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Going Ductless with Heat Pumps

November 2, 2009 - 9:06am


My home, unlike most homes in the United States, has no ducts. My wife and I bought the house nearly 20 years ago. Window air conditioners provided air conditioning during the hot muggy Washington, D.C., summers. Baseboard electric heaters provided heating in winter. Before a lot of you post your sympathies in the comments, let me say this: my house is well insulated and very air tight, as a whole house energy audit demonstrated about 15 years ago. Yet, even though electric baseboard heating is about 100% efficient, it is a costly way of heating a house. And as I got older, each year I enjoyed installing and removing the window air conditioners less and less.

To cut costs and energy consumption, we had a ductless heat pump installed in our bedroom. We liked it so much that we had an identical unit installed on the other end of the house in our dining room the following year. This provided efficient heating and cooling for the upper floor of our two-story house, totally eliminating the window air conditioners. We kept the baseboard heaters as a backup, and for use in the guest bedrooms. Since our house is built into the side of a hill, the downstairs stays fairly cool during the summer but requires dehumidification. I had bought a high efficiency dehumidifier about 15 years ago, and it performed great until last year, when it was unable to keep the humidity level in check. So I started thinking about replacing it.

Well, I recently learned that several models of ductless heat pumps were eligible for the federal energy efficiency tax credits. I decided to retire the dehumidifier and had two ultra-efficient ductless heat pumps installed downstairs. This summer we used them in dehumidification mode and they work great. Last month's electric bill was a pleasant surprise, so they seem to be dehumidifying efficiently. They have an incredible 25 Seasonal Energy Efficiency Ratio (SEER) in the air conditioning mode, and a high 10 Heating Seasonal Performance Factor (HSPF) in the heating mode, thanks to inverter technology, qualifying them for the federal tax credits.

How to identify ductless heat pumps that qualify for the federal tax credits

Set your browser to the CEE Directory Web site and select Find Variable Speed Mini-Split and Multi-Split Heat Pumps. Qualifying split system heat pumps must meet CEE Tier 2 standards, their highest tier for these systems.

Our ductless heat pumps are incredibly quiet. Outdoors, I can't even tell when they are running; the next door neighbors' conventional air conditioner drowns out the little noise our units make. I never have to clean ducts, nor worry about the many problems associated with leaky ductwork. Ductless heat pumps aren't for everyone, though. They're most appropriate for large open spaces. Multiple walled-in rooms would require many separate units, or one or more outdoor units connected to multiple indoor units, which gets quite expensive.

Ductless heat pump models are available anywhere in the continental United States. The Northwest Energy Efficiency Alliance (NEEA) and its partners recently launched a ductless heat pump pilot program to determine cost and energy savings potential of inverter-driven ductless heat pumps in single family homes across the U.S. Northwest. Their goal is to install 2,500 ductless heat pumps. NEEA is a private non-profit organization funded by Northwest utilities, the Energy Trust of Oregon, and the Bonneville Power Administration.

Certain ductless heat pumps are even suitable for quite cold areas. Although I didn't order the cold climate model, it is designed to provide 100% of rated heating capacity at 5°F and 87% at -4°F, and is also guaranteed to provide heating down to -13°F outdoor temperature.

None of my heat pumps contain back-up electric resistance heaters. Yet I'm surprised how effective my older models have been in winter, even when the temperatures drop below freezing. This again is due to the inverter technology they incorporate. I'm confident the newer models will perform even better. Though I don't look forward to winter, I'm sure my heating bills this winter will be much more palatable than last year.