

In general, if you use hot water several times a day but don't need an endless supply, a traditional water heater is likely a better solution. It's cheaper to buy, simpler to install and maintain, and more financially viable overall.

However, if you have a scenario where hot water is needed only occasionally (maybe every few days), or regularly need amounts in excess of what a traditional water heater can supply, then a tankless unit may be a better solution. Just realize that retrofitting for one varies from expensive to 'Damn!', and annual maintenance is an absolute requirement if you want them to last and/or maintain efficiency.

Austin builder Matt Risinger has a good "what to consider" video on tankless vs. traditional.

https://www.youtube.com/watch?v=8RFuFBI3r2c

*edit to add* Forgot to mention how critical knowing your water supply temp is when sizing a tankless. You absolutely must know your water supply temp if you are to get a properly sized unit. There is a finite input/output temp rise for a given BTU heater. If you don't account for the intended delta, it's way easy to undersize the unit. That endless supply doesn't mean much if it's only lukewarm. My sister and BIL found that out the hard way. Ended up having to install additional circuits for a larger unit, and that was on top of the retrofit costs already incurred.

Brad
« Last Edit: January 28, 2021, 04:52:45 PM by Brad Johnson »
It's all about the pancakes, people.
"And he thought cops wouldn't chase... a STOLEN DONUT TRUCK???? That would be like Willie Nelson ignoring a pickup full of weed."
-HankB

Boomhauer

  • Former Moderator, fired for embezzlement and abuse of power
  • friends
  • Senior Member
  • ***
  • Posts: 12,936
Re: Opinions on tankless water heaters
« Reply #3 on: January 28, 2021, 04:29:51 PM »

I had one in my first house took a long time to get the hot water to the faucet but once it was there it was great. I didn’t have to install it or pay for the propane so for me it was a good deal.

Quote from: Ben
Holy hell. It's like giving a loaded gun to a chimpanzee...

Quote from: bluestarlizzard
the last thing you need is rabies. You're already angry enough as it is.

OTOH, there wouldn't be a tweeker left in Georgia...

Quote from: Balog
BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! AND THROW SOME STEAK ON THE GRILL!

MillCreek

  • friend
  • Senior Member
  • ***
  • Posts: 16,789
  • APS Risk Manager
Re: Opinions on tankless water heaters
« Reply #4 on: January 28, 2021, 04:41:47 PM »

Brad, noting your comments about scale, we are on a well.  The well water does have some degree of mineral content and we see limescale buildup due to the calcium content.  We have little, if any, iron in the water. Does that change your thoughts?
_____________
Regards,
MillCreek
Snohomish County, WA  USA


Quote from: Angel Eyes on August 09, 2018, 01:56:15 AM
You are one lousy risk manager.

Brad Johnson

  • friend
  • Senior Member
  • ***
  • Posts: 15,705
  • Witty, charming, handsome, and completely insane.
Re: Opinions on tankless water heaters
« Reply #5 on: January 28, 2021, 04:47:03 PM »

Brad, noting your comments about scale, we are on a well.  The well water does have some degree of mineral content and we see limescale buildup due to the calcium content.  We have little, if any, iron in the water. Does that change your thoughts?

If you already experience visible lime and calcium scaling, you may want to up the flush schedule to semi-annually. From what I see and read, tankless units are hella sensitive to scale buildup. The flush process isn't complicated, but at $125-ish a pop the kits aren't cheap and the process is time-consuming. The channel I linked above has a video on the flush procedure.

Brad
It's all about the pancakes, people.
"And he thought cops wouldn't chase... a STOLEN DONUT TRUCK???? That would be like Willie Nelson ignoring a pickup full of weed."
-HankB

Jim147

  • friends
  • Senior Member
  • ***
  • Posts: 5,700
Re: Opinions on tankless water heaters
« Reply #6 on: January 28, 2021, 05:06:28 PM »

I've worked on and installed several. Outside of a rarely used weekend cabin or a restaurant I haven't really seen a need for one.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

RocketMan

  • Mad Rocket Scientist
  • friend
  • Senior Member
  • ***
  • Posts: 11,015
  • Semper Fidelis
Re: Opinions on tankless water heaters
« Reply #7 on: January 28, 2021, 07:59:43 PM »

