What are the Pros and Cons of Tankless Water Heaters?

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Mac Groetzinger

Subject: Integrating Radiant Floor Heat with other Uses

We are building a 2 story 5000SF (ICF) house in Charleston, SC. The floors are concrete and the ceilings are 11' 6"H. We are installing a hydronic radiant heating system in the concrete floors that promises to be very efficient for this type of construction. The contractor wishes to supply the hot water to this system with two propane fired tankless hot water heaters mounted under the first floor which will be integrated with bathrooms, kitchen and laundry room hot water supply. We live in a similar size house in CT with a tank heater that not only takes forever to get the hot water to the second floor but can't fill up one bathtub without trickling the flow. I suggested that we install a separate tankless hot water heater in the attic just above to service the Master Bath which is nothing less than you'd find in the finest 5 star hotel. The main shower has a rain fixture overhead that one would like to be pummeled by as well as a wall mounted and hand held system designed for deep or sensuous massage.
What's the best way to get that kind of Ritz Carelton water pressure without checking in?
What's the best way to fill up a big tub and never run out of hot water?
Should I go for multiple tankless systems, a traditional tank or boiler or a little bit of both?

Facility Manager Mike

Subject: tankless hot water heaters

Hello Mac! I have not heard of using actual water from your plumbing to heat a sub floor system and wondered how it recirculated? I assume it is not just draining but most systems use a liquid capable of retaining heat better then water and simply recirculate without fear of calcium buildup problems you often find circulating tap water. I would be very cautious of using an on demand hot water heater for any purpose though as they tend to use more electricity or gas then a normal tank heater does if you have three or more people in the home. Many also have plastic heating coil housings which I have had crack on two tankless units flooding the floor each time so I have no confidence in them at this point at all. A small tank will fit in most locations a tankless system will fit and will provide the same amount of hot water before running out for less $ upfront and down the road.

arcot

Subject: tankless water heater feasibility

George, can you please let me know if tankless water heater is appropriate in my circumstance we live in phoenix,az in a 4600 sqft house.currently have gas water tank heater for 6years and already have a circulating pump. wil the hot water be a problem if multiple users are using shower at the same time? thanks

Jamie

Subject: Installed tankless- HELP!

Two weeks ago I installed a gas tankless water heater and got rid of my old gas tank water heater. I live in a condo, so we installed the nortiz eztr40 Bc of the ability to connect to existing venting and I wouldn't have to create new holes in my building. My main reason for doing this was to free up space for some new built ins and I heard that it would lower my bill too. Well to my surprise, I just got my gas bill yesterday and it had increased 800%!! The unit was expensive, the installation was expensive, but I was not planning on an expensive bill for the rest of my life. I'm desperate to find out the cause and fix it. They are starting cabinets Monday and have utilized the space freed up by the removal of the old unit, but I just need to know if I am going to need to put it back in or if there is some solution while keeping my new tankless. My buildings water is paid by the hoa, so I assume that means out water is all running together which made me think, am I heating the water for my building, not just my unit?! Please help! Thanks

Justin Ervin

Subject: 800%

You make have a recirculating hot water line and pump. If you do and it is running your heater will continuously run. Try shutting off the recirc pump and your bill should go way down

Steve

Subject: Hot Water Space Heating

Posts on this blog seem to be coming from knowledgeable sources. How might a tankless gas unit perform as the source of hot water for a fan coil-type heat exchanger? Electric rates skyrocketed in Central Ohio last year, and I need to go back to gas heating. Am hoping to utilize the existing air handler (to save $) by inserting a hot water coil and forget about the 15KW "back-up" coil. Would using an existing (de-energized) tank unit help raise the incoming "cold" water to the tankless unit?

James Walters

Subject: Seems to be a great deal of misinformation

Not wanting to add additional misinformation I'll just provide my perspective. First, I'm not a plumber, just a DIY home owner. I purchased and installed a Navien NPE-240 tankless system for the following reasons:

(1) Capable of 11.2 GPM 35 degree temp rise / 8.7 GPM 45 degree temp rise. The ground water in my area in the mid-south averages 65 degrees year around so per the spec the capacity to fulfill a whole house requirement exists.

