Tankless Water Heaters via Microwave

Where? On my neighborhood mailing list.

The installation costs and permits are an issue when you're going to do retrofit work rather than new construction. Several neighbors have done it and it seem the San Jose is pretty easy to deal with on the permit side.

Unless things have changed in the last couple of years, the city of San Jose requires that you maintain a tanked water heater as well. I can only speculate on the reason, but my guess would be so that you have a source of some water during an emergency (e.g. earthquake). Chat with your neighbors about it.

But what do you need hot water for? Getting soft and cushy in your old age? :-)

Jeffrey

Hmm. Things much have changed. Everyone mentioned ditching their tanks and not needing to keep one around for any reason.

Uh... didn't your water heater break earlier this year? Are you anticipating a repeat offense already?

No, my plumbing broke. The tank is fine.

I was looking forward to installing a gas tankless during an upcoming remodel. The deal killer: it would require upgrading the gas pipe from 1/2" to 3/4", and it's ~80 ft from the meter. I can see how it's a no-brainer in new construction though. We used them for weeks while in Hong Kong and thought they were great.

Here in Prague (Czech Republic), I almost never see a water heater *with* a tank. The one here in my apartment was made by Junkers, and I much prefer it over the water heaters with tanks that I had in the U.S. It's especially nice when I have lots of company, and six people want to take a shower one after the other.

Because I never saw them in the U.S., I assumed a water heater with a tank was more energy efficient, and the reason we put up with the higher energy costs of a tankless model is that it is much smaller and easier to fit in an apartment. If it's not true that the tankless models use more energy, why do water heaters with tanks exist at all?

There can be an issue with cheap tankless heaters in the amount of time the take to detect a drop in pressure and turn themselves on.

This can be particlularly annoying if you have just run a sink of water and decide it just a bit more hot. When you turn the tap on again you get cold water out for a few seconds while the heater fires up again.

It is better to get a more expensive model that has a heat store in it.

The other issue with my tankless is that it can only supply one outlet at a time. So, if you're in the shower upstairs, and someone turns on the hot tap in the kitchen, the shower immediately runs cold.

I've always thought this was just a question of designing in sufficient capacity, but it is the reason I have been given why tankless models aren't used in larger family homes. I guess it is complex to vary the heating, water volume and maintain a constant temperature. As it is, the design is very simple.

Would be very interested to know the efficiency of the microwave version, as a big chunk of the heat in my gas model goes out of the flue (newer, condensing models are designed to salvage more of this heat, but are quite a bit more complex and have a reputation for reliability problems).

I live in another part of Europe - where the water heating situation is very diverse. And I see a misconception: there are tankless electic water heaters - they need lots of power and usually that means higher requirements for electric instalation and higher fixed montly payment to the power company, thus making this approach very costly. Then there are gas-based tankless heaters - you can pay a lot more for the machine if you want enough power to support more than one user at the same time, but of course the water never runs out and the system is rather efficient. This system has probably been around from the gas-light era, and some new systems are extremly relieable, efficient and have a low TCO - even with their high purchasing price. The downside are the permits and the difficult instalation (coaxial exhaust pipes, anyone?) And then there are the classic electric water-heaters with storage - we all know those.

Until now, if you could afford it, the best solution was the gas-based system with an added water store and lots of extra powe, avoiding the annoying wait and cold surpises when you significant other opens the tap.

The promise of the microwave system is that it would allow fast and efficient _electric_ water heating systems, eliminating high costs of installation of gas pipes and exhausts, becoming accessible where it is difficult to get gas and avoiding high eletric bills.

And that, my friends, is a nice idea.

Tanked heaters still exist because they are a proven, cheap technology, and most newer US homes use forced hot air heat. If you use a hydronic heat system, it has been a no brainer to get an add-on tankless hot water addon.

Tanked heaters are less efficient because they are always on. You pay to keep 80 gallons of water at 125-145 degrees at 3AM when you are sleeping and at 3PM when you are at work.

Looks like we can see what the hordes of slashdorks think:
http://science.slashdot.org/science/05/11/25/0413215.shtml

I like how the article links to the company's worthless under-construction home page.

