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SJ Teddy Plumbing

SJ Teddy Plumbing
Hot Water Specialists · Kirkland, WA
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(425) 399-2448
Expert Technical Guide · 15 min read

Hot Water Tanks, Explained by the Installers

The full anatomy — burners, dip tubes, anodes, T&P valves, expansion tanks — plus venting categories, gallon-per-day sizing, PNW water chemistry, seismic code, and the operating-cost math that decides gas vs electric for your home.

On this page
  1. Anatomy of a storage tank water heater
  2. Gas vs electric — how they actually heat
  3. Venting categories: atmospheric, power vent, direct vent, FVIR
  4. Sizing: gallons, FHR, and recovery
  5. Interactive sizing & cost worksheet
  6. Sacrificial vs powered anode rods
  7. Dip tubes, stratification & why the top gets hot first
  8. T&P valves, expansion tanks & thermal expansion code
  9. Seismic strapping, drain pans & IRC code
  10. Puget Sound water chemistry & sediment
  11. UEF, EF, standby loss & real efficiency
  12. Gas vs electric operating cost in the Eastside
  13. Real lifespan and what shortens it
  14. Repair vs replace decision framework
  15. Set point, scalding, and Legionella
  16. Brand notes: Rheem, A.O. Smith, Bradford White, State
  17. Permits, inspections & WA state code
  18. Annual maintenance that adds 5+ years
  19. When a tank still beats tankless / heat pump
  20. 10 install mistakes we rip out and redo
Fundamentals

Anatomy of a storage tank water heater

A tank water heater is a deceptively simple pressure vessel with six subsystems that all fail differently. Understanding the anatomy tells you what to inspect, what’s worth repairing, and when the tank has quietly reached end of life.

  • Steel tank & glass lining: A welded steel shell coated internally with vitreous glass (porcelain enamel). The glass lining is what stops the tank from rusting — every microscopic pinhole in that lining is where corrosion starts.
  • Sacrificial anode rod: A magnesium or aluminum rod threaded into the top. It corrodes preferentially so the steel tank doesn’t. When the anode is gone, the tank starts eating itself. This is the single most important service item.
  • Dip tube: A plastic tube inside the cold inlet that pushes incoming cold water to the bottom of the tank, preserving hot-water stratification at the top.
  • Heat source: Bottom-fired burner (gas) or two immersion elements top/bottom (electric).
  • Thermostat/gas valve: Senses tank temperature and cycles the burner or elements. Modern gas units use an FVIR-compliant valve with LP/NG orifice and thermopile self-generation.
  • T&P (Temperature & Pressure) relief valve: Mechanical safety that opens if the tank exceeds 210°F or 150 psi. Prevents catastrophic BLEVE (boiling liquid expanding vapor explosion) failure. Non-negotiable.

Add a flue tube down the center of gas tanks (the exhaust path with a baffle for heat transfer) and you have the entire machine. Everything else — insulation jacket, drain valve, sight glass — is convenience.

Physics

Gas vs electric — how they actually heat

The two heat sources create very different tanks under the sheet metal:

  • Gas (atmospheric or power vent): A bottom burner fires up the center flue tube. Combustion gases rise, transferring heat through the flue wall into the surrounding water, then exit through a draft hood or power-vent blower. Typical input: 30,000–75,000 BTU/hr. Recovery: ~40 gal/hr at 70°F rise for a 40,000 BTU 50-gal unit.
  • Electric (immersion): Two 4,500W (or 5,500W) resistance elements — one at the bottom, one at the top — heat water directly by contact. Only one element runs at a time on a residential 4,500W tank (that’s the “non-simultaneous” wiring on a 30A breaker). Recovery: ~20 gal/hr at 70°F rise, roughly half of a comparable gas tank.

Recovery is the practical difference. A four-shower morning empties a 50-gal tank; the gas tank refills the hot layer in about 45 minutes, the electric takes closer to 90. That’s why “electric works fine for families of four” is only true when you upsize to 65 or 80 gallons.

  • Gas burner efficiency reality check

An atmospheric-vent gas tank is ~62% efficient overall (UEF ≈ 0.60–0.62). The other 38% of your gas bill leaves through the flue. Power vent (~0.66) and condensing (~0.90) tanks recapture some of that but cost more upfront. Electric resistance tanks are 95%+ efficient at the tank — but the cost per kWh vs per therm decides which is cheaper to run (see §12).

Combustion

Venting: atmospheric, power vent, direct vent, FVIR

Only gas tanks have to solve the “where do the combustion products go” problem. There are four architectures, and they’re not interchangeable in a swap.

