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Rheem · Furnace troubleshooting

Multiventing two or more direct-vent furnaces

96V

What is going on

Each furnace must have its own individual vent. Common venting is not allowed. Spacing rules depend on how many terminations are installed.

Check in this order

  1. Vent each furnace individually. Do not common-vent.
  2. With two furnaces, keep the terminations more than 8 in apart.
  3. With two furnaces, keep the terminations under 24 in apart or over 36 in apart.
  4. When more than two furnaces are vented, keep at least 4 ft between the first two furnaces and the third.
  5. For the third and any further furnace, keep each new termination more than 48 in from the previous one.
  6. Keep the termination at least 12 in (US) above average snow accumulation or grade, and no more than 24 in above the roof.
  7. If the vent rises more than 24 in above the roof penetration, add extra support.
  8. If 3 in venting is used, reduce both intake and exhaust pipes to 2 in before they go through the roof.

Applies to: Direct-vent installations with two or more furnaces

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Source: 96V series installation instructions, p. 66. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.