149156 – SUPPLY AIR TEMPERATURE SENSOR (DISCHARGE, DATS)

Braeburn replacement supply air (discharge air) temperature sensor for Braeburn zoning systems. In a Braeburn zone panel the supply air sensor monitors plenum temperature and provides adaptive staging plus supply air limit protection, staging or shutting down equipment before the plenum goes out of range. Braeburn lists it as a replacement part for the 140332 and 140404 Premier Series zone panels, the 140303 Economy Series zone panel, and the 7500 and 8500 BlueLink wireless thermostats.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• TypeReplacement supply air (plenum) temperature sensor
• FunctionMonitors plenum temperature; adaptive staging and supply air limit protection
• Compatible zone panels140332 and 140404 Premier Series, 140303 Economy Series
• Also listed with7500 and 8500 BlueLink wireless thermostats
• Warranty1-year

Do I need a C wire?

For almost any Wi-Fi or smart stat, yes. A screen, a radio and a relay board need continuous 24 volt power, and the C wire is that return path. Battery-only and power-stealing installs are where the nuisance calls come from, with stats that reboot, short cycle, or bump the blower for a second at a time to steal charge. If you only have four conductors at the wall, your options are to pull new 18/8, repurpose an unused conductor at both ends, or use an add-a-wire adapter at the board.

What is O/B and why does it matter?

On a heat pump, O/B controls the reversing valve. Most brands energize it in cooling, which is the O terminal. Rheem and Ruud energize in heating, which is B, and so do Weathermaker, Ameristar and residential Bosch air-source. Get it backwards and the system blows cold on a call for heat and hot on a call for cool. Confirm it off the wiring diagram on the unit rather than guessing by brand, because it varies inside product lines.

Will any thermostat run my system?

No. A communicating system of the ComfortNet, Infinity or Evolution type needs its own matched stat on a two-wire data bus, and a conventional 24V stat will not run it. Two-stage, dual fuel and heat pumps with auxiliary heat need enough terminals plus the right setting in the configuration menu. Millivolt and line voltage equipment take entirely different stats.

The thermostat screen is blank. Bad stat?

Check the board fuse and the float switch first. A blank display almost always means the 24 volts is gone, not that the stat died. A blown board fuse, a tripped condensate safety, an open blower door switch, or a rubbed-through wire in the attic account for most of them.