customer called a cheapo for wiring, now the furnace is toast

got a repeat client who balks at my rates and hires some fly-by-night guy for a simple thermostat swap. shows up today with smoke smell and no heat. turns out the hack crossed the r and w wires, backfed the whole 24v system straight to line voltage. unit's control board fried, and there's scorch marks on the junction box. now they're begging me to fix it quick, but it'll cost double what the original job would've. these diy disasters never end well.

damn, that's a classic mixup. r to hot leg? instant barbecue.

rip it all out and redo from the panel. anything less and it'll bite you later.

how'd the air handler look? bet the blower motor took a hit too from the voltage surge.

clients like that learn the hard way. charge 'em premium for the cleanup.

seen this twice last month. handymen think color coding is optional.

you document everything? pics of the mess for the invoice helps when they whine about cost. i always snap before touching, shows the fire hazard they almost had. then quote the full rewire with new parts. makes 'em think twice next time.

furnace been puffing sooty exhaust? that backfeed probably shorted the igniter too.