Tankless Water Heater - Seeking Suggestions

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Chuck1986

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I live in a 2 bed/1 bath condo and the current water heater has been in service since 1997, when the condo was originally built. I imagine it will be biting the dust any day considering it is nearly 15 years old and AZ water is notoriously salty.

With that said, I am looking to get a tankless water heater to cut down on the electric bill and save storage space. Electric is my only option since I do not have gas lines where I live. Keep in mind I live with only one other person and I have one bathroom so my hot water usage is very low. Your suggestions would be much appreciated, as I am sure many of you have experience with tankless water heaters. Thanks!
 
let me just say my sole experience with one was not a positive one.

My brother-in-law's family has an old lake Cottage a little south of here. few years back, as the summer was ending, the old tank gave out. so they got a tankless, to save $$(not sitting there heating water all winter, or all summer, gets used mainly on summer weekends)have it all installed, everything looks good, close the place up for the winter.
Come Spring, they find several inches of moldy yuck on the floor, either the guy that installed it didn't know much about tankless heaters, or this one was defective, or something. cuz some time over the winter, the unit sprung a big leak, and flooded the place. needless to say they had to replace the carpets, furniture, the wall boards,etc. and have another plumber come fix the heater.

Bottom line, they are more expensive than a traditional heater, more expensive/complicated to install, and for the love of god,Make sure the person doing the install knows what they are doing.
 
The only "Tank-less" water heater that I know of that is electric is one that fits under a sink, or bathtub, and turns on when it detects the water running.

Most true tank-less systems are gas. But being that you have a small place with minimal use of the hot water heater you may be able to get away with the small electric job.

You may want to start to call around to professional pluming supplies. Don't trust a big box store for something like this. Their personnel can be hit or miss and so can their advice.

BTW, the thing that really costs a bunch for tank-less water heater is the stainless steel duct. Most people don't realize this until they begin research.
Aluminum melts and burns at pretty low temperatures, not a good thing for something whose job is to heat large quantities of water quickly. It is NECESSARY to have stainless steel ducting put in for a gas fired tankless water heater.
 
hmmmm. Its a matter of standby losses. An electric has no flue, and electric, while expensive, has 100% efficiency.

I have an indirect gas (no flue), which looses less than 1/2 degree per hour, IIRC.

IMO the electric load capability for getting reasonable flow is way too high. Youre probably looking at 10kW or more to be able to run one shower at a time at reasonable flow rate.

Id probably look at what is the best/most insulated tank heater, as the electric work will be cheaper.
 
I have a 2 bed/2 bath condo on the 3RD floor..The condo board got a company in Miami to install tankless water heaters at a great price..As long as 25 owners took the deal they said they would install the tankless water heaters for 500 bucks each..There are 56 units in the building..30 owners took the deal..The board made the deal after a bunch of hot water heaters took a dump [a lot of owners were away when they took a dump] and caused big time damage to condos below them.

They put in Titan tankless water heaters..So far out of 30 owners only one had an issue..They put in a new control unit for the owner and all is well..Everyone is happy with them..Including me.

I do not see any change to the electric bill..But I am glad to have it as I know how much damage those water heaters can do.
 
I have a TAKAGI gas tankless...when i was doing research the best electric ones were made by Stiebel Eltron... they have different sizes from point of use to whole house...make sure your wiring is up to date in terms of amperage draw.... went with gas since i have a wife and daughter that can run the equivalent of a small lake down the drain when they shower
 
I bought a tankless electric water heater from Bo sch 2 years ago. It required 2 40 amp breakers and wiring for service. So far it has been great with no problems, leaks, etc. We had a tornado here and lost electricity for 6 days and it did not make hot water while our gas heater in our bedroom did make hot water. Small difference in elec bill each month. Cost of heater and install was about 600 bucks with about 175 just for the copper wire. Man, copper sure has gotten expensive
 
I have a Stiebel Eltron 100 amp unit. Very high quality, made in Germany. Small and compact. Yep, it takes two 50 amp breakers. No problems in 4 yrs. Easier to install in new construction or a remodel. I also ran a filter and softener before the unit to help protect from wear and tear. I'm on a private well.
 
Not everyone is happy with tankless. But i know one family that uses elec tankless(no gas) and he does like his set up. His uses 3 40 amp breakers to feed it. 8 gauge wire.
Tankless units have to descaled!
Don't forget about regular tank heaters that have EFs up tp .95
There is very little stand by losses on the best elec models
 
We have a Rinnai gas tankless and we will never recoup the install/unit costs on a gas savings basis. New tanked units can be had with wonderfully high efficiency levels.

With our family of six though, having hot water all day long is priceless! We can empty a typical 50 gallon heater with no problems. And the space savings was a small bonus, too.

When we had ours installed (almost three years ago); our plumber also recommended an A.O. Smith Vertex tank heater. Said he has one in his home and is very pleased with it.

