{
  "slug": "water-heater-comparison",
  "title": "Water Heater Type Cost Comparison Calculator",
  "heading": "Tank vs Tankless vs Heat Pump Water Heater Calculator",
  "category": "financial",
  "url": "https://www.revenuelab.fyi/toolbox/water-heater-comparison",
  "summary": "Annual operating cost and payback across three water heater types.",
  "description": "Compares annual energy cost across a standard tank, a tankless (on-demand), and a heat pump water heater based on your household hot water use and each technology's energy factor (EF) or uniform energy factor (UEF). Heat pump water heaters extract ambient heat like a mini refrigerator in reverse, typically hitting a UEF of 3.0+ (300% efficient) versus 0.6-0.7 for standard electric tanks and 0.95+ for tankless gas units. It also factors in the higher upfront cost of tankless and heat pump units to show simple payback against a standard tank replacement, which is the real decision point for most homeowners replacing a failed unit.",
  "formula": "Annual cost = annual hot water energy demand ÷ UEF × fuel price; payback = incremental cost ÷ annual savings vs baseline tank.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=water-heater-comparison",
  "inputs": [
    {
      "id": "dailyGallons",
      "label": "Household hot water use",
      "kind": "number",
      "hint": null,
      "default": 60,
      "unit": "gal/day",
      "min": 10,
      "max": null
    },
    {
      "id": "tankUef",
      "label": "Standard tank UEF",
      "kind": "number",
      "hint": null,
      "default": 0.6,
      "unit": null,
      "min": 0.4,
      "max": 0.95
    },
    {
      "id": "tanklessUef",
      "label": "Tankless UEF",
      "kind": "number",
      "hint": null,
      "default": 0.82,
      "unit": null,
      "min": 0.6,
      "max": 0.99
    },
    {
      "id": "hpwhUef",
      "label": "Heat pump water heater UEF",
      "kind": "number",
      "hint": null,
      "default": 3.3,
      "unit": null,
      "min": 2,
      "max": 4.5
    },
    {
      "id": "elecPrice",
      "label": "Electricity price",
      "kind": "number",
      "hint": null,
      "default": 0.15,
      "unit": "$/kWh",
      "min": 0.02,
      "max": 0.6
    },
    {
      "id": "gasPrice",
      "label": "Gas price (for tankless)",
      "kind": "number",
      "hint": null,
      "default": 1.4,
      "unit": "$/therm",
      "min": 0.3,
      "max": 5
    },
    {
      "id": "hpwhExtraCost",
      "label": "Heat pump WH extra cost vs standard tank",
      "kind": "number",
      "hint": null,
      "default": 900,
      "unit": "$",
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "hpwhCost",
      "label": "Heat pump water heater annual cost",
      "format": "currency",
      "hint": null,
      "primary": true
    },
    {
      "id": "tankCost",
      "label": "Standard electric tank annual cost",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "tanklessCost",
      "label": "Gas tankless annual cost",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "hpwhSavings",
      "label": "Annual savings, heat pump vs standard tank",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "hpwhPayback",
      "label": "Payback for heat pump premium",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Household hot water use: 60 gal/day",
      "Standard tank UEF: 0.6",
      "Tankless UEF: 0.82",
      "Heat pump water heater UEF: 3.3",
      "Electricity price: 0.15 $/kWh",
      "Gas price (for tankless): 1.4 $/therm",
      "Heat pump WH extra cost vs standard tank: 900 $"
    ],
    "outputs": [
      "Heat pump water heater annual cost: $170",
      "Standard electric tank annual cost: $936",
      "Gas tankless annual cost: $218",
      "Annual savings, heat pump vs standard tank: $766",
      "Payback for heat pump premium: 1.2"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter household hot water use (gal/day).",
      "Enter standard tank uef.",
      "Enter tankless uef.",
      "Enter heat pump water heater uef.",
      "Enter electricity price ($/kWh).",
      "Enter gas price (for tankless) ($/therm).",
      "Enter heat pump wh extra cost vs standard tank ($).",
      "Read your heat pump water heater annual cost on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "dailyGallons": 35,
        "tankUef": 0.4,
        "tanklessUef": 0.6,
        "hpwhUef": 2,
        "elecPrice": 0.09,
        "gasPrice": 0.84,
        "hpwhExtraCost": 550
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "dailyGallons": 60,
        "tankUef": 0.6,
        "tanklessUef": 0.82,
        "hpwhUef": 3.3,
        "elecPrice": 0.15,
        "gasPrice": 1.4,
        "hpwhExtraCost": 900
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "dailyGallons": 95,
        "tankUef": 0.95,
        "tanklessUef": 0.99,
        "hpwhUef": 4.5,
        "elecPrice": 0.24,
        "gasPrice": 2.2399999999999998,
        "hpwhExtraCost": 1450
      }
    }
  ],
  "limitations": [
    "Results are estimates before tax, fees, and inflation unless an input explicitly covers them.",
    "Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.",
    "This is educational maths, not financial advice. Check anything contractual with the lender or your accountant."
  ],
  "faq": [
    {
      "q": "Why is a heat pump water heater so much more efficient?",
      "a": "It works like a refrigerator in reverse, pulling ambient heat from surrounding air and concentrating it into the tank rather than converting electricity directly into heat via resistance elements. That lets it deliver 3-4 units of heat per unit of electricity consumed, versus roughly 1-to-1 for a standard electric tank."
    },
    {
      "q": "What's the catch with heat pump water heaters?",
      "a": "They need 700+ cubic feet of surrounding air space (typically a basement or garage, not a small closet) to draw heat from, they cool and slightly dehumidify that space as a side effect, and they cost $800-$1,500 more upfront than a standard tank plus sometimes need a dedicated 240V circuit if replacing a gas unit."
    },
    {
      "q": "Is tankless actually cheaper to run?",
      "a": "Tankless gas units are efficient (no standby heat loss from a stored tank) but the savings versus a modern standard tank are usually modest — the bigger selling point is endless hot water and space savings, not dramatic bill reduction. The math favors heat pump electric over tankless gas almost everywhere except very cheap-gas regions."
    },
    {
      "q": "How do UEF numbers translate to real savings?",
      "a": "UEF (Uniform Energy Factor) is the EPA/DOE-standardized efficiency rating printed on the EnergyGuide label — divide your hot water energy demand by UEF to get consumption, exactly like this calculator does. Always compare UEF, not the older EF rating, since the test method changed in 2017 and the numbers aren't directly comparable."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/heat-pump-vs-furnace",
    "https://www.revenuelab.fyi/toolbox/insulation-payback",
    "https://www.revenuelab.fyi/toolbox/kwh-bill-breakdown"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Water Heater Type Cost Comparison Calculator (https://www.revenuelab.fyi/toolbox/water-heater-comparison)"
}