Alumasc Harmer Roof AV is an economic, general purpose range of outlets that provides anti-vortex performance. Harmer Roof AV incorporates a patented baffle within the grating to prevent water swirl and air entrapment, enabling the outlet to drain at 90% of its pipe capacity.

The Harmer AV Multi Gulley roof outlet is designed to provide multi-directional drainage. Rotated on site, the interchangeable spigot pipe allows for any angled outflow from vertical to horizontal. It directly connects to PVC O-ring socketed pipe or to cast iron and HDPE pipework by means of a suitable coupling.

General information


Cast in grade LM6 aluminium silicon alloy

Specification data

Product Reference

Harmer AV Multi Gulley roof outlet


MAV75, dome grating, 75 mm pipe

MAV75/F, flat grating, 75 mm pipe

MAV100, dome grating, 100 mm pipe

MAV100/F, flat grating, 100 mm pipe

As drawing ___

Contractor's choice



Grate extension piece

Not required

23 EP, aluminium, 150 mm diameter

46 EP, aluminium, 222 mm diameter

As drawing ___

Contractor's choice

Terrace grate

Not required

23 TG, aluminium

Use with 150 mm diameter grate extension to raise terrace grate to level of paved surface.

46 TG, aluminium

Use with 222 mm diameter grate extension to raise terrace grate to level of paved surface.

As drawing ___

Contractor's choice

Metal deck support plate

Not required

SP1, 50/75 mm pipe diameter

SP2, 100/150 mm pipe diameter

As drawing ___

Contractor's choice

Standard product features


Cast in grade LM6 aluminium silicon alloy.

Diameter (visible):

305 mm.

Pipe diameter:

  • MAV75 range: 75 mm.
  • MAV100 range: 100 mm.

Flow rate:

  • MAV75 range: 4.97 L/s.
  • MAV100 range: 9 L/s.

Product Options


– Grate extension piece:

  • For applications where it is necessary to raise the level of the grate above the body of the outlet such as in inverted roof construction. Extension pieces can be cut down if necessary to suit thickness of paving or tiles.

– Terrace grate:

  • Designed for installation in terrace tiles or brick paviors. Used in connection with grate extension pieces which raise the terrace grate to the level of the paved surface. Adjustable through 90° to suit surrounding paving prior to final tightening.

– Metal deck support plate:

  • Recommended for use where Harmer Roof metal and insulated outlets are installed in metal deck roof construction. Designed to provide a secure and stable junction between roof deck and rainwater outlet. Manufactured from 1.5 mm (16 gauge) steel sheet, finished in red oxide.

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