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Pipes actually hold very little water - it takes over 40 feet of 3/4" pipe to hold one gallon of water, around 100 feet of 1/2" pipe. So the plumbing is adding very little to the available hot water.</p>
<p>Again, it depends on the house (and for how long the inhabitants like to shower) :)</p>
<p>We had an 80 gallon water heater which we down-sized to a 50 when it came time to replace it. I have a small B&B and my business is closely tied to the university calendar (football, concerts, etc.); during the week it is usually just DH and me. When I have a full house (eight) I turn the setting on the water heater up so that less hot water is mixed in to achieve a comfortable shower temperature. I always shower last and have never lacked hot water. Most of the time of the time the heater is set to the minimum, so we don’t pay to heat more water than we will actually use. </p>
<p>These days I do most of my laundry with cold water and my dishwasher has its own heating element.</p>
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<p>How varied is the natiral gas price? $15 is a lot less than what I pay with my 40 gallon water heater.</p>
<p>Our first tankless lasted about 7 years and had maintenance problems.
The replacement tankless is same model ~12+ yo, but is now a german brand. Probably first generation. </p>
<p>I now see electronic start, power vent, indoor installations, hydro-gen-electonic start, etc. </p>
<p>Can those who recently purchased a new tankless give me a product review via PM.</p>