What people keep running into with heating
Complaints tagged heating, each raised by more than one person. One-off posts are not included.
76 recurring problems · 920 people · 18 forums we read
Raised more than once
Most people first.
- 4Furnace won't turn on after new AC installationThe gas valve may have been left closed or something was missed during the recent HVAC installation, preventing the furnace from starting up when the weather turns cold. Homeowners worry that waiting too long to report the issue will make the warranty company or contractor upset about the delay.
- 4Oven igniter glows bright orange but gas won't turn onA glowing igniter that fails to open the safety valve usually means the igniter is too weak to draw the necessary electrical current, even though it still gets hot. This prevents the gas from flowing, leaving the oven unable to heat up despite the visible glow.
- 4Furnace lights up briefly then hums and shuts offThe heating system attempts to start and ignites momentarily before making a humming noise and shutting down completely. This failure prevents warm air from blowing through the vents, leaving the house temperature unchanged regardless of thermostat adjustments.
- 4Is my wood stove installation safe to use?Tenant evaluation of a rental wood-burning stove often involves confusing structural modifications like strange concrete pieces around the flue and unusual flame colors during the first fire up. Because renters cannot easily verify whether these anomalies indicate dangerous venting blocks or normal operation, they are left guessing if it is safe to light a fire.
- 4Why is my boiler making a constant humming noise when heat is on?A constant humming or whirring sound that starts when a specific heating zone turns on and stops the moment it turns off is typically tied to active heating components in that circuit. This persistent background noise can drive homeowners mad, especially in a quiet house, leading to concern that an older or newly installed unit is developing a fault.
- 3How to stop cold drafts coming through a sliding glass doorPoorly sealed or misaligned sliding doors let in freezing air that turns an entire room into an icebox, leaving noticeable gaps even when the door appears closed. This draft makes it impossible to keep the space warm without blocking off adjoining doorways or constantly fighting with faulty hardware.
- 3Loud howling and whistling noise from vents after replacing blower motorSystem replacements like a new blower motor or squirrel cage often alter airflow dynamics, and if technicians skip installing a necessary bypass damper due to space limits, the system creates intense static pressure and howling. This leaves homeowners with a constant, disruptive noise through their vents and rooms blowing air even when their specific zone isn't calling for it.
- 3Propane boiler making puffing exhaust noise in extreme coldWhen temperatures drop significantly and multiple zones call for heat, propane boilers can develop a rhythmic puffing exhaust noise that may escalate into a loud whistle. This issue can persist even after replacing the fan and cleaning the unit, forcing homeowners to shut the system down manually.
- 3Grinding sound when turning off a new HVAC unitA brand new HVAC unit often makes a grinding noise at shutdown that leaves homeowners questioning if it is normal. This unexpected sound creates immediate worry over a fresh installation and leaves owners unsure whether to trust the technician's reassurance or demand a service check.
- 3How to know if I need an 80k or 100k BTU furnaceContractors often give conflicting estimates and recommendations, leaving homeowners unsure whether to downsize or stick with their current capacity. This confusion makes it difficult to choose the correct size without risking a home that is either underheated or overpaying for equipment.
- 3Why is my furnace inducer motor spinning slow and making noise?A sluggish inducer motor can spin slowly and make a liquid-y noise that prevents the heating system from starting. Replacement motors often produce an annoying fluorescent light or generator hum that is much louder than the original unit. This leaves homeowners wondering whether the loud humming is normal or if they should demand an OEM part.
- 3Why is my heat pump always running on emergency heat in the winter?Heat pumps frequently switch to expensive auxiliary or emergency heat during cold months, causing winter electricity bills to skyrocket to $600 or even $950. This forces homeowners to keep their thermostats as low as 65 degrees while still dealing with freezing temperatures and unaffordable power costs.
- 3Why is ice building up on my furnace exhaust?Heavy ice builds up outside on furnace exhaust pipes during winter, forcing homeowners to go out and knock it down every three to four days. It leaves people wondering whether this constant freezing is a normal amount of ice accumulation.
- 3Do mini-split heat pumps need a backup heat source in freezing weather?Mini-split systems can handle extreme cold up to a certain threshold — such as around -35°C — after which they stop heating and leave rooms unusable without alternative warmth. As outdoor temperatures drop, longer runtimes of 30 minutes or more are normal, though it can be difficult for homeowners to tell if this indicates expected behavior or an early warning sign of trouble.
- 3How to replace an old mercury thermostat with a programmable oneOld mercury tube thermostats often use just two or three wires for furnace-only heating systems, which can make wiring a new programmable model confusing. Accidentally touching the wires together without turning off the power can blow the low voltage fuse, requiring a fuse replacement before the new unit will work.
- 3Why won't my new thermostat turn on the heat?New thermostat installations often fail to communicate properly with heating systems, causing the unit to incorrectly call for cooling or prevent the furnace from igniting. This configuration or wiring mismatch can successfully trigger the blower fan while failing to activate the boiler's circulator pump, leaving the home without heat.
- 3Navien boiler has no hot water and shows T High errorWhen a combi boiler provides central heating but no hot water through the taps—often accompanied by a circulation flow rate warning like the Navien T High error—the unit fails to switch over or heat the water properly. This leaves households completely without hot water until the flow restriction or sensor issue is resolved.
- 3How to turn off a thermostat when the system smells like burning hairThe thermostat controls only allow setting the system to heat or cool at specific temperatures, making it impossible to shut down the malfunctioning system without accidentally triggering the HVAC. This leaves people unable to stop a dangerous burning smell or prevent the unit from randomly turning back on.
- 2Can I reuse electrical wires that got wet and hot?Electrical wires that overheat underwater or look "cooked" after heavy seasonal use leave homeowners unsure whether the wiring is safe once dry. This uncertainty makes it difficult to decide whether to replace the damaged cables or continue using them without professional help.
- 2Using a tankless water heater for radiant floor heatTankless water heaters used for radiant heat systems frequently suffer from black magnetic debris choking the inline filter and face skepticism from professionals who insist on boilers instead. This leaves homeowners struggling to select the right replacement setup, manage magnetite buildup, and handle simultaneous household hot water demands without running out.
Comes up alongside
Topics that keep appearing on the same problems — not topics with similar names.