We've had a Rinnai tankless water heater for a few years now.  It uses natural gas for the heat source and also requires 120VAC for the control circuits.  We love the darn thing.  It heats water quickly to the set temperature and doesn't have any problem with colder winter feed water temperatures.
Our unit was about $1200 if I remember correctly, and the plumbers charged us $800 to install it, including all exhaust venting.  Of course, we did get the family rate on that since the plumbers were my stepson's inlaws.  It also helped that I had previously replaced all the copper water pipe with Pex pipe and fittings.
The tankless heater replaced a standard 40 gallon electric water heater, so we saw our electric bill go down.  The natural gas bill went up a bit, but the decrease in the electric bill was substantially more.  It's paid for itself by this point.
“Don’t be so open-minded that your brains fall out.” - G.K. Chesterton

Conservatives see George Orwell's "1984" as a cautionary tale.  Progressives view it as a "how to" manual.

My wife often says to me, "You are evil and must be destroyed." She may be right.

How many Democrats does it take to fix a problem?  No one knows because it's never happened.

zahc

  • friend
  • Senior Member
  • ***
  • Posts: 5,211
Re: Opinions on tankless water heaters
« Reply #8 on: January 28, 2021, 10:07:21 PM »

They work, but aren't worth it. Expensive to install, prone to being installed incorrectly, expensive to fix, require maintenance. Why not just get a tank type that sits there and just works. For what I paid replacing the cracked manifold on my Rinnai, I could have just converted back to tank type almost twice over.

If you cannot spare the space for a tank or otherwise have no choice then sure, they do work. Just double-check the requirements for gas line size, pressure, max run, ambient temperature, water temperature, water hardness, and if mounted outside, don't forget freeze protection and protection for the freeze protection in case of power outages.
Maybe a rare occurence, but then you only have to get murdered once to ruin your whole day.
--Tallpine

sumpnz

  • friend
  • Senior Member
  • ***
  • Posts: 6,169
Re: Opinions on tankless water heaters
« Reply #9 on: January 28, 2021, 11:08:02 PM »

What’s the expected life span of a traditional electric water heater given typical lax maintenance and well water (high iron content)?  Is my 16-17 year old heater’s fuse about done?

MillCreek

  • friend
  • Senior Member
  • ***
  • Posts: 16,789
  • APS Risk Manager
Re: Opinions on tankless water heaters
« Reply #10 on: January 29, 2021, 08:38:18 AM »

In our previous house, we had a builder-grade electric water heater with a five year warranty.  It lasted for 15 years before springing a leak.
_____________
Regards,
MillCreek
Snohomish County, WA  USA


Quote from: Angel Eyes on August 09, 2018, 01:56:15 AM
You are one lousy risk manager.

K Frame

  • friend
  • Senior Member
  • ***
  • Posts: 34,696
  • I Am Inimical
Re: Opinions on tankless water heaters
« Reply #11 on: January 29, 2021, 10:07:50 AM »

What’s the expected life span of a traditional electric water heater given typical lax maintenance and well water (high iron content)?  Is my 16-17 year old heater’s fuse about done?

Well, a lot would depend on the quality of the water heater to begin with. A "9 year" water heater has a better anode and better interior coatings than a "5 year" model.

The easiest way to make a water heater last a LOT longer?

Replace the anode rod regularly.

In your case? You're likely on borrowed time.

A quick way to find out the state of your water heater is to drain a few gallons of water out of the bottom drain and into a bucket. Then leave it settle and look for rust flakes.

If you find rust, start planning on a replacement now. Not later.
Carbon Monoxide, sucking the life out of idiots, 'tards, and fools since man tamed fire.

