Author Topic: Hot water heater - to tank or not to tank?  (Read 13704 times)

Journeyman

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Hot water heater - to tank or not to tank?
« on: October 22, 2012, 08:33:41 PM »
I wanted to find out if anyone has had good/bad experiences with tank vs. tankless water heaters in terms of efficiency and cost.  My tank electric heater is due to be replaced and I am on the fence between tank vs. tankless.  Our hot water usage is realtively low, about 10 minutes per day (15 gallons) for showers (use cold water for everything else).
      
My current electric tank is 52 Gallons, 4500 watts with an energy factor of .86.  The tank I am considering is 40 gallons with an energy factor of .92.  The tankless I am looking at is 18KW and is capable of heating 1.5 GPM during the coldest days of winter in my area (enough for my low flow shower head - we take one shower at a time).
      
A lot of comparisons I read mention high upgrade costs to tankless and little to no savings over time with tankless and other trade-offs (example http://michaelbluejay.com/electricity/waterheaters.html).  My situation is such that I just need to put in new circuits and 8-guage wire and that will run me about $350.  The cost of the tank vs. tankless is equivelent, so I would just be looking at $350 additional upfront for tankless (and better tanks actually cost more than the tankless unit).
      
Looking at my usage, I have run some basic calulations, and it would appear I should save a little money on my electic bill with the tankless (factoring in the $350 differential on the tankless).  I also think that only heating the water we use daily (~15 gals) should be more efficient than heating 40 gallons 24/7 (understanding only a small percentage of the heat is lost from the tank, especially if we blanket the tank).
      
I wanted to find out if others have been in a similiar situation and/or have converted to electric tankless and if they have found an appreciable drop in electic consumption?

Bakari

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Re: Hot water heater - to tank or not to tank?
« Reply #1 on: October 22, 2012, 09:06:37 PM »
I don't know much about the electric type, but I installed a gas tankless a couple years ago.

Like you, I only use hot water for showers, which is where I think you save the most by switching to instant - if a household is using hot water constantly, the penalty for heating water 24/7 just to sit there and radiate said heat away again is smaller, percentagewise.

The one I got was very simple, with manual controls, and it cost substantially less upfront than a standard tank heater. 
It reduced by use of gas rather dramatically (very roughly in half), and I only had a 5 gallon tank heater to begin with!
Definitely worth it.

I've noticed, (in online discussions, client's houses, and even from MMM himself) that the standard default is to buy a complicated instant heater filled with "features" - automatic temperature control, automatic pressure control, compensator, regulators, all sort of extra stuff which we never expected on tank heaters.  All that stuff drives up the price and (according to an installer I spoke to) reduces the reliability.  But that's all you will find offered by contractors and big box home improvement stores, so its all most people think exists.
You have to shop around internet style.  I got mine (new) off of ebay.  About $179 IIRC.  Including shipping.  Installed it myself in less than an hour. 

If, like me, you adjust it to the temperature you need, so that you don't have to turn on the cold tap when you shower,
you have to adjust the temperature control between seasons. 

All that said, the new wiring issue may change everything.  Then again, for that price, if you have any gas lines in the house at all (stove?  furnace?  past appliances no longer in use?) you could route them to the water heater location for a lot less than $350 (more like $20 if you do the work yourself, which is easy), and just get a NG model instead.

TomTX

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Re: Hot water heater - to tank or not to tank?
« Reply #2 on: October 22, 2012, 09:09:55 PM »
Natural gas also typically requires incoming air and a significant vent stack.

Journeyman

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Re: Hot water heater - to tank or not to tank?
« Reply #3 on: October 23, 2012, 09:16:52 AM »
Yes, good points on the NG.  I do have NG in my home, however the venting was of concern.  I will do a bit more research on the venting requirements and as suggested look at the basic models without all the extras.

TheDude

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Re: Hot water heater - to tank or not to tank?
« Reply #4 on: October 23, 2012, 09:24:51 AM »
Lots of talk on here about water heaters lately. I would think for the cost differences. It might better to just stick with a tank design. You could add some insulation and timer if its electric. Replace the anode rods (every 5years) and flush (1-2 times a year) and that baby will probably out life you.

