Heat pump repair in Centreville.

Three in four Centreville owners heat with gas, so the box out back is usually an air conditioner that sits idle all winter while a furnace does the work. About one owner in four heats with electricity, and in those homes that box is a heat pump that runs year round. They look almost the same. So when a Centreville call starts with no heat, we check the label and the lines before anything else, because the fix lives in different places.

Three quick tells. The outdoor unit’s nameplate or manual says heat pump. The thermostat has an aux or emergency heat setting. The indoor unit has no gas pipe and no flue running out of it. A gas house with a plain air conditioner gets a heating repair visit for the furnace instead. A heat pump house gets this one, starting with the $99 diagnostic.

Nearly half of Centreville’s homes are townhouses, most from the 80s and 90s, and in a lot of those rows the air handler sits in the attic above the top floor. The filter up there gets skipped because it’s a ladder job. When it clogs, the pump trips on high pressure in heat mode and the strips carry the house. If you can’t remember the last attic filter change, that’s the first thing to rule out.

The outdoor unit in these rows usually sits on a small pad beside the patio or the back gate. Every defrost cycle dumps meltwater, and on a hard morning that water runs onto the walk and freezes into a sheet. It’s a slip hazard, and if the pad has sunk, the ice can climb back into the base of the unit and lock the fan. Power-wise, most of Centreville is on Dominion, with some streets on NOVEC; tell us which if the trouble began with an outage.