Tankless hot water? Savings?

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Old 11-07-06, 04:40 PM
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Tankless hot water? Savings?

I'm considering going to a tankless system but I'm a starving for information on energy savings in a low volume environment. All of the calculators out there and articles seem to reference to quite high loads on the tankless system and the very reason I'm considering tankless is because our household is the opposite.

Me and my girlfriend live in a home in a temperate area (Vancouver, BC, Avg summer tmp 17-30 deg C, Avg fall/spring temp 8-15 deg C, Avg winter tmp 0-10 dec C, freezing and snow are rare).

We only use hot water for

- Showers and occasional bath (one bath every three weeks or less, mostly take showers)
- Dishwasher
- Hand operations (handwashing, dishes, misc)

I havent done any official tests but excl the shower we probably use about an average of 3 gallons of hot water per day. A 15 minute shower with a low flow head at 1.0gal would be another 15 gallons so lets say an average of 20 gal/day of hot water.

Our water heater is pretty efficient and uses natural gas. I'm thinking a small single function (we never do multiple anyway) tankless running electric. While the electric costs more per BTU than natural gas I'm thinking the savings must be there because we have a 80 gallon hot water tank and the only time it's ever run out is when we've both been sick or something and wanted to take baths one after another which is something that probably only happens once every few years.

All of the calculators are based on 60-80 gals of hot water usage per day, this is way more than we use and they all seem to indicate 30% savings at that level, I'm thinking at very low use the savings would be higher?
 
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Old 11-07-06, 06:33 PM
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One consideration, if it applies, is elevation. Every plumber I talked with indicated that at our elevation (8300 ft), gas tankless water heaters have alot of trouble, and some heaters warranties aren't valid this high. As much as I wanted one, it turned out to be the less efficient option, ironically.
 
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Old 11-07-06, 10:43 PM
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Originally Posted by logcabincook
One consideration, if it applies, is elevation. Every plumber I talked with indicated that at our elevation (8300 ft), gas tankless water heaters have alot of trouble, and some heaters warranties aren't valid this high. As much as I wanted one, it turned out to be the less efficient option, ironically.
Yeah were about 750ft above sea level. Plus I was thinking of the electric because I'm in the middle of a battle with the gas company
 
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Old 11-08-06, 08:38 PM
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Electric tankless, you have a very High electric demand (60 + amps).
This could include an electrical service upgrade. More money to consider.
 
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Old 01-01-07, 04:52 PM
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I don't know anything about the subject, but it seems to me that if you don't use the hot water much, tankless would be a good way to go because it's not keeping a tank of water hot all the time, when you hardly ever use it.

But, by the same token, like you were saying, you don't use it much anyway, which means you are already going to have a pretty small gas bill, which in turn means any savings you get (even if they are really high, like 50% even), is not going to mean much when you look at the whole months bill, since it's so small to begin with.

I have always thought that with a tankless water heater, you may actually end up with higher bills because (for me anyway), when I start running out of hot water is when I consider my shower is done. With a tankless it's real easy to just stand under the steaming hot shower for a long time, since you never run out of hot water.
 
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Old 01-01-07, 08:22 PM
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Savings?

Do you have 200 amp service (and not have electric heat already)? If not, get a Marathon electric tank. They're cool (and well insulated)! Get a smaller one.

All an instantaneous will do for you is make your computer need much better surge protection. These are often 120amp circuits.

If you have the space for a small tank...
 
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Old 01-01-07, 08:26 PM
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jdraughn

My boiler's efficiency is over 90%. My indirect is fired by my boiler and it's heat losses are extremely low, even though the outer tank is hotter boiler water. This is far more efficient than instantaneous, and gives the boiler something to do in the summer. This is "boilers - steam and hot water" as in hot water heating systems but the boiler and an indirect is what rules here.
 
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Old 01-01-07, 08:29 PM
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Smile How do you heat your house?

If you have a circulating hot water system, you may want to consider an indirect water heater. Check out www.heat-flo.com . The standby loss is much lower than that of a gas water heater and the recovery rate is excellent.
 
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