(2) The technology in this unit eliminates the "cold-water sandwich" , has a built in recirculaton pump, can be adjusted to 140 degree water output, 95 AFUE, and is vented with common 2 or 3 inch pvc.

My experience has been outstanding. It took me half a day to install (I already had the required water and gas inputs, condensate to sewer drain, 120 volt electrical supply, and exhaust through roof opening available). The only maintenance I perform is to give it a good cleaning once a year and run a couple of gallons of vinegar through it for about an hour to descale. I have tested it by running the three showers in the house at the same time (a total of 9 shower heads). The pressure is not as strong as if only one were running but all are hot for as long as I choose to run them. My gas bills have been lower, not significantly lower, just about 15% lower than before installation (significantly lower might come into play if we couldn't take 30 minute showers with no problem!

The reality is that given the low cost of natural gas these units don't warrant the investment. There may be a break even point 15 - 20 years into them if there's not a great deal of infrastructure required to support installation, But that's not the reason I installed it, I did it for the endless hot water. I'll never go back to a tank!

Jack Amberg

Subject: Considering the same system

Hi James,

Your info is greatly appreciated as I am trying to decide very soon on a new system. I had a plumber out last week who is recommending the same Navien tankless system. I have the required water and gas inputs, condensate to sewer drain, 120 volt electrical supply, and exhaust through. He tells me no piping upgrades are necessary.

Currently I have two tanks in the attic and would really like to get rid of them. So I am leaning towards doing the tankless system but I've never heard of Navien. Did you research the different brands? ....how did you come to select Navien?

Thx for your insight!
Jack

David Davis

Subject: unsatisfaction guaranteed

I picked up this water heater about 4 years ago. I really dislike it in the winter time because it can barely fill up the large bathtub and still have any hot water left to rinse off after soaking. My job requires I sometimes get dirty and soaking is often required to become clean again. I am very unsatisfied with what I purchased for many hundreds of dollars.

andro

Subject: water heater cost

not sure but i do prefer a tank over tankless due to having continuous water . just a shame about the eco nes . maybe one day get solar to help.

Charles Flaum

Subject: Electric Tank vs. Tankless

Hi everyone~

We live in the far north where winters are usually very cold (and long) in a small ranch (1,600 sq ft.) It currently takes 30+ seconds (maybe 35 feet) for hot water to get from our electric hot water heater tank to the farthest faucet. I don't worry about water usage as we have powerful well and septic and there are only 2 of us. Our electrical panel is w/in 10ft of the the current water heater.

Given this scenario does it seem like we will save $ on our electric bill switching to a tankless electric hot water system? Will it take approx the same amount of time to get hot water to the farthest faucet? Does this seem like it makes sense for us?

Charles

john kelly

Subject: hot water problem

sounds to me like you need a recirculation pump. it's a small pump you install in the existing water line under one of your sinks. its supposed to keep the water in your pipes hot by recirculating the water to your hot water tank. therefore there is no delay when you turn on the hot water.

Ahman

Subject: Elec vs Gas

I was wondering if anyone has noticed the speed of heating between the Gas and Electric? I ask this because Electric like an electric stove heats faster than gas and I would expect the same with Tankless water heater.

Nancy S.

Subject: Depends on where you are

We live in Arizona, where the summer temps regularly top 110, and installed a whole-house tankless about 7-8 years ago. During the summer, our incoming cold water temperature can be measured at 95 degrees at times. Our (Rheem) tankless model needs a minimum difference in the cold water temp and the temperature it will heat the water to, in order to function (ours will heat to a max of 120). It also needs a particular flow rate in order to trigger the "on" mechanism.
All of this means it regularly shuts itself off mid-stream in the summer, and results in more water being used. I had to remove the flow restrictor in our shower head to allow the tankless to function. Not a good idea in the desert, where we really need to conserve water!
I wish I had known these things before we purchased ours; I hope they have made improvements to them over the years.

james

Subject: Tankless Water Heater

Tankless water heaters are basically a marketing fad, here today but probably not for the long haul in a residential setting. Don't get me wrong, tankless has it's place but for whole house hot water needs in a "normal" use home, tankless does not make much economic sense. They are expensive, they waste water which isn't free, you are likely to have cold water "sandwich" in low flow applications (like shaving for instance) and they require service yearly which isn't free either.

