Takagi TK-540P-NEH Outdoor Natural Gas condensing tankless water heater
Integrated recirculation pump
Ultra Low NOx
The TK-540P-NEH (a.k.a TH-3) integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. The pump is easily controlled with a simple user interface and multiple pump settings allow you to customize pump operation to meet your needs while maximizing heater efficiency.
Feature Highlights
- ENERGY STAR® qualified
- Residential Warranty: 15-year Limited on Heat Exchanger. 5-year on parts, 1-year for labor
- Commercial Warranty: 6-year Limited on Heat Exchanger, 5-year on parts, 1-year for labor
- Integrated Recirculation Pump up to 100' with 1/2" pipe. Up to 500' for 3/4" pipe
- Primary heat exchanger made of commercial grade copper that is more resistant to corrosion
- Secondary heat exchanger made of type 316L stainless steel.
- Complies with SCAQMD 1146.2 Ultra-Low NOx regulations of less than 14 ng/J (<20 ppm)
- Easy-Link with up to three other TK-540P-NEH units for applications that need high hot water flow rates
- Safety features
- Air to Fuel ratio (AFR) sensor
- Freeze protection
- Overheat cut-off fuse
- Exhaust and water temperature control
- Diagnostic error codes for troubleshooting
Feature Details
Freeze Protection
Every tankless heater by Takagi has an internal freeze protection system, rated to protect the heaters in sub-freezing conditions. This prevents the water in the heat exchanger from freezing that would burst the water heater's waterway pipes.
Hi-Limit Switch
This ensures that the water temperature does not reach dangerous levels. It shuts off the gas valve to stop the the water heating.
Air-Fuel Ratio Sensor
Takagi's unique sensor technology monitors and maintains optimal combustion at all times. The onboard computer adjusts the fan motor speed for a proper air/fuel mixture ratio to minimize emissions and maximize efficiency.
HRS35 Copper Alloy
The HRS35 copper alloy is heat-resistant, with additive elements. This makes it much harder and stronger than the standard C1220 copper alloy typically used in other brands of heat exchangers. HRS35 is 8 times stronger than regular copper, even at high temperatures. It's also resistant to the damaging corrosion, which is the main cause of leaks in heat exchangers.
316L Stainless Steel Secondary Heat Exchanger
The secondary heat exchanger, where the remaining heat transfer occurs, is made of high quality 316L stainless steel. The lower temperature here causes acidic condensation, and stainless steel is needed to prevent corrosion. 316L stainless steel is the best material for condensing heat exchangers because of the extreme environment (heat, chloride, acidic condensation) that the material is exposed to.
Better Water Pathway Design
By redirecting and redesigning water flow, the heat exchanger drum and finned coil's temperature stay above dew point, making it more difficult for condensate to build up.
Heat Exchanger Fin Pitch
Widening the pitch of the heat exchanger fins improves durability by reducing blockage. Plus, it maintains higher temperature levels on the upper finned coils. The higher temps at the coils reduces the chances of condensate formation.
Match the Unit to Your Needs
Flow Rate Guide (Values are in gallons per minute, "GPM".)