Argyle

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Re: Hot water heater - to tank or not to tank?
« Reply #5 on: August 09, 2013, 01:02:38 AM »
Coming back to this -- I'm looking at installing a tankless heater and am wondering about the details of the ~$179 heater you found, Bakari.  Can you give the make and model?  The pros I consulted hadn't heard of anything nearly that cheap and couldn't suggest anything.  I'd love to know how to find one of these.

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Re: Hot water heater - to tank or not to tank?
« Reply #6 on: August 09, 2013, 12:06:35 PM »
Coming back to this -- I'm looking at installing a tankless heater and am wondering about the details of the ~$179 heater you found, Bakari.  Can you give the make and model?  The pros I consulted hadn't heard of anything nearly that cheap and couldn't suggest anything.  I'd love to know how to find one of these.

I got mine through a dealer on Ebay.  All they sold was simple instant water heaters.  Was new, had a warranty (though I haven't needed it), but I think they sold exclusively through ebay.  The exact seller isn't there anymore (I checked when looking up the same question for someone else on the forum), but there are plenty of others selling the same or similar products on ebay and google shopping.

3 years so far,zero problems

I have to adjust the temperature at least 4 times a year as the ground temp outside changes with the seasons.  I like to keep it so that if I turn on the hot water only (no cold), it is the perfect temperature for a shower (why heat it hotter than you want it, and then cool it off again?  It would be like stepping on the gas and brake at the same time).  And I've had to replace the batteries that provide the spark once.
Aside from that, it just works, no need to think about it, despite missing all the fancy bells and whistles of the $1000+ models.

GuitarStv

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Re: Hot water heater - to tank or not to tank?
« Reply #7 on: August 09, 2013, 02:03:09 PM »
We looked into getting a tankless heater installed a couple years back, and in our area it would have come out to over a grand.  A tank water heater of similar capability runs about 3-400$.  They both have estimated lifespans of between 10 - 20 years.

Our gas bill is 25 - 40$ every two months, but only 5-15$ of that is the charge for gas, the rest is for the privileged of having gas attached to your home.  Water heater costs are estimated at about 30% of your gas bill, so  . . .  let's assume that we have control over 15$ x 12 months = 180$ of gas usage a year.  30% of that is 54$.  If we brought that down to zero it's going to take you more than 12 years to break even with the cost of a tanked water heater.  That's assuming the tankless heater uses NO energy at all . . . so you can expect it to take much more time than that.

Granted that was a few years back, maybe tankless is a lot cheaper now . . . but it sure wasn't worth it when I was looking at it.



(Our current tanked water heater is 22 years, and I'm hoping that by the time it dies tankless will be significantly cheaper.)

Spork

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Re: Hot water heater - to tank or not to tank?
« Reply #8 on: August 09, 2013, 02:23:34 PM »

Granted that was a few years back, maybe tankless is a lot cheaper now . . . but it sure wasn't worth it when I was looking at it.

(Our current tanked water heater is 22 years, and I'm hoping that by the time it dies tankless will be significantly cheaper.)

When we built and put in a tankless, our "break even" was in the 7-10 year time frame.  I'm not 100% sure it even works out that way, as there is a bit of "comfort creep."  If you get in a tank-supplied shower and feel the water getting colder, you get out.  In a tankless, you can run all day long.  They are nice... I can't say I'm upset I got one.  But ... I suspect in the end it's probably about even money.

Oh, and our tankless has a supposed life expectancy of 20+ years.

They also take up a whole lot less room than a tank.  Ours fits between studs on an exterior wall.  It's self-venting, since it is partly outdoors.

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Re: Hot water heater - to tank or not to tank?
« Reply #9 on: August 09, 2013, 02:29:08 PM »
We looked into getting a tankless heater installed...

As I mentioned in my original post in this thread, installers only offer the most expensive, feature rich models, because they make more from installing them.
Just like no solar installer will offer a 12V non-grid-intertie system, and car dealers like to push luxury cars and SUVs - the higher the cost of the product, the higher mark-up you can get away with adding.

