| heat the air | 0.47 |
| get hot | 0.45 |
| transfer heat | 0.43 |
| fail in first 10 years | 0.34 |
| fail under specific con… | 0.25 |
| look good | 0.25 |
| leak carbon monoxide | 0.20 |
| a crack or rust hole | 0.20 |
| aluminized steel | 0.29 |
| cracked | 0.59 |
| inspected | 0.43 |
| replaced | 0.41 |
| damaged | 0.27 |
| expensive to fix | 0.25 |
| inspected for crack | 0.25 |
| vented through brick or… | 0.25 |
| cleaned | 0.25 |