Heating Flashcards
This concentration of carbon monoxide is allowable for an exposure of 8 hours.
50 PPM
These concentrations of carbon monoxide are fatal within one hour.
4000+ PPM
What is the difference between intermittent and interrupted pilots?
Intermittent - pilot stays on while there is a call for heat.
Interrupted - pilot stays on only until the main burner is proving, then shuts off.
What causes yellow flame tips?
Not enough primary air flow.
What causes lifting flame?
Too high velocity, can be caused by too high gas pressure or too much primary air.
What causes waving blue flames?
Drafts/air blowing on burner.
What causes flashback?
Not enough gas pressure or the ratio of primary air to gas ratio is skewed. Increase gas pressure or reduce primary air.
What causes the main burner flame to be to large?
Too much gas getting to burner. Could be overfired, orifices are too large, or defective regulator.
What causes noisy flame?
Too high velocity. Usually caused by too much primary air.
When a unit retry’s more than one time for ignition, it is considered to have what kind of control system?
Recycling control.
What is the benefit of a connection diagram?
Shows colour and location of wires and location of components.
What is the benefit of a ladder diagram?
Shows how the appliance works and helps with troubleshooting.
Which part of incomplete combustion can you smell?
Aldehydes.
What should an open circuit test on a thermocouple read?
30+-5 mVDC
What should a closed circuit test on a thermocouple read?
15+- 5 mVDC
What mVDC should a typical pilot drop out at during a drop out test?
1-2mVDC and should take around 90 second or less.
Which test should be conducted on all pilots for safety purposes?
Pilot turn down test. This ensures the pilot can light the burner under all conditions.
What are two types of burners and what is the difference between them?
Atmospheric - No fan, uses the venturi effect to deliver primary air to the burner.
Power Burner - Uses an inducer fan to supply primary air.
What are 5 burner types and what are their defining characteristics?
Fanmix: Gas pressure rotates a fan blade which draws in the air used for combustion.
Closed burner: All combustion air is primary air provided directly to the burner.
Open burner: open to atmosphere and allows secondary air.
Upshot: Vertical burner ports.
Inshot: horizontal burner ports.
Where can radiant tube burners not be used?
Anywhere except explosion proof areas or areas where flammable vapours are present.
What is turndown ratio?
Turndown ratio defines a heating appliance’s ability to stage between its minimum and maximum outputs. A unit with a 5:1 turndown ratios means that the unit can stage anywhere from a minimum of 20% and a maximum of 100% in 20% increments. A unit with a higher turndown ratio will be able to modulate in smaller increments and therefore be more efficient. These units are typcally fitted with modulating gas valves and vfds in order to properly control the fuel/gas mixture being delivered to the burners.
What is done on mid-efficient furnances to prevent positive pressure in the flue?
The fan outlet is increased in size. this is typcailly C or B vent. This results in the pressure in the flue being negative in mid efficient furnaces.
In the 1970’s, heating equipment had an efficiency rating of about __________?
55%
In the late 1970’s, federal government introduced standards that required heating appliances to be at least _________ efficient.
78%
