Needs power
One of 7 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
Needs a sufficient volume of unheated air to draw from (a garage or cellar is the usual answer) or ducting to outside; it cools that space, which is a benefit in summer and a cost in winter
A small heat pump on top of an insulated tank moves ambient heat into the water instead of making it from electricity, so it delivers two to three and a half units of heat per unit drawn. That free ambient heat is what the coefficient of performance already expresses, which is why it is not drawn as an input. It needs a large enough volume of unheated air to draw from, or ducting to outside, and it cools whatever space it takes that air from.
No build tutorial recorded yet.
Compare building and maintaining complexity, as well as efficiency where possible.
| Solution | Build skill | Upkeep burden | Efficiency |
|---|---|---|---|
| Thermosiphon solar water heater | Intermediate | 3 | #1 |
| Compost-coil water pre-heater | Basic | 3 | #3 |
| Electric resistive water heater (cumulus) | Intermediate | 5 | #5 |
| Batch solar water heater (integrated collector-storage) | Intermediate | 3 | #2 |
| Wood-stove flue water heater (thermosiphon coil) | Intermediate | 4 | #2 |
| Gas water heater | Specialist | 6 | N/A |
| Heat-pump water heater (chauffe-eau thermodynamique) | Specialist | 8 | #4 |
Build skill and upkeep burden are proxies (lower burden = simpler to maintain); the efficiency column is this sub-function’s ranking, 1 = best. “N/A” where an axis isn’t rated here.
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.