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Homeowners know when they are cold and they know where the cold is. They may not know how to turn on a pilot light, or air-seal an attic floor, or balance a home’s heating system, but they know when they’re cold. Bedrooms are often the coldest room in the house and most of the time people just live with it. Put the child in the cool bedroom, throw a couple of extra blankets on the bed, and tell him to finish his homework.
Dealing with a cool bedroom is frustrating. If you turn up the temperature to heat the room, the rest of the house gets too hot. Close all heating registers except the bedroom and put too much back pressure on the furnace. Too often I see a home try to adjust the temperature of one room by turning off the heating registers in other rooms and soon they have half the registers in the house closed and the home’s heating system working overtime to meet the request for heating on the thermostat.
Typically, the home’s heating system is designed by a professional heating contractor who has attended HVAC school for several hours a week for several years. A heating contractor must pass an apprentice program before he or she can take the exam for their journeyman license.
HVAC Education
During the educational phase of heating and cooling training, they are taught how to do a home heating load calculation. They take the heating load and develop a designed heating system that includes furnace size, fan capacity, duct size, airflows, and register size. In other words, heating systems are designed to heat all rooms evenly and to work as one system with all registers open.
If you have a bedroom that is cooler than the rest of the house, one of two things has happened:
- The heating system was designed by a contractor who barely passed the test, or
- the heating system is broken.
A homeowner recently complained that too little air was coming out of the heating register in his dining room. The dining room was cooler than other parts of the house. With a flow hood, I recorded a 75% decrease in airflow in the register compared to the register in the living room. I removed the register grate, got a flashlight and mirror and looked inside the heating duct.
Using the mirror to see around the initial elbow, I could see that a damper valve was installed in the heating duct. Further inspection showed that all heating ducts in the house had a damper installed near the registers. The dining room hatch was the only one that was mostly closed. The owner did not know that the flow dampers were part of the heating system of the houses.
Heating duct damper
Flow dampers are a bit unusual in my neck of the woods, I don’t see them very often. Flow dampers are added to a heating system to allow manual adjustment of airflow to the registers. With dampers, the flow of air conditioning can be balanced so that hot and cold areas of the house can be eliminated. To avoid increasing pressure on the heater blower motor, when one damper closes, another damper must open.
Sometimes I think a heating contractor can throw a bunch of flow dampers when he loses his pencil and can’t be sure how big the heating ducts need to be or how many registers need to be in a room.
6 ways to turn up the heat in a cold bedroom.
Repair of heating ducts:
There is always the possibility that the duct system has a problem that can be fixed. Ducts can be partially or completely disconnected and flexible ducts can be crushed or collapsed. This is the first and most important solution considering the cold bedroom. This solution will not only heat the bedroom, but also increase energy efficiency and energy savings.
The first step is the inspection of the conduit that goes from the camera to the register to make sure that it is well connected. Also, look for holes, folds, or collapsed areas. Animal damaged heating ducts is also a possibility you should be looking for.
Disconnected heating ducts can be reconnected, but damaged heating ducts usually need to be replaced as they are difficult to repair.
Check if there is a damper:
The clever heating contractor may have put a damper in the heating duct and is keeping it a secret. Look and feel inside the duct by removing the manhole cover. Also, remove the insulation from the outside of the duct, especially near the register, and check for telltale signs of a damper. A metal bar with a small handle and some anchor bolts indicate a shock absorber inside. Open the hatch and your cold room problems may be over.
Balance room pressure with a crossover duct:
Now we have to talk about room pressure and balloons. Open the door to the room an inch, turn on the furnace and see if pressure builds up in the room and close the door.
The heating system is an air circle. Air is heated in the heater, pushed through the heating ducts into a room, and then sucked out of the room by the heater itself, back through the return air duct to the heater. If air from the room cannot return to the furnace, the room builds up air pressure, like a balloon, restricting the flow of conditioned air into the room in the first place.
With a pressure increase in the bedroom, the air conditioner is forced through a different duct into an adjoining room.
To address the potential problem, many homes have crossover ducts installed in the ceiling or above the door that allow air from the room to return to the hallway even when the door is closed. In some larger, higher priced homes, they may have eliminated the room pressure problem by installing a return air register in each room.
To balance room pressure and stop this problem, the two most commonly used repairs are to install cross duct through the wall above the door or simply cut the bottom of the door so there is a wider gap between the door and the carpet.
Increase the size of the duct:
Maybe the heating contractor ran out of 8-inch duct, so he decided 6-inch was close enough. There is a real possibility that the back bedroom is cool because the heating duct system was not designed correctly. When this happens, the best solution is to correct the error and replace the duct with a larger one. If the house is fairly new and the contractor is still around, you can do this as a freebee.
In this way, the cold room will receive a greater part of the air coming from the oven. This repair can still be a do it yourself if you are willing. Both ribbed and flexible heating duct material can be purchased at your favorite home improvement store. Some zip ties, some sheet metal screws, a sharp knife and a pair of tin snips should do the trick.
If the heating duct size is simply too small to service the room, aside from replacing the duct with a larger one, the only other solution that might work is to install a booster fan in the duct or add a second full duct and registration.
duct fan
Place a baffle in the heating chamber:
This adjustment can be very effective, especially in a manufactured home. A section of the main heating duct (the plenum) must be opened up so that a baffle or metal shield can be placed in the main duct line that will direct more air to the heating duct going to the walk-in cooler. This is a very effective way of capturing more of the conditioned air that is going through the main heating duct and directing it in the direction you want it to go. This is an inexpensive, permanent solution that works very well.
Install a booster fan in the duct:
This $30 part will not generate more heat, but it will draw more heat into the cold room. The booster fan should be installed as close to the affected room as possible and can be connected directly to the heater fan so that the booster fan runs every time the heater is turned on. Installing it can be a pain. A section of round metal conduit must be lowered or added to the system. Make sure the duct system is air sealed or this extra fan will draw unconditioned air into the system and reduce its energy efficiency.
I know dealing with a cold spot in your home can be a frustrating ordeal. I hope I have provided some solutions to the problem that will work for you and your home. Your home heating system was designed to give you the comfort you expect and deserve, and with a little care, it will provide years of energy-efficient service.
Thanks for stopping by Detect Energy, I hope to see you again soon, but I won’t leave the light on for you… Don Ames