Whether you're adding a family room, enlarging the kitchen or creating a brand new master suite, you're going to need to provide heat (and probably air conditioning) for the new space. That can be as simple as adding some ductwork (for forced air systems) or hot water piping (for houses with radiators) to the existing network.
But there's another option that's often far better. Known as a split system or ductless heat pump, it consists of two main parts: A blower unit that gets installed in an exterior wall and a condenser unit that sits on the ground outside, much like a standard central air conditioner has. But a heat pump can do much more than a standard system. For one thing, it not only cools in the summer but it also provides heat in the winter. Here are some reasons why you might want to go with this option:
If your existing systems can't handle the new space and you're not prepared to replace everything now. Sometimes the old furnace and/or air conditioner aren't big enough to take on the added load of the new space. Or they may be reaching the end of their service life, so you'd need to do a complete replacement in order to have one system for the newly expanded house, says Castle Rock, Colo., design-build contractor Dean Bennett. Replacement could add $5,000 to $10,000 or more to your costs, so if that's not in the budget, you can postpone the upgrade and put in a split system to handle the addition.
If the old and new spaces have very different heating and cooling needs. When you extend the existing ducts (or heating pipes) into the new space, it can be tricky to get the temperature in your addition to align with the rest of the house. If the addition is on the far side of the house from the air handler, it may get insufficient heating and cooling power. If it's better insulated than the old house, on the other hand, and is close to the air handler, it may get too much heating and cooling. And if it has a lot more sunny windows than the main house, it may need an extra boost of cooling. Because a split system has its own thermostat (usually in a hand-held remote) and works independent of the rest of the house, you won't have any of these balancing problems.
If your locale has strict air conditioning regulations. Existing systems are "grandfathered," meaning they don't have to meet modern efficiency standards. But if you start altering those systems by expanding them to incorporate an addition, the grandfathering is over and you'll need to bring it up to date. In California, for example, adding onto an air conditioning system often means you not only have to replace the condenser with a modern unit, but you have to test all the old ductwork for leaks and quite possibly replace it as well. "It's really a can of worms for anyone building an addition," says Curt Schultz, a Realtor-architect-builder in Pasadena, Calif.a state with some of the strictest codes around. "So most people are doing split systems these days." Because that avoids any work on the old equipment, the homeowners save thousands.