Bleh.

Just happened to stumble upon your site and thought you guy might be able to help me. I have an old, small house with a ugly gas water heater in my very small bathroom. (The whole house is only 800 sq ft) The gas water heater is 13 years old and about to fail. I have been contemplating the expense of a tankless water heater but have not come up with an answer. I would like to switch from gas to electric (a good idea??? not sure)and would like some feedback. My house is not wired with the newer electrical standards b/c when I was looking at central heat and air they told me I would have to upgrade from my 100 volts to 200 volts (if this makes sense...). Here's the situation....this is my first house...a starter home by all definitions....and I do not have a large budget. Any advice would be greatly appreciated!!!

I had an electric tankless water heater installed and it works fine with all faucets except the tub. The water from that faucet is barely warm while the water in the shower, 5 feet away, is as hot as can be. The place from which I purchased it is ignoring me and will not even talk to me about it. Has anyone had this problem?

I work in the industry. Electric storage tank water heaters are extremely efficient in terms of getting the power consumed by the heater into the water...far more efficient than are conventional gas water heaters. Around 99% of the electricity drawn by the elements is converted into heat in the water. By contrast, most gas-fired water heaters put only 60 to 75% of the heat created by combustion into the water...the rest goes up the chimney. Gas heaters tend to be more cost efficient because even though they send much more of their energy out into the atmosphere, the cost of a unit of gas versus a unit of electricity is so much cheaper that you can waste a lot of it and still come out ahead...even after the recent run-up of gas cost. Higher efficiency gas models are available, for a higher price, but as they approach 83% thermal efficiency or above they become "condensing" heaters...enough of the heat in the exhaust gases is pulled out (and put into the water) that the exhaust gasses are cool enough that the water vapor present will condense out of the gas...and onto the surface of your flue. That creates two problems...you have to deal with the water, and you have to deal with the weak acids that are present in the water. Typically, condensing systems require expensive (up to 1$ per inch) stainless Type 3 exhaust flues, and some way of capturing and neutralizing the condensate (weak acid). Some people just dump it down a drain, but that's not usually legal.
That brings us to the current tankless offerings in the US. The "whole home" solutions (ones that will heat enough water to supply more than one or two uses simultaneously) are available in as either gas or electric. The electric units that are large enough to supply the whole house typically require around 100 amps of 220 volt service to power them...about what most homes have in them for the entire household use. So, you're talking about doubling your electrical service if you want to use an electric tankless. Gas-fired tankless models have their own issues too. The whole house solution models on the market presently require a 3/4" gas supply line, expensive flue ducting unless you mount them on an exterior wall or outside, and they cost upwards of a thousand dollars just to purchase...figure that again in installation cost on a remodel. Yes, you avoid the "standby losses"...the energy wasted in a storage tank water heater when it's just sitting there in the garage. However, most people will save around ten to fifteen dollars a month using a gas tankless as compared to a gas storage heater, and they'll spend at least five hundred to a thousand dollars more on the tankless. Even if you don't consider the time value of money (what you could earn on the difference in expenditure in interest over time), it would still take years just to break even.
All that being said, I'll be very interested to see what this new microwave technology brings to the table. It seems unlikely that it will change the game...but something will someday, so you can't afford to ignore any new technologies. They all have their costs and benefits.

Electric heating coils are always around 99% efficient. Electric storage tank water heaters rely on the efficiency of the tank to maintain water temperature. High efficiency tanks are available at a greater cost and work as well as tankless electric water heaters, for the first 35 gallons or so. Without upgrading your house service to 200 amps a traditional tankless electric water heater will only heat water for one location at a time. That is because it takes a tremendous ammount of electricity all at once to instantaneously heat water with an electric coil. It has always taken a long time for electric storage tank water heaters to heat up. So the question until now has been, a little water for a long time or a lot of water for a little time. If this new water heater can offer a lot of water for as long as you like, without upgrading your electrical service, there is no question that it is more efficient. Cost, reliability and availability?

