Choosing the right water heater dip tube is essential for maximizing hot water delivery and system efficiency. This guide compares five common dip tubes, highlighting who they’re best for and where to use them. Whether you’re replacing an old unit or optimizing a new install, the right dip tube can improve cold-water return and hot-water availability.
Product snapshot: the following table summarizes key points to compare at a glance. Use it to narrow your choices before reading detailed sections.
- Reliance 9006178-005: Best for long, straightforward cold-water delivery in standard 52-inch tanks.
- AO Smith 100112695: Best for PEX fittings and HT2 configurations in mid-size 40.75″ tanks.
- AO Smith 100217958: Best for differential (DIFF) setups with 42″ length and 3/4″ connections.
- Rheem AP12933: Best for older water heaters (pre-1996) needing a close nipple and 53″ length.
- AO Smith 100273983: Best for CE5.5X3/4 and 52.5″ length in certain Smith configurations.
Reliance 9006178-005 52-Inch Dip Tube
Features: Dip tube, Carries cold water to the bottom of the tank for maximum hot water delivery, 52-Inch long.
Best for: Standard, long-tank installations where a full-length dip tube ensures efficient displacement of cold water. It’s a straightforward choice for older or budget-friendly systems that use a 52-inch profile and require a simple, direct path to the tank bottom.
Why selected: Its length and simple design make it a reliable option for achieving consistent hot-water delivery in typical residential setups. The 52-inch length aligns with common tank dimensions, reducing installation guesswork.
Caution: This model does not specify additional features like DIFF or specialized fittings, so confirm your tank’s compatibility with a 52-inch plain dip tube before purchasing.
AO Smith 100112695 Dip Tube
Features: K, DIPTUBE, PEX, 3/4″NPT X 4″, HT2, 40.75″
Best for: Systems using PEX connections with HT2 configurations and a shorter 40.75″ dip tube. Suitable for mid-sized tanks where PEX adaptability is a priority and where HT2 specifications align with installation needs.
Why selected: This dip tube emphasizes PEX compatibility and the HT2 designation, making it a better choice for modern PEX-enabled water heater installations where a precise diameter and thread fit matter.
Caution: The 40.75″ length may not reach the bottom in taller tanks; verify tank depth and existing dip-tube routing before selecting this option.
AO Smith 100217958 Dip Tube, Diff, 3/4″ x 3″ x 42″
Features: K, DIPTUBE, DIFF, 3/4″ X 3″ X 42″
Best for: DIFF configurations, where differential measurement or targeted flow considerations exist. The 42″ length supports mid-size tanks with specific DIFF requirements and 3/4″ fittings.
Why selected: The DIFF configuration signals a specialized design for particular tank models and installation layouts, offering optimized hot-water refill dynamics in compatible systems.
Caution: This part is more niche; ensure your water heater model supports the DIFF dip-tube design before purchase.
Rheem AP12933 Dip Tube/Nipple
Features: 1/2-Inch diameter x 53-Inch long, Close nipple, For water heaters manufactured prior to 1996
Best for: Older water heaters that require a longer 53″ dip tube paired with a close nipple connection. This option is typical for vintage installations or replacements in legacy systems.
Why selected: The extended length accommodates tanks with deeper profiles, while the close nipple helps maintain a compact, leak-resistant connection in older units.
Caution: Only suitable for pre-1996 models; verify compatibility with your current tank and fittings to avoid fit issues.
AO Smith 100273983 Dip Tube
Features: K, DIPTUBE, .65X52.5″, CE5.5X3/4
Best for: Specific AO Smith CE5.5X3/4 configurations, offering a precise diameter and length for certain high-efficiency or newer tank models.
Why selected: This dip tube matches particular Smith-engineered tank families, delivering a compatibility-driven option for builders using those series components.
Caution: Availability may depend on model compatibility; confirm the exact tank model and connection size before purchasing.
Buying Guide
- What length do I need? Consider tank depth. Longer tubes deliver cold water to the bottom in tall tanks, shorter tubes fit compact units. Measure tank depth and compare to tube length to avoid blocking hot-water delivery.
- Which connection type matters? Look for NPT sizing (such as 3/4″ or 1/2″) and whether your heater uses PEX or copper connections. Mismatches cause leaks or improper flow.
- DIFF versus standard? Some heaters use differential or specialty dip-tube designs. Choose DIFF only if your tank model specifies compatibility; otherwise, a standard tube is typically sufficient.
- Older versus newer models? Older tanks may require longer or differently threaded tubes and close nipples. Verify pre-1996 compatibility if selecting a retired-model dip tube.
- Material and build quality? Dip tubes are typically plastic or composite in modern units and brass in some older designs. Match to your water chemistry and regulatory requirements if needed.
- Installation considerations? Ensure the tube reaches the tank bottom and is aligned with the cold-water inlet. A misaligned tube can reduce hot-water recovery and create turbulence.
Frequently Asked Questions
What is a water heater dip tube?
A dip tube directs cold water entering the tank to the bottom, allowing hot water to be drawn from the top.
Why is my hot water running out quickly?
A faulty or undersized dip tube can mix cold water into the hot layer, reducing available hot water. Replacing with a correct-length tube can help.
How do I know which dip tube fits my heater?
Check your tank brand, model number, and the required diameter and length. Some tubes are designed for PEX connections, others for standard copper fittings.
Can I replace a dip tube myself?
Yes, with basic plumbing skills and proper shutoff procedures. Always turn off power or gas and relieve tank pressure before service.
Are there differences between DIFF and standard dip tubes?
Yes. DIFF tubes are designed for specific tank configurations and may offer improved flow in certain setups; verify compatibility with your heater.
Do all tanks require the same length?
No. Tank depth varies by model; choose a dip tube that reaches near the tank bottom without bottoming out.