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TK-4-IN Takagi Tankless Indoor Water Heater (Natural Gas)
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MANUALS (4)
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Product Highlights
Description
The Takagi brand has been discontinued by the manufacturer as of December 31, 2025. Suggested replacement units will be available on our website and replacement parts will continue to be available as supplies last. If you'd like any further assistance, please contact our customer service team.
Think Green, Save Green. Rebate and incentive programs provide cash-back to consumers for the purchase of appliances that meet certain energy efficiency standards. Most states are offering rebates in the $50 to $250 range. You can search for rebates in your area from here.
Note: Isolation valves are not included but are recommended for installation.
TK-REO2 Remote Control is included: TK-REO2 Remote Control
Released in 2010, the T-K4 improves upon many of the features from the T-K3. The T-K4 is one of Takagi's smaller tankless water heaters. At 13.8 inches wide and weighing only 38 pounds, its ultra-compact design allows it to be mounted on a wall.
Takagi's newest tankless water heater also features an energy factor of 0.82, so it is extremely efficient and environmentally friendly. Since tankless water heaters only burn gas when hot water is needed, installing this unit can help homeowners save up to 45% on their monthly gas bills.
Specifications:
- Capacity: 2 to 3 Bathrooms
- Flow Rate: Maximum 8.0 GPM
- Gas Inputs: 11,000 to 190,000 BTU per hour
- Energy Factor Rating: 0.82
- Inlet Gas Pressure: Min: 5.0" W.C. / Max 10.5" W.C.
- Dimensions: 20.3" H x 13.8" W x 8.5" D
- Direct Vent Capability
- Electric Ignition
Specs
| Application: | 2-3 Showers |
|---|---|
| Product Type: | Tankless Heater |
| Installation Type: | Indoor Only |
| Fuel Type: | Natural Gas |
| Height: | 20.3" |
| Energy Factor: | 0.82 |
| Width: | 13.8" |
| Vent Size: | 4" |
| Depth (Inches): | 8-1/2" 9-1/2" |
| Max Flow (GPM): | 8 |
| Inlet Gas Pressure: | 5.0-10.5"W.C. |
| Voltage: | 120v |
| Manifold Pressure: | 2.0-2.5"W.C. |
| Gas Input: | 11000-190000 BTU/h |
| Energy Star Rated: | No |
| Water Connection: | 3/4" |
| Venting Requirement: | Category III Stainless Steel |
| Gas Connection: | 3/4" |
| Vent Type: | Direct Vent Convertible |
| Temperature Range (F): | 99°F - 167°F |
| BTU (Max): | 190000 |
| BTU (Min): | 11000 |
| PSI Range: | 15-150 psi |
| Height (Inches): | 20.25" |
| Weight (lbs): | 38 lbs |
| Width (Inches): | 13-3/4" |
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Product Reviews
Yes!
nice unit for propane
Great heater
Quick shipping, excellent packaging
I will buy this same product again
Works GREAT and Quick delivery
Great heater and awesome service!
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Great product, but do your research
This is my second TK-4-IN.
Takagi has been great to us.
Product Q&A
31 QuestionsQ: Does it have to be mounted on an outside wall?
Asked by 14 years ago
Add your answer
Verified Reply- PexSupply StaffThe unit does not have to be mounted on an exterior wall, although doing so may make venting easier.
Q: does the tk4 have the energy star rating?
Asked by shep 14 years ago
Add your answer
Verified Reply- PexSupply StaffYes, it is. This unit meets the .82 minimum Energy Factor requirement for tankless water heaters.
Q: Can your Takagi water heater be used for infloor radiant heating and can you use it with glycol or will it void the warranty.
Asked by BamBam 14 years ago
Add your answer
Verified Reply- PexSupply StaffYou can use up to a 30% mixture of glycol with this unit. Using it for heating (glycol or no glycol) cuts the warranty in half.
Q: I want to install a water lobster in the kitchen to decrease the flow of cold water to the hot water faucet in the sink. Will this unit interfere with circulating warm water through the cold water pipes? Hot water lobsters work well to shorten the wait for hot water when used with conventional tank heaters.
Asked by limudad 14 years ago
Add your answer
Verified Reply- PexSupply StaffWe do not sell the product, but it is our understanding that hot water lobsters are designed to work only with tank-style water heaters.
Q: Would Takagi TK-4-in model is sufficient for one family house with 3 showers and 2 kitchens.
Asked by Ed 15 years ago
Add your answer
Verified Reply- PexSupply StaffThis unit can provide the maximum per-minute flow displayed on page 2 of the manual linked below. In New York, you may need to make the water 60 degrees hotter during the winter. When this is the case, the T-K4 can produce 5 gallons of hot water per minute. This should be enough for two simultaneous showers, but not much else. During warmer times of the year, the unit is capable of higher flow rates. http://s3.pexsupply.com/manuals/1289421083326/41441_PROD_FILE.pdf
Q: I am planning to put TK-4-IN in the 2 car garage on the wall facing outside.Will it need direct vent for intake air from outside for combusion? Will exhaust vent be enough?.Will Z vent kit be enough?
Asked by Denis 15 years ago
Add your answer
Verified Reply- PexSupply StaffIf you are looking to direct vent the TK-4IN we would recommend using TK-TV10 and DDV-47
Q: I notice persons using the OS model in the northwest part of the country and in Canada. I will be installing the unit in Arkansas where the outside temp in Late jan or early Feb may reach zero or at the very lowest 5 below. Is there a freeze issue with the OS? I know there is flame but only when in use. Please advise, ASAP. I will be installing in less than 6 weeks.
Asked by Steven 15 years ago
Add your answer
Verified Reply- PexSupply StaffWe would not recommend using the OS outdoor unit in your area. It may pick up some heat from the house, and you can use the unit's freeze protection and insulate the pipes, but the manufacturer only recommends outdoor installation in very warm climates.
Q: What is the minimum flow rate to turn the burners on?
Asked by 15 years ago
Add your answer
Verified Reply- PexSupply StaffYou will need 0.2 GPM in order to start the unit.
Q: can you install a recirculating pump on a TK-4
Asked by jess 15 years ago
Add your answer
Verified Reply- PexSupply StaffYes, you can.
Q: is this tk-4 can operate a 3 to 4 shower bathroom
Asked by loyd 15 years ago
Add your answer
Verified Reply- PexSupply StaffIt can, as long as you do not require a greater flow rate than those listed on the chart at the top left of page 2 of the following specification sheet: http://s3.pexsupply.com/manuals/1289421083326/41441_PROD_FILE.pdf . For example, when the temperature of incoming water needs to be raised by 80°F, this unit will produce a maximum of 4 gallons of hot water per minute.
I can be placed into a home with 3 showers but if you plan on using all 3 or even 4 showers at the same time, you will need more heat. Unless you use low flow shower heads and possibly lower the temperature setting of the unit. It's all about BTU energy. Frankly, we run it with 2 showers and never worry about the dishwasher, washer or kitchen sink at the same time.