Tank vs tankless water heaters

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Any suggestions between the two?
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Is this a house being built or an older one ? If older, you will have to have heavy wiring or a gas line ran. Location may be a factor, If it is very cold in the area, many of the tankless may not heat the water hot enough for you.
Cost is usually much more for the tankless.
I would say stay with the tank.
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Kurt Ullman wrote:

When I was considering the tankless, the initial cost was VERY high. We have 4 bathrooms of which one has a Jacuzzi tub. Installing bigger gas feed line, preparing to mount the unit on the wall, correct unit sizing, etc. Felt like I was getting into possible headaches. Stayed with NG gas fired conventional top end model tanks. At least I could replace tanks twice and some for the cost of tankless install.
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On Thursday, August 8, 2013 2:29:48 PM UTC-4, Kurt Ullman wrote:

If you use a lot of hot water I think the tankless will edge out the tanks. But you need to have the gas or electrical supply. Tankless use a lot of energy over a short period requiring big "pipes" to get it to them
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I'm sure there were, but I wasn't there to hear them talking.
I'm told it was something like this
Tankless: Hey, you need to lose some water weight.
Tank: Why would I listen to you? You have no substance.
. Christopher A. Young Learn about Jesus www.lds.org .
On 8/8/2013 2:29 PM, Kurt Ullman wrote:

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If it were me, I would stick with the conventional tank style water heaters because they CAN supply all the hot water you need, whereas that's still a big question with tankless heaters.
In fact, in a house in the town I grew up in, the builder (who was a plumber by trade) put a ball valve in the basement separating the kitchen and one bathroom from the laundry room and the other bathroom. He installed two 60 gallon hot water tanks and had one to supply each side of the house. He did that because he had three daughters and they were always fighting over the one bathroom in their old house.
I thought that was actually a smart idea because the cost of a water heater isn't that much, AND the two water heaters don't have to be identical. They can be totally different and his system would still work fine. And, the best part of it is, if you ever have to shut one water heater down (to replace the annode rod, for example), then you can open that ball valve and have the heater that's still operational supply water to the whole house until the work is done.
If I were building a house, that's probably the route I'd go.
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nestork


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On Thursday, August 8, 2013 8:30:15 PM UTC-4, nestork wrote:

No reason it's a big question. You determine your maximum simultaneous demand, the lowest incoming water temp, and buy a tankless that is spec'd to deliver it. They all have that spec, it's not a mystery.

So, there is a similar sizing problem with the tank type.

The downside of course is that you have to replace two water heaters when they reach EOL.

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' snipped-for-privacy@optonline.net[_2_ Wrote: > ;3104416']

Maybe, but there's little difference in economy.
The lifespan of a water heater's tank is largely determined by the amount of thermal shocking it endures, and that's directly related to the sizing of the tank. The larger the tank, the smaller the drop in temperature in the tank when hot water goes out and cold water comes in, so the smaller the thermal shock each time hot water is used. So, by using a 60 gallon tank for one bathroom instead of two, you SHOULD expect to get a much longer lifespan of the tank in that heater. I don't know if it would be double, but it would be much longer than using that one tank for both bathrooms.
So, it's a pretty good overall gameplan in my books.
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nestork


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On Friday, August 9, 2013 11:23:13 AM UTC-4, nestork wrote:

Interesting theory, but I suspect it's not true. I don't accept the idea that thermal shock is the dominant failure mechanism.
I

If you have any real data that says the above is true, I'm sure we'd all like to see it.
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<stuff snipped>