They also don't offer simple instant heaters in bigbox home improvement stores - but that doesn't mean they don't exist.
I know this with absolute 100% confidence, because I personally have purchased and installed one, just a couple years ago, for less than $200 (including shipping and hardware).

"Installation" consisted of turning off the gas and water lines, taking off the gas and water lines from my old broken tank heater with a wrench, and attaching them to the new one with a wrench.  Then turning the gas and water back on.  No matter how mechanically inept you are, this is something you can do instead of paying someone else to do it.

Spork

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Re: Hot water heater - to tank or not to tank?
« Reply #10 on: August 09, 2013, 02:43:49 PM »
They also don't offer simple instant heaters in bigbox home improvement stores - but that doesn't mean they don't exist.
I know this with absolute 100% confidence, because I personally have purchased and installed one, just a couple years ago, for less than $200 (including shipping and hardware).

I think the larger whole-house units are about 1.5x the cost of a tanked heater.... something in the $1200-1300 range if I remember (and that is suspect.  I am terrible with numbers.)

...but yes, installation is "water in; water out; gas in".  (Possibly 120v electric circuit if it's electronic ignition.)  Easy.

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Re: Hot water heater - to tank or not to tank?
« Reply #11 on: August 09, 2013, 03:39:38 PM »
They also don't offer simple instant heaters in bigbox home improvement stores - but that doesn't mean they don't exist.
I know this with absolute 100% confidence, because I personally have purchased and installed one, just a couple years ago, for less than $200 (including shipping and hardware).

I think the larger whole-house units are about 1.5x the cost of a tanked heater.... something in the $1200-1300 range if I remember (and that is suspect.  I am terrible with numbers.)


Depends what you mean by "whole house unit"

If you have 2 low flow showers and a low flow kitchen sink faucet all running on full all at the same time, then you need 4.5 gallons per minute of hot water.

Now, by typical American standards one would say that maybe at some point in the future you will want to run 2 showers, a kitchen sink, a bathroom sink, the dishwasher, and a washing machine all simultaneously, and therefor nothing short of 15gpm can qualify as "whole house" size.
But the Mustacian knows the better solution than sizing for the most possible use imaginable: just don't run all that hot water at the same time.  All of a sudden the size of the heater you "need" is 1/3 as big, and along with it, the price.

Seriously, you don't have to take my word for it - just type "instant hot water heater natural gas" into google shopping, put the price range at $200-$600, and see how many show up with 4+ gpm rates, plenty enough for a couple fixtures running at once (in a reasonable climate, or one fixture at a time in subfreezing weather - yet another reason not to live somewhere it snows...)

Here's a few:
http://www.build.com/takagi-tkjr2inng-n-a-6-6-gpm-natural-gas-indoor-tankless-water-heater/p1716377
http://www.ecodirect.com/ProductDetails.asp?ProductCode=Rheem-RTG-64XN&gclid=CILHkuao8bgCFZFcQgodZSEAag
http://compare.ebay.com/like/110981325561?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar (<- this is the brand I have, though mine is smaller)
http://www.faucet.com/eccotemp-40hi-ng-6-3-gpm-natural-gas-whole-house-tankless-water-heater/p1931084
http://www.amazon.com/home-improvement/dp/B00882OBM0

Simple Abundant Living

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Re: Hot water heater - to tank or not to tank?
« Reply #12 on: August 09, 2013, 10:27:31 PM »
Is anyone using a larger tankless water heater?  We have a family of eight, and occasionally over night guests.  I may need to do two-three low flow showers at once. Laundry and dishes can wait.  I currently have two inefficient 40 gal water heaters which aren't that old, but use too much gas. Thanks.

Spork

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Re: Hot water heater - to tank or not to tank?
« Reply #13 on: August 10, 2013, 08:55:27 AM »
Is anyone using a larger tankless water heater?  We have a family of eight, and occasionally over night guests.  I may need to do two-three low flow showers at once. Laundry and dishes can wait.  I currently have two inefficient 40 gal water heaters which aren't that old, but use too much gas. Thanks.