Jay's last sentence sums it up, they all have their costs and benefits. As a Cetified Energy Manager it's my job to drill down into the details of cost and benefit. I saw my first tankless unit in Japan in 1968 as a soldier stationed there. I often wondered when the U.S. would see this technology. I don't care for electric tank units for a number of reasons.
1. They are a throw-away product.
2. The effeciency drops from day one as scale builds up on the inside reducing the efficiency (on gas units).
3. Standby costs (electric & gas). I installed a Takagi TK2 when gas was $4.60/MCF. It cut my bill in half. I went from 1.8 MCF through the summer months (I heat with NG as well) to .6 MCF. Keep in mind I cook with NG. I have a gas-on-gas stove top with a convection oven.) So even with todays prices of $15.00/MCF my monthly gas bill to cook and heat water is less than $15 even with all the taxes and other stuff they stick on the bill.
4. In electric units the heating elements decay putting heavy metals into the water.
5. Lack of immediate adjustment to water temperature. I have a digital thermostat with my unit. I run the setpoint at 104F in the summer time and 106F in the winter time. This allow me to wash my hands or shower by only using the hot water faucet. Why heat up the water at the tankless and cool it down at the faucet? The dishwasher has it's own heating coil and clothes are washed in cold or warm. If I need immediate higher temperature for a tub full of aching bones I'll punch in 120F, draw the tub, and set it back down.
6. Low FHR (first hour rating). FHR is the true measurement of comparison between water heaters. In other words, how quickly can a unit respond to demand and replenish the hot water. While my family is small (total of three) I know of many families that often run out of hot water. My Takagi (TK2) at 185,000 BTU's with a temperature rise of 50F (incoming water temperature of 60F) can produce 5.3 GPM @ a setpoint of 110F. As long as I have a source of water and natural gas the FHR is 318 gallons/hour. The next time you're in Lowe's look at the FHR of the tank units.
There are two calculation C.E.M.'s go through when examing alternative fuels and alternative units, with regard to water heaters. The first is called point of use calculation (POU). It examines the BTU content of the fuel as related to the cost of the fuel and the efficiency of the device. The second is called life cycle cost analysis. It examines the comparitive useful life of devices as a function of interest rates. The calculations are a bit busy, but is provides concrete data for decision making.
In general terms one can plan on throwing away a tanked unit every 10 years, so over the course of twenty years one will purchase 3 units (o year purchase, 10 year purchase, 20 year purchase). Aside from the efficiency drops as a function of time, especially in electric tanked units, there are tankless units approaching 30 years of reliability. Twenty to twenty five is typical. For the record I don't sell them. I have an energy consulting business (part time) and help people sort through the morass of data and products. My company statement is "Helping people build healthy, efficient, and low maintenance homes." I help with additions to existing homes as well. My full time job is a Facilities Control Engineer to Toyota Motor Mfg. of Kentucky.
Hope this has some value and helps.

Thanks.

Lannie seems to be the go to guy regarding hands on knowledge. I'm in the middle of a redo of a small house in Hot Springs. My plumber tells me that the problem is that with a 3/4" water supply line I won't have enough pressure. The solution he says is to have our service upgraded to 1 ". Is this necessary? Lannie, what is your Tagaki heater hooked up to? Is your service line all 3/4" or did you step it down from 1"??? I currently have a small titan elecctric tankless heater that I got on ebay that is in my pool/guest house where I have minimal hot water needs and it seems to work ok.
I don't believe it would do a whole house as claimed so I'm looking for a higher capacity unit. Does anyone know about electric tankless and heavy metals leaching into the water?

I, being a single woman, having lived in condos for the past 20 years, find myself tired of having to replace electric tank water heaters. Am now on # 4. Now that I live in a second floor condo, I wonder how good a tankless electric water heater would be for me. My heater is stuffed in a kitchen closet, is now corroding around the bottom after 6 years, and fear potential leakage to my carpeting around this closet, and neighbors below.

Any suggestions?

I have installed these heaters on two of my properties and they are a pain.
They do not provide hot water quickly and I have not even tried to run multiple devices. The idea is great but get a BIG one and you may need to install more than one. Once they are heating they are fine. They just take forever to kick in, often depending on where in the house you are using water.

