OT: Tankless Hot Water Heaters?

I am going to have to put in a new NG water heater soon. Does anyone in this group have a tankless hot water heater? What do you think, is it
worth the extra cost? Any problems with them?
TIA
Jay Cups
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There is an excellent overview of water heaters, tank and tankless in the recent issue of Fine Homebuilding's KItchen and Bath Edition. The most recent issue Fine Homebuilding discusses tankless and it's inherent problems, along with fixes are discussed in the issue.
Sorry, I can't give all the details-- a complicated decision which include: number of occupant (and teens), lifestyle, length of intended residence (high upfront cost), increased gas supply lines etc.
Good Luck
Dustin
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There are two kinds of "tankless". Traditionally it has meant a heat exchanger coil in a hot water heating boiler. Now, it can mean a point-of-use in-line heater. Which do you mean?
Bob
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We installed an Aquastar Tankless whole house water heater in our house some years ago. It was the 125,000 btu model. It cut our gas bill big time. They are faboulous!!!!!! We LOVED IT. You will love it. Never run out of hot water again. Take a shower for 4 hours if you want to, no problem. I used to hook a water hose up to the hot water faucet at the washing machine and fill the 8 person hot tub with hot water. 100 deg. They are great! You'll never go back to a tank type water heater again. Tank type water heaters are very in efficient. The aquastar had a 10 year warrinty on the heat exchanger and 2 years on everything else. Great Company. I think Bosch owns them now. Current house we live in is 100% electric so I don't have a tankless water heater in this house. Bummer. Dan
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In our new house we installed two Rinnai units and I like them a lot. The only water you heat that's not used up is what stays in the pipe after you shut off the faucet. I'd buy them again.
Kingfish
On Thu, 15 Nov 2007 18:40:46 -0600, JayCups

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Kingfish,
Can you get 115+ degree F water out of the tap. I read one manual that stated that it would do an increase of 50 degrees at 4 gpm. That concerns me in the winter time. That would indicate some tepid water on a cold day.
Jay
snipped-for-privacy@spam.net wrote:

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Jay,
I had never checked mine until this morning. My well water was 59* and the Rinnai was set at 120*. The water from the faucet was 117*. I bumped the control up to 125* and 130* and the water temp rose accordingly. (the control panel was still off a few degrees each time). My unit's rating is 4 gpm @ 90* rise and I think it will probably do it.
One interesting thing I've noticed between the two units I have is that the exhaust from the inside-mounted unit is not as hot as that from the outside-mounted unit. You can hold your hand over one and leave it there but the other one gets a little too hot. I wonder if one is doing a more efficient job than the other one.
Kingfish
On Fri, 16 Nov 2007 18:06:11 -0600, JayCups

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Thanks Kingfish,
That sounds like it will meet my needs. I checked my hot water flow and it is @ 3gpm. That ought to give me a lot of fudge factor with the high capacity units.
Jay
snipped-for-privacy@spam.net wrote:

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Try to make it as centrally located as you can. I hate it when I turn on the hot water, knowing the unit has fired, and it takes half a minute before the hot water comes out of the faucet.
Kingfish
On Sun, 18 Nov 2007 19:28:36 -0600, JayCups

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On Sun, 18 Nov 2007 21:59:46 -0500, snipped-for-privacy@spam.net wrote:

And if you have a really long ranch style house with bathrooms and kitchen/laundry at opposite ends, consider replumbing the house to have two instant water heaters at the opposite ends. Solves the distance issue and gives you redundancy.
We have two tank heaters, and they'll be changed to tankless when and as they die.
--<< Bruce >>--
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On Sat, 17 Nov 2007 12:46:36 -0500, snipped-for-privacy@spam.net wrote:

The instructions that came with mine said to set the temperature so that you have to add just alittle cold water while taking a shower. They claim that is hot enough. I set mine so that my wife had to add a little cold water cuz she takes a hotter shower than I can. That seemed to be plenty hot for us.
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My daughter installed one last year. massive reduction in gas bill. Only negative I can tell, is that if you only turn on a trickle of water ( like for shaving), the flow isn't enough to kick on the burner.
Other than that...high praise... When my tank one finally goes, it will be replaced with a tankless.
al in colorado
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I have Takagi tankless units at my home, my office and at three rental units. On the whole I have been very happy with them BUT there ARE a lot of issues with tankless installations, especially if you are replacing a tank-type unit. I finally ended putting up a page where I discuss some of the ones we have encountered, it also has a link to a pretty good OA Smith white paper on calculating the payback of tankless heaters:
http://paragoninspects.com/home-inspection-tankless-water-heater-installation-problems-faq.html
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Thanks MDT:
I didn't get the answer I wanted, but I probably saved a couple of grand. 8^)
It looks like I will be looking for a new NG tank type water heater. My 3/4" gas pipe is way too long and I thought I was safe with 3/4" pipe.
Jay
snipped-for-privacy@paragoninspects.com wrote:

http://paragoninspects.com/home-inspection-tankless-water-heater-installation-problems-faq.html

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It depends on what part of the country you live in. If you live in an area where it is heating season most of the year a lot of the perceived inefficiency of traditional hot water heaters is just heat the is leaked into the house that you would otherwise have to produce with the furnace. However if you live in an area where most of your energy is spent cooling than it might be a different story.
It really comes down to trying to make an educated guess as to what your savings might be and multiply by the expected life of the hot water heater. Then you have to decide if the ROI is in a reasonable range. Personally if I can't see an ROI within 3 - 5 years I don't do it.
Steve
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I disagree Steve, the heat lost from a conventional water heater is up the stack, not lost into the house.

I could only do one thing at a time in our house as it was so there was no real change there. My two cents, Dan
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And I disagree with "up the stack". The Riello burner on my furnace has a door on the air intake that shuts when the burner is not running. Some stacks are equipped with a damper that shuts when the burner is off. From what I have read, unless one has very expensive gas or electricity, the cost of the tankless heater will likely not be paid off before the heater wears out.

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On Nov 16, 7:03 am, Dan@ (Dan ) wrote:

Dan,
You may be correct that a certain amount of is lost up the flue when the water heater is not running, but consider the surface area of the inside of the flue compared to the surface area of the outside of the tank. Also if loss up the flue is truly a big concern, an automatic damper is far less expensive (and less complicated) than an on-demand hot water heater.
I only live in a two person household, but during the summer months when the only thing using natural gas is my hot water heater my usage is approximately $7/month so as you can see it would take a long time for me to recover the cost of a tankless unit.
Also if the in efficiency of traditional units is because of "idle" time when the hot water is just sitting in the tank, as your usage goes up, your efficiency should increase (less idle time).
Steve
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On Fri, 16 Nov 2007 19:18:11 -0800 (PST), with neither quill nor

Aren't the new gas heaters pilotless and auto-damped?!? Where's the loss?
--
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On Sat, 17 Nov 2007 04:40:42 -0800, Larry Jaques

There's less loss if it's well insulated, but if you have a tank of water just sitting there simmering all day and night, there will always be some losses. The damper reduces the stack losses, but can't eliminate them. And you can only wrap so much insulation around the outside of the tank - you can't insulate the bottom or you cut off the combustion air.
With an instant heater, if there's no demand for hot water it's stone cold. And it doesn't take any energy to maintain that cold - unless you count a frost protection circuit. (Which is why you want to install it indoors in snow country - milder climes can mount the water heater outside direct-vent.)
--<< Bruce >>--
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