  • Atmospheric / natural draft: Single-wall or B-vent pipe rises vertically to a rooftop cap. Buoyancy of hot exhaust does the work. Requires 100 sq in of combustion-air openings (or 50 sq in per 1,000 BTU by the code alternative). Cheapest, most common, but backdraft-prone in tight new homes.
  • Power vent: Integral blower pushes exhaust out through 2″ or 3″ PVC/ABS horizontally through a sidewall. Frees you from a chimney chase. Requires a 120V outlet within reach. The 2025 code allows CPVC/PVC for Category IV appliances at low flue temps; check your specific unit.
  • Direct vent (sealed combustion): Concentric or twin-pipe intake + exhaust to outside. Draws no room air, dumps no exhaust into the room. Required in tight closets, mechanical rooms without adequate combustion-air openings, and any location where a spillage/backdraft test fails.
  • FVIR (Flammable Vapor Ignition Resistant): Not a venting type — a burner/base design mandated on all residential gas tanks since 2003. A flame arrestor screen and thermal cutoff prevent ignition of gasoline vapors from a garage floor. Non-negotiable; any replacement must be FVIR-compliant.
  • The most common venting mistake in the Eastside

Swapping a 40,000 BTU atmospheric tank for a 50,000 BTU tank without upsizing the B-vent. The oversized burner produces more exhaust than a 3″ B-vent can carry — flue temperatures drop, condensate forms inside a non-condensing vent, and the vent corrodes from the inside out. Every atmospheric-vent replacement gets a vent-sizing check per NFPA 54 Table 13.

Sizing

Gallons, first-hour rating, and recovery — pick the right pair

Nominal gallons alone don’t size a tank. Two other numbers matter: First-Hour Rating (FHR) — DOE-measured delivered hot water in the first hour from a fully-heated tank — and recovery rate — gallons per hour of continuous heating at a 70°F rise. Gas tanks favor recovery; electric tanks favor gallons.

Household Peak-hour demand Gas tank pick Electric tank pick
1--2 people ~34 gal 40 gal / 40k BTU 50 gal
3 people ~48 gal 40--50 gal / 40k BTU 50 gal
4 people ~62 gal 50 gal / 40--50k BTU 65--80 gal
5+ or big-tub master ~78+ gal 75 gal / 75k BTU 80 gal or two 50s

Peak-hour demand = showers (17 gal each) + baths (20 gal) + dishwasher hot draw (~6 gal) + hot laundry cycle (~7 gal) + kitchen prep (~5 gal) inside your worst hour, which is usually 7–8 AM on a weekday.

Interactive tool

Sizing & operating-cost worksheet

Set your household and fuel type — we’ll estimate peak-hour demand, the right gallons and burner size, and a realistic annual energy cost at 2026 PSE rates. Then talk to us for a real quote with a specific model and out-the-door install price.

Your household
People in household4
Showers per morning (peak hour)2
Baths per morning0
Fuel type
Estimated result
Peak-hour hot-water demand52 gal
Average daily hot-water use~64 gal/day
Recovery rate (70°F rise)~40 gal/hr
Estimated annual energy cost~$357/yr
Recommendation
50-gal gas (40k BTU)
Sized to cover your ~52 gal peak hour with recovery margin for a normal weekday morning.
Request a real quote → (425) 399-2448

Estimate only. A free in-home assessment confirms venting, gas line capacity, electrical service, and code upgrades required for your specific install.

Corrosion

Sacrificial vs powered anodes — the #1 lifespan lever

Every tank ships with a magnesium or aluminum rod threaded into the top. It’s a battery: the anode metal is more electrochemically active than the steel tank, so it corrodes first. When the rod is consumed, the tank steel starts corroding. Replace the anode on schedule and a tank lasts 15–20 years; ignore it and you get 8–10.

  • Magnesium anode (default): Best performance in soft water like the Cedar/Tolt supply. Lasts 4–6 years in Kirkland/Bellevue. Can produce a rotten-egg smell in wells with sulfate-reducing bacteria — swap to aluminum-zinc if that happens.
  • Aluminum-zinc anode: Longer life in hard water, eliminates sulfur smell. Slightly less protective than magnesium in soft PNW water. Standard on many Bradford White “Defender” units.
  • Powered / impressed-current anode (Corro-Protec, Rheem P3): A titanium rod driven by a small DC power supply. Never depletes. Roughly $200 hardware; will double the tank’s realistic life if installed at year 3.
  • Combo (hex-head + nipple) anodes: Some tanks bury the anode under the hot-outlet nipple (Bradford White does this on space-saver models). A combo anode replaces both in one part.

