For a strange reason, during the Winter Time (cold outside air at ~35 F and return air at ~70 F) result in Mixed Air ~60?F that needs to be heated up.
Even though the Mixed Air entering the Unit is ~60?F the air temperature leaving the Heating Coil is constantly 51 F despite the Central Heating Coil consuming around 40 kBtu/hr.
Is there simply a reporting bug or is this indicative of a larger bug that the Heating Coil is consuming energy but not providing any heat. As a result, my Electric Resistance Reheat at the VAV Boxes is huge.
Any suggestions on how to properly turn on my HHW Coil would be very appreciated.
Regards
Ian Doebber
I have also found very strange results on the hourly reports of heating
coil temperature, cooling coil temperature , and coil entering
temperature. Often the reported values do not make much sense, and
depending on the system type the nosense is in one way or in another. In
general, it seems the 'entering coil temperature' gives the right value
for the mixing of return and OA air. The 51?F for the heating coil
temperature looks like a standard for this hourly output (almost always
the same). It always alarms rather a lot to find these numeric values
without sense (you can't help thinking what about the other values you
are using to take important desitions from your simulation results...),
but I have done some testing and it seems that energy values are on the
right direction in spite of this wrong reported coil temperatures (whe
baseboards are present energy values do not fit as good as with coil
heating, but still it goes on the right direction).
So, I would think this afaire is mostly a bug in reporting those
variables, but it would be nice if one of those involved in eQuest
development could confirm this point.
Regards,
*Xavier Garc?a Casals*
The "Temp of air leaving heat coil" is in fact not applicable for most
system types including VAVS (see attached). For VAVS, it is the "Temp
of air leaving cool coil" that does the "heating" work. Just pick any
hour from your hourly report, with some hand calculations (a few heat
transfer / mass flow equations), you will be amazed to find that the
"Temp of air leaving cool coil" is indeed doing all the "heating".
Bruno Lee