Tankless Water Heaters any good?

jdgarza_tx · Aug 30, 2006

Anyone have any experience good/bad with tankless water heaters. I am considering installing one to replace my existing conventional water heater.

Any brands to stay away from or any brand that is known for it's quality?

I am looking for a good quality Electric water heater.

Thanks in advance for any info!

-jd

Mikey · Aug 30, 2006

Do a search on "tankless" on this forum and you'll find a ton of discussion, both pro and con.

Sponsor · 2022-01-29T12:20:58-0800

jdgarza_tx · Aug 30, 2006

Yep, I just did that.....

I'm new to this board but i poked around and found the info and debates about tankless......The search button is amazing. Wealth of knowledge on this board.

seems i'm gonna stick with conventional.

Jadnashua · Aug 30, 2006

There are numerous heated discussions here...use the search function to review them. FOr an electric unit, make sure you have a very significant supply, as you'll probably need to run a very heavy gauge wire to the thing. The advantage is that it only goes while you are using water, but, especially for an electric storage tank, the things rarely run unless you are running water, so there is very little standby losses.

There are periodic maintenance requirments that you won't find until you read the fine print, sometimes as often as once a month required with a tankless system depending on the incoming water quality. Plus, they are designed to raise the incoming water a certain amount...they are speced with incoming water at 50 degrees. Depending on where you live, it could be nearly 20 degrees colder in the winter. Believe me, you will not be happy if that is the case. The output temperature can vary signficantly, too, depending on the flow rate. THe faster the flow, the lower the resulting output temp. Also, note, that most have a flow restirctor, and it will take longer to fill your tub or washing machine.

Getting them serviced is harder, too, as not that many people are familiar with them.

Read the other comments after you do your search. Under the right conditions (and they don't exist in the northern part of the country in my opinion), they may have an advantage. Otherwise, they cost more to install, take more maintenance, and if you have a quallity storage tank type, don't save significant money during normal operations.

Bob NH · Aug 30, 2006

Here is the electrical circuit requirement:

2.5 GPM shower x 8.34 Lbs/Gallon x 60 min/hour = 1251 Lbs/hour
(You need that heating rate even for only a 10 minute shower)

50 degree F temperature rise x 1251 Lbs/hour = 62,550 BTU/hour

(62,550 BTU/Hr)/3413 BTU/kWHr = 18.327 kW = 18,327 Watts

18,327 Watts/230 Volts = 79.7 Amps

So if you have an 80 Amp breaker, you are right on the edge. Most places would install a 100 Amp circuit.

You can adjust any of the numbers to your conditions.

I don't know if you can even buy an 18 kW electric instantaneous water heater.

Maybe your supply water if warmer, if the tx on the end of your ID means Texas.

I have used showers with instantaneous electric hot water heaters. They are fairly common in Europe. The good part is that they make you wet with warm water. The bad part is that all they do is make you wet with warm water. They don't provide what most people in this country would call an acceptable shower.

You would be far better off with a tank type heater. If you need a lot of water, put two of them in series. They will cost a lot less than the tankless electric and will give you better service.

If you really want a tankless heater and don't have natural gas, you might consider one fired with propane.

Jadnashua · Aug 30, 2006

Most systems are designed to raise the incoming water 70 degrees, so scale Bob's numbers up by 40%.

Master Plumber Mark · Aug 30, 2006

tankless troubles everywhere

Take this for what you think its worth.....

I send all my curious tankless customers to

my site and let them read this for themselves........

in my honest opinion they are a scam and as the person
a few back mentioned......

read the fine print before you buy one.....

http://www.weilhammerplumbing.com/houseofhorrors/

Don Metzinger · Aug 30, 2006

I am not a pro but helped a customer of mine research tankless sytems about a year ago and with thier high water usage it did not make sense for them. The real killer was the need for additonal venting and possible need for a larger gas supply line. There was a lot of doubt about performance during the winters here in Colorado. For what its worth, need to do a lot of research beforehand! - don

Winslow · Aug 30, 2006

The gas models work great. It is impractical to get an electric one to repace an existing tank type unless your GPM requirements are low. To get an adaquate supply of GPM beyond one major fixture (shower, laundry) you usaually have to upgrade your electrical service. Therefore you are lucky to recoup the cost in your lifetime, unless your a youngun.

Jadnashua · Aug 31, 2006

IF the house is built for it, you might get satisfactory performance with a gas unit, but you'll also probably have to increase your gas service. For multiple shower use, you'd need one with around 200K BTU input capability. That's larger than many furnaces, and most people seem to ignore the makeup air required for burn that much.

Smith333 · Sep 5, 2006

I've been lurking here for a few months and just had to put in my 2 cents...

I too was star struck by the concept of a tankless water heater. It seemed intuitive that removing the idle 40 gallon tank of hot water would surely slash my gas bill. And I'm in a situation where it seems much more appealing. My two sons moved out about two years ago, leaving just me. They were famous, like most young people, for using copious amounts of hot water for their multiple and long daily showers. Without them here, the hot water heater goes unused for most hours of the day.

Being the inquizitive type, I decided to check back through my old utility bills and just see how much Natural gas I use, before and after my sons left. In particular the months of June, July, and August - the months I knew that the furnace was not operating. The following is the amount of natural gas used for those three months combined:

2003: 95 therms
2004: 85 therms
2005: 37 therms
2006: 32 therms

As you can probably tell, my sons left in late 2004. Using a generous estimate of $1 per therm, I am currently paying all of $11.50 per month for natural gas used during the summer months. Even ignoring the fact that I also use a natural gas stove and clothes dryer, as well as the recent spike in natural gas prices, this is hardly an indication that the hot water heater is an energy wasting monstrosity and, at least in my opinion, blows the "energy efficiency" argument in favor of the tankless right out of the water.

