PlumbingSupply.com® logo
The Leading Online Plumbing Supplier Since 1995
Contact Us | Customer Reviews | View Cart
Our motto: "under-promise...over-perform"
Product Search:

Largest Inventory - Best Service - Lowest Prices
Find your plumbing supplies starting with:   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Simple, straightforward and low shipping rates for these tankless water heaters.


T-K4-OS Outdoor Tankless Water Heater

By Takagi

Add a tankless water heater to your home and enjoy never running out of hot water, always knowing that there will be enough hot water for every shower, bath, or other use. These units are designed for outdoor installation, but will still take up far less space without that bulky holding tank, and is powerful enough for up to three bathrooms. Let PlumbingSupply.com® be your source for Takagi products. To make these fantastic tankless water heaters even better, you may qualify for a 2013 federal tax credit - click for more info.

We also offer many more tankless water heaters by Takagi:
to Takagi T-K3 (TK3) - to T-KJr2-IN
to T-KJr2-OS - to T-K4-IN - to T-D2-IN - to T-D2-OS

Takagi T-K4-OS - Tankless Gas Water Heater For Outdoor Installations
image of T-K4-OS outdoor tankless water heater
Takagi T-K4-OS

(wall brackets are built onto the unit)
Takagi's T-K4-OS is a small, yet powerful tankless water heater which is designed to handle heavy residential use (or light commercial needs), and be installed outside mounted on an exterior wall. As it is installed outside, you will see a huge savings on the costs for the stainless steel venting required for any indoor heaters. This water heater is only 20.5" x 13.8" x 8.5", so it will save space for those looking to maximize storage space in your home and garage.

Takagi is the leader in tankless water heaters and the T-K4 can significantly reduce your heating bills, again saving you money. It will take the place of your common 50 to 80 gallon, old tank-style, water heater - simplifying your maintenance. There's no pilot light to waste gas and the heater itself turns on (by electronic ignition) only when it senses a very low .75GPM (gallons per minute), so this will prevent hot water loss from leaky fixtures and faucets, but will be enough so you can get hot water to your bathroom sink for hand washing.

The bottom line is that the Takagi T-K4-OS can save costs and labor on install, free up space, reduce your monthly bills, and make your life more efficient. Of course with newer technology there is a need to learn it as well. Tankless water heaters will not stop heating the water until the flow stops. So if you decide to take an hour-long shower, you can, but keep in mind that you are no longer saving money on your energy bills, or water costs. Teaching your family how tankless water heaters work is key.

See Lucas's (our company President) own outdoor Takagi water heater that he installed at his home to replace an old inefficient 75 gallon water heater

(If you have very cold incoming water, or live in a place that freezes often, then you may want to consider the indoor tankless water heater model. For determining how to choose the size water heater for your needs, consult the specifications as you'll need to know a few things: 1. Your inlet water temperature, 2. Your desired water temperature, and 3. Your needed flow rate - remember to consider all of your showers, fixtures, and appliances.)


Takagi T-K4-OS Water Heaters
Model # Description Price & Quantity
T-K4-OS-NG Tankless Water Heater - Natural Gas, 190,000 max BTU's Add to quote →
T-K4-OS-LPG Tankless Water Heater - Propane, 190,000 max BTU's Add to quote →

Please note: some areas do not allow installation of a few of these water heaters. Read more

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.


Find great deals on other Takagi tankless water heaters! Click here.



Accessories for Takagi T-K4-OS
Note: Wall brackets are built onto the T-K4-OS and do not need to be purchased separately
- click here for stainless steel gas venting products -
Model # Description Price & Quantity
TK-RE02 Additional Temperature Remote Controller (one is included with each T-K4-OS) - Use the remote controller to change the preset 122°F temperature and to read diagnostic codes Add to quote →
WS1019 Wall Mount Drain Pan for Tankless Water Heaters - more info Add to quote →
12-pack Wall Mount Drain Pans Add to quote →
PVC Drain Connector Drain connector for the tankless water heater drain pan (listed above)
Includes 1 each: 1" PVC male adapter, gasket, and locknut
Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.



Pressure Relief Valves
A pressure relief valve is required for all tankless water heaters. In some areas, a temperature and pressure relief valve is required. Check your local plumbing code for more information.
Pressure Relief Valve - Brass - 3/4" - 150 PSI Add to quote →
Temperature and Pressure Relief Valve - up to 200,000 BTU Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.




