• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

While searching for a new water heater, the figures on its packaging may seem cryptic. These ratings indicate how effectively the device converts fuel into hot water, yet they vary in type. Knowing the meaning, measurement, and actual cost of each rating can guide you to a wiser choice.

Why Efficiency Is Key

Heating water is one of the biggest energy drains in a home. Typically, American households spend 5–7% of their yearly electricity costs on hot water. This equates to about $150–$200 annually for the average family. Selecting a unit with a better efficiency rating may lower costs, reduce your carbon impact, and often increase longevity.

The Most Common Ratings
Annual Fuel Utilization Efficiency (AFUE)

Applicable to gas and oil tank heaters.

Expressed as a percentage, it represents how much of the fuel’s energy is actually used to heat water over a year.

For instance, an 80 % AFUE unit converts 80 % of the gas into hot water, while the remainder escapes via venting or standby losses.
EF: Energy Factor

Serves as the contemporary alternative to AFUE for electric and gas tank heaters.

Includes standby losses, cycling losses, and the overall efficiency of the unit.

Typical EF values: 0.70–0.95. The higher, the better.
Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER)

Used for electric heat pumps and air‑conditioning systems.

hr) against power input (W).

SEER is the average EER over a typical cooling season.

When applied to water heaters, the analogous metric is the Heat‑pump Coil Efficiency of the heat pump, often listed as a "COP" (Coefficient of Performance).
Coefficient of Performance (COP)

Designed for electric heat‑pump water heaters.

It measures heat energy supplied against electrical energy used.

A COP of 3 means that for every 1 kWh of electricity, the heater delivers 3 kWh of hot water energy.
Rate of Recovery

Not a percentage, but a key performance metric.

It shows how fast a heater can heat a fixed volume (e.g., 50 gal) by a given degree rise.

hr.

Crucial for homes with high concurrent hot‑water usage.
Capacity of the Tank

The total amount of water the tank can hold (in gallons).

For tankless systems, the metric is "Gallons per Minute" (GPM).

High capacity or GPM means you’re less likely to run out of hot water during peak use.

Translating Ratings into Actual Costs

Let’s illustrate with a straightforward example. Suppose you’re choosing between two 50‑gal electric tank heaters:

- Heater A: EF = 0.75, Recovery = 40 GPH

- Heater B: EF = 0.90, Recovery = 70 GPH

If your home uses 200 gal of hot water each month and the electricity cost is $0.13

1. Convert the EF into annual energy consumption:

• Heater A consumes 200 gal ÷ 0.75 = 266.7 gal‑equivalent energy units.

• Heater B consumes 200 gal ÷ 0.90 = 222.2 gal‑equivalent energy units.

°F, 1°F rise ≈ 1 BTU per lb).

• This is a ballpark figure; actual cost varies with temperature rise, but the comparative savings are obvious: Heater B uses roughly 16 % less energy.

3. Translate to kWh (1 kWh ≈ 3412 BTU).

• Heater A: 266.7 gal × 8.34 lb × ΔT ÷ 3412 BTU

• Heater B: 222.2 gal × …

The calculations demonstrate that a 15 % EF boost can cut $20–$30 from your monthly bill, totaling $200–$300 annually.

Tank vs. Tankless – Which Is More Efficient?

- Tank‑Based Heaters

• Always keep a reservoir of hot water.

• Standby losses can be high, especially in cold climates.

• Recovery rate limits simultaneous usage; you can run out of hot water if many appliances are on.

- Tankless Heaters

• Heat water on demand, eliminating standby losses.

{• Higher EF or COP values (often 0.95–0.99 for electric, 名古屋市東区 給湯器 修理 3–4.5 COP for heat pumps).|• They usually boast higher EF or COP (often 0.95–0.99 for electric, 3–4.5 COP for heat pumps).|• They typically achieve higher EF or COP (usually 0.