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Ralph Barhorst
12-12-2007, 9:07 AM
Our hot water heater is 12 years old and I am thinking about replacing it with a "on demand hot water heater". I am specifically looking at the Bosch AquaStar 2400E Natural Gas Tankless Water Heater.

Does anyone have a tankless water heater? If so, how long does it take to get hot water and does it actually reduce your gas bill by 50%?

Mitchell Andrus
12-12-2007, 9:20 AM
Discussed not long ago:

http://www.sawmillcreek.org/showthread.php?t=64297&highlight=tankless

Dan Mages
12-12-2007, 9:28 AM
I installed a tankless unit in my previous house and really liked it. There were months during the summer where my estimated gas usage was lower than the actual reading the next month due to how much I was saving with it.

In hind sight, I should not have gone with Bosch's basic low end model which barely keeps up with one unit. If you get one, make sure it can handle several requests at once.

Dan

Jim Becker
12-12-2007, 10:33 AM
There is one going in our addition "as we speak"...

Greg Peterson
12-12-2007, 11:25 AM
I can not speak the actual savings of a tankless unit as I also converted from an electric to gas clothes dryer at the time of the tankless install.

It takes any on demand tankless unit a few seconds to purge the heating core of standing water and get the heating core up to operating temperature. I've never really had a problem getting the unit to exceed the minimum flow rate required to activate the unit.

So long as you remember that the unit is an On Demand hot water supply and not an Instant On Demand hot water supply, your expectations should be met.

No regrets for me. And the savings in space is substantial. And being in earthquake country, I don't have to worry about a 40 gallon tank falling off its 18 inch pedestal and making a mess.

You have until the end of 2007 to receive a $300 federal tax credit on an energy star approved tankless water heater.

For some folks the tankless on demand option provides a a reasonable solution even though the numbers may not add up. For us, a tankless unit was a great solution. I did the installation work myself, which in conjunction with the tax credit, made the numbers work to our advantage. Numbers aside, I am very happy with the tankless.

Mike Henderson
12-12-2007, 11:42 AM
I'm sure you've done the math, but it takes a long time to recover the cost of a tankless water heater (actually the difference in cost between it and a regular water heater). If you already have a tank water heater, you can slap a new one in yourself. But a tankless requires quite a bit of installation costs as well as the extra cost of the heater itself. The difference can easily be $500 and can go upwards from there.

I never could make the numbers work for me.

Mike

Terre Hooks
12-12-2007, 9:46 PM
I'm sure you've done the math, but it takes a long time to recover the cost of a tankless water heater (actually the difference in cost between it and a regular water heater). If you already have a tank water heater, you can slap a new one in yourself. But a tankless requires quite a bit of installation costs as well as the extra cost of the heater itself. The difference can easily be $500 and can go upwards from there.

I never could make the numbers work for me.

Mike


When gas gets to be $3 a therm it will.

Jim Becker
12-12-2007, 10:42 PM
Mike you're right, but for me, it's the principle that I'm only burning gas when I'm actually requiring hot water. I also like the footpri...err...wall-print. And trust me, the venting requirements for the higher output heaters really raise the installation cost...it's not just the price of the unit. It's "majorly" well north of the machine cost. But I'm doing it anyway.

Frank Hagan
12-13-2007, 1:21 AM
I'm sure you've done the math, but it takes a long time to recover the cost of a tankless water heater (actually the difference in cost between it and a regular water heater). If you already have a tank water heater, you can slap a new one in yourself. But a tankless requires quite a bit of installation costs as well as the extra cost of the heater itself. The difference can easily be $500 and can go upwards from there.

I never could make the numbers work for me.

Mike

One part of the math that people often miss is the extra installation some of these require. For the larger tankless units, a lot of homes require a larger gas line, which can be very expensive to run. Some of the units require stainless steel or other special venting which can cost more than the cost of the unit itself (depending on the length of the run).

