Tank vs. Tankless Water Heaters
 

a bit of background information--I live alone in a small guest house, and up until this weekend I had a 52 gallon water heater (electric). Without warning, my water turned cold. I thought I just burned out a heating element, but when i went to investigate, it became apparent that the wiring harness was shorted out, and the condition of the rest of the unit helped me decide that it was time to replace the whole shebang. At this point, I remembered about tankless water heaters.

The place is small, and the tank takes up a lot of space. My only hot water needs are the kitchen faucet (literally right next to the heater) and the shower and tub (less than 10ft away). My incoming line is probably somewhere between 50 and 60F, depending on the Central/Northern Californian climate, so I probably want something that can raise the temperature by about 50F at a rate of ~2gpm, or whatever a decent shower requires. The situation seems perfect for a tankless system, the only question is which one to get. Obviously, I'm looking for the most affordable solution, but I don't want something underpowered that'll disappoint (like giving lukewarm showers).

So what I'd like to know is what kind of experience anyone has with tankless water heaters, and which brands and models you would recommend for my situation (and where to get them!). I'm having a hard time finding many online, even at big retailers like Home Depot.

Thanks for your help

My friend in the UK has a tankless heater for her flat and it works extremely well. I've also stayed in flats in France that have them and never had cold water.

The benefit is that you don't have to use energy to keep water hot that you are not using. I should also say that the only tankless systems I've see use natural gas to heat the water.

I was hoping to get one in my place in Toronto but, unfortunately, our water heater died while I was away on business and wasn't there to ask about the availability of an inline system (I later found out that they were available from the gas company).

Home Depot Canada has these models: LINK

I know a couple of people who have them not in small apartments but houses. They have nothing bad to say about them.

Were I looking for a HWH myself, tankless is where I would likely go.

I have a friend that retrofitted his c. 1910 house with a tankless system and he loves it. Granted he's in Florida, not Chicago, so he doesn't have to deal with bringing the water temp up 70 or 80 degrees, but he thinks it's the greatest thing ever.

They are the norm here in Holland. Natural gas powered. Work fine, last long time.

Check with your electrical company.

damn, it's so cold here right now that i'm mad at you just because you live in a place that barely needs water to be heated for it to be suitable for showers

All of the dorms on our university campus are fitted with steam-heated tankless water heaters. They are marvelous.

The beauty of the tankless system is the seemingly endless supply of hot water.

Thanks to everyone for your input; I've been doing a bit of research and I've narrowed it down to just a couple models. I’ve been looking at the Stiebel Eltrons, as they seem to have the most comprehensive range from low-flow, single point of access heaters to monster systems . Also, I heard there’s a $300 tax rebate from the electric company for getting a system rated somewhere over 80% efficiency. I'll call tomorrow to confirm.

I Found this site, the Tempra 15 and 20 seem to be the same price here, but pricegrabber found the 15 for as little as $400.

I measured my shower and tub flow rates, and the shower was about ~2.3gpm without the shower head, 1.8-2gpm with the shower head (this seems to be the magic number), and the tub was ~2.5gpm, so the Tempra 20 looks like it would be just a bit more than what I need. The only problem: it says I need TWO 240V breakers at 50amps apiece, I have 8 120v at 20amps apiece (6 are free). My old heater ran off two breakers, but I don't know if the tankless heater is ok essentially running off 4 120v 20amp breakers. For the Tempra 20, it looks like I need an electrician to wire some more breakers.

The Tempra 15 seems like it could go in without any modification, but if the incoming water temperature is under 50 (I haven't been able to measure it yet), it might not be enough. There’s an equivalent Bosch model that has slightly better specs at about the same price. I'm calling the plumber tomorrow to see what can be done.

What do you think? Any user reviews for a particular model I've mentioned? This is exciting business, I'm looking forward to taking a hot shower again.

//added: I also came across this site with a video guide to choosing the tankless system for you.

I've had one since last May. It cost 20 times the price of a tank heater. It can produce up to 7.5 gallons of hot water per minute, which should be enough to supply three showers at once. But it doesn't. I'm not sure why, but all the hot water seems to go to one place. If the second shower is used while the first shower is on, all the hot water goes to the second shower. This problem is not unique to me. I've heard many tankless users complain of this problem. The good news is that your gas or electric bill will go down.

so you only experience this problem when you run both showers at once? When you run a single application are there any problems?

do any of you know/have experience with how the heating elements/heating surfaces in these tankless heaters hold up to high mineral content water? While my home has a different, much lower mineral laden water source than a place I worked, we had a small electric heated boiler in work that used to completely cake up about every 6 months.