I am (regardless of Bakari's opinion).  We are certainly not a family of 8... but I suspect you can wing it.  The other side benefit of the tankless is you can crank up the heat on an ad-hoc basis.  If 120 degrees works for your family normally and you have extra guests, you can bump it to 130 or even 140.  It'll suck the gas when you do it... but it's instant.  And when you're done, you turn it back to what's comfortable for you normally.

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Re: Hot water heater - to tank or not to tank?
« Reply #14 on: August 10, 2013, 03:39:57 PM »
Is anyone using a larger tankless water heater?  We have a family of eight, and occasionally over night guests.  I may need to do two-three low flow showers at once. Laundry and dishes can wait.  I currently have two inefficient 40 gal water heaters which aren't that old, but use too much gas. Thanks.

I am (regardless of Bakari's opinion).  We are certainly not a family of 8... but I suspect you can wing it.  The other side benefit of the tankless is you can crank up the heat on an ad-hoc basis.  If 120 degrees works for your family normally and you have extra guests, you can bump it to 130 or even 140.  It'll suck the gas when you do it... but it's instant.  And when you're done, you turn it back to what's comfortable for you normally.

What size would you recommend?

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Re: Hot water heater - to tank or not to tank?
« Reply #15 on: August 10, 2013, 06:15:04 PM »
Is anyone using a larger tankless water heater?  We have a family of eight, and occasionally over night guests.  I may need to do two-three low flow showers at once. Laundry and dishes can wait.  I currently have two inefficient 40 gal water heaters which aren't that old, but use too much gas. Thanks.

I am (regardless of Bakari's opinion).

:P

I'm not saying one should avoid the big units if that works for you, I'm just pointing out that one shouldn't write off tankless as an option just because installers won't offer anything under $1000

Spork

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Re: Hot water heater - to tank or not to tank?
« Reply #16 on: August 10, 2013, 06:34:48 PM »
Is anyone using a larger tankless water heater?  We have a family of eight, and occasionally over night guests.  I may need to do two-three low flow showers at once. Laundry and dishes can wait.  I currently have two inefficient 40 gal water heaters which aren't that old, but use too much gas. Thanks.

I am (regardless of Bakari's opinion).

:P

I'm not saying one should avoid the big units if that works for you, I'm just pointing out that one shouldn't write off tankless as an option just because installers won't offer anything under $1000

I wasn't really trying to argue, either... just that "it could be done."  It's a trade off: cost vs flow rate.... and probably cost vs life of unit (though... not necessarily). 

I've considered the idea of a solar pre-heater, too.  And by that, I mean one or more large vessels painted black with a good southern exposure.  I think this could be a huge low cost win.  I am not sure I have a good place to put it... and I didn't really pre-plan for it when I built the house.  (I didn't put in conduit or any easy access method and my exterior walls are foam insulated, so it could be a little difficult.)

moostachio

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Re: Hot water heater - to tank or not to tank?
« Reply #17 on: August 10, 2013, 08:25:59 PM »
I went through the research on tankless about a year ago, I decided against it, and instead have a direct vent gas tank type water heater.  A direct vent gas water heater which we had before, I was able to install myself, we like it.  The direct vent unit itself was not inexpensive though. Some things to consider:

1) If you have a small family and do not use much hot water tankless could be a good option.
2) In our area we have natural gas at the house, and it is much cheaper than electricity, so gas would be the choice no matter what. The gas vs. electricity question could be very central to your decision making. Also in case the electricity goes out gas still provides hot water, with our direct vent tank model that has a pieseoelectric ignition allowing it to operate without electricity.  Electricity outages are common.  The direct vent model has a sealed combustion chamber, so only outside air is used for combustion, no air from inside the house is used at all.
3) If you install a gas tankless with a lot of capacity the installation cost will be considerable, as it will require installation of larger gas lines, plumbing, and air vents.  I did think the outdoor installation of the gas unit was interesting as an option.
4) I am into DIY.  However be aware if you buy a large tankless water heater and think about installing the lines and the unit yourself be aware that most of the tankless companies void their warranty unless it is installed by a professional.  Also your homeowners insurance in most areas will require professional installation of gas units with significant installation complication... in case of a fire, you would not want to have voided homeowners insurance.

