| Value | Category | Cases | |
|---|---|---|---|
| boiler | 1 |
3.8%
|
|
| central heating | 6 |
23.1%
|
|
| fire | 12 |
46.2%
|
|
| heating | 2 |
7.7%
|
|
| solar heater | 5 |
19.2%
|