When I run a single application there are no problems. It works fine.

i live in dubai, and i dont need a water heater to have showers. especially in summer!

in the middle of smmer we try and have showers later in the evening or early morning so that we dont get scolded by the hot water.

as for instantaneous hot water systems. they are good. but only run on gas. so u need to fing out what u have

I dunno about them personally but I saw an ad for one of these the other day and I was really shocked. The physics of the process is just mindblowing. Gotta get one : )

Not to make light of what blows peoples' minds, but it's really just very basic high school physics (now adays my kids are learning this in middle school).

You need a big enough electric heater or gas or oil fired heater so you can heat up the water. For example,

2 GPM = 1,000 pounds per hour of water (this converts gpm to mass flow)
Let's say typical water temperature rise required is 40F to 90F, so 50F temp rise.
Since it takes one BTU to raise the temp of a pound of water by 1F:
1000 X 50 = 50,000 BTU per hour heater required
50,000 BTU/hr is 14.6 kilowatts in electrical terms

Sorry for the delay, folks. It's been a long couple of weeks and I dragged my feet for a while trying to determine whether to purchase the unit or not, mainly because I was worried that my service wouldn't be sufficient to power the heater. Despite the fact that it's a relatively small unit, it requires massive amounts of electricity (2 separate 2-pole 240v 40amp breakers, for a grand total of four 8awg wires O_O)

I called around to see what the local plumbers thought of this. I was a bit shocked to learn that none of them had heard of an electric tankless water heater. One coped with this by insisting they didn't exist, while another just assumed I didn't know I was talking about (not too far off the mark), and kept giving advice about installing a gas heater, quoting me $1300 in labor to install, etc. I gave him my info and he said he'd come by to give a quote, but he never called back (shocking).

Finally, I got a good reference and the guy came out to see what he could do. He'd also installed gas heaters, but in 20 years in the business, had never been asked about an electric tankless system. He poked around a bit and told me it should be a simple job, and that I could just do it myself. I'm tempted to think that he would just rather not mess with it.

Already seduced by the space and energy efficiency of the tankless system, and emboldened by the plumber's encouragement, I took the plunge and ordered one from an out-of-state website. With free shipping and no sales tax, I got the Bosch AE115 for about $426.

After having mentioned my predicament at work, my boss sent his handyman over to install the unit for me (and is footing the bill--I'm swooning). We spent all day setting things up: replacing some pretty nasty encrusted pipes, mounting the unit to the wall, cutting out some of the sheetrock and finally running the cabling to the breaker box, mercifully close to the heater. Got everything hooked up, flushed all the crap out of the line (learned that I should only use teflon tape to seal the threads, as goop sealant will clog the line). Hooked up the new breakers and flipped the switch. The unit turned on and began to heat the water, but as we turned the temperature knob up, the lights went out. We were overloading the breaker on the main panel feeding the guest house. I can get slightly steamy water coming out of the faucet, but the shower is just too much, even with all the other electronics turned off.

I was worried this would happen, so it's not completely unexpected, but it is unfortunate. The next step is to increase the power to the guest house, either by replacing the line or adding an additional one. I'll keep y'all posted.

The moral of the story thus far is: Installing an electric tankless water heater is not a job for a plumber, it's a job for an electrician.

..

I have to say this sounds very interesting. Living in a cooler climate it seems my energy bills are always climbing with winter heating, summer cooling etc. It keeps getting more and more expensive, pretty soon it will be a luxury to heat over 60F in my home. Let me know how it goes, I have a very old water heater myself that I have considered replacing.

Considering the headache I'm going through, unless if you have loads of electricity coming to your house and you aren't using much of it (minimum recommended service for my relatively small model is 150amps), I would not recommend an electric tankless heater. Plumbers don't know shit about them, so you might as well install them yourself, but even though it's pretty straightforward, I would be wary about installing it myself. A 'qualified' professional is recommended by the manufacturer, which pisses me off a bit because I simply couldn't find a qualified professional that has any experience installing the damned things.

In short, for a whole house, you're probably better off getting a gas heater that is suited for your needs. A lot more is involved in the installation, but if you're going to hire a professional you might as well make them work for it.