Anyway the above considerations may be helpful in evaluating your choice.  Best of luck.

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Re: Hot water heater - to tank or not to tank?
« Reply #18 on: August 10, 2013, 08:52:25 PM »




I wasn't really trying to argue, either... just that "it could be done."  It's a trade off: cost vs flow rate.... and probably cost vs life of unit (though... not necessarily). 

I've considered the idea of a solar pre-heater, too.  And by that, I mean one or more large vessels painted black with a good southern exposure.  I think this could be a huge low cost win.  I am not sure I have a good place to put it... and I didn't really pre-plan for it when I built the house.  (I didn't put in conduit or any easy access method and my exterior walls are foam insulated, so it could be a little difficult.)

I would love a solar water pre-heater.  I should look into that option before doing anything else.  Great idea!

meadow lark

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Re: Hot water heater - to tank or not to tank?
« Reply #19 on: August 10, 2013, 10:00:48 PM »
Bakari - do you know if a little one would run a dishwasher?  That would be the limiting factor for me, I gotta have my dishwasher!

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Re: Hot water heater - to tank or not to tank?
« Reply #20 on: August 10, 2013, 11:40:39 PM »
We installed a Rinnai tankless water heater (natural gas) after a basement remodel six years ago. We have a small house, so every square inch in the basement is useful and the tankless is hidden behind a cabinet door. It's worked very well and I like the energy savings in the long run. If I had a big house with room to spare, I'd consider an electric one. But I have no regrets of spending 1k plus on this tankless heater.

fiveoclockshadow

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Re: Hot water heater - to tank or not to tank?
« Reply #21 on: August 11, 2013, 04:17:34 AM »
Bakari - do you know if a little one would run a dishwasher?  That would be the limiting factor for me, I gotta have my dishwasher!

Don't most dishwashers heat their own water?  They are usually connected to hot, but I thought most could also heat the water as often the desired temperature (scalding) is higher than what you set a house water heater to (not scalding). You might check what your model does.

Bakari

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Re: Hot water heater - to tank or not to tank?
« Reply #22 on: August 11, 2013, 06:46:43 AM »
Bakari - do you know if a little one would run a dishwasher?  That would be the limiting factor for me, I gotta have my dishwasher!

Don't most dishwashers heat their own water?  They are usually connected to hot, but I thought most could also heat the water as often the desired temperature (scalding) is higher than what you set a house water heater to (not scalding). You might check what your model does.

I think that's true, though not 100% sure.
You probably wouldn't want t try to shower while the dishwasher is actually running, but a typical dishwasher only uses 1-3gpm, so plenty of smaller units could keep up even if the supply water has to be hot.  Just look up the specs for your specific unit

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Re: Hot water heater - to tank or not to tank?
« Reply #23 on: August 11, 2013, 07:53:08 AM »
We installed a Rinnai tankless water heater (natural gas) after a basement remodel six years ago. We have a small house, so every square inch in the basement is useful and the tankless is hidden behind a cabinet door. It's worked very well and I like the energy savings in the long run. If I had a big house with room to spare, I'd consider an electric one. But I have no regrets of spending 1k plus on this tankless heater.

Electric tankless heaters are often much more expensive than gas.  You probably need 400amp (or larger) service into the house. (Source: friend that used to be a plumber and out right refused to install electric tankless heaters.)

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Re: Hot water heater - to tank or not to tank?
« Reply #24 on: August 11, 2013, 08:19:06 AM »
I also had a Rennai installed during a renovation to save space and money. I can't complain about it at all. We do dishes, laundry, and take showers/baths simultaneously. We had issues with our tank water heater before that. We even got a Recovery Act tax credit, but I think it has expired. My gas bill is about $20 in the warmer months when we're not paying for gas heat. I'm sure it would be significantly higher with a tank.

