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Is it worth replacing a tank water heater with a tankless?
Yes, replacing a tank water heater with a tankless can be worth it when you want longer service life and improved efficiency and your home can support the installation requirements. For a Reliance 5-40-NORT6 tank unit, the value depends most on hot-water demand and retrofit cost.
Quick decision guide
- Worth it for large households with frequent back-to-back showers.
- Worth it when you plan to stay in the home long enough to benefit from lower operating costs.
- Worth it when space is tight and a wall-mounted unit helps.
- Not worth it when the retrofit needs major gas, venting, or electrical changes.
- Not worth it when your current tank already meets demand at a reasonable cost.
Tank vs. tankless (typical differences)
| Factor | Tank (like 5-40-NORT6) | Tankless |
|---|---|---|
| Hot water | Can run out | Continuous, limited by flow rate |
| Efficiency | Standby heat loss | Less standby loss |
| Lifespan | 8 to 12 years | 15 to 20+ years |
| Maintenance | Flush, anode checks | Regular descaling |
Retrofit items that drive cost
- Larger or re-routed gas supply line for higher BTU demand
- Different venting materials or routing
- Condensate drain (condensing models)
- Dedicated electrical circuit or outlet
If you keep the tank: smart fixes that often pay off
- Stop a weeping discharge line by replacing the water heater temperature and pressure relief valve 100108279
- Restore reliable ignition by servicing or replacing the pilot 100109070
- Improve hot-water delivery by flushing sediment and replacing a failed dip tube if needed
Why it matters
A tankless change is a home-system upgrade, not just a like-for-like swap. When the install is simple, tankless delivers the best payoff; when upgrades are extensive, maintaining a tank heater often costs less overall.
You can order replacement parts for your Reliance 5-40-NORT6 from the parts list for this model, or search by model number on Sears PartsDirect.
Last updated: February 2026
What are common Reliance water heater problems?
Common problems on a Reliance 5-40-NORT6 gas water heater include no hot water (pilot will not stay lit), not enough hot water, water that is too hot, and leaking from fittings or the tank area. Many issues trace back to the pilot/thermocouple, burner operation, or a failing valve.
Most common symptoms and likely causes
- Pilot will not light or won’t stay lit: dirty pilot, weak thermocouple, or a problem in the pilot assembly
- No hot water but pilot is on: burner not igniting, restricted air intake, or gas control issues
- Not enough hot water: sediment buildup, dip tube problems, or thermostat setting too low
- Water too hot: thermostat set too high or temperature control not regulating correctly
- Water leaking: loose plumbing connections, leaking drain valve, or the temperature and pressure relief valve opening
Quick checks we recommend (safe, no disassembly)
- Confirm the gas shutoff valve is fully open and other gas appliances are working.
- Look for water around the base, at the drain valve, and at the relief valve discharge pipe.
- Listen for burner ignition after a call for heat; a “click” without ignition points to pilot/burner issues.
- Check for soot or scorching around the burner area (sign of combustion/venting problems).
- If hot water runs out fast, suspect sediment or a dip tube issue.
Parts that commonly solve these problems (for model 5-40-NORT6)
| Symptom | Common part involved | What it affects |
|---|---|---|
| Pilot won’t stay lit | Pilot 100109070 | Keeps a stable pilot flame for ignition |
| Pilot lights but drops out | Water heater thermocouple h06e-36 | Proves flame presence to keep gas flowing |
| Weak/dirty flame, delayed ignition | Water heater burner 100108399 | Main flame for heating water |
| Dripping from discharge pipe | Water heater temperature and pressure relief valve 100108279 | Safety pressure/temperature relief |
| Hot water runs out quickly | Dip tube 100108608 | Directs incoming cold water to bottom of tank |
Why it matters
Gas water heater problems can affect safety, efficiency, and hot water recovery. For example, a weak pilot/thermocouple can cause repeated shutdowns, while a leaking relief valve can signal overheating or excess pressure that needs attention.
Ordering the right replacement part
We recommend matching your exact model number (5-40-NORT6) and then selecting the part from the list for this model. If you need additional options beyond the parts shown, search by model number on Sears PartsDirect.
