I've just finished building brand new house and I put standard domestic
Hot Water heater with tank. Now I see that Takagi and other
manufacturers makes tankless water heaters and they are not that much
more expensive than standard domestic ones. My question is, if I ever
decide to get rid of domestic ones can I put Takagi tankless water
heater instead eventhou I was told It will be bloody expensive because
my mecanical room is not on outside wall, it is in the middle of the
house. Does that make any sense to you?
That's exactly what I intend to do in the primary zone in my house.
Everything is there except the 110v outlet, and there is one I can
daisy chain from within 5'. I may not be the final authority on this,
but an air intake from the attic is there, gas connection, cold water
in pipe, hot water out pipe, vent pipe, blow-off pressure valve drain
pipe. What else would you need?. I see it as a direct exchange
I'm not an expert on these but I understand it is not a direct replacement
for a standard water heater. The gas line should be larger is what I've
seen (like 1" or more....not sure on that). Better keep investigating
My 1988 Kenmore gas 40gallon has a 40,000 BTU input.
Read the specs for the gas tagaki, its BTU input is several times larger.
In terms of gas usage, the tankless will be the largest single consumer
of gas in your house by a LARGE margin at any instant of time. Granted
it only runs when hot water is flowing so its total gas use is not that
great. But when its on, it uses ALOT of gas.
Whole house Electric tankless is similar. Dedicated circuits must be
To go from natural gas traditional to natural gas tankless, you will
need the following
1. New gas line installed from meter or from the distribution line
in your house.
2. Stainless steel exhaust installed thru the roof (can't share with
furnace, and this baby is HOT)
3. new 115V circuit.
The costs of the install may well rival or exceed the costs of the
For example, I see a competitor's tankless electric. Depending on
capacity, they recommend minimum wire size of 6 guage, and 60 to 180AMPs
of circuit breaker capacity (60A, 2x40A, 2x50A, 2x60A, 3x50A, or 3x60A)
In the manual my Bosch states it can be run to a chimney, so it can
share it with a furnace. My 117000 btu unit uses and was sized to use
the existing Ng pipe. Of course the large 190000 btu units use alot more
Changing from tank to tankless should not be particularly expensive if
the two heaters are the same fuel type. If you have an electric tank
type and install an electric tankless or have a gas tank type and
install a gas tankless.
If you have an electric tank type heater and no chimney or exterior wall
nearby, switching to a gas heater, whether tank type or tankless will be
With power venting my tankless Bosch can run maybe 25ft, or longer.
Replace it you will save maybe 25% easily. They are full btu
replacements if you size it right, but the cost is 2-6x that of a tank.
I left my old tank in place as a tempering tank for the cold incomming
Both the gas or electric tankless consume many times the fuel gas or
electric used by a tank type while they are operating.
figure a upgrade to 200 amps just for a electric tankless, plus a
second main for regular home power uses...
He said he just built the house so it's highly unlikely to have less
than a 200A electric service to begin with. Not many homes would need
dual 200A service (split 400A) just to handle the house and a tankless
I agree with both assertions above.
tankless whole house hot water heaters are the largest single consumer
of energy in your house while they are running.
The difference for gas is 40,000 BTU input that runs several hours a day
to keep 40 gallons at 125F vs 198,000 BTU input that runs maybe 30
minutes a day.
And yes, an extra 200Amp circuit will have to be run from the local
utility JUST to supply the tankless Electric as so few of us will have
more than 200Amps already installed, much less as spare capacity. But
keep in mind 200Amps is for the largest of the tankless units. The
smaller ones can get away with 50 to 60Amps, and we MAY have the spare
capacity for that in our breaker panel.
rgamon, when you say a tankless is the single biggest user of gas, that
is untrue for many users. Ng tankless have true modulating gas valves.
My 117000 bosch runs from apx 30000 btu to 117000 btu, I have never
needed or used 117000 Btu even with 35f incomming water, I have never
set it to high and have hot showers. Now in summer even the lowest
setting is to warm for me. The bigger Takagi goes even lower to maybe
15000 btu, Tankless only use the energy needed to reach the temp
desired. Tankless have a much higher "Energy Factor" a true rating, than
You dont know what BTU yours is running at, unless theres a digital
besides its largely of flow.
some folks are happy with a anemic shower and never have more than one
hot water thing on at the same time.
whereas I like a nice strong shower and removed the flow restrictor
from my wand shower.
I also occasionally have 2 washers and a dishwasher running at one
time. although I avoid showeriung when anything else is on.
Our tank from november of 2000 is a Rudd 50 gallon 75,000 BTU unit. It
was the largest tank that would fit the space.
with normal showering we never run out of hot water
At the instant that the gas tankless fires, if it fires anything close
to its max setting, and yours is not, will rival or exceed the gas
demand of natural gas furnace.
Even at 30,000BTU input it consumes a large volume of gas in a very
short interval. This gas use is smaller, and shorter in duration, than
the gas use of a 40,000BTU gas tank type.
Yes, the efficiency of tankless is great!!!
You are clearly saving money. But $20/mo, $240 a year will take you
several years to payback this investment.
The Takagi requires special stainless venting, probably the largest
expense in an interior installation. I seem to recall wholesale
materials cost of our exhaust stack components was over $400 for a
somewhat long run from an interior room.
Larger tankless heaters require a lot of gas. The gas guys mistakenly
ran a 1/2" line when plumbing for ours, it needed a 1" line because of
the length of the run, otherwise 3/4" would have been OK.
email@example.com is Joshua Putnam
Why are you choosing a tankless?
First they cost so much more than a standard tank the energy payback
exceeds the probable life of the heater:(
You MAY need to upgade your electric service, if the tankless is
electric, or your gas service, tankless consume LOTS when they are on..
In the winter a standard tanks heat loss goes to help heat the
building, so its not really lost, this probably cuts your energy saving
by 1/2 kinda dependent on local temperatures.
good your aware low flow may result in cold water, like washing
hands....or using a spray wand on dishes.
exceeed max flow and cool shower is result.
Of course the UNLIMITED hot water may result in longer showers
ultimately consuming more water sewer and heating fuel....
People who have owned a tankless say there are two great
the day its installed and the day its replaced by a standard
so why are you buyng a tankless?
If you have a power failure with a standard gas or electric tank you
have HOT water ayt least whats in the tank
A power failure in a tanklless either gas or electric means instant no
just what you need first thing in the morning:(
Living in an area with power cuts regular like, I sure appreciate the
natural gas water heater I use. No electric needed. And a hot shower
in the morning is nice when the power is off, and the portable heater
isn't doing the job.
Christopher A. Young
You can\'t shout down a troll.
Hallerb, my Bosch 117000 btu unit has a payback of 4 yrs, I save 20$ a
month, in summer my total Ng bill is now 6$ and that includes cooking
and Ng dryer. I used a 1/2" pipe, no additional work. Tankless are the
way to go, to bad few know the facts.
last time I checked the energy guide label a regular hot water tank
barely uses 20 bucks of gas per month, so please explain how you save
20 buckjs a month? unless you convered from electric to gas
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