We are looking for Tankless Hot water heaters. I have 2 Uses. One in my home
and one for a Granny unit we are building.
For the Main Home, I was going to install it at the Far end of the house
closest to the 2 Full Bathrooms and leave the Existing 40 Gallon LP Tank to
service the Kitchen and Laundry.
The Granny will be for the entire unit. It will have 1.5 baths, Kitchen
Sink, Dishwasher and Laundry.
So I'm thinking a 4 Gallon unit would work fine for both applications.
Most of my local home improvement center carry the Bosh Auqastar line of
tankless hot water heaters, our LP Supplier recommends the Rinnai and I've
had Friends tell me the Takagi is the way to go.
There seems to be a big price jump with the ones they sell at the home
improvement centers vs. the Rinnai and the Takagi. Makes me think that the
ones at the home improvement centers are just ones to get you by...
Any one have an opinion on any of the Tankess options out there?
I saw a thread in a news group where someone bought a Bosch and had a
difficult time with consistent water temperature if the incoming water was
too warm. I did a search on Google and yahoo and this review showed up. I'm
beginning to think about one myself.
Takagi makes Bosches larger 188000 btu unit, The small 117000 btu Bosch
is what I have, a pilotless piezo ignition powered by 2 d cells, My D
cells last 2 years so far. It heats 33f incomming for a 110f shower not
being set on high so it works well. Water flow Gpm, and Temp rise per
Gpm, are how you rate all of them. so if you are in a cold area measure
incomming water temp now, but for me near Chicago with a warm winter it
is not accurate now since my incomming is 40 but can in a cold -20f
winter be 33f, so adjust your temp to calculate a lower temp.
Why not heat the whole house water with it, I figured my savings at 25
a month from removing an electric tank, my payback is substantial, apx 4
A Rinnai or Takagi, or Bosch-Takagi-same thing, output in the
180000-190000 btu range, enough heat for full house Gpm and Temp rise in
cold incomming water areas. The better units have remote thermostats,
and the Rinnai and better Takagi may heat To a Temp. My bosch 120 heat
to Temp Rise and gets hotter as incomming gets warmer, so I turn down
the temp as summer comes, the better units may maintain a set point. The
cheap Bosch 120 is 83% efficient, The Takagi TH1 is 93% efficient.
The best gas sears tank has an energy factor in the 60s, Tankless go
into the 90s, there is your proof tanks are Crap for energy efficiency
and another reason to prove to junk your tank you plan to keep.
One thing you must know first is Gas supply, a 190000 btu unit takes
alot of gas, my little 117000btu unit needs 3/4 Ng line over 10ft, a
190000 btu unit at a long run will need a big big pipe. You must use a
Manometer with competing loads on to calculate flow and account for
supply pressure variances, or you will never get 100% output. If cost is
not an issue get the Takagi TH1, Rinnai is also good, reasearch all the
specs. tankless are the way to go.
Thank you all for your replies.
I think what I need is something that will do 70 Degree Temp Rise @ 4
gallons/minute. So that leaves me with
So if Takagi makes the high end Bosh, which one? The 250SX is only 175,000
BTU, Is that the one you are referring to? Which Takagi would be its
Are you sure 4 gpm at your main incomming, mine varies on time of day
70 f rise , did you test water temp at-near the heater and the loss it
experiances at its use point, you should measure shower head output
temp, I loose apx 5-10f.
What is your temp incomming lowest, in a cold year, test now but lower
it 10f easily.
Cross comparing can only be done possibly on a specification since
rebadging, recasing, or a single line for Bosch is likely.
It is better to upsize than make an expensive mistake. Although I do
fine with 117000 btu and 4 gpm and 33f incomming not even set to high,
my shower output might be 1-2 gpm. Be sure your gas can handle the extra
load, im sure your furnace is not near 180000+ btu. Load must be
measured with all apliances on.
Look for a unit that maintains output temp and has a remote thermostat,
my unit does not maintain output temp, it maintains temp rise, so in
winter I must turn it up manualy. But I am happy with the savings I get.
this is New Construction, at least for the Granny. So its hard to take Temp
Measurements now. (-; We live off well water. Though when the Granny unit
is all said and done, it will be pumped out of a semi buried 2500 gallon
For the Granny, its going to have at most the Dishwasher and the Shower
going at once, so that would top out the 4gpm, and if the water was 33f, a
70f rise at 4gpm would be enough even if it dropped a few between the
tankless and the shower. That is worst case. Most of the time it will be
just one application at a time in the Granny, so at 2gpm for the shower most
units are 120f+ temp rise. The LP under the house is 3/4" and the main feed
is not in yet. They know we are going tankless, so they did things
The one I really need to think about is the main house.
