04:48PM | 12/02/02
Member Since: 12/01/02
2 lifetime posts
This forum seems like a good place to ask tankless water heater questions. I’ve been researching this for months and, now down to the wire, continue to discover reasons I cannot install a tankless system. Unless, of course, someone reading this has faced these issues and overcome them.

First some background on the house: it is in California where energy costs have soared. It has three floors, per our building department. (It’s really on a hill and since we’re converting the basement, more than half under ground, into living space, it is considered a floor, I’ve digressed.)

We have three and a half bathrooms, a washing machine, and a kitchen with a couple of sinks and a dishwasher. The kicker is the large master bathtub and a multi-head shower. (Sounds decadent, but we’re going for broke, literally.) With all of this, we’ve calculated needing two larger units: one in the attic and one in the ground floor mechanical room where the furnace is located. In reality, based on our likely usage, we’d never need this kind of horsepower, but, since there are so many bathrooms and sinks, a future owner, clearly absent any common sense, may need to run so many appliances at once.

As for brands, I had honed in on the Rinnai version until I discovered that their venting system is proprietary and runs around $35 a foot. (Ouch.) This isn’t an issue for the attic-mounted unit, but the one in the basement mechanical room needs a 45-foot vertical rise to clear the peaked roof. (Quick math says that vent will run more than the unit.) I could put both in the attic, but that means running water lines back down to the basement level and running the taps until it arrives. (Seems to me like it defeats the energy saving advantage.)

So I decided to look at the Takagi units, which can use standard b-vents. Problem here is that they are limited by a 35-foot vertical rise in the vent. (This problem may also exist in the Rinnai, I haven’t checked.)

Now, even if I can work around the venting issues, perhaps by putting both units in the attic, the local utility company wants me to install a 2-inch service because “in theory” all of the gas appliances could be on at once and demand would exceed my inch-and-a-half service. Argh! (To their point, the btu draw of the tankless units is around 180,000.)

So, if you’ve made it this far, thank you for indulging me and here are my questions: is the Takagi vertical rise limit a hard and fast rule? Can I push this and will I be all right? From personal experience, are people finding that running the tap to get hot water through “miles” of piping takes a long time and wastes energy? (I’m thinking of putting them in the attic in this case and I know this isn’t good for water usage, but focus on the energy.) What’s the risk of having an undersized gas line besides the fact that I won’t be able to cook for the entire population of Texas while they’re showering for dinner?

Any feedback is welcome.



12:12PM | 12/17/02
Member Since: 10/15/02
359 lifetime posts
Also for the vent problem, aquastar has a unit that has a powered vent for through the wall applications, no need to run a chimney then and you can put it any where you want. Have you considered electric point of presence units for the sinks?


02:50PM | 12/17/02
Member Since: 12/01/02
2 lifetime posts
I had considered point of use of the sinks, but adding the electrical service in each location proved costly.

At this point, I have decided to go with the Rinnai units for two reasons: their equipment can be daisy-chained whereas with the Takagi, you must go to the industrial units at twice the price; I also found the rinnai rep much more willing to take calls and answer questions. Rinnai is clearly interested in gaining market share over Takagi and will go the extra mile to assist consumers.


06:30AM | 12/18/02
Member Since: 10/15/02
359 lifetime posts
Looking at it that way puts a funny twist on the plan. I happen to have installed the Aquastar not so much for savings, but for space. I my case I will actually save much more than what you claim based on the fact that I dont use as much water as a normal family since there are only 2 of us and we are not home for most of the day, so storing hot water 24 hours a day everyday is a waste in my case. After going over the numbers of BTUH it will actually be much cheaper for me to run a 120K BTU heater for a few minutes when I need hot water than to have a 40K BTU heater that kicks on 4 or 5 times a day to heat up the water that cooled down while just sitting there. Since I am on Propane, it makes a big difference since my last fill was at $1.029 a gallon. So far I show a savings of $200 since I have installed it a year ago. Now if I could only afford to replace my 80% monster 12 YO furnace with a nice 90+% furnace. ah well maybe next year.


01:16AM | 12/20/02
Member Since: 12/19/02
1 lifetime posts
Until we sold our home recently used a tankless hot water heatered that was imported from england. This was before they were seen as anything but for cabins. In our new home we will be installing a dual zone gas fired tankless hot water heater. Leading candidates are Bosch and Takmar. In either case they will be vented trough the furnace exhaust system. If you can couple into furnace exhaust the draw will be great enough for WH to work properly. As to electric heat verse gas - unless your gas cost is very high you will find that gas is much more economical. Our current home buuilder offered and electric unit but we rejected it since at best it was point of delivery. From where I stand Tankless Hot Water Heaters are the future. We had ownened ours for 15 years and I had to repair it only four times. Twice I had to lube a sensor pin that regulated water temp. Once I had to replace a regulator diaphram. Also replaced thermocouple once. Future heaters will not have a pilot light.


04:39PM | 12/24/02
Member Since: 12/23/02
1 lifetime posts
We installed the Seisco Tankless Water Heater Model RA-28 last winter. I love it!In Dayton, OH, our incoming water is probably colder than yours, but we always have HOT water. For installation, we did upgrade to a 200amp electrical box. We were replacing an electric tank, and have seen a decrease in our electric bill (even though we use more water because it never gets cold). Now, 2 family members have installed the unit. Our home is all 1 level, so you are smart for considering 2 units for the different levels. I would strongly recommend this brand.

[This message has been edited by brunstc (edited December 24, 2002).]



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