11 Installing Condensing Tankless Water Heater of 2026 To Prevent Pipe Damage

1

NEW Rinnai RXP160iN Condensing Smart Sense Natural Gas or Propane

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  9.6
• Brand
  Rinnai

Key specs2

Recirculation Pump

Built-in pump with Smart-Circ usage learning

Venting & Fuel Flexibility

Versa Vent technology enables either indoor or outdoor mounting, but exterior locations require the optional RX-OVC cap. The Smart Sense gas valve automatically manages natural gas or propane lines without separate orifice changes.

Pros & cons43

Pros

• Dual-fuel Smart Sense valve works with natural gas or propane without a conversion kit
• Integrated recirculation pump with Smart-Circ technology automates hot water delivery
• High 0.97 UEF rating extracts maximum thermal energy through condensing operation
• Delivers up to 9 GPM flow to run up to 6 fixtures at once

Cons

• Requires an external RX-OVC vent cap purchase if mounted in outdoor locations
• Controlr WiFi module is sold separately rather than built in
• Produces acidic runoff that requires dedicated drainage and neutralizer media

2

ThermoMate Condensing Tankless Water Heater Propane, Up to 5.28 GPM

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  9.5
• Brand
  thermomate

Key specs2

Freeze Protection

4 ceramic heating cores activate at 41°F

Utility Connection Specs

• Water inlet and outlet: standard 3/4-inch NPT
• Gas connection: 1/2-inch NPT for liquid propane
• Venting: 3-inch outer diameter flue pipe
• Electrical: 120V outlet cord with 5-foot reach

Pros & cons42

Pros

• Dual heat exchanger combines stainless steel condensing with copper for 0.86 UEF efficiency
• Built-in frost protection uses 4 ceramic cores activating automatically at 41 degrees Fahrenheit
• Compact 21-inch cabinet fits tight indoor mechanical spaces with standard 3/4-inch NPT ports
• Digital 3.5-inch touchscreen monitors real-time flow and error diagnostics

Cons

• Propane-only fuel configuration requires dedicated LP tank and gas hookup
• Needs an external condensate drain line and neutralizer to safeguard household pipes

3

Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  9.3
• Brand
  Rheem

Key specs2

Condensate Drain Requirement

None needed (non-condensing outdoor exhaust)

Outdoor Clearance & Venting

Direct exterior mounting eliminates indoor exhaust piping and flue penetrations through ceilings. Because flue gases vent directly to the open air, you avoid indoor acidic condensate drains entirely, though external water lines require pipe freeze shielding.

Pros & cons43

Pros

• Outdoor-only installation eliminates the need for indoor venting and condensate drain lines
• Generates 160,000 BTU output supplying up to 7.0 GPM for 2 to 3 simultaneous showers
• Produces no acidic runoff, eliminating the risk of drain line pipe corrosion
• Backed by a 15-year heat exchanger and 5-year parts residential warranty

Cons

• Outdoor placement requires exposed pipe insulation against freezing weather
• Lower 0.82 UEF efficiency compared to condensing tankless alternatives
• Does not support indoor mechanical closet mounting

4

Rinnai RE140iN Non-Condensing Natural Gas Tankless Water Heater

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  9.2
• Brand
  Rinnai

Key specs2

Venting Material Requirement

Requires high-heat exhaust venting, not PVC

Warranty Coverage

• Heat exchanger: 15-year residential warranty
• Labor coverage: 5-year residential warranty
• Parts: 1-year limited warranty

Pros & cons43

Pros

• Non-condensing operation avoids acidic wastewater disposal and neutralizer kit requirements
• Delivers up to 5.3 GPM to support up to 5 fixtures simultaneously
• Compact suitcase-style profile speeds up wall mounting in tight locations
• Extended warranty covers 15 years on the heat exchanger and 5 years on parts

Cons

• Venting requirements call for high-temperature exhaust materials instead of PVC
• Lacks an internal recirculation pump, requiring external accessories for faster flow
• WiFi connectivity requires purchasing a separate Controlr module

5

ThermoMate CZ480NG 5.28GPM Condensing Tankless Water Heater, 0.86 UEF High

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  9.1
• Brand
  thermomate

Key specs2

Shower Capacity

Runs two 2 GPM showers at 105°F with 65°F inlet water

Condensate Treatment

The secondary heat exchanger condenses flue gases into mildly acidic runoff. Routing this drainage directly into household pipes can cause corrosion over time, so pairing the drain line with an external limestone neutralizer kit protects indoor plumbing.

