G2 Gas Technician Module 22 Revised 100% Pass

G2 Gas Technician Module 22 Revised 100% Pass What pressure does atmospheric pressure exert on the earth at sea level? 14.74 psia What two things mean you must bring in combustion air. 1. Total BTU of appliance if greater than 400000 you must bring in combustion air. 2. If house is tight construction you also must bring in air. What is the maximum flue gases should be for a natural draft system? Why? 450 F is the max this is because safety concerns of having high heat in a combustible building and the hotter the gasses the more inefficient the system is. What is the minimum flue gas temperature should be? Why? Greater then 127 F, this is when the flue gases will condense causing corrosion due to its highly acidic nature What do special venting systems do? They are used with high efficient or condensing furnaces. They condense the flue gases to release more heat back into the building. Latent heat of 1 lb of water vapor converting to liquid will release 970 btu back into the structure. What does direct venting do? Supplies combustion air directly from the outside and expels flue gases directly to the outside. What is an example of a positive vent pressure system? Non - positive system? Positive - Hi eff. furnace Non positive - natural draft What does flue loss determine? If the appliance is a condensing system. What is a type A vent? They are chimneys made of masonry or steel What are B vents? Are double walled vents that can run through a ceiling to the outside What are Type L vents? Where are they used? What is max flue temp? 1. They are double walled insulated vents with interior wall constructed of stainless steel 2. They are used when heat/corrosion could be a problem 3. Must not exceed 550 F What is a BH Vent? When is it used? What kind of flue temps? 1. They are single walled flexible stainless steel pipe or S636 schedule 40 pvc plastic pipe. 2. Used in high efficient condensing furnaces 3. Use in low flue temperatures and positive vent pressures What are type C vent connectors? What are some limitations? 1. They are single wall vent connectors made of galvanized steel. 2. They are not allowed to go through floors, ceilings or concealed areas of the building structure. What must be done to an exterior chimney? It must be insulated When using the vent sizing tables what must be done with the fan assisted appliances btuh? They must fall between the min and max on the chart When you have a vent connector sharing a common vent between a draft controlled appliance and a non draft controlled appliance what must be done? The draft controlled appliance must enter the vent above the fan assisted one. If a water heater has an input of 50000 btuh or less and is the only appliance in the structure does it require outdoor combustion air to be brought in? No clause 8.2.3 Where must the air supply duct from outside be located? within 1 ft above, and within 2 ft horizontally from the burner level of the appliance having the largest output. clause 8.3.1.d When bringing in ventilation air what is the minimum cross sectional area allowed? 10 " clause 8.4.1 What is the minimum wall dimension a square or rectangular duct can have? 3 " clause 8.3.2 A 7 " diameter vent connector is serving an appliance with a draft hood. what is the minimum gauge of material? No. 26 GSG Clause 8.18.3 An appliance requiring zero over fire draft shall be installed with a ? Draft hood A square or rectangular shape duct shall only be used whn the required free air supply opening is? 9 square inches or greater clause 8.3.2 Where shall a baffle or neutral pressure point adjuster be located? Upstream of the draft regulator A power venter that is used as an add-on to a water heater can only be used if the input does not exceed? 50000 Btuh clause 8.29.2 When sizing a vent connector with 3 or greater 90 Degree elbows what must be done? Reduce the capacity by 10% per elbow. 2 elbows are already assumed in the charts calculation. clause C.2.4 If a vent terminates to a paved sidewalk it shall not be less than? 7 feet above A single acting type draft regulator is ususally used on? Incinerator What is the maximum lateral length for a 6 " single wall vent connector? Double wall? 10 ft - single wall 20 ft - double wall Table C.9 (double distance for double wall) What must be done when vent connectors are combined prior to entering the common vent? Capacity must be reduced by 10% When can fan assisted appliances be connected to a clay lined masonry chimney? When it is common vented with another appliance that is equipped with a draft control device When using a chimney liner what tables must be used? What must be done to the Btuh capacities? Use the B-vent tables and the capacities must be reduced by 20% If the common vertical vent is offset using two 90 degree elbows what must be done to the capacity? must be reduced by 20% Can an oil burning appliance be common vented with a gas burning appliance in the same chimney flue? Yes clause 8.10.2 Where can't a single wall vent connector pass? Floor or ceiling