Forget about Europe & Japan, they do not use tankless for whole house water heating, they use it for a single fixture or a single bathroom group where it makes much more sense.

Basia

Subject: Wrong info about Europe

What you said is not true. Maybe in the 40s and 50 there were one-room water heaters, but they went out of fashion for safety reasons (carbon mon. poisonings and gas leaks). New constructions NEVER have water heaters located in bathroom or serving only one room. Now, the water heaters are located in one place in the house (typically the basement) and heat up all the water in the house.

Pascal

Subject: Thankless Water Heater

Sorry to disagree, but in Europe and also in Japan we do not use tank at all. I worked in construction in France. We installed usually a gas heater which is sufficient for the entire house. I also travel every year to Japan, and they use thankless systems, usually gas heater for an entire house.

Phil Callahan

Subject: The wait for hot water

George Trail is absolutely correct. No matter how you heat your water, the wait for hot water is entirely dependent on the distance the water must travel (and the flow rate) to the point the water is used. To make the wait shorter, turn the faucet or shower on full force to increase the flow rate. If a tankless system significantly reduces the flow rate, then the wait may be longer.

Al. Hartlaub

Subject: Water. Heaters.

As some people mentioned,in Europe we use tankless water heaters for a long time, (. Durchlauferhitzer )
I'm a professional plumber, and was in business for 35 years, in 2010 i installed a Navian tankless water heater with a circulation capability,and a additional
On. Off divide by my thermostat, When i need hot water,push two bottens, and in 3 minutes,I have all the hot water I need,after iam done,push one botten,
Everything is turned off, excellent setup.

Ernie Olmsted

Subject: on/off divide

what do you mean by an on/off divide, curious because this sounds like a good system, I understand the circulation capability but just don't know what you mean with an on /off divide. thanks

Lindsey McWilliams

Subject: circulation capability?

Do you mean your system has a water recirculation pump between the heater and the furthest fixture from the heater? Fine Homebuilding's March issue had an article about low wattage recirc pumps that was intriguing. A friend installed one and is ecstatic about the instant hot water and reduced water use. We have an aged gas tank hot water heater and expect to replace it. I haven't heard of anyone using a tankless heater with a recirc pump. If that's what you have, I'd like to know more about it.

Pat

Subject: Wish I Hadn't

Florida resident here. I can agree with those who say more water is used with a tankless heater. My natural gas water heater is right outside my kitchen so it doesn't take quite as long to heat as my daughter's whose tank is in her garage a good distance from her kitchen. I have to run her water at least 3 or 4 minutes before it begins to warm. It's horrible. I usually just resolve that I have to use cold water or be in the kitchen forever doing dishes. My gas bill is higher than it used to be as well as my water bill. Have considered going back to a tank and selling this tankless heater.

George Trail

Subject: supposed tankless heater water waste

I do no understand why tankless systems are said to waste more water. In neither system does the water in the line between the heater and the appliance empty, nor remain hot when the faucet closes. when the tanked system is turned on the cold in the line before the faucet was opened runs out. Exactly the same thing happens with the tankless system. The water in a tankless system heats immediately as it runs through the line, which happens when the faucet is opened. In both systems you have to "wait" for the hot water, not for the water to "get hot" because its is hot from the point the faucet is turned on. In both tanked and tankless systems your "wait" for hot water is determined only by the distance of the faucet from the heater.

Michelle Harritt

Subject: Question -

How does very hard water effect tankless water heaters? Our water is very hard and is a problem our traditional gas hot water tank.

