I am looking for some help in troubleshooting a VRF model I created by following the attached Mitsubishi documents.
I followed all of the steps with no problems up to the point of selecting the VRF heating capacity curve. As soon as I selected VRF Heating Capacity Curve under the Cap Curve/Waste Heat tab, the space heating kWh disappears (in addition to a massive negative utility bill for the month of January).
There is an additional twist - I was able to select the VRF Heating Capacity Curve for all basement zones and assign it without the model going bonkers, it just goes off the rails when selecting this curve for any of the above grade zones. I have been combing through the model trying to figure out what is causing this but with no luck so far.
I have attached my project file in the zip file titled Bank as well as the original Mitsubishi info. Thanks again in advance for any help.
Travis
Below are a couple of screenshots describing what is happening with the model when I select the VRF Heating Capacity Curve. Has anybody seen something like this happen before? Do the curves not like my weather file which is for Pocatello, ID?
[Description: C:\Users\tmiller\Desktop\VRF 1.PNG]
[Description: C:\Users\tmiller\Desktop\Capture.PNG]
Travis,
By searching through the SS-H reports, I identified system 3 FC-3.10 (G.C4) as the culprit. This is the only system causing the errors. The "VRF Heating Capacity Curve" curve you are using gives negative values for the multiplier on heating capacity, at 25?F Ewb or lower. The system giving the error has OA ratio of 57%, causing errors in January and December due to low entering air temperatures, as shown in this custom hourly report:
[cid:image004.jpg at 01CECBEF.B6707A50]
(Heating capacity values in the reports are normally negative numbers, not positive.)
There are different things you can do to get rid of the error.
? Increase heating capacity
? Decrease OA cfm
? Outside air MIN-AIR-SCH
? Increase MIN-HP-T
? Etc.
Regards,
Bill
William Bishop, PE, BEMP, BEAP, LEED AP
Thanks Bill, I noticed that by decreasing the OSA I could get the error to go away. Thanks for shedding some additional light on why this error was occurring. Much Appreciated.
Travis