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Eccotemp 45HI-NG + Horizontal Vent Kit Indoor Gas Tankless Water Heater

Original price $917.00 - Original price $936.95
Original price
$917.00 - $936.95
Current price $917.00


On Backorder, the Expected availability date is 31st May 2023

140,000 BTU heater for homes with up to 2 bathrooms for natural gas
plus Thru-Wall Vent Kit

Eccotemp 45HI-NG Indoor Natural Gas Tankless Water HeaterThe 45HI is the indoor equivalent of the 45H Eccotemp outdoor tankless water heater. It is designed to provide hot water to standard three bedroom, two bathroom homes. The 45HI-NG is for indoor Natural Gas installations only. For Liquid Propane applications, please see the 45HI-LP.

All the basic venting pieces for a standard horizontal through-the-wall installation are included.

Rated at an impressive 6.8 GPM, the 45HI is adaptable to split systems, which can further increase hot water delivery speed and efficiency. The 45HI is the ideal choice for standard sized homes, thanks to its fully automated control system.

Eccotemp 45HI-NG + Horizontal Vent Kit Indoor Gas Tankless Water Heater


• Natural gas powered
• 110 volt UL listed power cord
• 10 year warranty on heat exchanger. 5 year warranty on parts.
• CSA certified for use in Canada and USA
• Power vented: includes internal exhaust fan
• Integrated freeze protection (Will not prevent freezing in all conditions. See manual.)
• Optional: Digital remote with diagnostics and simple controls


• Water/gas connections: 3/4 inch water inlet/outlet, gas inlet
• Venting: 4" diameter
• Flow Rate:
→ 35 degree rise: 6.8 GPM
→ 50 degree rise: 5.0 GPM
→ 70 degree rise: 3.4 GPM
• Minimum gas rate: 19,800 BTUs
• Maximum gas rate: 140,000 BTUs
• Weight: 39 lbs
• Dimensions: 22" x 15" x 6"
• Energy rating: 82%
• Energy Factor: 0.80
• Hot water capacity: 1.2 - 6.8 GPM
• Minimum water pressure: 14 psi
• Minimum water flow rate: 0.75 GPM
• Power requirements: 120V AC, 60Hz, 2 Amps

Download here the Use & care manual.

Included: Horizontal Vent Kit with 4" Diameter Single Walled Stainless Steel

Made by Z-Flex Z-Vent with lifetime warranty. Includes all the basic components for a quick and easy installation.

Note this heater allows for a maximum vent run of 20 feet, subtracting 4 feet for each 90° elbow in the run.

Included pieces, all 4" diameter, USA-made stainless steel

  • qty 1 Universal Appliance Adapter ("UAA")
  • qty 1 backflow preventer (included in the UAA above)
  • qty 1 straight vent pipe, 1-foot
  • qty 1 90° elbow
  • qty 1 wall thimble for wall thickness of 4" to 7"
  • qty 1 termination hood

Note that this kit does not include a condensate drain pipe which may be required depending on your water heater manual guidelines and building code.
This 3-in-1 gadget (UAA, backflow preventer, condensate drain) can replace the UAA in this kit.
This part has only the condensate drain and can be connected to the UAA in this kit.

Contact us if you need to buy additional Z-Vent parts or assistance, or browse our Venting section at the top of this web page.

The stainless steel is AL-294C alloy with a lifetime warranty from Z-Flex, and is Category II/III and UL approved.

Frequently Asked Question ("FAQ")

Q1: What is the difference between the 40H and the 45H?
A1: The 45HI has a lower turn-on flow rate of 0.8 GPM, is smaller and lighter, and has updated self-diagnostics. The 45HI maintains the same connections and water heating capacity as the 40H.

Q2: Can I convert this from natural gas to propane?
A2: No, sorry, according to Eccotemp.

Q3: Is the heated output water potable (drinkable)?
A3: Yes. Eccotemp has tested the heated output water as acceptable according to water safety standards.

Q4: The manual states, "Unit not recommended for elevations in excess of 2,000 feet." Really? That's very low.
A4: Elsewhere Eccotemp states that the maximum elevation is 3000 ft. Using it at higher elevations will likely result in the error code E8 indicating insufficient oxygen mix for combustion. has other heaters that will work at higher elevations. Please ask if you need assistance with a selection.