Pros & cons42

Pros

• Dual heat exchanger pairs corrosion-resistant stainless steel with copper for 0.86 UEF
• Delivers 5.28 GPM flow rate to handle two simultaneous showers at 114,000 BTU
• Integrated frost protection uses 4 ceramic cores kicking in at 41 degrees Fahrenheit
• Clear manufacturer instructions alert homeowners to add an external acid neutralizer

Cons

• Condensate neutralizer kit is not included and must be purchased separately
• Limited to natural gas supply lines without dual-fuel adaptability

6

Rinnai RE140iP Non-Condensing Propane Tankless Water Heater, Up to 5.3

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  8.8
• Brand
  Rinnai

Key specs2

Fuel & Installation Location

Propane dedicated for indoor residential mounting

Warranty Coverage

• Heat exchanger: 15 years residential
• Labor: 5 years residential
• Parts: 1 year residential

Pros & cons43

Pros

• Non-condensing design produces zero acidic discharge, protecting domestic plumbing
• Supplies 140,000 BTU output delivering up to 5.3 GPM for residential fixtures
• Compact suitcase-sized chassis fits smaller utility closets easily
• Clean internal layout simplifies servicing and displays diagnostic codes on an LED screen

Cons

• Requires dedicated non-condensing metal venting rather than standard PVC runs
• Propane-specific design cannot be switched directly to natural gas
• Internal recirculation pump is not included on this base model

7

Vancepic Condensing Natural Gas Tankless Water Heater Indoor, 120,000 BTU

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  8.3
• Brand
  VancEpic

Key specs2

Freeze Protection

Integrated 114W internal anti-freeze heater

Included Installation Parts

• Exhaust vent pipe included in carton
• Flexible condensate drain line supplied
• Standard wall mounting bracket hardware

Pros & cons42

Pros

• Includes both the vent pipe and condensate drain line in the box for easier hookup
• Built-in 114W anti-freeze heater protects internal water pathways in freezing weather
• Generates 120,000 BTU to supply 5.1 GPM across 2 to 3 bathrooms
• Stainless steel heat exchanger withstands acidic exhaust condensate

Cons

• Warranty coverage is limited to 2 years on parts and the heat exchanger
• Requires an external neutralizing filter to treat acidic drainage before municipal discharge

8

NEW Rinnai RX130iN Condensing Smart Sense Natural Gas or Propane

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  8.1
• Brand
  Rinnai

Key specs2

Efficiency Factor

0.97 UEF condensing thermal efficiency

Venting & Fuel Flexibility

The Smart Sense system adapts dynamically to natural gas or liquid propane supplies. Versa Vent permits indoor venting runs or exterior setup when fitted with the RX-OVC cap, producing cooler flue gases compatible with approved polypropylene or PVC vents.

Pros & cons43

Pros

• Smart Sense technology adapts to either natural gas or propane configurations
• High 0.97 UEF rating maximizes heat capture while maintaining low exhaust temperatures
• Versa Vent design supports flexible indoor or outdoor mounting setups
• Quick Flush feature simplifies routine descaling and maintenance flushes

Cons

• Outdoor installation requires purchasing an optional RX-OVC vent cap
• 7.1 GPM maximum flow rate is lower than 160,000 BTU models in the same lineup
• Requires dedicated condensate drainage routing with neutralizer media

9

Rinnai RU160iN Condensing Tankless Hot Water Heater, 9 GPM, Natural

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  7.6
• Brand
  Rinnai

Key specs2

Recirculation Compatibility

Circ-Logic logic pairs with external pumps

High-Demand Flow Delivery

Delivering up to 9 GPM, this 160,000 BTU condensing heater serves whole homes with multiple high-draw fixtures running together. The secondary heat exchanger wrings heat from flue gases, creating acidic drainage that requires dedicated neutralizer routing.

Pros & cons43

Pros

• Robust 9 GPM flow rate supports whole-home demand across up to 6 appliances at once
• Circ-Logic technology integrates with external recirculation pumps for rapid hot water
• Condensing heat recovery delivers superior efficiency for high-demand natural gas setups
• Heavy-duty build backed by a 15-year residential heat exchanger warranty

Cons

• At 72.5 pounds, it is heavier to mount than newer RX-series alternatives
• Restricted to indoor natural gas connections without dual-fuel flexibility
• Un-neutralized condensate runoff will corrode metal drain pipes if routed directly

10

NEW Rinnai RX160iN Condensing Smart Sense Natural Gas or Propane

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  7.5
• Brand
  Rinnai

Key specs2

Gas Line Demand

160,000 BTU max burner for natural gas or propane

Indoor vs Outdoor Setup

Engineered for either interior utility closets or outdoor walls via the Versa Vent system. For exterior installations, the RX-OVC vent cap is necessary to shield the unit, while indoor installs require a dedicated trap and neutralizer for condensate liquid.