Carol

Subject: Hard Water with Tankless Heaters

We also have very hard water. We were told that a softener was mandatory to eliminate the scale buildup. I really like the unlimited hot water but if I had time to do a do-over I would have put a point-of-use heater in the kitchen. Some genius installed two 40 gallon units in the attic of a house that is backed into a hill so the water pipes run down three levels to the kitchen and it takes a while to get hot water. When the old tank blew, we had three floors of damage before we noticed the leak. This one won't do that since it doesn't store water and has a shutoff. That alone makes it free when compared to the flooring replacement costs we had three years ago.

Tony Neece

Subject: What nobody seems to be aware of

In all the chatter about electric vs gas appliances I do hear mention of the carbon cost of generating electric power. I never hear mention that many power plants are located near large bodies of water and take in huge volumes of water for cooling. That same volume of water is returned to the sea or lake, at a higher temperature affecting sea life and further contributing to global warming.

Ken Austin

Subject: Tankless water heater efficiency

It should be mentioned that the cost of running a tankless should consider water loss as well as gas use. Here in central Florida natural gas is cheap but water is expensive, because water use is used as a base for sewer charges too. Our heater has the following issues:

It takes 2 to 3 gallons of water to heat depending on the user location in the house.

It has never worked correctly, shutting off hot water at unexpected intervals. The "plumbing" company who installed it claims it's due to one thing, the manufacturer says another.

We're sorry we ever had it installed. It's expensive to operate, and unreliable for a steady supply of hot water.

Lavina

Subject: hot water turning cool

This is a belated response, but I just watched a video online (and you may also have seen it) that shows how to replace a dip tube (on the cold water intake). If this breaks off, the cold water is deposited at the top or nearer the top of the tank. The cold water should come in at the bottom of the tank so that the thermostat registers this intake of cold water and the heater ignites. That could be (or have been) the problem.

Robert McFarland

Subject: Tankless Hot Water Heaters

Be careful if you live in an area where water is in short supply and expensive.
My tankless heaters (I have two) waste a huge amount of water before the hot begins to flow. Anybody who tells you it's just the cold water in the pipes that's coming before the hot is not being straightforward. I have had two qualified plumbers out to try and change this situation but to no avail. They just waste a lot of water. If I could, I would change them out for a pair of Tank heaters in a New York minute but the house was plumbed for them and that plumbing won't work with Tank heaters without major remodel.....

Blue Max

Subject: Water useage.

In the plumbing business in Kansas with many customers which I have installed Tankles Heaters and use the gas model. As a family of three girls and two boy, myself and wife and on a well, have enjoyed the warmth for ten years.

I can understand the expense of water and drainage fees when applied in some areas. What I do not understand you speaking of waste of water. . Maybe you need to find a new one.

For instance, if you have plumbing in a home, guest room or studio that's far from the main water heater, cold water standing in the pipes might delay the delivery of hot water for minutes, and waste a lot of water in the process. That same waste would be both with Storage Tank system or Tankless. The council says that, at most, an electric tankless unit may be appropriate for small applications, such as a remote bathroom without a bath tub.

If before you used storage tank system and for example used three gallons of water in three minutes for an showers, including the wait to drain the cooler water from the lines you will use the same amount with the Tankless in three minutes. Unless you enjoy it so much more you stay longer then three minuted. Waste NO. It seems your plumber is not straightforward with you.

I would consider a new qualified plumber. Maybe he can suggest an circulater at the remote bath. The recirculate resupplies the heated water back the heater via the cold water lines. Now that is saving water.

Dan

Subject: Exactly

That is exactly my concern also (64 currently). More expensive, longer rate of 'return' AND who, other then much younger persons, have THAT money to pitch away? Being semi-retired, I know I don't. Last Water Heater purchased was OVER 20yrs ago (Kenmore Survivor 50gall, Nat.Gas)) which now has reach 'the end of it's serviceability. I believe that purchasing the 'old stand-by' type will do just fine; though they are 'pricey' also...... starting at above four hundred (400+) plus.

