RMGA EXAM 2024 QUESTIONS WITH 100% CORRECT ANSWERS!!

Which of the following is the chemical formula for natural gas? - ANS CH4 What is the best method to locate a gas leak? - ANS Combustible Gas Detector Is natural gas heavier than air? - ANS Yes What is 2-4 times heavier than air? - ANS Gasoline What component make Natural Gas "sour gas"? - ANS Hydrogen Sulfide What is added to Natural Gas to give it an identified odor? - ANS Butyl Mercaptan/Thiophene T/F? When Natural Gas comes out of the ground, it has no odor? - ANS True What is the flammability of Natural Gas? - ANS 4%-14% What temperature does Natural Gas ignite at? - ANS 1200 degrees How toxic is Natural Gas? - ANS Non-toxic When can combustion air be taken inside a home with tight construction? - ANS Never How many inches of free area are required for horizontal ducts into a mechanical room? - ANS 1 in.(squared) per 2,000 BTUH How many inches of free area are required for vertical ducts into a mechanical room? - ANS 1 in. (squared) per 4,000 BTUH What percentage of a wood grill is considerate to be free area? - ANS 25% What is the smallest single duct that would be large enough to supply air into a mechanical room with a 153,000 BTUH? - ANS 7 in. x 8 in. duct What is required when converting 2 horizontal ducts to a single duct? - ANS A clearance of 1 in. on the back and sides and 6 in. to the front of all appliances What is the smallest size that will meet a 43 in. (squared) free area? - ANS 6 in. x 8 in. duct T/F? Vertical ducts are sized the same as horizontal ducts. - ANS False What size metal grill would be the smallest needed to provide a 140 in. (squared) of free area? - ANS 14 in. x 14 in duct If combustion air is obtained from a crawl space, how large must the grills be? - ANS 1 square inch per 4,000 BTUH of all appliances in the space What size horizontal ducts would be the smallest required for a mechanical room with TWO 120,000 BTUH furnaces and a 45,000 BTUH water heater? - ANS 12 in. x 12 in. duct how many inches of free area would be needed for vertical combustion air ducts supplying a 110,000 BTUH furnace and a 42,000 BTUH water heater? - ANS 38 in. (squared) An upper combustion air duct must always...? - ANS Slope upwards A mechanical room has a 150,000 BTUH furnace, a 77,000 BTUH boiler and a 55,000 BTUH water heater. If there one combustion air duct installed horizontally, how much free are is required? - ANS 94 in. (squared) A 34 in. long by 20 in. wide basement with an 8 in. ceiling has a 110,000 BTUH boiler in it. The building isn't tight construction. The Required Volume for the boiler to use inside air is....1...and the volume of the room is...2.....? - ANS 1. 5500 ft. (cubed) 2. 5440 ft. (cubed) What is the smallest acceptable combustion air duct opening that will satisfy a 48 in.(squared) free area requirement? - ANS 3.5 in. x 15.0 in. duct What size metal grill will meet an 80 in(squared) free area requirement? - ANS 10 in. x 12 in. duct What is the smallest size grill or screen permitted in the mechanical room inlet for a vertical duct that gets Combustion Air from attic? - ANS Gills or screens are not permitted for Combustion Air ducts witch terminate in an attic What size wood grill will meet the combustion air requirements for an 80,000 BTUH furnace when using inside air? - ANS 400 in.(squared) What size wood grill will satisfy an 80 in. (squared) free area requirement? - ANS 16 in. x 20 in. duct How much excess air is typically supplied to gas appliances? - ANS 40%-50% When is corrosion likely to occur in a vent system? - ANS When the vent system doesn't dry out before the appliance cycles off When does condensation form in a vent system? - ANS When the flue gases cool too much What are the clearance to combustibles requirements for single wall vent pipe? - ANS 6 in. What are the clearance to combustibles requirements for Type B vent pipe? - ANS 1 in. The "Least Total Height" is measured from the outlet of the vent system to the...? - ANS Top of the tallest appliance How many elbows are permitted in a vent system with a ZERO LATERAL? - ANS 0 How much should vent table capacities be reduced when using a listed, corrugated chimney liner system in a masonry chimney? - ANS 20% No part of a vent system can be more than...?... times the flow area of a flue collar or draft hood outlet - ANS 7 times When can vent table be extrapolated? - ANS Never If a . 40,000 BTUH water heater is to be replaced with a 200,000 BTUH tankless water heater, what is the minimum size branch line that will be required if the most distance appliance is 50 feet on a 4 oz. system in Salt Lake? - ANS 1 in. A St. George home has a 100,000 BTUH furnace and a 50,000 BTUH water heater. The homeowner is considering replacing the water heater with a 190,000 BTUH demand water heater. If the gas line to the mechanical rooms is 1 in. and the most distant appliance is 50 feet on a 4 oz. system, what will you tell the homeowner? - ANS The gas line will work is the gas supply pressure is increased to 2 PSI In Park City, a 50,000 BTUH water heater is being replaced with a 150,000 BTUH tankless water heater. How many CFH of gas will the new water heater require if the most distant appliance is 77 feet on a 4 oz. system? - ANS 187 CFH If a 300,000 BTUH boiler system is added to a mechanical room that contains a 100,00 BTUH furnace and a 125,000 BTUH water heater, what is the smallest size pipe that will supply enough from the meter on a 4 oz. system in Salt Lake City? - ANS 1-1/2 inch A tankless water heater is being installed to meet the hot water requirements of a jetted bathtub that will be installed in the future. The new water heater will be 180,000 BTUH. What size branch line to the water heater will be required if the most distant appliance is 50 feet on a 2 PSI system in St. George? - ANS 1/2 inch A 50,000 BTUH water heater being replaced with an 180,000 BTUH tankless style that obtains combustion air from the mechanical room which is supplied through a single 8 x 10 horizontal duct. There is a 100,000 BTUH furnace in the room as well. What can you determine about the combustion air duct? - ANS The duct needs to be increased to a 10 x 10 inch A mechanical room with combustion air supplied through two vertical ducts contains a 35,000 BTUH water heater that is being replaced with a 210,000 BTUH tankless style. There are also two 100,000 BTUH furnaces in the room. What combustion air ducts are the smallest that ca be used to replace the existing ducts to satisfy the combustion air requirements fi the furnaces have zero rear clearance? - ANS 10 x 10 If replacing a natural draft furnace with a direct vent 95% condensing furnace, will the existing 8 in. vertical vent that has a height of 10 feet with a 3 inch lateral be suitable for a 35,000 BTUH water heater with a 3 inch draft hood? - ANS No. The maximum allowed vertical vent is 7 inches If you were to replace a 30 foot high vent system with a 10 foot lateral on a 55,000 BTUH water heater, which is the smallest and least costly option for the vent connector? - ANS 4 inch single wall If a water heater has a 3 inch draft hood, what is the maximum vent size it can be connected to? - ANS 7 inch