I have decided that my specific problem with my TITAN heater is proximity. My shower is too far away, and the piping is umder the slab. so in winter( like now) the ground cools the water too much. I'm going to re plumb and put one in that bathroom. These heaters are about $200 a piece through ebay. Although the won't heat water for multiple uses I have found that they do kick in very fast and are very adequate for a single person or couple in a small house or apartment where the fixture is less than 15 feet to the heater. Joyce, I would check ebay and try out a Titan. It will require a 60 amp breaker. Since you are single, I would just not shower and wash clothes at the same time.

To Bob Shaw;
Sorry about my tardiness. I had the last two weeks off in Dec. and January has been busy. Late, but....
I have a 3/4" water line and my gas line is 1/2" the preceding 40' to my heater. According to the installation manual, 3/4" is recommended to reduce the pressure drop and ensure sufficient kBTU supply. I've not had any issues and have placed the plumbing upgrade into the round-to-it file. Your plumber is probably mis-speaking. Let the installation manual of the product in question drive any plumbing decisions.

Miss Joyce,
While 10 years is typical, having a corroded tank in 6 is very unusual. It sounds as if you may have an external corrosion problem, rather than something happening inside the tank itself. Tankless electric water heaters require fairly significant amperage and you could require any where from 40 to 120 amps of breakers. That could easily be a deal breaker in a condo electrical panel. Try contacting the water heater company directly and ask what may be happening. Have the condo operator check the air quality in this closet. Store nothing in this closet, especially cleaning fluids that could leak liquids or vapors into this closed environment. Hope things get better.

I want to know how works the microwave heating sytem. It is the low cost compared with electrical heating method? What kind of material is using for the coil into a chamber with heating on deamnd?

Best regards,
besim ismnaili

Hello All,

This discussion has been very helpful for me, only to realize that I still don't quite know what to do. I own a rental 2BR/2 BA condo at the beach, my renters shower a lot and complain that the water heater can't keep up with the demand. The tank is fitted under the kitchen counter, in that dead corner between the stove top and the corner base cabinet unit. I grew up in Europe with tankless heaters and was about to install one in the condo, but with 2 bathrooms and folks coming back from the beach at the same time of the day and using both showers at the same time, I am now questioning what to do... Is there such a thing as a "fast recovery" tank water heater system? Would this be the best option for this condo?

Veronique,
The key to your solution is a clear understanding of your needs. Make yourself a list of all the hot water faucets and measure their output in gallon per min and gallons per hours. The easiest way to do this is to get a 1 gallon bucket, stick it under the fauces and time how long it takes to fill it. You will need one or the other (gpm or gph) when you start your research. Once you have these calculation, apply a reasonable judgement as to how many of these faucets will use hot water simultaneously. Once you have the worst case scenario, review what each water heater has to offer. Your focus will be on FHR (first hour rating). Go to electricwaterheaters .com for a good starting place for water heaters. Generally each water heater will have a link to the manufacturer's web site where you will find performance details. Let the facts drive your decision. Once you've established the unit of choice, focus on price and installation issues. Hang tough. Only rocket science is rocket science.

Lannie,
You seem very knowledgeable about tankless water heaters. I live in northern Indiana where the water temp is around 50 deg. I just purchased a Sets 240/3 elec. heater and I'm having second thaughts about hooking it up. It seems that the amount of electricty used to heat the water is outragous. This system requires a 120amp breaker at main to run the sub panel with 3 40amp breakers in it. (1 for each element) What do you know about this system? From what I've read it is better to cut down the heat at the unit instead of mixing cold water with it. This should cut down on the electric being used, correct? I've never heard of a 120amp breaker, other than a main. Do they make such a thing or do I use a main breaker for this? Also would you know what size wire I need to run from the main to the sub-panel? I need to carry 120amps for about 15 to 20 feet.
If anyone has a Sets tankless system please fill free to leave me some input about your experience with them. Any input would be helpful.
Thanks, Chad

Aloha Lannie,
I just ran Into this site while seaching online for a Tagaki TK2. Your insite was very helpful in my decision to go tankless. My current LP 50 gal.tank system is running out of life. I currently have the standard galvanized venting system though the roof and this should be changed to stainless steel?
My LP feed line is 1/2" to the current heater. I'm trying to configure this to the least expensive conversion. I'm only 8 feet to an outside wall if I move it I won't have to deal with venting? Rain protection? Probably easier to reroute a couple water lines.
Are there any other consideration that I might be not seeing though my rookie eyes?
Also where is the best place to purchase a TK2? Lowe's in Hawaii is not currently bring them in.
Mahalo for your insite.

