Tankless Hot water system?

Hello,
I just had a person that rates houses for energy efficiency come and rate our house. One of his suggestions he made was to pull out my existing Gas fired hot water tank and install a Tankless hot water heating system. We don't have a family living here only my wife and I and we're both away through the day working .....so the hot water demand is only morning and evenings. It makes sense when he explains it. He says "why have a large tank down there heating water 24/7 when your demand is about an hour a day?" Are there any disadvantages to this tankless system? Does anybody here have one that would care to comment? Thanks.. Jim
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There are pros and cons to both systems, alot more than I feel or want to write about for full info, which you need to research. But I will answer a few points since all you heard from are people that never owned one but think they are no good. I have a 460$ 117000btu Bosch aquastar that has given me a 4 yr payback, I installes it, its single use and heats fully with maybe 35f incomming for a hot shower. If two people will use hw the 117000 btu ng unit may not be enough in winter if incomming is cold. I kept my tank to temper incomming water and it raises it 1-2f so I save a bit more. Gas line sizing is where most mistakes are made. A tankless can use more than your furnace or boiler so sizing and gas line testing is critical if you want 100% output. In winter where I am pressure drops on the coldest days. if you have the heating system, dryer, oven and stove on your supply can be even less. You need to test gas flow and calculate these reductions or you could starve a tankless.
Most tanks that HD etc sell are near 55-65% efficent. Read about Energy Factor. That is the tank efficency rating system. Tankless start at 82EF and go to 96-98EF. Tanks start at 55EF and go to only 85EF even for a 97% AO Vertex. so tankless is more efficent by design. Tanks loose heat up the uninsulated middle, up the chimney 24x7. Tank also loose efficency every year due to scale. I removed a 20 yr old tank and it had about 12- 14" of scale in it. That scale reduced my efficency so much that a new 82EF tank cut my bill 30%, a tankless could have done better but this was a commercial use tank so in that location I wanted a tank.
Tankless have more to break than a cheap 55 EF tank, but not more than a 85EF Vertex as I have one of those also. Tankless coils should by design last 30 years \\ How much do you spend to heat water, if you cook and dry clothes with ng it will be hard to tell but your summer ng bill is where you start. With my Ng tankless, gas dryer and cooking my Ng bill is always now around 10$ in summer, down from 35-45$ . But I try to save on HW as my game. HW to me is really money down the drain.
If you need a big 190000 btu unit and wont do the install it could cost you 1500-3000 for tankless. a cheap tank maybe 600, a AO Vertex maybe 2400. You have to run your numbers, its also about being energy minded.
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Much more common in Europe as we understand it. They use a lot of heat for the very short period of time that hot water is needed and that is claimed to be 'overall' (over long period of time) more efficient than heating and having a tank of water kept hot all day and night.
Most "Instant Hot Water Heaters" we understand are 'electric tankless' heaters. And use many kilowatts for the very short periods of time they are in use. Some claim them to be totally adequate; others find that if, for example someone is showering, there is not adequate hot water to rinse a few dishes, so they install a second one for say the kitchen or a second bathroom.
Have seen (tankless) numbers ranging from nine kilowatts to fifteen kilowatts. That needs fairly heavy wiring, but again they only draw electrcity when in use.
Based on our experience with 40 US gallon electric hot water tank heaters, am not personally convinced that they are that much less efficient than 'tankless' heaters.
Typically our tank heaters have 3 kilowatt heaters and in any case any heat that even well insulated ones do lose help warm the house!
Perhaps a reasonable alternative for the OP could be a typical 3 kilowatt electric 40 gallon tank? Very easy to install needs reasonable wiring and will typically last 10 to 15 years. Perhaps in same space and using same plumbing as the gas heater but does not need a flue/chimney or gas lines.
Here the basic cost of such a tank is less than $300** (not installed) and our electricity cost is about ten cents per kilowatt/hour. Our electric utility mentions that about 8% of a typical, all electric family home, cost is for hot water. So in our case that means that our hot water costs a bit less than $20 per month. (All charges incl, sales tax.)
This is cool climate; most months need some home heating, especially during cool evenings. So again some of the heat from hot water that doesn't go straight down the drain helps slightly to warm the house.
So just a suggestion.
Our most current tanks ** are US made and sold here in eastern Canada. (Haven't yet seen a Chinese one!!!!!).
There is by the way planning for a large additional hydro power project 'The Lower Churchill' in Labrador, that will supply power to the north east USA and eastern Canada during next few years. This will be a reasonable and less polluting alternative to coal, oil or even atomic generation. And since it will be using 'renewable water power' will also keep electricity rates at a reasonable level;.
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As ransley said run your numbers. Especially the ones for repair service and parts. Just because it has a 4 yr payback doesnt necessarily mean that after four years youre not going to wind-up paying what you saved on your utility bill for parts and service. Many companies dont even make parts for what they sold five years ago and even when you do find the part it is usually a cheap generic knock-off that either wont fit or falls apart after a few weeks. In places like Europe and Asia labor is cheap so owners dont pay as much for a service call and the technicians dont have to worry as much about liability if they jerry-rig the tank-less water heater to function if they cant find the part. Check out the length and fine print on the warranty to make sure you can get a new one if they cant fix it. Of course thats assuming the company will still be in business after many years.
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We have 2 gas water heaters (tanks) and heat our house with NG. In summer, when there is no heating demand, our bill for the 2 heaters is about $ 8 per month, and that includes the gas dryer. This amount is negligible if you compare it to the installation cost of a 2 tankless heaters. I believe the benefit of tankless heaters is vastly overrated.
--

Walter
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wrote:

The initial cost of tankless is very high. For example, you can buy 3-4 tanks over 50 years for just one tankless. Get a tank and put extra insulation around it.
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I had one put in. Overly expensive. Probably not worth it. I've had it for over a year.

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On May 3, 12:53am, uwe3071_at_aol_dot snipped-for-privacy@foo.com (uwe) wrote:

Oh horse shit, my proven payback is 4 years, and that was 7 years ago with my bosch tankless Ng unit. There is nothing like idiots like you posting total crap.
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I'm not so sure it's total BS. His number of $4000 for an install is certainly high. But I agree with his premise that the standby losses of a conventional tank water heater cannot be very large. My gas bill during the non-heating months, when only my water heater is being run, is under $20 a month. That includes USAGE as well as the standby losses. So, what could the standby loss be? His estimate of 22% seems reasonable. If that's right, then you only save $50 a year. BTW, my tank is an avg efficiency one, not high efficiency direct vent.
So, I suspect it has to take a hell of a long time to come out even. And if you factor in the time value of money, it seems to me, you might never recover. If there is anything I'm missing, please let me know.
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There's a well documented human behavoir where once an individual is invested in something (politics, expensive purchase, etc.), it's extremely difficult to admit that you might be wrong.
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Robert Neville wrote:

It's called cognitive dissonance, but I may have the spelling wrong.
It also cause folks who go through a horrible experience (terrible work place, boot camp, etc.) to later brag about how great it was.
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And then there are the ignorant tank folks , I own both tank and tankless, Tankless do what is advertised, gee I got a 4-5 yr payback already, im happy.
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