Hi,
I have a quick question about the EER requirement for the PTAC and PTHP
system. In Standard 2004, Table 6.8.1D gives out the minimum requirement
for the PTAC and PTHP system. My question is does this EER include the
fan power or not?
Also for the PTAC and PTHP system, following the Appendix G fan power
energy calculation, the fan power would be about 0.7~0.8W/cfm. However
the manufacture's catalog data usually gives out the value around
0.2~0.3W/cfm, which means the proposed case would get a lot of fan
energy savings. Does this make sense? Thanks a lot.
Xiaowei Xu
The EER does include the fan power. The baseline fan power allowance in Appendix G from 90.1 2004 was recognized as being much too high for PTACs and PTHPs. An addendum was issued lowering the value to 0.3 W/cfm. This is captured in the new 2007 version of 90.1 Appendix G.
Michael Rosenberg
Hi,
I have a quick question about the EER requirement for the PTAC and PTHP
system. In Standard 2004, Table 6.8.1D gives out the minimum requirement
for the PTAC and PTHP system. My question is does this EER include the
fan power or not?
Also for the PTAC and PTHP system, following the Appendix G fan power
energy calculation, the fan power would be about 0.7~0.8W/cfm. However
the manufacture's catalog data usually gives out the value around
0.2~0.3W/cfm, which means the proposed case would get a lot of fan
energy savings. Does this make sense? Thanks a lot.
Xiaowei Xu
Could anyone else comment on this? I had asked this question a couple of
months ago, and through some research and guidance received the answer that:
The EER does include the fan power, which you would calculate from Table
6.8.1.D and you would calculate this for each system based upon it's
auto-sized capacity; thus, you will use a different EER for each system.
An important clause to then look at is G3.1.2.1 which states that equipment
efficiencies must be broken down into their component parts, such as the EER
into EIR and fan power. One way of doing this is to parse it out using
equest, capturing the correct EIR and then plugging that back in with a
separate fan power.
To get the fan power you would use Table G3.1.2.9 to get BHP and calculate
the fan power from this.
All of this, though, is according to ASHRAE 2004, I have not been using the
2007 Addendum. I just wanted to see if this is what everyone else has been
doing?
Thanks
* Loren Appin*
The issue is slightly more complicated for unitary equipment over 5 tons
because the ARI 340/360 testing standard for determining the EER of larger
unitary equipment has pre-defined limits on the allowed fan ESP during test
conditions. If you are simulating packaged equipment that is designed with
higher external fan static pressures than required by ARI 340/360 and you
use the as-designed fan power or fan power allowed by ASHRAE90.1 for
calculating "Cooling-Only" EER, you will over-estimate cooling energy
savings. This issues applies to Appendix G baseline systems 3,4,5 and 7 and
any as-designed equipment whose performance is covered by ARI 340/360 (see
minimum efficiency tables in Chapter 6 of ASHRAE 90).
For packaged equipment over 5 tons you should estimate fan power at the ARI
340/360 test conditions when separating EER into fan and cooling energy
components rather than using rated fan power or the ASHRAE fan power
allowance.
Michael Tillou, PE, LEED