The biggest advantage of the room-by-room approach is easy zoning, with each heating device controlled by its own thermostat (or by you). It can also be a logical choice for a new addition if extending your existing system isn’t an option.
With room-by-room systems, there is usually no distribution heat loss, and unlike central systems, they don’t consume energy running a fan or pump. They are also flexible and easily adapted to new layouts—and if one unit fails, you still have heat in the rest of the house.
Portable electric radiators can be a cheap, quick way to heat a room. Plug-in radiators can be moved to warm up cold spots. The best ones are filled with fluid, so they heat up and cool down more slowly. They don’t need a special outlet, but they will put a big demand on an electrical circuit. If the room is so cold that you need the radiator on full-time, a built-in solution is better—and easier on your circuits.
There are also gas-, propane-, and kerosene-fired portable heaters, but these must be vented to the outside or the CO they can produce will be a deadly threat.
Direct-vent gas wall heaters may be appropriate for a one-room addition if your central system can’t easily be extended. These sealed-combustion units mount on an outside wall, need no ductwork, and can be very energy efficient. Some require electricity, and some do not. Some come with fans, and some provide air conditioning. [FIG
Natural-gas fireplaces are not particularly energy efficient. The energy-saving models are direct-vent, meaning they’re ducted to the exterior, have exterior air intake, have sealed glass doors, and are controlled by an electric switch. A fan moves the warmed air into the room.
A woodstove is one of the best choices for sensory appeal, and a well-built stove is fairly efficient at burning wood or pellets. But a woodstove is very high maintenance, and the chimney, outdoor air ducts, hearth, and firewood storage take up a lot of space.
As is true of other radiant-heat sources, wherever you can see the stove, you can feel its heat; the closer you are, the warmer you feel. But if you can’t see the stove, you can’t feel the heat, which influences furniture placement. Woodstoves also present a significant fire hazard. That said, adding a very efficient wood-burning insert (with external combustion) to an old fireplace is an excellent choice, provided you have easy access to firewood. Correct installation is crucial for safety and efficiency.
Ductless heat pumps, or mini-splits, have an outside unit, often called the condenser, and as many as four inside units that deliver winter heat and summer cooling. They allow for easy zoning (each room can have its own thermostat), and they save a lot of space by eliminating ducts. However, a separate indoor unit must be installed in each room. Mini-splits are highly visible, they take up space, and the fan is audible—probably more audible than the central fan of a ducted heat pump system. Having several units places limits on where you can put the furniture. Mini-splits can be hung from the ceiling, recessed in a suspended ceiling, or mounted on walls or floors.
The controller and installation are currently the weak links in a mini-split system. Make sure the installer commissions the control system in both the heating and the cooling mode.