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Flashcards in HVAC Deck (36)
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2. Tracking a problem of a gas burner?

1. Make sure the pilot is lit. 2. Clean the nozzle. 3. Chack the thermocouple. If You find ash built up on the tip of the thermocouple , it needs to be cleaned or replaced. 4. Ash build up is also an indication that the burners are in need of cleaning. Cleaning and reassembling the thermocouple is easier with the burners out of the furnace, so You might as well clean them at the same time.


3. Adjusting the burner flame by turning the air shutter?

Right color - blue with a green core. Flame is starved for air - a yellow. Flame is getting too much air - blue with dark blue center.


4. Lighting the pilot?

1. Take access cover off the furnace and look for the gas control knob. 2. Turn the knob until the arrow points at the word pilot. Push the knob for the button next to it down to start the flow of gas. 3. Hold a long match or a long-nose butane lighter designed for the fireplace up to the pilot nozzle to light the pilot. Once the flame is lit, hold the knob down for about a minute, than release it. If the pilot stays lit turn the knob back to the On position. If it goes out try again. If the flame still goes out, the nozzle may be dirty.


5. When can the thermocouple be the problem?

If the pilot flames mostly blue.


6. What does indicate smoke for an oil furnace?

1. A smoky furnace may be caused by a dirty nozzle or a dirty fan. 2. Smoke, in particular, may indicate a cracked firebox and the presence of deadly carbon monoxide in your house.


7. 2 systems ensures that the oil has ignited in furnace?

1. An electric eye senses the flame. 2. A sensor in the chimney notes a rise in temperature.


8. How a hot water heat system works?

1. The thermostat calls for heat - the furnace stars a fire in the boiler and a thermometer (an aquastat) measures water temperature in boiler. 2. The temperature of water in the boiler reaches a set point, the aquastat activates a switch and circulator starts pumping water through the convectors. 3. The temperature of the aquastat activates a switch and circulator starts pumping water through the convectors. 4. If the water in the boiler gets too hot, aquastat shuts down the furnace before too much pressure can build up in the boiler


9. 2 parts of aquastat?

1. The larger aquastat dial controls the set point - the tempe at which it will turn off the burner or pump. 2. The smaooer dial controls the differential or number of degrees below the set point of which the burner or a regulator will come on.


10. Testing the burner (set point) aquastat?

1. Lower the setting less than 100*F (38*C) - the burner should go off. 2. Return the burner aquastat to its original setting - the burner should go back on within 10 minutes.


11. Testing the circulator aquastat?

1. Lower the temperature setting to less than 100*F (38*C) - the circulator shall go on. 2. Reset the aquastat to more than 100*F - the circulator should go off.


12. What shall you do if the existing well may not match the replacement aquastat?

1. Make sure you have the correct aquastat. 2. Replace the well by following the manufacturers direction after you have drained boiler using pressure-relief valve.


13. What shall You do if your circulator break at winter time?

Turn up the thermostat all the way to keep hot water move slowly by natural convection until You replace circulator.


14. What is heat pump?

It heat your house in the winter because liquid refrigerant is pumped out doors, where it absorbs whatever heat is there, turning the refrigerant into a gas in the process.The refrigerant flows through a compressor which turns on into a liquid again, and the heat is released by this process as released through coils inside the house and distributed by the fan and duct system. It cool Your house in the summer because the refrigerant absorbs heat inside the house and releases it outside. To do this it has a reversing valve.


15. How does direct-vent heater differ from vented one?

The vent on a direct-vent heater is a pipe within a pipe. The core pipe acts like a chimney: the outer section pulls fresh air from outside.


16. What is the sealant of choice of the U.S. Department of Energy for Efficiency and durability for duct work?

Duct mastic, which is water-base, flexible sealant, that can be applied by brush, or with gloved hand.


17. Name of outlet of ductwork?

Register boot.


18. Name of the fitting that connects branch line to a plenum of a ductwork?

Starter collar.


19. How shall You support a ductwork?

Nail plumber tape to the rafters every 4 feet and within 6 inches of any connections. Flex duct does not snag more than1/2" per foot.


20. Type of auxiliary gas heaters?

1. Vent free. 2. Vented. 3. Direct-vent.


21. Use of vent-free gas heater?

For an area that is used occasionally. The U.S. Department of Energy warns against operating for more than 2 hours a day.


22. What does vented gas heater need to operate accept gas line?

An exhaust vent must be need to install register to get fresh air into the room.


23. Prohibited locations of gas heaters?

Bedroom, bathroom, mobile home.


24. How can You determine the proper size for heater?

H(btu) = 20(btu) x L' x W' x H'.


25. How can You choose a window air-conditioner?

Space 100-150 square feet need a 5,000 btu unit. Add 1,000 btu for each additional 100 square feet.


26. Vertical location of fan of a central air system?

1" above the motor body.


27. How does evaporative coolers work?

Swamp coolers blows air through a water soaked pad, cooling it by evaporation of water and then blowing it into house.


28. Temperature range of evaporative coolers?

In driver climates (/Arizona) the conditioned air may be as much as a 30* cooler than outside air. Where air is much more humid (on the East coast), the air produced may be only 10* cooler.


29. How much efficient are evaporative coolers?

They use about 1/4 of the electricity an air-conditioner uses.


1. House hold oil?

10W non-detergent oil.


30. Made of plastic or rubber, they apply decorative finishes to surfaces, clean fins on air-conditioning units?