We include an anode inspection in every annual visit. When the wire core is exposed for more than 6″, we quote a swap. It’s a 20-minute job that adds years of tank life.

Internal flow

Dip tubes, stratification & why the top gets hot first

The cold inlet at the top of a tank feeds a plastic dip tube that drops nearly to the bottom. This preserves thermal stratification — a distinct hot layer at the top and cold layer at the bottom — so the hot draw off the top port stays consistently hot until the tank is mostly depleted.

Dip tubes fail two ways. Old (pre-1997) polypropylene tubes disintegrated into white flakes that clogged aerators nationwide — the class-action era. Modern PEX dip tubes rarely fail, but a cracked tube causes cold water to enter at the top, mixing with the hot layer and reducing effective capacity by 30–40%. If you get lukewarm showers from a tank that hits its temperature setpoint, suspect the dip tube. It’s a $30 part and a 45-minute repair.

Safety

T&P valves, expansion tanks & thermal expansion code

Two related pieces of safety plumbing that get missed on cheap installs and cause slow leaks or dramatic failures.

  • T&P (Temperature & Pressure) relief valve: Mechanical valve set to open at 210°F or 150 psi. Required by IRC P2803. Must terminate to within 6″ of the floor (or to a drain) in the same room, unthreaded, no shutoff between it and the tank. A T&P that has ever weeped needs replacement — the seat is compromised.
  • Thermal expansion tank: A small captive-air pressure vessel (2 or 5 gal typical). Required when the incoming water service has a check valve or pressure-reducing valve (PRV) — which is nearly every Kirkland/Bellevue home built after 1995. Without one, every burner cycle raises system pressure until the T&P weeps. IRC P2903.4.
  • Expansion tank pre-charge: Bladder pressure must match your incoming static water pressure (typically 60–75 psi in the Eastside). Ship-pressure is usually 40 psi — always check with a tire gauge and adjust before mounting.
  • A dripping T&P is not a broken valve

90% of the time a T&P drips because you have thermal expansion with no working expansion tank (dead bladder, wrong pre-charge, or none installed). Replace the T&P and skip the expansion tank and it will drip again in six months. Every one of our installs includes a checked-and-charged expansion tank.

Code

Seismic strapping, drain pans & IRC compliance

Washington State amends the IRC to require seismic strapping (WAC 51-51 amendments; also L&I / WABO). Every tank we install gets the code package, whether the inspector’s coming or not:

  • Two seismic straps at 1/3 and 2/3 of tank height, anchored to studs (not drywall). Metal plumber’s tape or dedicated Holdrite/Guardian kit. IRC M1307.2 as adopted in WA.
  • Drain pan with 1-1/2″ drain to daylight (or a safe termination) any time a tank sits in an attic, above a finished space, or in any location where a leak causes damage. IRC P2801.6. Aluminum or heavy plastic — the flimsy $8 pans do not comply.
  • 18″ combustion-source elevation: Gas tanks in garages must have the ignition source 18″ above the floor unless the tank is FVIR-labeled. All modern tanks are FVIR — but AHJ inspectors still look. We install on a code-required platform where the AHJ requires it.
  • Full-port service ball valve on the cold inlet. Gate valves are still legal but seize up in 5 years; every serviceable tank should have a lever valve.
Local knowledge

Puget Sound water chemistry & sediment

The Cedar and Tolt watersheds deliver very soft, slightly acidic water (15–35 ppm total hardness, pH 7.2–7.5) to most of Kirkland, Bellevue, Redmond and Bothell. Two consequences for tank life:

  • Almost no calcium scale — the popping/rumbling you hear in a Midwest tank rarely happens here.
  • The slight acidity accelerates anode consumption. Expect a magnesium rod to be spent in 4–5 years vs. 6–8 in harder water.
  • Well-water customers (parts of Woodinville, Duvall) see the opposite: sediment builds up on the tank bottom, insulating the burner from the water and dropping efficiency 10–15%. Annual flushes matter more on wells.
  • The garage-hose flush

Once a year: kill power/gas, connect a hose to the drain valve, open the T&P to break vacuum, and drain 5–10 gallons until the water runs clear. Takes 10 minutes and removes the sediment that would otherwise cook onto the tank bottom.

