Water Heating Cost Comparison
Heating 1,000 litres from 27°C to 60°C takes 38.4 kWh of heat. On an electric heater, about ₱461. On an LPG boiler, ₱393. On a diesel boiler, ₱384. On a Karnot heat pump, about ₱115.
Same water, same temperature, four ways to heat it. Every price and efficiency below is editable — put in your own tariff and fuel invoice prices and the comparison recalculates honestly. No thumb on the scale.
Your Demand & Prices
Cost Per Day, Compared
| Method | ₱ / 1,000 L | ₱ / Day | ₱ / Year | ₱ / kWh of Heat |
|---|
The Formulas
Heat required:
Cost per method (η = burner efficiency or COP; NCV = net calorific value):
Method & Sources
- Water — cp = 4.186 kJ/kg·K, density 1 kg/L. 1,000 L × 33 K = 38.4 kWh of heat.
- Net calorific values — LPG 13.6 kWh/kg, diesel 10.0 kWh/L — the same hub-standard table used in our Boiler Converter and Energy & Carbon Converter, aligned with UK Government GHG conversion factor publications.
- Efficiencies — electric heater 100% (all heat ends up in the water), LPG and diesel boilers default 85% (editable; flue and standby losses are why it is not 100), heat pump COP default 4.0 (AquaHERO rated; drop it to 3.4 if you want the conservative case — the ranking does not change).
- Honest point — at today's cylinder prices the fuels land close together: LPG and diesel around ₱10 per kWh of heat, electric at ₱12. The heat pump is about ₱3. We show all of it, exactly as it prices up.
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Frequently Asked Questions
How much does it cost to heat 1,000 litres of water?
From 27°C to 60°C: 38.4 kWh of heat. At typical Philippine prices: ~₱461 electric heater, ~₱393 LPG boiler, ~₱384 diesel boiler, ~₱115 heat pump at COP 4. Edit every price above to match your bills.
Is LPG cheaper than electric for water heating?
Only just, at today's cylinder prices — about ₱10/kWh of heat at ₱118/kg (a ₱1,300 11-kg cylinder), versus ₱12 for the electric heater, with diesel also around ₱10. The fuels cluster together; the heat pump sits far below them all at about ₱3/kWh of heat — no cylinders, flame or flue.
Why does a heat pump cost a quarter of an electric heater?
A resistance element turns 1 kWh of electricity into 1 kWh of heat. A heat pump uses 1 kWh of electricity to move ~4 kWh of heat from the air into the water (COP 4). Same tariff, a quarter of the kWh purchased — and warm Philippine air keeps the COP high all year.
What temperature rise should I use?
Philippine inlet water is 25–28°C and storage practice is 60°C — a 33 K rise. UK/US figures assume 45–50 K because their water is colder, which is why imported running-cost numbers overstate Philippine costs by a third or more.
Still Heating Water the Expensive Way?
Tell us how many people or rooms you serve and what you pay for power. We will size the right heat pump and show the payback against what you burn today — honestly, both ways.
Get the Comparison for Your SiteSpecifying a real system?
Karnot builds R290 and CO₂ heat pumps in the Philippines — 9.5–100 kW, EN 378 design. Free load calculations for consulting engineers and contractors.