Visibility of Glass
The ability to see a nice flame is important to many consumers. Some stoves maintain clean glass far longer than others. No stove that we tested keeps the glass completely clean but the better stoves only got soot on the edges of the glass, leaving most of the middle of the glass clear. We consistently observed the Ravelli, the Quadra-Fire, and the Harman having the cleanest glass after many days of continuous operation. Next came the Enviro, and in the middle of the range was the Englander. The stove that was consistently the dirtiest, almost completely obscuring the flame after several days, was the Piazzetta. Even with a relatively good quality pellet, the Sabrina appears to need a quick glass clean on a daily basis, if the stove is operated around the clock.
Figure 7. Three of the stoves maintained very clean glass over a seven day period including the Quadra-Fire, pictured here, the Harman and the Ravelli.
We did not try to rate the quality of the flame or how well the consumer can see it based on the size of the glass. We only rated how much of the glass became obscured and the transparency of the obscuration. We took assessments of the glass after five to seven days of continuous operation three times during the thirty-day testing.
Figure 14. Cleanliness of glass after 7 days of continuous burning.
Stoves were assessed for glass visibility and cleanliness three times during the 30-day testing period. Stove glass was assessed for two attributes: transparency and coverage. Transparency was measured by how well you could see through dirty glass and coverage was measured by how much of the glass was sooty. Transparency and coverage were given equal weighting in our scoring regimen.
​The whole glass panel was assessed although some of the stoves have features that conceal the dirtiest part of the glass, like the Enviro insert for example. The Piazzetta consistently had the dirtiest glass, while the Quadra-Fire and the Ravelli had the cleanest glass, week after week. Pictures were taken documenting the glass cleanliness both before and after cleaning, and one set of pictures is shown above.