Differential pressure per floor · diagnosing ERV/HRV vs. atmospheric appliance backdraft
CHECKING—
Cross-section
Δ Pa vs. outdoor reference (when tubed)
Per-floor detail
last 60 s
Combustion context
from hvac.lucheestiy.com
Pressure timeline
— · raw readings + appliance overlays
boiler runningwater heater estimated firing
Hourly averages
— · raw samples grouped by hour
Context
House has an active backdrafting problem when ERV (1st floor) + HRV (2nd floor) run — atmospheric gas boiler & WH in basement share a chimney flue. The basement's continuous 4" supply fan is undersized vs. combined upstairs exhaust.
What this dashboard tells you: each floor's pressure relative to its outdoor reference. A healthy basement reads near zero or slightly positive. Sustained negative basement pressure while gas appliances are firing = real CO risk.
Sensor: Sensirion SDP810-500Pa on Olimex ESP32-POE-ISO. 1 Hz sampling, 60 s averaging.
Diagnostic only — not in any safety interlock chain. Keep your UL-2034 CO alarms on every floor.