Mini-Split Heat Pumps
I’d like to mention an option for heating and cooling a modular home. It’s a ductless, mini-split heat pump. The technology is not new, but it has improved so much that I’ve recently taken a closer look at it, and I like what I see. In fact, we’re going to replace the HVAC system in our T-Ranch model home with one of these systems.
Why Today’s Mini-Split Heating and Cooling Systems are Better
In the past, heat pumps did not work well in the northeast because of the cold winters. But heat pump technology has improved so much that these mini-split delivery systems can take care of your heating needs on all but the coldest winter days. They also can keep you cool in summer.
Mini-split systems have also become more viable because today’s building code makes their job easier. The “thermal envelope” of all homes built today is so energy efficient that heating and cooling systems have to work less to maintain a home’s temperature, even in more extreme temperatures. Given that modular homes are especially well insulated and air sealed, they make it even easier to take advantage of mini-split systems.
How Ductless Mini-Split Heating Systems Work
Like central forced air systems, mini-split systems place the compressor and condenser outside the home. But they don’t need a single air handler in the basement or attic to distribute the conditioned air through a network of ducts. Instead they use thin tubing that pumps refrigerant from the outside unit directly to a single wall mounted unit in each room.
Advantages of Mini-Split Systems
The use of individual units for each room allows flexibility in where the heating and cooling can be delivered. Since one outdoor unit can be connected to as many as four indoor units, you can control the heating and cooling in several zones or rooms independently of each other.
Mini-split systems are less expensive than gas or oil central air systems when you factor in the cost to install insulated and well-sealed ductwork that meets the current energy code. They also offer higher efficiency (up to 27.1 SEER). Not only is the core technology of mini-split systems more energy efficient, but it also avoids the energy losses associated with the ductwork of conventional HVAC systems, even ones insulated to current energy codes.
Another advantage to mini-split systems is that they offer greater interior design flexibility. You don’t need to enlarge walls or lose headroom in your basement or floor space in your attic to accommodate the ductwork. The indoor air handlers can be hung on a wall or mounted on the ceiling. Many systems include a remote control to adjust the system when it’s positioned on a wall or ceiling.
A ductless system is a great solution for building an addition to a home. You get both heating and cooling for a reasonable price and you don’t need to hook-up to the existing system, which may not be sized for the additional load.
Disadvantages of Mini-Split Systems
There are a couple of disadvantages to mini-split systems. One, of course, is that they can’t keep your home warm when it is bitterly cold, say below 10 degrees. You will need a supplemental heating system for those days. Electric resistance heat is a low cost solution. Also, keep in mind that heat pumps are not able to bring a cold house up to temperature quickly.
Another disadvantage is that the indoor air handlers of a mini-split system are not silent, since they blow air through a grill. But they also aren’t loud. If you are particularly sensitive to a low level whoosh, find someone with an installed system so you can hear it for yourself.
Finally, take a close look at the photo posted here and make sure you’re comfortable with the appearance of the air handlers. After all, you will likely have one in every room.
Weighing the advantages against the disadvantages, I think the mini-split systems are an excellent option.
For more information about heating and cooling systems, see Modular Home Specifications and Features and The General Contractor’s Responsibilities for Building a Modular Home in my book The Modular Home.