Andrea Pappas

Subject: Tankless not good in earthquake country

The energy savings of tankless heaters is a plus, but here in earthquake country we rely on our hot water heaters to provide a back up supply of drinking water as water is typically cut off for a couple of days after a big one (and can be contaminated when it does come back: ten days after the Northridge Quake, for example).

John

Subject:

We have been installing and SERVICING BOSCH Tankless for the past 7 years; we have made a commitment to this brand and to the education of the technology. Get an installation from a highly qualified company and you will have no problems. We are a local BOSCH sevice provider for Tankless if we cannot fix your tankless nobody can.

John J

Subject:

Tnakless water heaters have been in use in Europe and Asian countries for many more years than here in the United States. These units have very sophisicated burners that require calibration. We have been installing and servicing Tankless units for 7 years and the number one problem we found is poor installation. Once installed correctly and calibrated the unit will run correctly and last three times longer than a traditional hot water tank.

Travis Kim

Subject:

A few years ago I researched tankless water heaters. The first thing I discovered was the gas versions were more efficient than electric ones. I was looking for an electric whole house version for my condo so I could increase my storage space. Unfortunately, the wiring to a electric tankless whole house heater is not standard for most houses. In my case I would have to have an electrician run the proper wiring from my electric box to the heater. Also in my part of the country the incoming water temp can be very cold in the Winter.

The reason for the big difference in gas and electric tankless systems is that gas can heat the water at a single point with less cost than electricity. Gas uses a controlled high temp flame whereas electric has to use elements that have a high draw.

Electric units work best as "point of service" heaters for individual sinks or separate showers and in warmer climates.

Don't depend on a contractor to know this stuff. Refer to the manufacturers specifications as to the performance you can expect for your usage in your climate.

George

Subject:

While it's probably true that the overall efficiency of electric appliances is diminished by the efficiency of the powerplant supplying the energy and the loss in transmission, I'm guessing that the efficiency described in the blurb is in regards to the end-user's supply. Perhaps the amount of heat generated by the amount of gas the user must purchase is less per dollar than the amount of heat generated by the amount of electricity a user must purchase. I suppose clarifying that point would be helpful, however.

Still, if it's about "greenitude," then yeah, check the efficiency of the powerplant. Mine's a nuke plant, so bah to emissions (and hello NIMBY controversy).

Dave

Subject:

Walter Merrill is correct - electric appliances in general, and a water heater in particular, are substantially LESS efficient than gas powered, because power plants are not that efficient and the transmission losses can be enormous.

Larry Collins

Subject:

`I have a Noritz 841MC whole house tankless water heater. It was professionally installed 11/20/2008. There is a venting problem. I have had 2 reps, a Noritz technician, and my local licensed plumber out 3 different times to survey the problem. It still has not been fixed. One smells gas when in rooms next to the outside venting. The way our house is built may not have a good solution. Make certain the installer knows how to prevent this problem.

Ed Wyrick

Subject: Tankless gas water heater

I am a medium skilled DIYer. I self-installed a gas tankless water heater two years ago. It was rated for a family of 4, we are 3. We never run out of hot water here in Nebraska. Installation instructions said to use 3/4" gas line but this old house only has 1/2". I'm glad I did it.

Walter Merrill

Subject:

Stating that an electric water heater is 93 percent efficient compared to 60 percent for a gas heater is comparing apples and oranges. The efficiency of a power plant is only about 60 percent and then there are transmission losses in getting the electricity to your home. You should not be misleading consumers like this.

