Boiler to Heat Pump Converter
A 100 kW diesel boiler running 4,000 hours a year at 60% load burns about ₱2.4 million of fuel. The same heat from an iHEAT cascade costs about ₱0.9 million of electricity — a 63% cut.
Enter your boiler in kW, boiler horsepower, or steam kg/h. The converter sizes the heat pump equivalent, compares yearly running cost against diesel, LPG, natural gas or HFO, and is honest about the temperature limit: heat pumps replace duties up to 75°C, not live steam.
Your Boiler
Conversion Results
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The Formulas
Boiler horsepower and steam conversions:
Yearly heat, fuel and electricity:
Effective COP (catalogue COP at A7/W35, derated for delivery temperature — 1.00 at 45°C, 0.85 at 60°C, 0.72 at 75°C):
Method & Sources
Every constant has a source, and the temperature limit is stated rather than hidden.
- 1 BoHP = 33,475 BTU/h = 9.81 kW — ASME boiler horsepower definition.
- Steam enthalpy 2,773 kJ/kg — saturated steam at ~8 bar gauge, IAPWS-IF97 steam tables (the same basis as our Boiler Energy Flow Analyser). Feedwater credit = 4.186 kJ/kg·K × feedwater temperature.
- Fuel net calorific values — diesel 10.0 kWh/L, LPG 13.6 kWh/kg, natural gas 10.55 kWh/m³, HFO 11.1 kWh/L. Same table used across all Karnot Engineering Hub tools, aligned with UK Government GHG conversion factor publications.
- CO₂e factors — diesel 2.68 kg/L, LPG 3.0 kg/kg, natural gas 1.98 kg/m³, HFO 3.15 kg/L (combustion, same publications). Philippine grid electricity default 0.71 kg CO₂e/kWh, editable.
- iHEAT COPs — manufacturer ratings at A7/W35 (4.42 at 9.5 kW down to 3.80 at 50 kW), derated by a stated factor for delivery temperature: ×1.00 at 45°C, ×0.85 at 60°C, ×0.72 at 75°C. The derate is our conservative convention so the savings figure under-promises rather than over-promises.
- The honest limit — air-source R290 heat pumps top out at 75°C. If you selected steam, the result shows the conversion for the sub-75°C share of your load and points you to the Feedwater Pre-Heat tool for the steam that remains.
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Frequently Asked Questions
Can a heat pump replace a steam boiler?
Up to 75°C delivery, yes — hot water, washdown, CIP first stages, feedwater pre-heat. For live steam above 100°C, no: the heat pump takes over everything below 75°C and pre-heats the feedwater, which typically cuts fuel use 10–15% on the steam that remains. Anyone claiming a standard air-source unit makes 8-bar steam is overselling.
How many kW is one boiler horsepower?
1 BoHP = 33,475 BTU/h = 9.81 kW of heat output (ASME definition). A 50 BoHP boiler is about 490 kW. Note this is different from mechanical horsepower (0.746 kW).
How do I convert steam kg/h into kW?
kW = kg/h × (2773 − 4.186 × Tfeed) ÷ 3600, using saturated steam enthalpy at ~8 bar(g) from the IAPWS-IF97 tables. Example: 300 kg/h with 80°C feedwater = 300 × 2438 ÷ 3600 ≈ 203 kW.
What boiler efficiency should I assume?
On a net CV basis, well-maintained boilers run 84–88%: diesel ~85, LPG ~87, natural gas ~88, HFO ~84. Older or frequently cycling boilers run lower. If you have a flue gas analysis, use your measured figure — the field is editable.
How much does switching from diesel to a heat pump save?
A 100 kW diesel boiler at 60% load for 4,000 h/yr burns about 28,000 L — around ₱2.4M at ₱85/L. The same heat from an iHEAT cascade uses about 74,000 kWh — roughly ₱0.9M at ₱12/kWh. About a 63% cut. Run your own prices, then have us verify it against your bills before you commit.
What happens to my Scope 1 emissions?
On-site fuel is Scope 1; purchased electricity is Scope 2. Replacing the boiler removes the heating from Scope 1 entirely. Total CO₂e falls too, but on the current Philippine grid (~0.71 kg/kWh) the carbon cut is smaller than the cost cut — typically 25–35% for diesel. It improves automatically as the grid greens, or immediately if you add solar.
Boiler Due for Replacement?
Send us the boiler nameplate and a recent fuel invoice. Our engineers will run the real numbers — including the duties a heat pump should not take — and quote only what pays.
Get the Real Numbers