Chad,
I have no specific information on this particular electric unit. In general terms they are a difficult application for a whole house solution. The average water temperatue in the U.S. is 55F so you're a little cooler on the average. You've clearly identified your concerns; the installation is typically half of a house panel and the KwH consumption is a killer. I would give serious look at a propane unit if NG is not available.

Howzit808,
Thank you for the kind words. As well as being a C.E.M, I'm also a solar enthuisiast with a certification in photovoltaic (PV) design. I've been a passive solar champion for years and I drool over the solar potential of Hawai. To answer your question, however, you will probably need to go to the internet. www.electricwaterheaters.com is an excellent source of information as to what the industry and the marketplace has to offer. If you are living where you plan to live for the foreseeable future, please look at a solar water heater with propane back-up. As you review the tankless literature make sure the unit will function with a solar system. Not all do. One of the attributes I used when I selected and installed my Takagi was its' interface with solar. As far as your rookie eyes are concerned, let the installation manual, practical sense (not common), and safety be your guide. I just returned from a two day solar water install session and the gentleman who instructed us is in his 27 year with his original tankless unit. It does back up his solar system. He's spent $25 in repair in that time. By the way, he lives in Wisconsin. Get your solar system in and you'll probably hear compaints from the gas company you're not using enough gas!

I live in Europe, in a former farmhouse. I bought it five years ago. I've got a Junkers tankless water heater that is at least as old as me (I'm 44). It works with butane gas cylinders. When the Junkers man came years ago to do rutinary maintenance, he looked at it in stupor and refused to touch it, for fear of breaking anything irreplaceable, so I have to do it (cleaning the burners). It's too small for the house, and the bathroom is very far away, so it takes quite long to fill the tub, but the water comes really hot.
Now we are going to switch to piped gas, so I'm afraid its time has arrived. The next one will be another tankless, just a bit bigger. Junkers, of course.

I dont get it. Tankless hot water device? Where will the water be held? How does it supply water?

Hi guys!

Somebody asked about the consumption of the microwave water heater. The answer is simple: it is worse compared to an electric water heater. Why is that? Because the efficiency of an electric water heater is 99%. About all of the electrical energy goes into water as heat! Into the microwave heater the energy goes from electric into microwave radiation and into the water as heat. Every energy transfer comes with some loss, so I don't think the overall efficiency will be above regular electric water heater. Even at 100% efficiency ( we live into an real world ) the microwave water heater will draw a lot of amps because 1-2% doesn't count too much.
Lannie, why have you choose Tagaky? It's efficiency seems to be smaller than Bosch's 250 SX.
I live in Canada and I thinking about entering into Energy consulting bussiness too. Lannie, could you contact me at dusanstangmailcom ? I have a bussiness proposal to you.

Lannie, my email is: dusan -dot- stan -at- gmail -dot- com. Replace -dot- and -at- with you know what

Dusan, microwaves would be more efficient because they make the water molecules vibrate faster, causing a more rapid rise in temperature than would be possible by using the electricity to generate heat the conventional way. This is why you can cook a potato in 5 minutes in the microwave versus 60 minutes in a regular oven.

Heat pump water heaters can actually be 500% efficient compared to the 99-100% efficiency of electric resistance heat. Electricity can move heat more efficiently than it can generate it.

Way back in 1964 I started a three year tour in East Africa.
Our house there had an LP JUNKERS heater on the shower wall and also one on the kitchen wall, both of these units operated flawlessy for the entire tour, both provided instant hot water with each request. I am building a house in WV and would like a dealers name if someone can help.
I think single point of use is a perfect plan as when they are not being used, they just set there and wait.

