17173190
Description
Flashcards by Andrew Adams, updated more than 1 year ago
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Created by Andrew Adams
over 5 years ago
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| Question | Answer |
| Categories of Furnaces | I-IV based on vent gas temperature and pressure(positive or negative) |
| Category I | vent gas is around 300º; uses stack effect to vent exhaust. Low and Mid efficiency and draft hood furnaces |
| Category II | vents at 140º; difficult to create stack effect so very uncommon(not covered on NHIE) |
| Category III | gas is hotter than Category I usually; uses factory components rather than conventional venting ducts. Can have condensate issues; look for collection system issues. |
| Category IV | vents at 140º, using high efficiency heat exchangers. Draws heat from exhaust, cooling enough to use PVC as vent; positive pressure. Must have appropriate condensation collection system. |
| draft hood type furnace | Category I production ended in the 70s. Low efficiency ribbon type burners(65%) |
| induced draft type furnace | Category 1 2-6 in shot burners; medium efficiency(80%) |
| Category I inspection key points | scorching or staining(flame rollout) bypassed controls undamaged wires(grommets) vent system intact |
| Draft hood ignition sequence | click of gas valve burner ignition fan activation |
| induced draft ignition sequence | inducer fan activation ignition device activation click of gas valve burner ignition fan activation |
| gas flame is blue | properly burning; yellow tip ok too. |
| gas flame is yellow/orange | improperly adjust burner or valve; inadequate combustion air |
| gas flame distorts or flickers | may indicate cracked heat exchanger |
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