| Temp Rise, °F |
110/U |
310/U |
510/U |
T-TH3J |
T-H3S |
T-H3 |
TK-540P |
T-M32 |
T-M50 |
| 30° |
6.6 |
8.0 |
10.0 |
6.6 |
8.0 |
10.0 |
10.0 |
9.0 |
14.5 |
| 35° |
6.6 |
8.0 |
9.3 |
6.6 |
8.0 |
10.0 |
10.0 |
9.0 |
14.5 |
| 40° |
5.7 |
7.8 |
8.1 |
6.6 |
8.0 |
9.5 |
9.5 |
9.0 |
14.5 |
| 45° |
5.1 |
6.9 |
7.2 |
6.6 |
7.6 |
8.4 |
8.4 |
8.5 |
13.5 |
| 50° |
4.6 |
6.2 |
6.5 |
6.1 |
6.8 |
7.6 |
7.6 |
7.7 |
12.2 |
| 55° |
4.2 |
5.7 |
5.9 |
5.5 |
6.2 |
6.9 |
6.9 |
7.0 |
11.1 |
| 60° |
3.8 |
5.2 |
5.4 |
5.1 |
5.7 |
6.3 |
6.3 |
6.4 |
10.1 |
| 65° |
3.5 |
4.8 |
5.0 |
4.7 |
5.3 |
5.8 |
5.8 |
5.9 |
9.4 |
| 70° |
3.3 |
4.4 |
4.7 |
4.3 |
4.9 |
5.4 |
5.4 |
5.5 |
8.7 |
| 75° |
3.1 |
4.1 |
4.3 |
4.1 |
4.6 |
5.0 |
5.0 |
5.1 |
8.1 |
| 80° |
2.9 |
3.9 |
4.1 |
3.8 |
4.3 |
4.7 |
4.7 |
4.8 |
7.6 |
| 85° |
2.7 |
3.7 |
3.8 |
3.6 |
4.0 |
4.4 |
4.4 |
4.5 |
7.2 |
| 90° |
2.5 |
3.5 |
3.6 |
3.4 |
3.8 |
4.2 |
4.2 |
4.3 |
6.8 |
| 95° |
2.4 |
3.3 |
3.4 |
3.2 |
3.6 |
4.0 |
4.0 |
4.0 |
6.4 |
| 100° |
2.3 |
3.1 |
3.3 |
3.0 |
3.4 |
3.8 |
3.8 |
3.8 |
6.1 |
Specifications
| |
Natural Gas, NG |
Liquid Propane, LP |
| Installation Type |
Indoor with Schedule 40 PVC 3" or 4" Direct Vent, or Outdoor |
| Dimensions |
23.625" (H) X 17.75" (W) X 11.25" (D) |
| Weight |
Indoor model: 70 lbs. Outdoor model:68 lbs |
| Electric |
120 V, 1.27 A (Operation), 0.07 A (Standby), 1.73 A (Freeze-Protection) |
| Ignition |
Electronic Ignition with included 120V plug |
| Noise Level |
55 dB at maximum BTU output |
| Min. Input |
15,000 BTU/h |
13,000 BTU/h |
| Max. Input |
199,000 BTU/h |
| Uniform Energy Factor ("UEF") |
0.93 indoor, 0.95 outdoor |
| LEED Rating |
1.5 |
| ENERGY STAR® Qualified |
Yes |
| Min Gas Pressure |
4.0" W.C. |
8.0" W.C. |
| Max Gas Pressure |
10.5" W.C. |
14.0" W.C. |
| Maximum Flow Rate |
10 GPM based on factory testing. 0.4 GPM required for continuous fire after initial ignition at 0.5 GPM.
8.0 GPM when the set temperature is 130 °F (55 °C) or higher. |
| Hot/Cold/Gas Connection |
3/4" NPT |
| Coil Capacity |
≈0.2 Gallons |
| Water Pressure |
15-150 PSI. Pressure Only Relief Valve Requires (Min 200,000 BTUs, 150 PSI). 40 psi or above recommended for the 10 GPM max. flow. |
| Easy-Link System |
Up to 3 additional units, with no need for a system controller. |
| Dipswitches |
100°F 105°F 110°F 115°F 120°F (Default) 125°F 130°F 135°F 140°F, 145°F 150°F 155°F 160°F 165°F 170°F 175°F and 185°F (17 options) |
| Temperature Settings |
100°F to 185°F with 5°F intervals (16 options), 120°F Default Factory Setting |
| Remote Control |
Model # 100276687 remote included with outdoor model only. Max. distance 400’ from heater, 20 gauge wiring. |
Dimensions
Warranty
• Residential Use: 15 yrs limited heat exchanger, 5 yrs limited parts, 1 year labor
• Commercial Use: 6 yrs limited heat exchanger, 5 yrs limited parts, 1 year labor
Downloads
• User's Manual
• Spec Sheet
• Takagi Tankless Water Heater Product Line Brochure |
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