Thermostat and Heating-Control Repair
A surprising share of no-heat calls are control problems, not equipment problems. Before anyone quotes a furnace or a boiler, it is worth knowing whether the thermostat, the wiring or the zoning is what actually failed.
Tell us what the system is doing when you call — that decides which truck and which parts head to your address.
When the thermostat will not call for heat
A thermostat with a blank screen, a dead battery, or no 24-volt power from the equipment cannot ask for heat no matter what it is set to. On systems where the thermostat is powered by a common wire, a blown low-voltage fuse on the control board — usually caused by a shorted wire somewhere in the run — takes the whole control circuit down and looks exactly like a failed thermostat.
We meter the control circuit at the equipment and at the thermostat to establish where the signal stops. That five-minute test regularly prevents an unnecessary equipment repair.
Wrong temperature readings and calibration
A thermostat reading several degrees off the actual room temperature is usually sited badly rather than broken: direct sun, a lamp or television underneath, an exterior wall, a supply register blowing across it, or a draft coming through the wall opening behind it from an unconditioned space. Sealing that opening alone fixes a lot of complaints.
Where the sensor itself has drifted we calibrate or replace it, and on systems with remote or outdoor sensors we verify those readings too. Cycle-rate and swing settings also matter — a thermostat configured for the wrong equipment type will produce temperature swings that feel like an equipment fault.
Wiring, control and zoning problems
Zoned systems add dampers, a zone panel and multiple thermostats, and any of the three can fail. A stuck damper, a failed damper motor, a zone board with a burned relay, or two thermostats wired to the wrong zones will make one part of the building uncomfortable while the equipment itself tests perfectly.
We trace the wiring, test the zone panel outputs, confirm each damper actually moves, and verify that each thermostat controls the zone it is labelled for. On boiler systems the same logic applies to zone valves and circulator relays.
Compatibility and replacement
Not every thermostat works with every system. Two-stage furnaces, heat pumps with backup heat, dual-fuel systems, communicating equipment, millivolt systems and boiler zone controls all have specific requirements, and a mismatched smart thermostat can cause short cycling, backup heat running when it should not, or a heat pump locked out entirely.
When a replacement is the right answer we confirm the wiring available, the equipment type and the staging, then configure the new thermostat properly for it — including heat-pump balance points and backup-heat settings — instead of leaving it on factory defaults.
Where we do this work
We work from 2093 Rand Rd, Des Plaines, IL 60016 and cover Cook and DuPage county communities plus Chicago. Every community is listed on our service areas page, or start with one of these:
Questions we are asked about this service
My thermostat is blank. Is the thermostat broken?
Not necessarily. A blank thermostat is often dead batteries or a blown low-voltage fuse on the equipment control board caused by a shorted wire. We test the control circuit before replacing anything.
The thermostat reads a different temperature than my thermometer. Why?
Usually placement — sun, a nearby lamp, an exterior wall, a draft through the wall opening behind it, or a register blowing across it. Sometimes the sensor has drifted, in which case we calibrate or replace it.
Will a smart thermostat work with my furnace or heat pump?
It depends on the wiring available and the equipment type. Two-stage furnaces, heat pumps with backup heat and dual-fuel systems all have specific requirements, and mismatched controls cause short cycling or backup heat that runs when it should not. We confirm compatibility before installing.
One zone never gets warm. Is that the thermostat?
It can be, but a stuck damper, a failed damper motor, a zone-panel relay or a bad zone valve is just as likely. We test the whole zoning chain rather than swapping the thermostat and hoping.
Related services
Schedule this service
Call 847-550-3322 for Des Plaines and the suburbs, or 773-250-6060 in Chicago. You can also request service online.