Converting from domestic (tank) to tankless water heater

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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?
Thanks!
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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
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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 before purchasing!
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James "Cubby" Culbertson wrote:

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 installed.
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 equipment.
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)
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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 Ng.
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djenka2 wrote:

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 expensive.
Pete C.
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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 water.
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WRONG!
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...
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" snipped-for-privacy@aol.com" wrote:

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 water heater.
Pete C.
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snipped-for-privacy@aol.com wrote:

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.
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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 tank.
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m Ransley wrote:

You dont know what BTU yours is running at, unless theres a digital readout?
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
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m Ransley wrote:

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.
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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.
--
snipped-for-privacy@phred.org is Joshua Putnam
<http://www.phred.org/~josh/
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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 days.............
the day its installed and the day its replaced by a standard tank........
so why are you buyng a tankless?
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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 hot water:(
just what you need first thing in the morning:(
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I dont need AC with my Bosch it has battery pilotless ignition. Powerventing is an option for me.
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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.
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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.
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m Ransley wrote:

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 tankless....?
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