All,

I am currently having a problem where the compressors on my DX units are still kicking on during the Winter months even though I have an OA economizer. This change in results happened after I added Demand Control Ventilation as a parametric run. The overall savings were greater, but I was surprised how much cooling increased in the winter. My design is using Bridgeport, CT weather.

I have attached the .pd2, .inp, and .prd files. My concern is only for units labled RTU-1, AHU-2, and AHU-3. Please ignore all the little PSZ's.

I have done a thorough search through the archives and have found this link to be the most similar to my problem, but I don't see any resolutions that fully fixed my problem.

Here are two of the screen shots of how I set up RTU-1, which is essentially the same as the 2 other units:
[cid:image005.jpg at 01CCBFE8.0B2DF1A0]

[cid:image006.jpg at 01CCBFE8.0B2DF1A0]

Other notes: I only have a few unmet hours. SS-A report will show that winter cooling is more of a problem with RTU-1 and AHU-3. AHU-2 happens to be a 100% OA unit for Kitchen makeup and it has much less winter cooling load (not surprising since it is 100% OA so it is 'economizing' all the time. I also have modeled this project in Trace and the results in Trace have no winter cooling as expected (this project is a training exercise for me in eQuest.)

Any help is appreciated.

Jeremy Rapoza, P.E., LEED AP