"The Isolator" Isolation Valves - Lead Free - Includes pressure relief valve
Complete inlet/outlet valve system that provides everything you need for a secure installation including full port testing and flushing of the system with easy to install union connections. Includes pressure relief valve. Meets federal and state low lead regulations.
Isolation Valve - Set   (Hot & Cold)   3/4" FIP Union x 3/4" FIP Add to quote →
Isolation Valve - Set   (Hot & Cold)   3/4" FIP Union x 3/4" Sweat Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.




Gas Connectors - click here for more gas connectors
Coated Stainless Gasflex - 1" OD (3/4" ID) x 24" - with adapter to 3/4" FIP x 3/4" MIP Add to quote →
Gas Ball Valve 3/4" Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.



Lead-Free Ball Valves - click here for more lead-free ball valves
Lead-Free Ball Valve - 3/4" FIPS Add to quote →
Lead-Free Ball Valve - 3/4" Sweat Add to quote →
Stainless Steel Nipple - 3/4" MIP x 1-1/2" Long Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.




Water Connectors - click here for more flexible water supply lines
Flexible Corrugated Stainless Steel Water Connector - 3/4" FIP x 3/4" FIP - 18" Long Add to quote →
Flexible Corrugated Stainless Steel Water Connector - 3/4" FIP x 3/4" FIP - 24" Long Add to quote →
Flexible Corrugated Copper / Stainless Steel Water Connector - 3/4" FIP x 3/4" Nom Sweat - 18" Long Add to quote →
Flexible Corrugated Copper / Stainless Steel Water Connector - 3/4" FIP x 3/4" Nom Sweat - 24" Long Add to quote →

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.



Water Heater Scale Inhibitor System
Features: inhibits scale build-up, helps protect piping from corrosion, maintains efficiency & extends life of system, 3/4" NPT, 10 GPM, cold water feed line. Scale inhibitor media is siliphos which is suitable for drinking and cooking water and all food applications, and effective on all types of hot water systems-boilers, tankless, and tank-type (gas or electric). Replacement cartridges (AP431) are available for these in-line scale inhibitor systems.
Water Heater Scale Inhibitor System
  Order 6 or more for greater savings!
Add to quote →
Replacement cartridge for water heater scale inhibitor system
  Order 10 or more for even greater savings!
Add to quote →
Note: Recommended time to change/replace filter cartridge is 6 months. Purchase a replacement cartridge to have on hand when needed.

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.



FloodStop Systems for Water Heaters
Automatically shut off the water supply to the water heater and sounds an alarm, leaving all other household fixtures and appliances operational. Powered by AC Adaptor/Transformer or Batteries. Output contacts available, which allow the Controller to connect with Alarm, Home Automation or Auto-Dialer systems if desired. Easily installed in fifteen minutes. 1-Year Manufacturer's Warranty.
FS 3/4-NPT - 3/4" Pipe threaded - full-port motorized ball valve (brass) - lead-free
- Works with any 3/4" MIPT supply line
Add to quote →
FS 3/4-C - 3/4" Compression - full-port motorized ball valve (brass) - lead-free
- Works with any 3/4" copper applications
Add to quote →
Make sure to follow all of the manufacturer's instructions and directions by performing the proper maintenance and inspections to ensure that you are fully protected from flooding -this is ever-so-important with (man-made) safety devices as they will eventually fail.

- Or -
Click here to view items that you would like to have quoted

Save money and get a quick price quote ... it only takes a minute and is well worth it!!!
Unlike most other products, we cannot show our low pricing on the web for these items (click here to find out why).
To request a price quote, simply select the items you are interested in by clicking the box "Add to quote →"
Then click the button to add the item(s) to your quick quote request list.


to stainless steel vent pipe



Takagi T-K4 (TK4) Specifications
Dimensions (H x W x D) 20.5" x 13.8" x 8.5"
Net Weight 48 lbs.
Power input (BTU) NG 11,000 - 190,000
LP 11,000 - 190,000
Energy Factor NG 0.82
LP 0.82
GPH Rating (at 77°F rise/4.1 GPM) NG 246
LP 246
Gas Connection 3/4" Male NPT
Water Connection 3/4" Male NPT
Water Pressure Min: 15 PSI, Max: 150 PSI
NG Inlet Pressure Min: 5.0" w.c. Max: 10.5" w.c.
LP Inlet Pressure Min: 8" w.c. Max: 14.0" w.c.
Minimum Flow to Activate Burners 3/4 GPM






