Best Heater Vent Pipe Kits and Wall Thimbles for Tankless Water Heaters

Choosing The Right Vent Pipe Kit ensures safe, efficient exhaust for gas tankless water heaters. Below is a quick comparison of top vent pipe kits and wall sleeves selected for common household installations.

Product	Type	Material / Diameter	Key Feature
GASLAND 3″ Stainless Steel Vent Pipe Kit	Horizontal Vent Kit	T304 Stainless / 3″	Complete termination hood, elbow, multiple pipe lengths
CAMPLUX 2.75″ Water Heater Vent Pipe Kit	Direct Vent Set	Stainless / 2.75″	Low-resistance design to reduce flue gas restriction
Blulu 3″ Stainless Direct Vent Pipe	Straight Pipe + Elbow	201 Stainless / 3″ OD	Includes elbow and termination pipe with rain cap
Mr. Heater 4″ Horizontal Vent Kit	Complete Venting Kit	Metal / 4″	Comprehensive kit for Big Maxx unit heaters with roof flashing
VATTCEEL 3.15″ Ventilation Wall Sleeve	Wall Thimble / Sleeve	Stainless / Fits Up To 3.15″	Adjustable length for varied wall thicknesses

GASLAND 3″ Stainless Steel Vent Pipe Kit

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This horizontal vent pipe kit is designed specifically for residential tankless gas water heaters with a 3″ diameter requirement. The kit includes a 3″ termination hood, 90° elbow, and multiple straight pipe lengths plus a wall thimble to accommodate through-wall installations.

Construction uses T304 stainless steel for corrosion and high-temperature resistance, improving durability and reducing long-term maintenance. The kit’s detachable sections allow assembly to match the exact run length and routing needs.

Key performance points: the kit is intended to provide efficient gas venting and maintain safe exhaust flow. Installation flexibility and stainless construction are emphasized in the product features, making it suitable where a 3″ system is required and corrosion resistance is a priority.

CAMPLUX 2.75″ Water Heater Vent Pipe Kit

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The CAMPLUX kit provides a 2.75″ detachable horizontal vent intended for smaller indoor gas water heaters or matching tankless models that specify a sub-3″ diameter. It is marketed for use with multiple small heater models and other small combustion appliances.

Design features include a low-resistance vent profile to minimize flue gas restriction and an inlet guard to reduce entry of debris or rain. The kit’s purpose-built diameter helps maintain specified exhaust flow velocities for the applicable heater models.

Material specifications indicate stainless construction; this kit is useful when matching a heater’s required vent diameter and when keeping flue resistance low is important for combustion performance and safety compliance.

Blulu 3″ Stainless Steel Direct Vent Pipe

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The Blulu kit includes a 3″ OD elbow and a 19.7″ horizontal termination pipe with a chimney rain cap and clip. The package is aimed at small runs or as replacement components in a 3″ venting system for tankless water heaters.

Constructed from 201 stainless steel, the components provide temperature resistance and wear properties suitable for exhaust vents. The seller calls out precise dimensions to aid DIY installers in selecting compatible parts.

This selection is appropriate when a short termination and elbow are needed and where a straightforward, compact vent solution will meet the heater manufacturer’s venting layout requirements.

Mr. Heater 4″ Stainless Steel Horizontal Vent Kit

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This complete venting kit is designed for Mr. Heater Big Maxx unit heaters (models such as MHU50 and MHU80) and includes an adapter, b-vent pipe sections, 90° adjustable elbow, wall thimble, roof flashing, storm collar, and vent cap.

The kit is targeted toward 4″ vent systems and larger gas-fired unit heaters. Including roof flashing and storm collar positions it for through-roof as well as through-wall installations, providing a more comprehensive set of termination and weatherproofing components.

Because the kit contains multiple parts sized for larger vent diameters, it suits applications where a higher-capacity heater or furnace specifies larger flue sizes and where complete venting hardware is preferred for a single purchase.

