We read you columns in the Free Press every week, many thanks for the articles. We have one problem, which has not been addressed.
Our three bedroom and bathroom house, built in 1962, is a tri-level and the top floor has no cold air returns. This makes the top level very cold in the winter and unbearably hot in summer. We have hardwood floors throughout, and to alleviate this problem in the winter had wall-to-wall carpet installed in two of the bedrooms and a ceiling fan in the main bedroom for the summer.
Is there a possibility of having returns installed? We are planning on renovating (restoring the hardwood floors and having a new central air conditioner installed) and would appreciate any suggestions you may have.
For those homeowners that are not familiar with the specifics of forced-air heating systems, I will give some background on the function and need for return air ducting. I will also answer your question, but the difficulty of installing the new ducting may largely depend on the layout of the home, which cannot be determined without seeing the home.
Modern forced-air heating systems have two complete sets of ducting for movement of heated and cooled air through the home. The warm air ducting exits the furnace just downstream of the furnace heat exchanger. Air is blown around the heat exchanger by the furnace fan, which heats it before it enters the ducting and is distributed throughout the home. The heated air moves through the ducts and escapes through registers that open in the floor or walls in the various rooms. This is the part of the system that people are most familiar with, as they can feel the heated air when the furnace fan is running. For homes with central air conditioning, the system works the same way, with air being blown past the cooling coil in the ducting rather than the furnace heat exchanger.
The return air ducting is the lesser-known part of the system, as the registers are often not as noticeable as the warm air ones, because air is drawn inward. This return air enters the second set of ducts and is drawn toward the furnace, passing through an air filter, before entering the blower compartment, where the heating or cooling cycle repeats itself. The mechanics of how the return air is drawn back into the ducting is not important to fully understand, but we should know that it is important for proper operation. That is why a very dirty or blocked air filter can prevent proper air movement through the heating system. The return air is critical to effective operation of the system. If there is much less air returning to the furnace than is forced out, the system will not be balanced which may lead to uneven heating, as appears to be the case in your home.
To answer your question, it should be possible to install return air ducting to the rooms in which it is missing, but hiding the ducting may be the difficult part. Return air ducts are often installed in the cavities between the floor joists and covered by ceiling and wall finishes. Since your upper floor is fully finished, walls and ceiling finishes will have to be partially removed to accommodate the installation of the ducts. This will require removal of drywall and possibly wiring or other obstructions. The alternative to this is to install the ducting over top of the existing ceilings and walls, which will require building new boxes or chases to house the new ducting. This may be simpler, but having these blend in with the current décor and style of the home may be difficult.
Many split-level homes have less return air registers and ducts due the open design of the floor plan, which allows good passive air movement between the levels. That is likely why your home does not have return air registers in every room. There should, however, be at least one return air register on each level and in every room that has a door, such as bedrooms. If this is the situation in your home, then adding the appropriate ducting and registers will likely improve the heating and cooling considerably.
The sizing of the furnace and blower fan may also have some bearing on the effectiveness of the even heat distribution throughout the house. Upgrading to a more efficient furnace with a more powerful fan may also help the air movement in your upper level. The first step is to call a licensed heating contractor for an assessment of the needs of your home. The contractor should do a site visit and inspection and calculations to determine the proper locations for new ducting and registers. They should also be able to tell you if your current furnace and fan is adequate to provide heat for the home, or whether upgrades are required. You may also get some helpful advice on improving the situation with less drastic measures than a complete renovation and new ducting installation.