Common Plumbing Terms
FIP Female Iron Pipe (NPT threads)
MIP Male Iron Pipe (NPT threads)
NPT National Pipe Thread
FNPT Female National Pipe Thread
MNPT Male National Pipe Thread
Nom. Nominal: Used to describe copper pipe and fittings in plumbing. Refers to the inside diameter of the pipe which varies by thickness of the pipe
Sweat Copper pipe solder fitting


Related Items & Accessories:
example of a one handle shower system

image of copper fittings

Acrylic Clawfoot Tubs

Gas meters for many applications


Frequently Asked Questions

Q. "There are many companies selling all kinds of tankless water heaters. Why should I buy a Takagi tankless gas water heater from you rather than elsewhere?"
A. We are a large, reputable company that was here yesterday and we will be here tomorrow. We are often copied, but we don't believe that any one can match our service and certainly our base of satisfied customers is larger than any Internet plumbing supplier since 1995. We sell 1000's of other quality plumbing products as well, so you can rest assured that we know plumbing products. We are a very stable and reputable company. We love to sell what we believe in, and we definitely believe in Takagi.

Q. "If these units don't have a tank, how do they know when to turn on?"
A. These tankless water heaters have a flow switch built into them. When you turn on the hot side of a faucet the water begins moving. Once the water is traveling at minimum flow rate for the heater, the flow switch will turn on the gas.

Q. "I've heard that some Takagi tankless water heaters cannot be installed in a few areas. Is that true?"
A. Yes, there are some counties that do not allow for the installation of a few Takagi tankless water heaters. For this reason, the person purchasing one of the following models is responsible for checking with their local code authorities prior to ordering: T-M32-NG, T-D2-IN-NG, T-D2-OS-NG, T-K4-IN-NG, T-K4-OS-NG, T-KJr-IN-NG, T-KJr-OS-NG. Here's a list (not complete) of some California counties that do not allow these water heaters to be installed: Sacramento, Yolo, Sonoma, San Joaquin, Napa, Marin, Solano, Contra Costa, San Francisco, San Mateo, Alameda, and Santa Clara. Again, this list is not complete, so it's up to the purchaser to check with local code authorities prior to ordering.

Q. "Why can't I install the T-K4-OS myself?"
A. Improper installation of the T-K4-OS could create carbon monoxide gas and other dangerous gases. Installation of this unit by persons other than professionally trained technicians voids the warranty.

Q. "What's the first hour rating of this water heater?"
A. Traditional tank water heaters have a first hour rating which is determined by the amount of hot water the heater can produce in an hour when starting with a full tank of hot water. As tankless water heaters do not start with a tank of hot water, they don't really have a first hour rating the same way a tank water heater does. Instead, tankless water heaters have a gallons per hour rating, which is determined by how many gallons per hour the tankless water heater can produce when raising the incoming water temperature a specified amount.

Q. "I noticed that this tankless water heater is designed for residential use. Do you offer a tankless water heater that is designed for heavy-duty commercial applications?"
A. Yes we do! The Takagi Mobius T-M32 is designed specifically for heavy-duty commercial applications.

Q. "I live in an area where it freezes, what can I do to protect the heater from freezing?"
A. We recommend you use the TK-BF01 exhaust back flow prevention kit to prevent cold air from entering the vent and causing the heat exchanger to freeze.

Q. "Will an instantaneous water heater save me money on my utility bills?"
A.In many applications you can see a savings. There are some variables that could reduce the amount you save. One example is you will not run out of hot water, so longer showers could cut into your savings. Also, the cost of electricity, propane and natural gas in your area will affect the amount of money saved. The higher the cost for the energy type used to heat your water, the quicker you can recover the higher initial cost of installing a tankless versus tank style water heater.

Positives:

    You will never run out of hot water. "You want an hour long shower? No problem!"
    Electric units can be installed at the point of use.
    You're not paying energy costs to heat water 24 hours a day.
    They're easy to install.
    Our electric units don't require a T&P valve (no tank!) - if code allows
    Installing a tankless water heater can indeed be a bonus to the environment (why should we choose wastefulness when we're talking about finite natural resources?)