They do require more maintenance, apparently, but our Rinnai has not given us a flush code yet. We do have a water softener, but we use a *lot* of hot water. Maybe one day I'll have to do the vinegar flush.. but I'll wait until it tells me to.
 
Originally Posted By: JHZR2
hmmmm. Its a matter of standby losses. An electric has no flue, and electric, while expensive, has 100% efficiency.
....
IMO the electric load capability for getting reasonable flow is way too high. Youre probably looking at 10kW or more to be able to run one shower at a time at reasonable flow rate.


Some good points, tankless electric would require a huge amperage circuit (loads of copper wire, massive electrical work) .

Also, with no flue, the heat loss is probably a good bit smaller on an electric model, esp. if you add some blanket insulation around the heater.

For gas tankless heaters, I find the unevenness in heat and the inability to trickle a low flow of hot water on tankless heaters to be the deal breaker. Add to that that you need to likely install a new thicker gas line and it makes little sense at these gas prices.

One comment more, while it is about 100% efficient to convert electricity into heat with a resistance heater (electric heater), the problem is that at the power plant the efficiency of turning chemical energy into electricity is only around 35%. So, after losses outside of your house, your effective efficiency (counting power plant and transmission losses) for an electric water heater is going to be more like 30% if lucky.

If you don't have gas though, you really should consider a heat pump add on for your water heater. It will also cool your house in the summer (save with less AC use) while it heats your water. They are starting to become more commonplace and available, and the price is already right (much less than what an installed tankless will run you). The heat pump will just about make up for losses at the powerplant; likely more if you count the AC benefit in the summer, so even your effective efficiency will be greater than 100%.
 
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1. have you considered piping the tankless into say a small electric tank heater that's near the shower, say a tank under 10 gallons, and very well insulated. Just to even out the temperature, and also to save water that has cooled off sitting in the pipes. For any significant use of hot water the resistance heater would just be used to store and hold the temperature of the hot water; I wouldn't expect a big average wattage from that.

2. heat pumps are the way to go for electric only communities at southern lattitudes! esp if you for example were to live on a small hawaiian island where pretty much 100% of the electricity is generated from oil burning electric plants. Modern times and $100/bbl oil prices haven't yet made much of an impact to the small islands there yet, though recently wind and solar and renewables are being more seriously considered there. LNG would make the most sense there but the islanders lean too much towards hippie for that option to pan out.
 
Have had lots of ideas about water heating....tank sitting in the sun to provide low grade heat prior to the instal, a solar system prior to the tankless, just lots of ideas.

Hot water heaters are now limited to 50C by law, so Mrs showers with neat hot water, and storage at 50C probably isn't that effective overnight.
 
Solar hot water would make so much sense. I at one point thought about that too. The big difficulty is avoiding the risk region of temperature where Legionella can breed. I think that temp range is somewhere from like 85f to 110f, peaking somewhere near body temperature. As long as the major volume of water to be preheated isn't sitting in that range for long then all is ok, esp if you later feed it into a 50C / 122f tank of hot water.

Solar in combo with heat pump would be excellent in efficiency.
 
I don't think our gas tankless has un-even heat at all. I can take a shower at a set temperature and it never noticeably fluctuates.

It is true you need a certain amount of flow to activate the heater - but it's pretty small; and you get used to the couple seconds more it takes to get the water to the tap.
 
Originally Posted By: Virtuoso
We have a Rinnai gas tankless and we will never recoup the install/unit costs on a gas savings basis. New tanked units can be had with wonderfully high efficiency levels.


I can't speak for home use, but in high volume business use, the Rinnais make a nice difference. They certainly don't pay for themselves overnight, but over a two or three year period, they might.
 
Originally Posted By: Garak
Originally Posted By: Virtuoso
We have a Rinnai gas tankless and we will never recoup the install/unit costs on a gas savings basis. New tanked units can be had with wonderfully high efficiency levels.


I can't speak for home use, but in high volume business use, the Rinnais make a nice difference. They certainly don't pay for themselves overnight, but over a two or three year period, they might.



+1, the tankless is 30% more efficient than the best tanked gas heater.

Electric is 100% efficient though on heating, and has a tiny, low standby loss because there is no stack.
 
A bit of real world math:

It generally takes about 90,000-100,000 BTU to provide full flowing hot water, without a tank. Certainly, 40,000 BTU is not enough for a typical shower (unless flow rate is significantly restricted)

There are 3414 BTU in one KWH (1000 watts for an hour)

So, absolute bare minimum is 40,000 BTU/3414= about 12,000 watts or 54Amps draw at 220V.

But more realistic performance would require 100,000 BTU.
So, 100,000/3414= about 42,000Watts! or 190Amps draw.

So, you'll need 200A dedicated just to the water heater. Maybe in a condo, you could get away with 300A service...
 
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