Community Association Underwriters of America, Inc. (CAU), one of the largest insurance providers in the United States for community associations, residential and office condominiums, cooperative apartments and homeowners associations says on their site:
<< How do Water Heaters Fail?
A water heater holds and transfers water continuously - from installation to replacement or failure. Over time, deposits will accumulate on the bottom of the tank. These deposits corrode the tank liner and heater elements. Water quality, particularly water hardness, directly influences the amount of sediment deposited.
Moving water also causes wear on the tank and piping. The (!!) hotter the water, the greater the fatigue on the parts it touches. (!!) The constant heating of cold water also subjects the unit to extreme temperature swings. No household appliance works under tougher conditions than the storage water heater.
In most cases, water heaters fail gradually, but not always. Some of the telltale signs of imminent failure include water accumulation beneath the heater, a hissing or whistling sound characteristic of a worn valve, and chronic hot water shortages during periods of normal demand. Prompt corrective action is required once the signs of failure appear.
When the corroded bottom of a tank fails without warning, the water already in the tank and the continuously fed cold-water supply create a deluge. If not stopped, this water will continue to flow. In these cases, it's crucial to stop the flow of water by turning off the cold-water supply valve at the water heater or at the water main shut-off. >>
Community Association Underwriters of America, Inc.
http://www.cauinsure.com/
http://www.cauinsure.com/Include/Documents/P3%2520-%2520Minimizing%2520Water%2520Damage%2520From%2520Water%2520Heaters.pdf
I'd say they give fairly serious weight to the thermal shock a unit endures as a cause of failure. Certainly not 100% but I'd say a fair number of cracked tanks die from thermal fatigue.
With my limited experience with a water heater "plant" at a photofinishing plant I QC'ed at, water heaters are indeed sized professionally to never drop below half. If you run out of hot water, you are undersized in most cases. I would bet that running low with large amount of winter-cold street water has a negative effect on longevity very similar to what Nestork proposes. And it means you have a sizing problem - the tank(s) is not big enough.
As aside and a thread shift - the tank water heater deluge they mention could be worse. I think I would rather have a water heater tank crack than a washing machine hose split and turn into a fu&ing sprinkler. BTDT
Two major upgrades were monitoring and double-hulling the hoses. Now even the stainless steel braided super high quality replacement hoses are backed by a Floodstop and by covering them with smurf tube over their length so any spraying occurs in a sheath and runs down to the floor instead of watering the ceiling. And the workbench. And the washer. And the dryer. And the pet food shelves. )-:
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Bobby G.





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Wrote:

More importantly, in case of any gas or power interruption a tank heater has some reserve hot water. When a tankless unit fails in winter, nothing's left but cold, cold water. Sadly their rate of failure seems much higher and rightfully so, they are more complex and run very hot. Also, if you're the slightest bit a survivalist that's 50 gallons of stored water you don't have with a tankless. Depending on the disaster, of course. (-:
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Bobby G.




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On Sunday, August 11, 2013 3:26:30 AM UTC-4, Robert Green wrote:

There are tankless that don't require AC power to operate. As for gas interruption, that occurs so rarely that it's not a factor, at least not here. I've never had a gas outage. And if the unit itself fails, tank and tankless are about the same. You're typically not going to know that the unit is no longer operating until you don't have hot water.
Sadly their rate of failure seems much higher

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Good point. I was assuming that all tankless heaters needed AC power. The addition of the generator turbine indicates that they used to, and it was a bad idea for reasons we already discussed.
With AC powered tankless models, when there's a power failure, you *know* you're out of hot water whereas a tank will usually give at least one shower before it quits, and that's often enough to bridge any power disruption.
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Bobby G.



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If you have an electric tankless, you can not generate enough power to heat water. A 5 KW generator will run most tank water heaters. You can cut off about everything but a few lights, run the water heater for a while and then cut it back off and get another quick shower or two.
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Another good reason to avoid tankless. (-: Or at least another data point to consider when evaluating the two different types of technology. FWIW, my old pilot-light gas water heater doesn't need any electricity to keep churning out hot water day after day and that's just the way I like it! What bothers me most about gas tankless heaters is the large bore supply pipe that's needed. Lots of houses blow up from gas leaks every year. A very large supply pipe increases the potential of a serious and very fast moving gas leak. No thanks!
Thanks for your input, Ralph.
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Bobby G.



