Almost every North Jersey house has one: the bedroom over the garage, the back room on the second floor, the finished basement that never warms up. One room colder than the rest is one of the most common heating complaints we hear in the fall. The good news is that the cause is often simple, and you can check several of them yourself before calling anyone.
Start with the easy checks
- Open every vent or register in the room and make sure furniture, rugs or curtains aren't covering them. A blocked supply vent is the most common cause, and the cheapest fix.
- Don't forget the return vent. If air can't get back to the furnace from that room, warm air has a hard time getting in.
- Check the furnace filter. A clogged filter cuts airflow, and the rooms farthest from the furnace feel it first. See how often to change your furnace filter.
- Look at the thermostat's location. A thermostat in a sunny or warm spot shuts the heat off before the rest of the house is comfortable.
- Close the door and feel for drafts. Old windows, an uninsulated wall or a room over an unheated garage can lose heat faster than the system can replace it.
If you have forced-air heat (a furnace)
Warm air travels through ductwork to each room. If the duct to one room is long, crushed, disconnected or leaking into the attic or a crawl space, a lot of that heat never arrives. Many homes also have balancing dampers, small levers on the ducts near the furnace, that someone closed years ago for summer cooling and never opened again. A technician can check duct connections, measure airflow at each vent and rebalance the system.
If you have hot-water heat (a boiler)
- Air in the radiators or baseboard: a radiator that's warm at the bottom and cold at the top usually needs to be bled. Use a radiator key, open the bleed valve slowly with a rag underneath, and close it once water comes out steadily.
- A stuck zone valve or a failed circulator pump: in a zoned system, each area of the house has its own valve or pump. If one stops working, that whole zone stays cold while the rest of the house is fine.
- Low system pressure: if the boiler's pressure gauge reads low, water may not reach the top floor. This is a job for a technician.
When zoning makes sense
Some houses are simply hard to heat evenly from one thermostat: a cape with a finished upstairs, a big addition, or a home with rooms over a garage. Zoning splits the house into areas with their own thermostats. With a boiler, that usually means a separate circulator pump or zone valve for each zone. With a furnace, it means motorized dampers in the ductwork controlled by a zone panel. Whether it's worth it depends on the house, so it's worth a conversation before you spend money on space heaters.
Safety first
Space heaters are a common stopgap, but keep them away from beds, curtains and furniture, and plug them straight into the wall, not into an extension cord. If you ever smell gas, get everyone out and call your gas utility or 911 from outside.
How we help
Our NATE-certified technicians check the whole picture: the furnace or boiler, the filter, the ductwork or piping, and the room itself. We start with a $79 diagnostic, credited toward the repair if you go ahead, and give you a written price before any work starts. We offer same-day service, answer the phone 24/7, and every job comes with our 1-year parts and labor warranty.
Learn more about furnace service and boiler and hot-water heating, or read our furnace tune-up checklist.
- Why is one room in my house always cold?
- The most common causes are closed or blocked vents, a dirty furnace filter, leaky or disconnected ductwork, closed balancing dampers, or poor insulation. With hot-water heat, air in the radiators or a failed zone valve or circulator pump is often the cause.
- How do I know if my radiator needs bleeding?
- If a radiator is warm at the bottom and cold at the top, or you hear gurgling, it likely has trapped air. Bleeding it with a radiator key usually fixes it.
- Can zoning fix uneven heating?
- Often, yes. Zoning gives different areas of the house their own thermostats. It works best in homes with additions, finished upper floors or rooms over a garage.
- How much does a heating diagnostic cost?
- Our diagnostic is $79, and it's credited toward the repair if you go ahead with the work.