The energy savings for some units are "only" in not keeping a tank of hot water standing around all day. Otherwise, they are at about 85% efficient, the same as a tank type water heater. That savings can add up, especially if you have intermittent demand like most of us do. The "direct vent" tankless heaters, meaning those that "condense" as they heat water, are the most efficient, but also the most expensive to install. They can put up to 98% of the heat produced by the flame into the water, but they are more expensive because they have a combustion air fan to get the flue gasses out of the unit. You have to have a drain handy to handle the condensation flowing out of the drain tubing, and should not discharge it into cast iron drains (its mildly acidic, but would be OK in plastic drain pipes). Some municipalities may restrict discharging the condensate into the sewer, so check and see if you need a neutralizer kit for the drain.

Gas fired appliances are responsible for some 200 deaths per year, usually due to problems with the flue or improper installation. These units are much more challenging to install than a tank type water heater, so I really encourage people to either have their installations inspected, or installed by a pro to begin with.

Al Willits
12-13-2007, 11:14 AM
Also tank less require periodic maintance, Bosch says a rebuild every other year, and I believe its required to keep warrt current, think plumber for at least a hour plus rebuild parts, add that to your cost.
Also we are seeing scale build ups in these units, the harder your water, the worse it is, think plumber again if it can be repaired.
Venting is in many cases a problem too.

For some they work great for others not so, make sure you get all the numbers before you count all the money you think your gonna save.
fwiw I doubt out of the 375 service techs I work with, maybe 3 or 4 have them...fwiw
Al

Burt Alcantara
12-16-2007, 2:39 PM
I lived in London and Amsterdam during the 70s. In all places I lived they used tiny tankless water heaters. Never had a problem with hot water in any of them. I was amazed that this technology was unheard of in the US.

Burt

David G Baker
12-16-2007, 3:14 PM
Burt,
I lived in Germany in the 60's and had the small tankless water heaters and wondered the same thing. I never had a problem with them and as far as I know neither did my landlord.

Fred Woodward
12-26-2007, 12:41 PM
I had a tankless water heater installed in a home I had built in 1998. Had high efficiency windows, extra insulation, etc all to make the home as energy efficient as I could at the time. Installed a water softener (the home was in the country and had well water) to treat water before it went to the tankless heater. End result...my electric bill ran about $70/month in a 2300 sq ft home while my neighbors home electricity costs were about $250-300/mo. We had thermostats set about the same, had same # of people in each household and roughly same size homes built by the same builder. The additions I added to my home just for the effeciency cost me an additional ~$5000 initially. The tankless water heater I think was one of the biggest savers on my electric bill.

Al Willits
12-26-2007, 3:40 PM
I'll repeat myself, get ALL the numbers before you buy one, be cautious of 98% efficency claims and cutting your gas bill in half with one of these.
Make sure you consider ground water temps also, it makes a big difference.

Al

Tom Godley
12-26-2007, 5:26 PM
I have had tankless in two different houses -- back in the 90's. They provided only part of the hot water for the houses. One was for an bedroom/ bath addition, the other was used in a kitchen remodel - also providing hot water for an outdoor shower -- this was "down the shore" ---- that is NJ talk for the beach!

They can act strange at times -- you "must" make sure that the unit is sized properly. They have a min flow requirement that need to be maintained or the unit will not start -- or it shuts off! They also have a temp/ flow band that they like.

We had problems with the kitchen install. Depending on what faucet was being used - the temp would float all over the place -- not the best when taking a shower. The sink would work best with the hot faucet fully open and then adjust the temp with the amount of cold. I was told that some of the low flow faucets - especially Kohler -- can add to this problem.

The unit we installed for the addition was OK - it only provided hot water for one bath room-- we installed this one with a thermostatic shower valve and one handle sink faucets. The unit was installed in the bath closet - on an outside wall. I used it because the hot water heater was on the other end of the house -- and as luck would have it the NG line was not far away.

The units are great for houses that are not used all the time -- especially if propane is the only fuel available. You could also make the case for one of the units when a large tub needs to be filled vs having a very large standing hot water tank.

I am not sure how you would ever get the payback vs a NG tank unit used every day in a normal way. The original cost is higher and the units are quite complex - both our units required service more than once.