Efficiency

UEF, EF, standby loss & the numbers that lie

Water heater efficiency ratings have changed twice in the last decade. Reading a spec sheet correctly matters.

  • UEF (Uniform Energy Factor): Current DOE metric since 2017. Tested at a fixed daily draw pattern (small, medium, high — reported per bin). Includes standby loss over 24 hours. Higher is better.
  • EF (Energy Factor): Legacy pre-2017 rating. Not directly comparable to UEF; roughly UEF ≈ EF × 0.95 for tanks.
  • Standby loss: Heat lost through the tank jacket per hour when no water is drawn. A 50-gal gas tank loses ~1,500 BTU/hr, an equivalent electric loses ~120W. That’s why an unused vacation home costs less to keep hot on electric — even though electric is more expensive per unit of energy.
Type Typical UEF Notes
Atmospheric gas tank 0.58--0.64 Cheapest install, worst efficiency
Power-vent gas tank 0.64--0.70 Sidewall vent, needs 120V
Condensing gas tank 0.80--0.96 Rare in residential ≤75 gal
Standard electric tank 0.90--0.95 Efficient at the tank; cost per kWh is the wildcard
Heat pump water heater 3.4--4.0 Not a tank -- see the heat pump guide
Money

Gas vs electric operating cost — the Eastside numbers

Real 2026 residential rates for a typical Kirkland home: PSE electric ~$0.12/kWh and PSE natural gas ~$1.30/therm. A four-person household uses roughly 64 gallons/day of hot water at a 70°F rise = ~37,000 BTU/day = 108 therm/year of gas at 62% UEF, or ~3,750 kWh/year of electric at 92% UEF.

  • Atmospheric gas tank: ~$140/year
  • Power-vent gas tank: ~$125/year
  • Standard electric tank: ~$450/year
  • Heat pump water heater: ~$130/year

Gas wins on operating cost by a wide margin over a standard electric tank — roughly $300/year for a family of four. A heat pump matches gas operating cost while running on electricity. This is why the honest replacement conversation is “gas tank vs heat pump” rather than “gas tank vs electric tank” for anyone open to either fuel.

Lifespan

Real lifespan and what shortens it

Manufacturers publish 6, 9, 10, or 12-year warranties. Actual field lifespan is a different number driven by four variables:

  • Water chemistry:Aggressive water eats anodes faster; hard water dumps sediment on burners. PNW is kind on the second, harsh on the first.
  • Anode maintenance:A tank whose anode is replaced at year 5 lasts twice as long as one where it’s never inspected.
  • Set-point temperature:Every 10°F above 120°F roughly halves anode life and doubles standby loss. 120–125°F is the sweet spot.
  • Thermal expansion:A missing or dead expansion tank cycles the tank between shell yield stresses. Bathtub-curve failures at year 6–8.

Realistic PNW life expectancy with no maintenance: 8–10 years gas, 10–12 electric. With annual flush + anode swap at year 5: 15–18 gas, 18–20 electric.

Decision

Repair or replace? An honest framework

Every service call starts with the same triage. The math:

  • Tank is leaking from the shell?Always replace. A rusted-through tank cannot be repaired; the glass lining is gone.
  • Under 8 years old + gas valve, thermocouple, or single element failure?Repair. Parts run $80–$300; labor $200–$400. Cheaper than replacement.
  • 10+ years old + any major part failure?Replace. You’re 6 months from the next failure and the tank is past its warranty.
  • Both electric elements or both thermostats failed?Usually a sediment or scale issue that’s already damaged the tank. Replace.
  • T&P weeping?Repair (T&P + expansion tank), don’t replace the tank — unless it’s already past year 10.

We give a written go/no-go on repair vs replace before any parts are ordered. If we’d repair it, we say so — repairs are a lower ticket for us, but a customer we don’t oversell is a customer we service for the next 15 years.

Set point

Temperature, scalding, and Legionella

The temperature dial is a three-way trade-off between scald risk, energy use, and bacterial safety.

  • <120°F:Legionella pneumophila can survive and colonize the tank. Not recommended in any occupied home.
  • 120°F:Manufacturer default. Safe for daily use, low scald risk. 3-second exposure to 120°F takes ~5 minutes to cause a first-degree burn.
  • 130–140°F:Kills Legionella actively. Standard when a household is immunocompromised or when the tank is oversized for the household (long dwell time). Requires anti-scald mixing valves at fixtures — code in many jurisdictions.
  • >140°F:3rd-degree burn in under 5 seconds. Only appropriate with tempering valves throughout the house.

