Allied Furnace: Sizing intake and exhaust vent pipe
Sizing intake and exhaust vent pipe on a Allied furnace: Use the tables and flowchart to size pipe. Both intake and exhaust must use the same pipe diameter.
Applies to: Non-direct vent and direct vent installations
How to fix sizing intake and exhaust vent pipe: step by step
- Confirm the furnace capacity: 045, 070, 090, 110 or 135.
- Confirm the altitude.
- Choose the termination type: standard or concentric (table 3).
- Identify whether intake or exhaust has the most elbows, and count them.
- Choose the desired pipe size (2 in., 2-1/2 in., 3 in. or 4 in.).
- Use table 5 to find the maximum intake or exhaust length. Size intake and exhaust separately, and check the minimum length in table 4.
- The exhaust collar accepts 2 in. schedule 40 pipe. In horizontal runs, step up to a larger pipe only in vertical sections, after a 2 in. elbow.
- Do not transition from smaller to larger pipe in horizontal exhaust runs. Keep any 2 in. step-up PVC as short as possible.
If the unit shows an error code, look it up: Allied Furnace codes
Models
92G1UH92G1UH0450892G1UH0451292G1UH0700892G1UH0701292G1UH0901292G1UH0901692G1UH1101692G1UH1102092G1UH1352095G1UHA93UHA95UH
Source: Allied 92G1UH installation manual, p. 21-22 (PDF p. 21-22). Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.