Negatives:

    They all need a minimum flow rate & pressure to turn on.
    The faster water flows through them, the lower the temperature rise. So, if you expect to take a shower while the clothes washer is running, you will need to select a unit sized to your maximum hot water flow requirements. (Gas units generally handle this a little better than electric models)
    Electric units need heavy gauge wire. Example: the 9.5kw must have 8ga wire and a 50amp breaker.
    Gas units need a much larger, special flue pipe and larger gas supply than a conventional water heater.
    At times they can produce very hot water. It's easier to get scalded.
    Gas units are more complicated than a conventional water heater.
    With some brands, parts are hard to find (not a negative if you originally purchase from us, as we like to carry parts for the units that we sell).

Summary:
Tankless water heaters have their place. They're not "the answer" to every hot water need, but if they're used correctly they can be the solution to many of them.

Q. "Your products specify the 'temp. rise' based on the GPM flow; what do you mean by this?"
A. Temperature rise is the amount the heater raises the temperature of the incoming water, based on the flow rate shown of that water.

Q. "It sometimes drops below freezing where I live. Can I still install a Takagi tankless water heater outside?"
A. Takagi gas tankless water heaters are designed to be installed outdoors only in mild temperate climates. The factory-installed freeze protection device is rated for temperatures down to 5°F in a wind-free environment, so wind-chill factors must be taken into account when choosing whether or not to install a Takagi tankless water heater outdoors. If you are unsure if temperatures at your planned installation would work for an outdoor tankless water heater, we strongly recommend consulting with a trusted local professional.

Q. "What do I need to install these Takagi tankless water heaters outdoors?"
A. Outdoor-only Takagi tankless water heaters, such as the T-D2-OS or the T-K4-OS, require no additional venting components. Units that can be installed either indoors or outdoors, such as the T-M32, Mobius T-K3-PRO or the T-K3 are designed to need only the addition of an outdoor vent cap or properly vented recess box in order to function in an outdoor installation. Please note that Takagi tankless water heaters, like most brands of water heaters, are designed to be installed outdoors only in mild temperate climates. As always, please consult with your installer or another trusted professional before installation.

Q. "What are the best reasons to install a Scale Inhibitor System?"
A. The system inhibits scale build-up and protects the piping from corrosion, which helps maintain efficiency and extends the life of the system.

Q. "How does the Water Heater Scale Inhibitor System prevent corrosion?"
A. It forms a thin protective layer on the inside of pipes and metal parts. This film or layer is microscopic in thickness and will not build up over time.

Q. "What happens if you don't change cartridges often enough on the Scale Inhibitor System?"
A. The original water condition and problem will reappear. Hardness will begin to build up again, which you want to avoid.

Q. "What is siliphos?"
A. Siliphos is a water treatment compound; a glass-like Polyphosphate containing Sodium, Calcium Magnesium and Silicate, formulated specifically for the treatment of water problems and to prevent the build-up of scale in plumbing. It is made from a blend of food grade organic phosphates, and has been approved by the USDA for drinking water and all food applications. It is safe for ingestion by humans, animals, and plants, and does not build up in waste water.

Q. "Is the Water Heater Scale Inhibitor System's active ingredient safe?"
A. Yes! All ingredients used are 100% pure food grade materials. They are approved by the USDA and meet purity requirements as a food additive by the World Health Organization.

Q. "Will the Water Heater Scale Inhibitor System change the taste or odor of water?"
A. No. The active ingredient is colorless, tasteless, and odorless when used as recommended.

to other tankless heaters Frequently Asked Questions

Help save our environment by saving energy.
Stand-by heat loss wastes a LOT of energy.
Installing tankless water heaters saves
energy, as well as your pocket book in the
long run. Think future! Think green.

All Takagi tankless water heaters must be installed by a licensed professional.

return to top ↑

We hope that we have helped you on this page with Takagi T-K4-OS tankless water heaters,
and thank you for helping to make PlumbingSupply.com® the most famous Internet plumbing supplier.


Fun, inspirational quote of the day:
People prefer to follow those who help them, not those who intimidate them.
- C. Gene Wilkes



Is there something else that you are looking for?

Enter search terms:

OR - find plumbing supplies starting with: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Easy payment methods


Copyright© 1995-2013 PlumbingSupply.com. All Rights Reserved.