Hello all,

I have a fairly complicated residential project that I am working on that includes Variable Refrigerant Volume air handling units and a DOAS system with energy recovery. I've reviewed the archives and some online resources, but I'm still having trouble developing work arounds to input these systems in eQUEST. Any help would be greatly appreciated. Specific questions:

1. For the variable refrigerant volume system I am following a similar approach to that outlined here in this Energy Trust of Oregon presentation (http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110323/e43a8c5c/attachment.pdf), using PVVT air cooled heat pumps and hourly reports to show savings from simultaneous heating and cooling. This system is different from those I have dealt with in the past, in that the refrigerant exchange occurs at the outdoor unit and not at a branch selector box, but the same approach with hourly reports tracking heating and cooling energy should work. My problem is with the capacity and EIR curves.

I have manufacturer's data for the units, but have not come up with anything that makes sense yet. Developing accurate capacity curves is vital, as the units do not have supplemental strip heat and are designed to deliver heating and cooling in low ambient conditions, down to -4?F DB. My first stab has left me with unmet load hours around 40%.

The EIR curves I have built reduce the heating and cooling energy use by over 75%, doesn't seem realistic. Currently I am inputting the same EIR curve for both the Electric Input Ratio and Low Speed Electric Input Ratio on the Unitary Power tab of Heating/Cooling for each unit under the Performance Curves portion. Is this correct?

Any additional resources on curve building would be great. I'd be more than happy to share my results with the listserv.

2. For the DOAS with energy recovery my issues are on the control side. The unit includes DX cooling and electric heating with a heat wheel for energy recovery. The sequence of operations specifies that below 60?F ambient temperatures the heat wheel will operate, and the electric heat will maintain discharge temperature at 70?F. For ambient temperatures from 60?F to 75?F, the unit operates in economizer mode with the heat wheel not operating and no heating or cooling. Above 75?F, the heat wheel operates and the DX cooling kicks in to maintain discharge temperatures of 72?F. Can I use the Air Side Economizer Drybulb high limit and Economizer Low Limit, Cooling Control and Reset, and Heating Control and Reset inputs to implement this control strategy?

Thanks in advance,

Robert Stephenson, LEED AP