Hello, I have recently moved into a house with a Junkers on-demand gas-fired water heater, unfortunatley the ignition button hates me and does not work! I called the former residents for advice and they simply said "light it manualy *hangs up phone*" (derrrr WHERE!?!?) I have been showering in cold water whilst it is 4 degrees celcius outside and am starting to get quite angry....anybody got any idea on where in the system I should light? Diagrams would be much appreciated.

I have had great luck with my titan tankless water heater. I got mine threw tanklessplanet . com . Give them a try

to those people trying to prove the voices are real. You cannot prove it because the people you need to prove to are the ones doing it to you. You can't prove it to yourself that the voices are real by going under 6 feet of water. You will not be able to hear the voices underwater because your eardrum as water pressure on it and it cannot vibrate as easily.

Has anyone seen/heard anything on this microwave technology? In theory it would be much more efficient, but I cant find any updates on this via google or any other source....

For those of you who have asked for information in this forum, concerning the "microwave" technology, I can offer the following:
Instead of using a small-bore copper winding within the unit, which is then heated upon demand, the microwave version utilizes a tightly wound CERAMIC coil, which is then bombarded with the micro-waves. It is claimed that this is a much faster method of heating the cold water within the tube, and produces a more instantaeneous flow, at a lower cost.
There is a company on Pulrey Way, Croydon, Surrey, England (whose name escapes me) who have perfected this technology.

Microwave is the upcoming method and i am anxious to learn more. If you need a good primer to be prepared for the day your water heater quits, I suggest this link: Just a note for the new DIY people: A very well written ebook is available at a reasonable cost which is published by a mechanical engineer. If you want to be prepared for a tankless system before your water heater quits, this is a very good read. http://www.mechanicalengineeronline/Mini_Sites/Tankless_Water_Heaters_Ebook/Tankless_Water_Heaters.htm

I have read all of the comments regarding tankless water heater and the various heating sources such as electric, gas, propane, and I dont think there was any info on ground water heat exchangers. I was wondering if the most effecient although not the cheapest way to heat water would be a ground water heat exchanger feeding water to a solar heater and then to small on demand electric units. These cant be used in apts or houses in close areas but it might be the most effecient. Comments are invited

As a plumber with 20 ears experience I am hesitant to push customers to tankless heaters--for now! I expect that in perhaps 5-10 years the technology will settle down and mature(I know tankless has been in Europe for decades).In North America the storage tank heater is the standard and the homes have been designed for that type of heater.To upgrade hydro or increase gas pipe and vent sizes is not justifiable in my opinion.Better to maintain your existing tank by changing the anode every 2-3 years(its pretty easy) and occasionally flushing any sediment out the drain. If you are in an area with hard water then you probably need a water softener.I myself use a gas "direct vent" style heater and change the anode every 2 years. A neighbor has a gas "power vent"and uses a electronic timer to control the power to the appliance.It only runs when his family needs hot water-at night it is powered down and starts up again at 6am,off at 9,on again at 5pm ect.If you use this method be sure to have a timer with the proper amperage rating for the gas appliance. Microwave heaters sound cool--like warp drive! Probably many years in the future.

Hmmm.... Microwave technology for water heating device. It sounds unfamiliar to me. Is it the new technology for tankless heaters? If the answer is yes, then I hope it will better than previous technology, particularly about the efficiency to cut the energy bill, so I can save more money every month Lol!

Thank you for your article, it is helpful to me to know more about variety technology systems of tank-less water heaters.

Some of you "experts" have your eyes and ears coverded...The life of Freedom and Marathon tanks is "lifetime" and well backed...standby losses of a Freedom or Marathon unit are less than 3 degrees in 24 hours..these electric heaters cost 1/3 of a gas tankless. Add in expensive tankless installation...you do the math...payback maybe never?...worried about 1st hour recovery? buy a larger efficient tank and don't sweat the 3 degree loss...Paul Harvey was as dishonest about tankless as he was about many other things he sold...just $$$$ to him.