NoxPump
Heat Pump Planner
Only for iPhone
$0.99 · Designed for iPhone. Not verified for macOS.
iPhone
Is a heat pump right for your home? Calculate heat demand, compare ASHP vs ground source, estimate running costs and savings. NASA climate data for any location.
NoxPump is a heat pump planning and running cost calculator for homeowners considering the switch from gas, oil, or electric heating. Designed to be used at the kitchen table with a utility bill in hand, just punch in your house details, get honest answers.
WHAT IT DOES
NoxPump answers the four questions every homeowner asks:
How cold is my location?
Enter any location on Earth and get a detailed heating climate profile — monthly temperatures, heating degree days, frost days, ground temperatures at multiple depths, and the design minimum temperature engineers use for system sizing. All sourced from 20 years of NASA satellite data.
How much heat does my house need?
Select your house type, age, size, insulation level, and heat emitters. NoxPump calculates your estimated annual heat demand and peak heat load using standard building physics. Or skip the theory — enter your annual gas bill and let the app estimate from that instead.
What size heat pump do I need?
Get a sizing recommendation based on your peak load. Compare air source (ASHP) vs ground source (GSHP) side by side — efficiency ratings, seasonal COP estimates for your specific climate, and annual electricity consumption for each.
Will I save money?
Enter your current fuel costs, electricity rate, and installation budget. See your annual saving, payback period, and 20-year projection. Factor in grants, time-of-use electricity tariffs, and standing charge elimination. Full CO₂ offset calculation included.
FEATURES
• Location-specific climate data from NASA POWER for anywhere on Earth
• Monthly temperature charts, heating degree days, and ground temperature profiles
• Heat demand estimation from house characteristics or from your actual gas bill
• Peak heat load calculation for pump sizing
• Air source vs ground source comparison with COP estimates tuned to your climate
• Running cost comparison against gas, oil, electric, LPG, or solid fuel
• Time-of-use tariff support for cheap overnight electricity rates
• Standing charge elimination calculator for those ditching gas entirely
• 20-year financial projection with payback period and return on investment
• CO₂ savings with tree-equivalent offset
• Year-by-year cost breakdown table
• Metric and imperial units
• Multiple currency support (GBP, EUR, USD, or no symbol)
• Celsius and Fahrenheit
• Light and dark mode
• All inputs saved — pick up where you left off
• Works offline once climate data is cached
• No account required, no sign-up, no ads, no subscriptions
HOW IT WORKS
Climate data comes from NASA POWER (MERRA-2 reanalysis) — 20 years of satellite-derived temperature, soil temperature, and degree day data. Heat demand uses a simplified building fabric model with U-values by construction era, ventilation losses, and a utilisation factor for real-world gains. COP is estimated using the Carnot model with empirical efficiency fractions, adjusted for your emitter type and local conditions.
This is a planning tool for homeowners, not a substitute for a professional heat loss survey. The estimates help you understand the numbers before you talk to an installer — so you walk into that conversation knowing what to expect.
No jargon without explanation. Big controls. Clear results.
The kind of tool you use with a cup of tea, a custard cream, and a gas bill, wondering if the radiators will cope.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Stuart Woolley, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Stuart Woolley
- Size
- 2.2 MB
- Category
- Utilities
- Compatibility
Requires iOS 26.4 or later.
- iPhone
Requires iOS 26.4 or later. - Mac
Requires macOS 26.4 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 26.4 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Stuart Woolley