JTHunter

  • friends
  • Member
  • ***
  • Posts: 144
Re: Opinions on tankless water heaters
« Reply #12 on: January 30, 2021, 12:15:33 AM »

Don't you have to increase the diameter of the pipes feeding gas (natural or propane) to a tankless due to the higher fuel requirements?
“I have little patience with people who take the Bill of Rights for granted.  The Bill of Rights, contained in the first ten amendments to the Constitution, is every American’s guarantee of freedom.” - - President Harry S. Truman, “Years of Trial and Hope”

Jim147

  • friends
  • Senior Member
  • ***
  • Posts: 5,700
Re: Opinions on tankless water heaters
« Reply #13 on: January 30, 2021, 07:53:50 AM »

Depends on what is there but yes they need to be sized to the water heaters demand.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

RocketMan

  • Mad Rocket Scientist
  • friend
  • Senior Member
  • ***
  • Posts: 11,015
  • Semper Fidelis
Re: Opinions on tankless water heaters
« Reply #14 on: January 30, 2021, 09:55:01 AM »

Depends on what is there but yes they need to be sized to the water heaters demand.

We've got a half inch copper tap off the main NG line feeding our Rinnai tankless.  It's the smallest gas line in the house.
“Don’t be so open-minded that your brains fall out.” - G.K. Chesterton

Conservatives see George Orwell's "1984" as a cautionary tale.  Progressives view it as a "how to" manual.

My wife often says to me, "You are evil and must be destroyed." She may be right.

How many Democrats does it take to fix a problem?  No one knows because it's never happened.

Jim147

  • friends
  • Senior Member
  • ***
  • Posts: 5,700
Re: Opinions on tankless water heaters
« Reply #15 on: January 30, 2021, 10:07:14 AM »

Yeah it's a bunch of math to figure out. Start at the meter and end at the last leg. And up all appliances on each run and go from there.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

MillCreek

  • friend
  • Senior Member
  • ***
  • Posts: 16,789
  • APS Risk Manager
Re: Opinions on tankless water heaters
« Reply #16 on: May 02, 2021, 10:42:12 AM »

14 months after the Rheem gas heater needed a new flammable vapor sensor, for $ 265, the exact problem occurred again.  I did the software reset and it did not work.  Just like the first time, and again indicating a hardware problem with the vapor sensor. 

So I called the plumber and learned some interesting things:

Our Rheem unit is six years old, the same age as the house, and it has a six year warranty.

The plumber agrees that it does not make sense to put more money into a tank that is likely at the end of its service life.

He is not a fan of the Rheem products, and it would cost about $ 3200 to replace the existing unit with another Rheem or another gas equivalent

He too is on propane tanks and well water, and a couple of years ago replaced his tank with a Noritz EZ111 tankless water heater as a test.  The EZ111 has the water connections on the top, as does a tank, making the install much easier.  He is a real fan of the Noritz unit in terms of durability as long as you drain and descale it once a year.  He says the Noritz has a higher upfront cost by several hundred dollars, but you will see a payback in the lesser amount of propane used, since the tankless is not constantly cycling a propane burn on and off to keep 50 gallons of water at temperature.

So I signed us up for the Noritz install.  It should be in stock at the Seattle plumbing supply house, so we should have a new water heater by the middle of this week.
_____________
Regards,
MillCreek
Snohomish County, WA  USA


Quote from: Angel Eyes on August 09, 2018, 01:56:15 AM
You are one lousy risk manager.

MillCreek

  • friend
  • Senior Member
  • ***
  • Posts: 16,789
  • APS Risk Manager
Re: Opinions on tankless water heaters
« Reply #17 on: May 02, 2021, 06:51:58 PM »

Out of curiosity, I looked up the same model of Rheem water heater that we have.  Home Depot sells the same 50 gallon power vent tank for just under $ 1200 out the door.  In reading further about power vent gas water heaters, they cost 50 to 75% more than a direct vent model, is more expensive to install, and six years warranty is considered top of the line.  Also of interest are the many negative comments about the flammable vapor sensor, including some cases in which a newly-installed unit has this error code immedately on start up.  When this problem first happened 15 months ago, i remember thinking how odd it was that the majority of the plumbers I called said they do not work on Rheem units.

This is the first gas water heater I have ever had.  I now realize how easy it was to maintain and replace the electric units I had before.  If I had an electric water heater breaker in the panel and circuit in the garage in the right location, I would just go with an electric heater.
_____________
Regards,
MillCreek
Snohomish County, WA  USA


Quote from: Angel Eyes on August 09, 2018, 01:56:15 AM
You are one lousy risk manager.