Edit: I should also mention that the hot water heater is located in the basement, where the temperature is usually much cooler than the air in the rest of the house and outside.

Jadnashua · Sep 5, 2006

A gas WH, because of the flue, will lose more heat than an electric one. A power vented one will lose less than a conventional gas one since you won't have as much loss through the flue.

If you are using an electric WH or an indirect heated one, they are even more efficient. A good indirect tank will lose less than 0.25 degrees per hour, so even over a whole day, may not cool off enough for the thermostat to turn back on to reheat. So, what is the cost? Heating it up in a batch that is ready whenever you want and is fairly cheap, or a much more expensive, and complicated system?

ffmedic7 · Sep 6, 2006

IMHO, Electric tankless heaters are only for point-of-use, ie..under the sink. There is no efficiency gain from them over gas heaters. Now to the payback issue, they can be expensive up front, depending on what needs to be done. But for most applications, it is worth it. Mine has been running like a champ for 5 years now and since I went from electric tank, to gas tankless (installed myself), my payback is done. But more importantly is the never ending supply of hot water. That is a HUGE issue for our house...1 bathroom, 4 people.

There is a reason you will be hard pressed to find tank heaters in Europe, and that tankless heaters have been proven for many years. We are very stubborn here to new technologies, that the Europeans have proven and they have to pay WAY more for fuel than we do.

A good model like Rinnai or Takagi will do the job and you'll never be sorry.

SteveW · Sep 6, 2006

Smith333 said:
I've been lurking here for a few months and just had to put in my 2 cents...

I too was star struck by the concept of a tankless water heater. It seemed intuitive that removing the idle 40 gallon tank of hot water would surely slash my gas bill. And I'm in a situation where it seems much more appealing. My two sons moved out about two years ago, leaving just me. They were famous, like most young people, for using copious amounts of hot water for their multiple and long daily showers. Without them here, the hot water heater goes unused for most hours of the day.

Being the inquizitive type, I decided to check back through my old utility bills and just see how much Natural gas I use, before and after my sons left. In particular the months of June, July, and August - the months I knew that the furnace was not operating. The following is the amount of natural gas used for those three months combined:

2003: 95 therms
2004: 85 therms
2005: 37 therms
2006: 32 therms

As you can probably tell, my sons left in late 2004. Using a generous estimate of $1 per therm, I am currently paying all of $11.50 per month for natural gas used during the summer months. Even ignoring the fact that I also use a natural gas stove and clothes dryer, as well as the recent spike in natural gas prices, this is hardly an indication that the hot water heater is an energy wasting monstrosity and, at least in my opinion, blows the "energy efficiency" argument in favor of the tankless right out of the water.

Edit: I should also mention that the hot water heater is located in the basement, where the temperature is usually much cooler than the air in the rest of the house and outside.

I think this is one of the most helpful illustrations of the concept I've seen. I too had thought about going tankless a couple years ago, based on the rave reviews seen on "This Old House," but reading many, many posts here and elsewhere of inconsistent water temps, need for regular deliming, and up-front costs convinced me to stick with the tried-and-true technology of a regular tank-type WH when mine went bad. A well-insulated tank of hot water just doesn't lose as much heat as most people would think.

And no, this is not just American stubbornness to change. Just because a new technology is used in Europe does not necessarily mean it's well suited to our climate, water supply temperatures, lifestyle, etc.

Rancher · Sep 6, 2006

SteveW said:
And no, this is not just American stubbornness to change. Just because a new technology is used in Europe does not necessarily mean it's well suited to our climate, water supply temperatures, lifestyle, etc.

Could it be the europeans don't use as much hot water? I seem to remember on the few times I've been over there, that the water is not as hot.

Rancher

Jadnashua · Sep 6, 2006

The compromises seem just too great for me. I lived in a house in Germany for awhile with one...while surely workable, it was not an invigorating shower and forget about trying to fill up a tub in any time. A typical tankless requires a flow restrictor, can change the outlet temperature depending on volume, doesn't work until you have a minimum flow, and can only raise the water temperature a finite amount that decreases with flow increases. Where I live, the winter-time cold water inlet is 33-34 degrees. This means that by the time the water gets to my showerhead 30' of pipe away, it is tepid. In the summer, it is fine. In a warm climate, it might be fine. Depending on your water, it might not lime up quickly, but it does, and your performance decreases - you use the same energy, but your outlet temperature goes down.

Give me the ability to fill the tub or washing machine quickly, not restrict the flow (boy does it make a difference if someone else opens a hot water tap), and the lower up-front costs and minimal maintenance. Plus, if it breaks, somebody that both stocks parts and can fix it the same day.

udder · Dec 8, 2006

My Tankless System

My personal expierience with the Takagi unit I put in has so far been excellent. I am not only using it for domestic hot water but also hydronic baseboard heat. I can certailny appreciate some of the issues expressed here about hard water and cold supply water but fortunatly where I reside in Illinois neither is a problem. I did install the valveing to be able to flush the heat exhanger properly. I do know that given my 45 year old boiler that this unit will pay for itself in one winter. That being said, the old boiler is still in my garage....just in case. I misght have been born yesterday but it was not last night.

hj · Dec 8, 2006

heaters

European living spaces are much smaller than US ones. They use tankless heaters so they do not have to provide the space for a tank type. It has little if anything to do with efficiency. Their appliances, such as dishwashers, washing machines, dryers, etc., are also narrower in order to take less space.

Tankless Water Heaters any good?

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