Paul Maher

Subject: Understanding efficiency quotes

Walter, I'm sorry, but you completely misinterpreted the meaning of the efficiency quotes that were made. The comparison IS valid and power plant or distribution efficiencies have nothing to do with those numbers. Saying "an electric water is 93 percent efficient" means that 93% of the energy being used by the water heater is converted into heat within the water. So, for the sake of numeric simplicity, if your home used 100 KWH of electricity to heat your water, 93 KWH would ACTUALLY be heating the water. The other 7 KWH would be lost to the electronic controls, efficiency of the heating element(s), thermal losses through the insulation, and perhaps a couple others. If you change to an electric water heater that is 99% efficient, all that means is that under the same conditions as above, your loss would only be 1 KWH, resulting in power consumption of 94 KWH to provide the same hot water as otherwise used 100 KWH. The efficiencies that have been used throughout the article and comments, except for yours, refer STRICTLY to how much of the energy that comes in to the heater goes out as hot water. Yes, most, perhaps all gas water heaters are less efficient in their energy conversion. That absolutely does NOT mean that electricity is a more efficient way to heat water. In fact, in an apples to apples comparison, gas will ALWAYS be more efficient than electricity if you begin at the producer. How does much of this country get its electricity? From generators that burn natural gas! Think about the losses in this system. Use natural gas to power an engine, that spins a generator, that produces electricity that goes into a transformer, that is sent down transmission lines, that goes through more transformers and sets of power distribution lines, that finally goes through the last transformer in your neighborhood to bring the voltage down to 3 phase 240v in your neighborhood, that runs through local power lines, and finally, into your home to heat water. Each item I listed has an inherent efficiency that is less than 100%. Now, what about the losses in this system? Use that same natural gas to heat your water. There no losses here other than the efficiency of the water heater! You can see the differences in losses every month by the differences in power bills between gas and electric customers. It would only be fair to add the gas and electric bills for the gas customer to allow for the electricity both use for lights, TVs, etc. The combined bills of the gas customer, under matching circumstances, will always be lower than the bill for the electric customer. A real-life example: One of our homes was all electric when we purchased it. We were friends of the sellers, so they had no qualms about showing us their electric bills. They were on a level-pay plan to avoid the dramatic increase in their bill in the winter. Within a few months of us moving in, the gas company ran a main through our neighborhood and offered discounts on the purchase and installation of a gas furnace and storage tank water heater, which we used. The previous owner's monthly, level-pay bill was over $300. Our combined gas and electric bill NEVER exceeded $300, even in the coldest part of the winter, and we kept the house warmer than they did! So, if you want to look at efficiencies beginning with generation/acquisition through final use in your home, gas will ALWAYS beat electricity. Even a nuke suffers from all the power/efficiency losses of the gas powered plant beginning with the generators. From there on, every electric power source has the same losses. The statement about efficiencies was neither misleading nor incorrect. The error was in your understanding of the meaning of those terms in the described scenarios. I hope that I have helped you to better understand this, and that knowledge help you purchase devices that are truly more efficient. Ignore the efficiency numbers on the devices unless you're comparing identical products to truly get the most efficient. However, in almost all cases, the more efficient device will be evident in the Government mandated power cost labels on most major appliances. Just find the one that meets your needs and has the lowest energy usage. I TRULY hope this helped, and apologize for the length!

Chester

Subject: Apples to apples

I think you may be missing the point. The efficiency is not about everything that happens in the generation and delivery of the energy to the unit - It is comparing *what the unit actually is using* without regards to how the energy was transported to the water heater. Unless they know your specific location and source of fuel, how would you expect the article to speak to your circumstances? Who would want to read such a narrowly focused article??? (other than you).

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You have to put your self in the shoes of a business that is in business to turn a profit of some sort. All businesses have different overhead which in turn decides what their bottom line would be on their services. I personally would not go with an unlicensed professional for this type of install. You are messing with gas, venting issues, electrical wiring{electric water heater} and updated code issues such as a drain pan and tempature and relief drain lines for heaters that currently do not have them. I do agree that there are some companies that are way out of line for their installs but most of these companies are the really big companies that have very high overheads  I would assume. Tank type water heaters have changed over the last several years and with these safety changes come bigger prices. The price of steel thanks to China is skyrocketing and tank type water heaters are made of steel. Most wholesale plumbing supply companies cannot match what the big box stores are selling at retail to consumers. I happen to think from research that heaters such as Rheem, Bradford White and AOSmith who have been in business forever make a better product than what you can buy in the big box outlets. You also have to take in consideration the location of the water heater that is being replaced. Is it in the house, basement, garage or attic. Most 40 and 50 gallon water heaters that are purchased in a plumbing wholesale store in Texas cost between 300-340 for a 6 year warranty heater with 6 year on parts and tank. Speaking of warranty. Most big box companies will take a least 24 hours to a week to get your warranty problem taken care of. Most reputable plumbing companies will give same day service if they installed the heater.

