Heat delivered per kilowatt-hour of electricity
The coefficient of performance says how many kilowatt-hours of heat you get per kilowatt-hour of electricity. It falls as it gets colder outside — when demand is highest.
All energy measures
Heating and hot water
Air-to-water heat pump
An air-to-water heat pump takes heat from outdoor air and delivers it to waterborne heating and hot water. It assumes the home has, or will get, a waterborne system.
See what this means for your homeThis measure is relevant if
- The home has waterborne underfloor heating or radiators
- You currently heat mainly with electricity, oil or wood
- There is room for an outdoor unit and a tank
- The building envelope is already upgraded, so the heat demand is known
What it does to energy use
It covers hot water too
Unlike air-to-air, the system can heat tap water — a large and steady part of energy use all year.
Sizing decides the economics
An oversized pump cycles on and off and loses efficiency. An undersized one falls back on the immersion heater on the coldest days.
Low flow temperature works best
Underfloor heating that manages on a low temperature gives a higher coefficient of performance than radiators that need a high one.
Sequence matters
This is the measure that should come last among the big ones. The pump is sized to the home's heat demand, and that demand changes with everything you do to walls, windows and ventilation. Insulate after the pump is installed and you are left with a system sized for a house you no longer have.
Enova funding
Air-to-water heat pumps are among the measures Enova funds. The terms have distinguished between ground-source and air-source systems, and between new installation and replacement.
Rates and terms change. What you can receive depends on the building, how the work is carried out and which schemes apply at the time. Always check Enova's own pages before relying on a figure.
The rates tell you what you can receive. The calculation tells you what the measure actually does to your home — how much it saves, what it costs, and whether it should come before or after the others.
Which measures pay off in your home?
Enter the address. Gadder collects what is known about the building, calculates the energy demand and ranks the measures by what they actually deliver.