f3s thermal: document rack position effect on f-host temps

f0 sits at the bottom of the rack with a fan directly underneath,
so it consistently runs 10-15°C cooler than f1/f2 at the same load.
f1/f2 are higher up in warmer rising air with no dedicated airflow.
Do not use f0 as a baseline when comparing temps across hosts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/prompts/skills/f3s/references/storage/troubleshooting.md b/prompts/skills/f3s/references/storage/troubleshooting.md
index 7f7adfd..756c36a 100644
--- a/prompts/skills/f3s/references/storage/troubleshooting.md
+++ b/prompts/skills/f3s/references/storage/troubleshooting.md
@@ -124,10 +124,12 @@ Observed ranges (coretemp per-core die temps via `sysctl dev.cpu | grep temperat
 
 Real-world observations (2026-05-17, post-reboot, k3s + bhyve running):
 - f3 (light load, no k3s): 43–44 °C — reference baseline
-- f0 (after drive reseat + cleaning): 64–66 °C — healthy
+- f0 (after drive reseat + cleaning): 64–66 °C — healthy; f0 sits at the bottom of the rack with a fan underneath, so it runs cooler than f1/f2 regardless of workload
 - f1 (full k3s + ZFS): 76–77 °C — elevated but within range
 - f2 (full k3s + ZFS): 79–80 °C — near concern threshold; physical check recommended
 
+**Rack note**: f0 is at the bottom with a direct fan underneath — do not use f0 as a temperature baseline for f1/f2. f1/f2 sit higher in the rack in warmer rising air with no dedicated airflow. A 10–15 °C delta between f0 and f1/f2 at similar load is expected and normal.
+
 NVMe sits close to the CPU in the small chassis — both heat each other.
 The enclosure gets hot to the touch before temps fully register in software.