Our default install is 120°F + a code-compliant thermostatic mixing valve on the tank output for households with kids or seniors. Belt and suspenders.

Brands

Brand notes: Rheem, A.O. Smith, Bradford White, State

The residential tank market is effectively three parent companies (Rheem, A.O. Smith, and Bradford White) and their re-badged sister brands (State = A.O. Smith; Ruud = Rheem; American = Bradford White contract).

  • Rheem / Ruud:Widest availability, strong 10-year warranties, well-engineered gas valves. Best parts-availability across the Eastside supply houses.
  • A.O. Smith / State:Signature line at Lowe’s is the entry-level; ProLine XE / Master series at trade supply is the real product. Strong electric line.
  • Bradford White: Trade-only (never sold at big-box retail). Combo hex-head anode design, Defender safety system, longer real-world life in our experience. Slightly more expensive at install — the difference tends to pay back at year 12.
  • Avoid:The “off-brand box store” 6-year warranty units on 40-gal atmospheric gas. Same tank as the 10-year but with a cheaper anode — you’re paying for the paper.
Compliance

Permits, inspections & WA state code

Every water heater replacement in Kirkland, Bellevue, Redmond, Bothell, Woodinville, Sammamish, and the rest of King County requires a mechanical/plumbing permit pulled by a licensed contractor. Cities inspect for:

  • Seismic strapping (two straps, into studs)
  • T&P discharge line — copper or CPVC, unthreaded, 6″ from floor
  • Expansion tank installed with correct pre-charge
  • Combustion air openings per NFPA 54 or sealed-combustion install
  • Drain pan where required (attic, above finished space)
  • Gas union + sediment trap (drip leg) on gas tanks

Skipping a permit is a $300 line-item savings today and a $2,000–$5,000 disclosure headache at resale. Every SJ Teddy install includes the permit fee in the flat-rate quote.

Care

Annual maintenance that adds 5+ years

The one-hour checklist that turns a 10-year tank into a 15-year tank:

  • Full 5–10 gallon flush from the drain valve
  • Anode rod inspection at year 3, replacement at year 5 (or install a powered anode)
  • T&P valve manual test (lift the lever, verify discharge, verify it re-seats)
  • Expansion tank pre-charge check against incoming static pressure
  • Combustion inspection on gas: burner cleanliness, flame color, draft test
  • Electrical inspection on electric: element resistance, thermostat calibration, breaker torque
  • Set-point verification (120°F target)

Our Teddy Care Plan bundles this at $189/year and pushes emergency response to same-day priority.

When to stay tank

When a standard tank still beats tankless or heat pump

Tankless and heat pump aren’t automatically the right upgrade. A standard tank is still the right pick when:

  • Emergency same-day swap.A tank is on the truck; tankless and heat pump usually aren’t. If your tank blew last night, a tank swap gets hot water back in 3 hours.
  • Rental / short-hold property.The payback period on a heat pump or tankless is 6–10 years; a tank breaks even day one.
  • Undersized gas line + no rebate motivation.A tankless retrofit that requires a 3/4″→1″ gas line upsize can add $800–$2,500. A tank sidesteps it entirely.
  • Tight closet with no ducting and no exterior wall.Heat pumps need air; power-vent tanks need a sidewall path — sometimes the atmospheric tank in a B-vent chase is the only clean install.

If you’re on the fence, our free assessment walks all three options with real prices, real rebates, and real ROI for your house — not a sales script.

Tankless expert guide →
Heat pump expert guide →
Failure modes

10 install mistakes we rip out and redo

  1. Missing or dead expansion tank on a PRV-equipped water service (T&P weeps within a year).
  2. Seismic straps into drywall instead of studs — fail on the first shake.
  3. T&P discharge line threaded, undersized, or routed uphill.
  4. Gas union missing or drip leg omitted; makes future service a shutoff-the-house job.
  5. Flex-connectors kinked at the base of the tank, restricting flow.
  6. Cold shutoff is a gate valve — seized within 5 years.
  7. Atmospheric vent upsized past the flue’s carrying capacity — flue corrosion.
  8. Dielectric unions installed backwards or omitted between copper and steel nipples.
  9. No pan under a tank sitting above a finished ceiling.
  10. Anode never inspected or replaced — tank dies at year 8 instead of 15.

Every one of these adds 30 minutes and $40 in parts on install day. All of them are 100% preventable.

Ready for a straight answer on your tank?

Free same-day quote. Repair, replace, or upgrade — we’ll tell you which is honestly best.

(425) 399-2448
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