Pros & cons43

Pros

• Adaptable Smart Sense gas system works with either propane or natural gas
• Delivers up to 9 GPM flow across 6 fixtures with a 160,000 BTU burner
• Reaches 0.97 UEF energy efficiency using a condensing secondary heat exchanger
• Versa Vent configuration permits indoor placement or outdoor mounting

Cons

• Does not include an integrated recirculation pump unlike the RXP sister model
• Requires buying an extra RX-OVC vent cap for exterior wall mounting
• Continuous acidic condensate production demands a dedicated drain and neutralizer

11

Condensate Neutralizer Kit for Rinnai Tankless Water Heater 804000074 Navien

View on Amazon

• BWP Score

  BWP Score is a ranking system developed by Bestwinterproducts.com. BWP score has no relationship or impact from any manufacturers or sales agent websites. Learn more

  7.1
• Brand
  VitaFlow Tool

Key specs3

BTU Capacity Limit

Treats condensing appliances up to 100,000 BTU/hr

Drain Protection Mechanism

Passes acidic runoff across neutralizing media to raise pH from roughly 2.0 up to 8.0 before discharge. A built-in Y-fitting creates a safety overflow bypass and sampling port to check pH levels without disconnecting the drain assembly.

Kit Components

• 10 feet of 1/2-inch ID clear vinyl tubing
• 3/4-inch NPT threaded inlet and outlet fittings
• Heavy-duty hose clamps and barbed connectors
• Clear capsule for checking media level

Pros & cons42

Pros

• Raises acidic wastewater pH from 2.0 up to a pipe-safe 8.0 before reaching the drain
• Transparent capsule allows quick visual checks of neutralizing media depletion
• Includes a Y-barb safety bypass fitting to prevent wastewater backups into the heater
• Comes as a 15-piece kit with 10 feet of tubing and 3/4-inch NPT fittings

Cons

• Heat load capacity is capped at 100,000 BTU/hr, requiring dual units for larger burners
• Granular neutralizing media requires periodic replacement as it dissolves

Last update on 2026-10-04 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

Do you need a condensate neutralizer when installing a condensing tankless water heater?

Yes, adding an external condensate neutralizer kit protects household drainage plumbing from acidic moisture produced during condensing operation. An inline unit, like a 15-piece kit rated for 100,000 BTU/HR systems, raises the pH of the drainage before it reaches your waste line. Without neutralization, acidic runoff can corrode metal drain lines and waste pipes over time. Check your water heater burner rating and local plumbing requirements to confirm the exact media volume and drain routing needed for your home.

What pipe materials and outdoor clearances are required for condensing exhaust vents?

Verify the specific vent piping materials and termination clearances in your unit manual before cutting wall openings. Condensing heaters lower exhaust temperatures by capturing extra heat with dual heat exchangers or stainless steel components, which allows different venting options than non-condensing systems. Some models, such as the Rinnai RX and RXP series, feature Versa Vent engineering for indoor or outdoor configurations. Always confirm required distances from doors, operable windows, and roof soffits to keep exhaust gases from entering living areas.

Will an existing gas line support a condensing tankless unit?

You must check your existing gas pipe diameter and regulator pressure against the burner rating listed on the water heater. Gas demand varies across models, from 114,000 BTU on the ThermoMate CZ480NG, to 120,000 BTU on the Vancepic, 130,000 BTU on the Rinnai RX130iN, and up to 160,000 BTU on the Rinnai RX160iN. Lines originally sized for standard storage tanks often deliver insufficient volume for high-demand tankless burners under full load. Have a licensed technician check your meter capacity and total pipe run before completing the installation.

Can a condensing tankless water heater be installed indoors or outdoors?

Mounting location depends strictly on the model rating. Units like the Rinnai RXP160iN, RX160iN, and RX130iN are built for indoor or outdoor installation using versatile venting hardware. Other models, including the Vancepic 5.1 GPM and Rinnai RU160iN, are designated specifically for indoor mounting. If you need exterior hot water delivery or want to pair a unit with an outdoor shower tankless water heater, check the product label to ensure the casing and electrical connections are approved for exterior use.

How do you protect condensate drains and water lines from freezing?

Prevent freezing by selecting a unit with built-in freeze protection and wrapping exposed supply lines in insulation. Models like the Vancepic 120,000 BTU heater include anti-freeze control to safeguard internal components in unheated utility areas. Because condensing units discharge water continuously while running, an uninsulated drain line routed outdoors or across a cold crawlspace can freeze solid, causing liquid to back up into the cabinet. Keep the unit connected to continuous electrical power so internal anti-freeze circuits remain active.

Can you convert a condensing tankless heater between natural gas and propane?

You can only switch fuel sources if the water heater is explicitly manufactured with dual-fuel capability or an approved conversion system. The Rinnai RX160iN and RXP160iN feature Smart Sense technology to operate on either natural gas or propane, while other models, such as the Vancepic and ThermoMate CZ480NG, are dedicated natural gas units. Connecting a heater to the wrong fuel supply causes incomplete combustion and equipment damage. If your property runs on bottled gas, evaluate dedicated configurations like a propane heater setup to confirm compatibility before purchasing.