So lets break down a typical install at cost to a licensed plumber in Texas

Heater: $315, water shut off $6.50, water flex lines or unions to code $20, gas flex line and cut off to code $12, misc fittings $15, Total $368.50 Lets add a 35% profit which is some what low  for a business $129, Total 497.50

This doesnt  include permits, pan and drain or any venting issues. The vent must go from the heater to the outside of roof using double wall vent.

Cost of permit on average $60

Most plumbing companies allow for 3 hours of time for a water heater. This includes picking the new one up. Delivering out to house. Draining and removing old water heater. Hauling off old heater. Installing new heater up to code. Going down to city and pulling permit.

Average Labor charges for heater installs $400

That would make this install run without extras on any code issues $957.50

I just had a 50 gallon gas water heater installed in my house for $1200 but I needed a pan installed. I used a licensed plumber.

 

 

 

?

I've seen and heard mixed reviews.  They aren't really popular here due to our super hard water which clogs and rots everything it sits in.  A company I used to work for tried electric units about 10 years ago in several homes but had to replace many of them within a few years because the build-up from the hard water hindered their productivity to little more than enough supply to run a sink.  I've heard better success with gas units since there are no electric elements to burn out and gas can get hotter, faster to get through the deposits on the tubing walls inside the unit.

 

Standard electric water heater usually take a 30 amp circuit so they are often wired with 10 guage wire.  Electric on-demand units large enough to service an entire house usually take 50 amps (or more) from what I've researched in the past.  That means they need a 50 amp breaker and will be wired with 6 guage wire.  By the time you factor in the initial cost of buying the much more expensive on-demand unit and rewiring for it I'm not sure you'll save money in the long run. 

 

A better and cheaper option would be to put a timer on your standard water heater so it only kicks on during typical demand times.  They have override switches so you can turn it to cycle normally when you are off of work or need it during the day/night if not during the preset times.  A cheaper point of use water heater at the kitchen sink will ensure you have hot water there even when the main heater is off.  This is usually the point that requires hot water the most frequently.  Remember that your water heater will hold hot water for over an hour once it has cycled off.  Take advantage of that.

 

Todd Shell

Todd's Home Services

San Antonio, TX

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Depends a lot on your configuration - he may have been including direct outside venting because your existing heater/furnace duct was not large enough to handle the added load, and may have figured running larger piping to the jetted tub and maybe upsizing the valve and flex tubing at the gas line. This all assumes you have adequate access and installation space for the larger tank - they tend to be fatter rather than much taller.

I would talk to several plumbers - if you get quotes from 3 or more, it should become obvious right off if one is high-balling you. Of course, do not tell the others what the other's bids were.

The water heater itself will cost about $1000-2000 for that size - about double a 50 gallon, which usually costs about $800-1500 installed (replacing an existing plumbed-in one). The larger heater may take a bit of beefing up of the support platform for the added weight, but assuming you have adequate headroom, installation cost using existing ductwork and piping would not be any more than for a 50 gallon, so say $2000-3500 range installed. The $4500-6000 definitely sounds high if it assumed using existing hookups.

?
There could be. Different municipalities have different rules (codes). However, I have never heard of a plumber being the code enforcement guy. I have never heard of a plumber being able to collect a fine from a homeowner. It may cost you $150 to bring it up to code, but that should be included in the repair cost. You would need to check with your city (usually Department of Code Enforcement or Plumbing Commission). If he put it in writing, you need to send them a copy.