Give the installer the pattern, not a guessed repair
Save the installation date, model information, previous service reports, and dates of lockouts. Include safe ground-level photos of the frost and surrounding terminations. Tell the installer what weather preceded each event and whether the same opening is affected every time.
Record a fault only if it is available on the ordinary display or through an existing viewing window. Do not open the furnace or erase its fault history.
Ask the installer to distinguish the observed frost from the measured reason heating stopped. That keeps “intake icing” from becoming a label applied without checking the equipment.
The installation needs its own review
For example, Lennox's EL296UHE (February 2013) instructions show several different vent termination arrangements with their own pipe and clearance requirements. An approved drawing must match the actual model and arrangement. Lennox venting instructions.
We recommend asking the installer to show which applicable instruction the current installation follows. Then ask what site condition could explain the recurrence: exhaust returning toward the intake, snow exposure, surrounding structures, or another issue identified during testing. These are assessment questions, not a diagnosis from the photo.
If relocation or a different approved vent kit is proposed, request its full scope and why it addresses the finding. An exterior change must be evaluated as part of the complete installation. Do not assume an added fitting is harmless because it appears small.
Close the recurring concern with a usable record
Ask for a written report identifying what was found, what changed, what was tested afterward, and what remains uncertain. If the troublesome weather is absent during the visit, ask how the correction will be followed through under similar conditions.
Clarify who owns that follow-up and what charge or warranty terms apply. “New” does not establish every labor, travel, or installation charge is covered. Equally, a claimed exclusion should be explained from the actual terms.
Your household needs a reliable plan while the issue remains open. Confirm repair timing, an update contact, and whether you need another warm place to stay if heat cannot be maintained. Do not rely on repeated nighttime resets as the plan.
Your next action is to request an installation-focused recurrence review, with the earlier reports and frost pattern in one place. That helps the next visit address the cause rather than repeat the last temporary result.