HYDRONICS | FROM THE FIELD | CONTINUED FROM PAGE 24
(including the Altherma system). The solar differential control interlocks with the
Altherma, locking out the heat pump when solar energy is available. This mode allows for solar DHW production, while simultaneously cooling the space. This is a mode that occurs frequently during our hot, humid summers. One important fact to keep in mind is that this system is
are satisfied with our choice.” Our second Altherma system was a replacement/retrofit
job in the home of nationally recognized architect David Peabody in Alexandria, Va. We replaced a conventional forced air gas furnace and electric AC system. We replaced the entire duct system, added an ERV ventilation system and added panel radiators in key locations. This mechanical upgrade was done in conjunction with building envelope upgrades and an insulation package. Peabody commented, “Our new Daikin Altherma system
has now been in for two seasons and has performed admirably. In a very cold winter, it gave us heat and hot water throughout. And we were able to keep the house cool on the warmest days last summer. The more marked difference from the old forced air system, however, is the comfort levels in the house. The ability of the Altherma to heat both via the duct system and hydronically in spot locations is, in my view, the key to that. Because we have not been through a whole year with the system yet, it is too soon to know the energy savings the system has provided.” Daikin is wise to require certification training to install
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their system. I attended the two-day class at its Somerville headquarters, but, even with that experience, there was a steep learning curve. It is different than any other system I have worked on, and it took some time to learn the unique terminology. To be fair, all of the information required to properly install and commission this system is contained in the I & O manuals provided with the equipment. It behooves the installer to read and understand the manuals.
The Altherma system supplies hot and chilled water to this variable speed air handler.
designed for low temperature heat emitters. The maximum supply water temperature is 130 F, and it would operate at higher COPs if designed around lower water temperatures. It is a perfect match for radiant floor heat and properly sized panel radiators. It will work fine tied to air handlers, as long as the heat exchange coil is properly sized. I hear that Daikin will soon release a high temperature system that will operate with an alternative refrigerant, but that system is not available at this writing. The first system I installed incorporated both radiant
floor heat in a concrete slab and two air handlers. This was in a new LEED Gold-rated house sitting on a bluff overlooking the Potomac River. The client, Lorraine Horbaly, had done her homework and actually approached me about the Altherma, which I knew nothing about. I called my local rep, Jeff Riley, Southern region manager for Thos. Somerville Co. He also knew nothing about it. A few phone calls got us pointed in the right direction, and we were on our way. Here is what Lorraine had to say about her Altherma
system: “We have lived in the house for just over eight months, so
we haven't experienced the extremes of summer. What we have experienced, however, is a quiet, energy efficient system that adequately heats and cools our home. For us, the alternative to Altherma was geo-thermal. Altherma is less expensive to install and, by all accounts from knowledgeable sources, is as energy efficient. To date, we
An Altherma Hydrobox mounted on mechanical room wall.
To their credit, both Jeff Riley and Lance Dyer made site visits to help me set up our first installation. The second installation went a little smoother, as we learned from our missteps on the first job. One lesson we learned the hard way is that the Altherma
requires a minimum flow rate of 5 gpm. on the five-ton unit we installed (this number will vary with other size units). We had a small radiant zone that did not meet this flow requirement, causing the unit to lock out on flow when this zone called by itself. It would do this intermittently, as this zone would rarely be the only one calling. By the time we got to the site and reset the lock- out, other zones would also be calling, masking the cause of the lock-out. I finally pulled up a chair and watched the system operate until I saw the exact conditions that caused
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phc may 2011
www.phcnews.com
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