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On Tuesday, August 13, 2013 7:04:38 AM UTC-4, Robert Green wrote:

I doubt there is much correlation between a larger gas pipe in a house and the risk of explosion. Probably more explosions are from small appliance hoses and their connections than from a supply line. And even if a 1.5" gas line started to leak, it's usually at a fitting, or maybe where some corrosion ate through a pin hole . and I'm not sure it's going to necessarily leak any more than a 1" pipe. Where it would matter would be if the whole pipe got severed and that is very rare. Even then, if it's a 1" or a 2", the result may very well be the same.
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<stuff snipped>

I believe that slow leaks and smaller pipes reduce the potential for a fast build-up of gas without anyone noticing the smell. I saw the results of a truck backing into a gas meter at a loading dock and remember seeing the "shadow" of the gas pouring out from the ruptured main on the ground. It was an impressive amount of gas escaping the broken pipe, but fortunately it was outside and couldn't build up to. A few years ago a similar event in a shopping center nearly knocked the entire building down just as the gas company techs were arriving on the scene. It was caught on CCTV surveillance video and it was a very impressive explosion.
I'll agree that the chances of a major rupture are small, at least in areas that don't have frequent earthquakes, but after we got shook with a 5+ quake in the DC area, an earth-quake induced rupture is not out of the question. I'd still rather have a smaller gas pipe entering the premises, just in case.
If for some reason I were to "heavy up" the gas line coming into the house, I might opt for this:
http://www.tracpipe.com/CSST_Gas_Pipe_Products/AutoTrip_EFV_Automatic_Gas_Shut_Off_Valve/
<<AutoTrip Excess Flow Valves are activated by the unrestricted flow of gas, resulting from a gas line rupture. This flow causes the valve to trip (shut down). The bypass flow feature restricts the gas flow to a safe level upon valve activation. Bypass flow provides automatic reset capability once the downstream gas piping has been repaired.>>
--
Bobby G.





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On Thursday, August 15, 2013 5:31:31 AM UTC-4, Robert Green wrote:

Small leaks do reduce the potential for a build-up of gas. But I don't think there is much, if any difference in the the size of a typical leak from a 1.5" pipe or a 3/4" pipe. If the pipe is leaking a little at a fitting, as is typically the case, probably not much difference. And chance of it somehow getting severed completely, which would make a difference, in the amount of gas released, is remote. Even then, if you have a 3/4" pipe or a 1.5 pipe spewing gas, not sue the outcome is going to be all that different either. I'd bet there are far more serious explosions and fires from the small hoses that connect dryers, stoves and such than from a large gas pipeline serving the whole house or a major appliance.
I saw the results of a

That apparently took out the gas meter and had gas spewing out from the high pressure side. Would have been pretty much the same thing with or without a tankless water heater.
It

But then you already have large service pipes entering homes and all kinds of buildings. What size service do you think goes into an apartment building with 100 people? Yet, we're supposed to worry about a slightly larger pipe to handle a tankless in a house? Where do you draw the line? Gas outdoor grill OK? Gas range? Gas ovens? Gas dryer? Gas water heaters, some houses have two? Gas furnace, some houses have two of those? Gas generator? They are all OK, but adding a tankless and suddenly it's so much more dangerous that it becomes a special consideration?

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-- More stuff snipped--
But then you already have large service pipes entering homes and all kinds of buildings. What size service do you think goes into an apartment building with 100 people? Yet, we're supposed to worry about a slightly larger pipe to handle a tankless in a house? Where do you draw the line? Gas outdoor grill OK? Gas range? Gas ovens? Gas dryer? Gas water heaters, some houses have two? Gas furnace, some houses have two of those? Gas generator? They are all OK, but adding a tankless and suddenly it's so much more dangerous that it becomes a special consideration?
-- Another snip --
Seems to me that knowing how to shut the gas off quickly in an accident or earthquake would be more helpful than worrying about pipe size. Our main gas valve is outside by the meter in plain sight. It takes a hefty wrench to turn the valve which is why I keep a large pipe wrench hanging on the wall by the back door. I suppose I could also get the special tool for the street valve; but that sounds like overkill.
Tomsic
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Can commoners like me buy a street valve wrench for gas? I know we can get water wrenches. But gas? Some day I should pop the cover off a gas street valve, look in with a light, and see what kind of lug it has.
As to the gas shut off by the meter, they are typically greased with heavy waterproof grease. I've turned off valve by the meter with 18 inch pipe wrench.
In case of earthquake, or large fire, a gender neutral politically correct adult person of nondescript racial and ethnic origin can save a lot of people a lot of damage. Just need a good man with a pipe wrench.
. Christopher A. Young Learn about Jesus www.lds.org .
On 8/15/2013 10:04 AM, Tomsic wrote:

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