Jim147

  • friends
  • Senior Member
  • ***
  • Posts: 5,700
Re: Opinions on tankless water heaters
« Reply #18 on: May 02, 2021, 07:27:52 PM »

Looks like I need to up my install charges again.
Sometimes we carry more weight then we owe.
And sometimes goes on and on and on.

BAH-WEEP-GRAAAGHNAH WHEEP NI-NI BONG

cordex

  • Administrator
  • Senior Member
  • *****
  • Posts: 5,899
Re: Opinions on tankless water heaters
« Reply #19 on: May 02, 2021, 09:05:30 PM »

This is the first gas water heater I have ever had.  I now realize how easy it was to maintain and replace the electric units I had before.  If I had an electric water heater breaker in the panel and circuit in the garage in the right location, I would just go with an electric heater.
I have had a gas water heater in my current house for 14 years.  It is (as far as I can tell) the original cheap contractor model installed when the house was built 17 years ago.

So far I have had to replace the pilot light sensor once.

In my new house I'm going to have an electric hot water heater ... I was just thinking how that was going to add to my maintenance load.

K Frame

  • friend
  • Senior Member
  • ***
  • Posts: 34,696
  • I Am Inimical
Re: Opinions on tankless water heaters
« Reply #20 on: May 04, 2021, 08:17:00 AM »

"In my new house I'm going to have an electric hot water heater ... I was just thinking how that was going to add to my maintenance load."

Are you also going to have an electric cold water cooler?

And, having had electric water heaters all of my life, I'm trying to figure out how one will add to your maintenance load.

Pretty much everything you have to do for a gas water heater you have to do for an electric water heater.
Carbon Monoxide, sucking the life out of idiots, 'tards, and fools since man tamed fire.

Brad Johnson

  • friend
  • Senior Member
  • ***
  • Posts: 15,705
  • Witty, charming, handsome, and completely insane.
Re: Opinions on tankless water heaters
« Reply #21 on: May 04, 2021, 11:07:40 AM »

I still prefer gas water heaters, mostly for the ability to continue supplying hot water during a power failure (callback to our local energy provider's new ERCOT affiliation). Doesn't hurt that natural gas is dirt cheap around here.

Brad
It's all about the pancakes, people.
"And he thought cops wouldn't chase... a STOLEN DONUT TRUCK???? That would be like Willie Nelson ignoring a pickup full of weed."
-HankB

K Frame

  • friend
  • Senior Member
  • ***
  • Posts: 34,696
  • I Am Inimical
Re: Opinions on tankless water heaters
« Reply #22 on: May 04, 2021, 11:13:47 AM »

I'd love to have a gas water heater.

They're cheaper to operate, SOME of them will work even with a power outage (models that require 120 volt for venting are becoming increasingly common), and they recover a lot faster.
Carbon Monoxide, sucking the life out of idiots, 'tards, and fools since man tamed fire.

charby

  • Necromancer
  • Administrator
  • Senior Member
  • *****
  • Posts: 27,397
  • APS's Resident Sikh/Muslim
Re: Opinions on tankless water heaters
« Reply #23 on: May 04, 2021, 11:43:59 AM »

I wanted a gas tankless for years, the more I read about them, I don't want them for my house. I look at the cost and the life, I'm having a hard time penciling the fuel savings vs replacing my current setup.

Currently I have a 17 year old 40 gallon tank water heater. I'm probably just going to upgrade it to a 50 gallon water heater sometime in the next six months. I see that the local big box lumber yard/hardware store has a 12 year 50 gallon non power vented water heater for ~$650. They ain't nothing to install for me.
« Last Edit: May 04, 2021, 11:57:54 AM by charby »
Iowa- 88% more livable that the rest of the US

Uranus is a gas giant.

Team 444: Member# 536

cordex

  • Administrator
  • Senior Member
  • *****
  • Posts: 5,899
Re: Opinions on tankless water heaters
« Reply #24 on: May 04, 2021, 11:50:35 AM »

And, having had electric water heaters all of my life, I'm trying to figure out how one will add to your maintenance load.

Pretty much everything you have to do for a gas water heater you have to do for an electric water heater.
I've helped replace a number of comparably new failed electric units for friends and family but my gas unit has been very reliable and low maintenance with the exception of the $6 thermocouple I replaced.  I could be entirely wrong - just going on what I've seen.
Pages: [1] 2