Suspended or platform install of horizontal furnace

What is going on

Horizontal units can hang from roof rafters or joists, or sit on a raised platform. Plan for service and drain access in either case.

Check in this order

1. Pick the location with service and required clearances in mind (see clearance figure 15).
2. For a platform, build a raised wood frame covered with plywood. If it sits over finished space, add an auxiliary drain pan under the unit.
3. Leave 8 in. of service clearance below the unit for the condensate trap.
4. Keep a service platform in front of the unit. In a crawl space, cement blocks can serve as the support.
5. Run the auxiliary drain line so water leaving it is easy for the homeowner to see.
6. If needed, use a condensate pump rated for condensing furnaces to meet slope. Protect the discharge line to the outside from freezing.
7. Hang straps so both ends are supported. Straps must not block the plenum or exhaust piping. Support cooling coil and plenums separately.

More furnace guides

• Annual planned service inspection
• Annual service checklist
• Blower access panel and carbon monoxide hazard
• Burner assembly cleaning
• Change blower speed tap
• Check temperature rise and adjust blower speed