I'm kind of stuck between a rock and a hard place. I have 2 location where
I need hot water. The back end of the house, 70'+ away from the Existing
tank heater, and the Kitchen, 20' from the tank heater in the opposite
it Currently takes 2 minutes for the water to get to the back end of the
house for showers. So I'm thinking of cutting off the Hot at the Kitchen
split and just putting in a 4gpm @ 70f temp rise at the back end of the
house. So the 2 full baths get the Instant Hot.
Then some day when I redo the front end of the house, replace the Tank with
another tankless to take care of that end of the house.
I've thought of getting just one bigger unit for the entire place and doing
recirc. I don't mind the 2 minute wait, its the water in the Septic
Tank/Leach field I worry about.
Better to have one big unit or two medium sized units? Cost Aside... hey
I could put in a By Bad valve so if one unit failed I'd have failover in a
I'm considering one for our second floor as the remodel
continues/restarts. The one thing I learned about these units is
sizing for the demands required of it.
I had to determine/measure the coldest temperature coming into the
house during the winter, determine the hotest temperature I needed at
the faucet and the flow rate at that termperature. This allowed me to
size the unit for it's purpose. I tell ya, I needed a unit much bigger
than I had originally planned when I started looking into these things.
I do not know if this helps at all, but it is certainly something to
think about during your planning stage.
As for manufacturer...
The Takagi adn Rinnai units "seem" to come out on top in most of the
reviews I found on the net; and I spent weeks researching these things.
Oh yes, one more thing...
Venting! The gas-fired units seem to put out more BTU's psf of unit
size and the vents need to be of higher grade materials, etc., etc..,
etc... This requires plannnig for the vents and routing.
My 33f incomming at -10 or lower comes from dirt eroding off the hill
the main was buried in over many decades, I know I lost 1 ft in 20 years
It may also be the contractor likely did not go as deep as he says he
did. It is city water and under street mains branches have frozen here
requiring a welder to melt them with electricity .
I read the link, so the idiots utility bill went up with his family,
so what, that is not a verification of anything but overuse. What is
verificartion is the Energy Factor and Efficency Rating, verified and
published. Sears best tank the PowerMiser, has an energy factor of .63
Sears lineup goes from .58-.63 Energy Factor with an efficency of only
in the 80% range. Tankless start with an Energy Factor of .81 an go to
90+ with efficiencies from 82%-94% for the Takagi Th1. That guy is a
total idiot if he can`t figure out ratings and math.
My unit lowered my utilities from 25-30 for a electric Newer Rheem foam
insulated, with added blanket, to 6$ Ng in the summer, and that
includes dryer and all cooking. So my payback is apx 4 years. Sure tell
the kids you have an endless supply of HW and watch what happens. As to
Eveness of temp, Rinnai-Takagi have units that keeps outflow monitored.
My Bosch 117000 btu unit does not, but never varies more than 3 degrees-
hardly an issue. Bottom line they work, just don`t tell you kids the HW
is endless, or your gas bill will be endless.
I spent two decades living overseas, mostly in small apartments with
tankless hot water. Where I lived these units are considered low end, and
larger/nicer places had hot water tanks. Whether the unit in my location
was gas or electric, I was never happy with the combination of water
temperature and water flow rate, and gladly moved to a MUCH nicer apartment
as soon as my employer was willing to spend the money (e.g., "Bamboo Grove"
apartments in Hong Kong, monthly rent of $11K US$).
Both types of units have compromises, but I wouldn't consider tankless units
when I renovated our current house in the U.S.
An institutional client I work with uses the Takagi. Less maintenance
(virtually none) and that means a lot to them. The units just work with
few parts that can wear out/break. They won't touch the "Home Depot"
stuff because of reliability issues.
Bosch sold at box stores are the same sold anywhere, you can get a 400
basic unit or order a better 1000 unit. the best Bosch -Takagi are near
1000. Rinnai I believe needs a factory certified installer for any
warranty to be in effect, Worth checking out before you purchase a
The Takagi says the same thing in their Manual too about having it
Front page of the T-K2 Manual:
This product must be installed and serviced by a licensed plumber, a
licensed gas fitter, or a professional service technician and/or in
accordance with all local code. Improper installation and/or operation, or
installation by an unqualified person, will void the warranty.
Rinnai has it there too:
Installation and service must be performed by a qualified installer,
service agency or the gas supplier.
Whats a DIYer to do?
Takagi-Bosch does not require a certified installer , Rinnai
certifies them, this is my understanding. They all say a Pro must
install it, but I think Rinnai wants their name to check on their
database. Look into it, I installed my Bosch and got warranty service.
But venting and sizing and measuring gas flow is not an average amature
job, you should get help, or you may never get 100% output.
On Tue, 07 Feb 2006 04:48:39 GMT, "Scott Townsend"
==============================>Install it himself..and go to his computer and print up an invoice
from an dealer...sign it and IF everything goes as it usually does
you will have no problems until 4 days after the warrenty period
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