VATTCEEL 3.15″ Stainless Steel Vent Wall Sleeve

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The VATTCEEL wall sleeve is an extendable vent wall thimble compatible with vent pipes under 3 inches, including 3″, 2.36″, and 2″ diameters. Its adjustable length adapts between approximately 4.9″ to 7.83″ to match different wall thicknesses.

Designed for indoor tankless water heaters, the sleeve’s external square face helps seal and finish the penetration while accommodating a range of vent pipe sizes. Being a wall sleeve rather than a full kit, it is a component for installations that require a finished wall penetration and code-compliant spacing.

Use this when the heater’s direct vent kit requires a compatible sleeve or when retrofitting a vent through an exterior wall where adjustable length and fit to variable wall depth is necessary.

Buying Guide: How To Choose The Right Heater Vent Pipe

Selecting the correct vent pipe or kit involves matching the heater manufacturer’s venting requirements with installation constraints and local codes. Below are the primary considerations to compare products effectively.

1. Match Diameter To Manufacturer Specifications

Vent Diameter is critical. Tankless water heaters and unit heaters specify required vent diameters (e.g., 2.75″, 3″, 4″). Using the incorrect diameter can increase flue gas backpressure, cause combustion problems, or fail to meet code.

2. Material And Corrosion Resistance

Stainless Steel Grades (e.g., 201 vs. 304/T304) vary in corrosion resistance and temperature tolerance. Higher-grade stainless like 304/T304 offers improved longevity in moist or salty environments. Choose materials rated by the manufacturer for exhaust temperatures and condensate exposure.

3. Kit Completeness And Installation Needs

Determine whether you need a complete kit (termination cap, elbows, pipes, wall thimble, flashing) or only certain components. Complete kits simplify purchases for through-wall or through-roof installations; individual pipes or elbows are suitable for repairs or custom runs.

4. Horizontal Vs. Vertical Termination

Check whether the heater and local code permit horizontal termination or require vertical venting. Horizontal vent kits often include wall thimbles and termination hoods; vertical systems require roof flashing and storm collars.

5. Adjustable/Extendable Components

Adjustable wall sleeves and telescoping thimbles simplify matching wall thicknesses and reduce cutting or custom fabrication. For retrofit projects, adjustable sleeves can save time and ensure better sealing.

6. Weather Protection And Debris Prevention

Look for rain caps, insect screens, and debris guards on termination pieces to prevent water, leaves, or pests from entering the vent. Proper caps also help prevent rainwater intrusion that can accelerate corrosion.

7. Compatibility With Condensing vs. Non-Condensing Units

Condensing tankless heaters produce acidic condensate and typically require corrosion-resistant materials and specific venting practices. Non-condensing units may use traditional stainless or coated materials but follow manufacturer guidance.

8. Pressure And Flow Considerations

Venting systems should minimize restrictions. Components described as low-resistance help keep flue gas velocity and backpressure within manufacturer limits. Avoid unnecessary elbows and long horizontal runs where possible.

9. Local Codes And Manufacturer Instructions

Always follow local building codes and the heater’s installation manual. Codes regulate clearances, termination locations, and materials. Manufacturers may void warranties if venting instructions are not followed.

10. Ease Of Installation And Support

Consider whether you will install the vent yourself or hire a pro. Kits with labeled parts, standard fittings, and clear dimensions reduce installation time. For complex roofs or multi-story routing, professional installation ensures compliance and safety.

Comparison Perspectives

When comparing the listed products, evaluate them across these perspectives:

• Application Fit: Match diameter and kit completeness to heater model and routing (horizontal vs. vertical).
• Durability: Prefer 304/T304 stainless where condensate or coastal exposure is expected.
• Installation Scope: Choose full kits for one-stop installs; select sleeves or pipes for repairs or partial upgrades.
• Weatherproofing: Kits with caps, flashing, and storm collars reduce maintenance needs and water intrusion risk.
• Flexibility: Adjustable thimbles and detachable sections help fit varied wall thicknesses and routing constraints.

Important Practical Tips: Measure actual wall thickness and route length before purchasing. Verify the heater’s required vent size and materials. When in doubt, consult a licensed HVAC or plumbing professional to confirm compliance with codes and safe combustion air/exhaust practices.