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IECC2012 Economizer Requirements with respect to Water-Source Heat Pumps
June 30, 2015
11:11 pm
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efbatchpl13@kennethdiabetesprotocol.com
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thanks for this great info

May 28, 2015
9:10 am
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maeustice@htlyons.com
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I am running into the same issue.  I would like to see this answered.  I'm doing a WSHP equipment replacement on one floor of a four story building (tenant fitout).  I can't pass ComCheck because it's requiring economizers on many of the WSHPs.  Is this really the intent of the code on this type of project? 

October 1, 2014
4:11 pm
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casey archacki
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I am working on a project where we have Water-Source Heat Pumps (WSHP's) serving individual tenant spaces as well as large common area spaces.  I have centralized Energy Recovery Units (ERV's) serving the ventilation air requirements for all the spaces throughout the building.  I also have a single cooling tower providing supplemental cooling to the space as well condensing boilers providing supplemental heating. During the summertime, the loop is maintained between an EWT of 85 degrees and a LWT 95 degrees. During the winter time, the loop is maintained between an EWT of 70 degrees and a LWT of 60 degrees.

The IECC specifically states either "air" or "water" economizers must be installed on units larger than 33,000 btu's. It does not appear to grant an exception to WHSP units.

While it is easy enough to get air-side economizer controls on the centralized larger ERV, units it is not possible to get them on the WSHP's.  Therefore, my other option is to provide water-side economizers on the WSHP's.

The concern I have is the operational side of this system.  In order to claim savings from a WSHP system with water-side economizers, I am told the loop temperature must drop to 55 degrees to get any useful cooling out of a water-side economizer.

Does anyone know if there any ways to comply with IECC2012 and provide economizers on heat pump units?  Or, possibly, is there an exception granted to the WSHP's because they already perform the basic function of economizers which is obtain free cooling by transferring cooling energy from the permiter of the building to the interior spaces and vice-versa?