750 mm.
The shaded areas are recommended for installation of rigid gas pipe.G.4 ¹⁄₂  (11.4 cm)H.8 (20.3 cm)I.17 (43.2 cm)J.2 (5.1 cm)K.4 ¹⁄₂  (11.4 cm)L.2 (5.1 cm) min. clearance from both sides of range to side wall or other combustible material.M.Grounded outletN.Cabinet door or hinges should not extend into the cutout.  Many are made of expensive stainless steel and have multiple burners. All of these stoves have their own clearances to combustibles-clearly written in the manufacturers instructions. For example, for a 60 Wolf range the minimum vertical clearance between the gas range and combustible materials above the range is 44. For a Thermador range the distance to the bottom of the hood is 30, and 40 to an unprotected cabinet.  It is recommended that a separate circuit serving only this range be provided. A. 18 (45.7 cm) upper side cabinet to countertopB. 13 (33 cm) max. upper cabinet depthC. 30 (76.2 cm) min. opening widthD. For minimum clearance to top of cooktop, see NOTE *.E. 30 1 / 8  (76.5 cm) min. opening widthF. The shaded areas are recommended for installation of rigid gas pipe.G. 11 (27.6 cm)H. 17 (43.2 cm)I. 2 (5.1 cm)J. 4 1 / 2  (11.4)K. 3 (7.6 cm) min. clearance from both sides of range to side wall or other combustible material.L. Grounded outletM. Cabinet door or hinges should not extend into the cutout.  The minimum clearance required directly above the range is 750 mm (approx 30) to combustibles. This clearance can be reduced to 600 mm (approx 24”) when the finish is protected as per Article 9.10.22.2. Vertical Clearances above Ranges of the Alberta Building Code. WARNING: Some gas ranges may require in-creased clearances from the Alberta Building Code minimum. Please consult the appliance manufac-ture’s installation instructions to determine if in-creased clearances are required. Additionally a gas permit may also be required if changes to the gas piping system are made. The 20.5 inches of clearance between the top of the cook top and the bottom of the microwave is more than adequate. The minimum amount of this clearance would be 14 inches (30 from the top of the cook top to the bottom of the counter above the microwave minus the 16 height of the microwave). This microwave can be installed above gas or electric ranges up to 36 wide. Since your new dual fuel range will only be 30 wide, the microwave can certainly be installed above this range using your current counter configuration. 1 All current over the range microwaves can be installed over gas cooking products up to and including 5 burner stoves. 2  As long as the 66 minimum from the floor to the top of the microwave is followed there will be no performance or warranty problem. 3  This includes Advantium ovens and convection microwaves. General List of Minimum Clearance Requirements. For proper air circulation and correct installation, some appliances must have air clearances around the product. Installations can vary, so checking the installation instructions to determine space requirements for your specific model is recommended. All ranges and cook tops require minimum clearance to combustibles (materials that fail to conform to ULC Standard CAN4-S114), whether the heating source is electric or gas. While gas ranges are approved for direct venting into the home, the ventilation code for newer homes requires a range hood of at least 100 cfm (cubic feet per minute) exhausting capacity to be installed above a standard 30 gas range or cook top. My understanding is that the clearance and ventilation required over a gas stove depends on the combined BTUs it puts out, so the numbers will depend on the stovetop you install, and will be listed in its specs. 3 Likes Bookmark June 29, 2013 at 8:15AM Thanked by r64obin. Thank you for reporting this comment.  The diagram below shows required clearance to combustibles for a typical residential gas range. High power pro type ranges must be looked at individually as their clearances are often much larger (e.g. in some cases directly above the cook top: 48 instead of 30, D in the diagram below). While gas ranges are approved for direct venting into the home, the ventilation code for newer homes requires a range hood of at least 100 cfm (cubic feet per minute) exhausting capacity to be installed above a standard 30 gas range or cook top. Where certified installation instructions do not prescribe these minimum clearances, one needs to refer to Section 7.32 of CSA B149-05, which requires a minimum 76.2 cm (30 inches) above, 15.24 cm (6 inches) from sides and back, and 121.92 cm (48 inches) in front of a gas or propane fuelled residential range. 
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clearance requirement for gas range