Last updated: February 2026
What is the average lifespan of a 40 gallon gas water heater?
A 40-gallon gas water heater like the Reliance 5-40-NORT6 typically lasts 8 to 12 years. With consistent maintenance (flushing sediment and protecting the tank from corrosion), it commonly reaches the upper end of that range and avoids early failure.
Typical lifespan range (what to expect)
Most 40-gallon atmospheric-vent gas water heaters fall into this window:
- 8 to 12 years: typical service life
- 6 to 8 years: common when water is very hard, maintenance is skipped, or the heater runs hot
- 12+ years: common with regular flushing and timely corrosion protection
Quick guide: age vs. what to do
| Water heater age | What we recommend | What it usually means |
|---|---|---|
| 0 to 5 years | Maintain and monitor | Normal operation period |
| 6 to 10 years | Inspect yearly, plan ahead | Wear starts to show (pilot, burner, valves) |
| 11 to 15 years | Budget for replacement | Higher leak and efficiency-risk window |
Maintenance that extends life the most
These actions have the biggest impact on tank life and reliability:
- Flush the tank yearly to reduce sediment buildup and overheating
- Test the temperature and pressure relief valve periodically for safe operation (replace if it won’t operate correctly)
- Replace the anode rod when it’s significantly depleted to slow tank corrosion
- Keep the burner area clean so combustion stays stable
- Address pilot issues early (weak pilot, nuisance outages) to prevent no-hot-water events
If you need common replacement parts for the Reliance 5-40-NORT6, we list options like the water heater temperature and pressure relief valve 100108279 and the annode rod 100108571 on this model’s parts list, or you can search by model number on Sears PartsDirect.
Why it matters
A gas water heater usually does not “wear out” all at once; it typically loses efficiency from sediment, then reliability from ignition or burner issues, and finally the tank can fail from internal corrosion. Staying ahead of sediment and corrosion is what protects the tank itself.
Last updated: February 2026
Why do plumbers not recommend tankless water heaters?
Plumbers often steer homeowners away from tankless water heaters because the total cost and complexity can be higher than expected, especially when a home needs gas line upgrades, new venting, or water treatment. For many households, a standard tank unit like the Reliance 5-40-NORT6 is simpler to maintain and more predictable.
The most common reasons plumbers push back
- Higher install complexity: Tankless units frequently need larger gas supply, different venting, and condensate handling (for condensing models).
- Hard water sensitivity: Mineral scale can reduce performance quickly without routine descaling and, in some homes, a softener.
- Flow-rate limits: Running multiple showers and appliances at once can exceed what a single tankless unit can deliver.
- “Cold water sandwich” and delay: You can get a brief temperature swing or a wait for hot water, depending on plumbing layout.
- More maintenance expectations: Annual flushing, inlet screen cleaning, and periodic service are normal ownership tasks.
Tank vs. tankless: quick comparison
| Topic | Tank water heater (like 5-40-NORT6) | Tankless water heater |
|---|---|---|
| Upfront cost | Usually lower | Usually higher |
| Installation changes | Often minimal | Often requires upgrades |
| Hot water delivery | Stored hot water, steady | On-demand, can be limited by flow |
| Maintenance | Periodic draining, anode checks | Regular descaling is common |
Why it matters for your home
A water heater is only “better” if it matches your gas capacity, venting path, water hardness, and peak hot-water demand. When those don’t line up, tankless can feel expensive, finicky, or underpowered, which is why many plumbers prefer recommending a conventional tank setup.
If you are troubleshooting a tank-style heater instead
If your Reliance 5-40-NORT6 is acting up (no hot water, pilot won’t stay lit, leaking), these parts are common fixes:
- Pilot 100109070 (ignition and flame source)
- Water heater thermocouple h06e-36 (proves pilot flame to keep gas valve open)
- Water heater temperature and pressure relief valve 100108279 (safety valve if pressure or temperature is too high)
You can order replacement parts from the parts list for your Reliance 5-40-NORT6, or search by model number on Sears PartsDirect.
Last updated: February 2026