Argyle

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Re: Hot water heater - to tank or not to tank?
« Reply #25 on: August 11, 2013, 11:18:51 AM »
After doing a lot more research, I'm guessing that Bokari's $179 water heater was something like a Rheem, which are available on eBay for around that.  There's a huge thread on tankless water heaters on GardenWeb at
http://ths.gardenweb.com/forums/load/plumbing/msg1113123123850.html (on brands) and
http://ths.gardenweb.com/forums/load/appl/msg0100054618751.html (on capacity and how they operate). 

The most-praised brands seem to be Rinnai and Takagi.  They are both considerably more expensive than Rheem.  I'm trying to figure out if that's just extra features and complications or if the reliability is significantly greater with a more expensive brand.  For instance the cheapest indoor-installation Rinnai (V65i) is $698.  Is it $517 more reliable than the cheap Rheem, I wonder?

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Re: Hot water heater - to tank or not to tank?
« Reply #26 on: August 11, 2013, 11:49:29 AM »
I have a tankless.  I live in new construction so I've never had experience with anything else (lived in apartments before).

For me, it takes a pretty long time to get hot water. Especially in the bathrooms.  It takes at LEAST a full minute before the water starts getting even warm.  However, I do wonder if that could be due to the heater being in the garage, which is our 1st floor, and our living area and bedrooms are on the 2nd and 3rd (tri-level condo, not a crazy 3 story mansion or anything ;-)

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Re: Hot water heater - to tank or not to tank?
« Reply #27 on: August 11, 2013, 06:43:31 PM »
I have a tankless.  I live in new construction so I've never had experience with anything else (lived in apartments before).

For me, it takes a pretty long time to get hot water. Especially in the bathrooms.  It takes at LEAST a full minute before the water starts getting even warm.  However, I do wonder if that could be due to the heater being in the garage, which is our 1st floor, and our living area and bedrooms are on the 2nd and 3rd (tri-level condo, not a crazy 3 story mansion or anything ;-)

Probably the distance.  I have noticed it taking a few seconds, maybe 10-15 longer, to get to full temperature, though it gets warm just as fast as it would before with a tank heater.
The only way to have instant hot water is with a mini tankless at the point of use, or a very expensive, complicated, and inefficient recirculating system.

After doing a lot more research, I'm guessing that Bokari's $179 water heater was something like a Rheem, which are available on eBay for around that.  There's a huge thread on tankless water heaters on GardenWeb at
http://ths.gardenweb.com/forums/load/plumbing/msg1113123123850.html (on brands) and
http://ths.gardenweb.com/forums/load/appl/msg0100054618751.html (on capacity and how they operate). 

The most-praised brands seem to be Rinnai and Takagi.  They are both considerably more expensive than Rheem.  I'm trying to figure out if that's just extra features and complications or if the reliability is significantly greater with a more expensive brand.  For instance the cheapest indoor-installation Rinnai (V65i) is $698.  Is it $517 more reliable than the cheap Rheem, I wonder?

Mine is an Aquah (10L)

This is just one single opinion, 2nd hand, from a plumber I spoke to online who installed instant water heaters, and I don't remember who or where this conversation took place, but I was told that, because of the extra pressure and temperature regulation features, the more expensive models are particularly unreliable.

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Re: Hot water heater - to tank or not to tank?
« Reply #28 on: August 11, 2013, 07:19:01 PM »
Would a solar water heater to a tankless heater be a good idea?  Or would the preheating not do much good in that situation?

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Re: Hot water heater - to tank or not to tank?
« Reply #29 on: August 11, 2013, 09:07:46 PM »
Would a solar water heater to a tankless heater be a good idea?  Or would the preheating not do much good in that situation?

Its a very good idea.  The instant heater doesn't raise temp to a set point, it raises it X degrees above inlet temp.  The higher inlet temp, the less work it has to do.  And it works with the simplest solar type, where the water itself travels through the heat collector.

There are a bunch of different designs of varying complexity and cost on the DIY website instructables.com

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Re: Hot water heater - to tank or not to tank?
« Reply #30 on: August 11, 2013, 09:11:18 PM »
The most simple I've seen is a series of 2-3 water tanks, painted black.  Usually it is the guts of an old tank water heater with the insulation torn off of it.  They can be very effective, especially as a pre-heater.