Carrier 50PQ - Manual (Page 8)

Selection procedure (with example)
I Determine job requirements. IV Adjustments to capacities and Kw's for additional indoor fan
Estimated requirements motor heat for statics above 0.2 in. wg at listed cfm's.
Cooling load - total capacity................................... 54,000 Btuh The .754 electric heater resistance at 2,000 cfm is 0 26
- sensible capacity........................... 42,000 Btuh '"■ ^9 n"
Outside air temperature (Cooling).....................................95 F operate at 2,000 cfm with 0.66 ESP to overcome the
Air entering indoor coil (Cooling) wb ................................ 64 F heater pressure drop.
gQ p From the fan tables at 2,000 cfm with 0.66 ESP requires
Air quantity (cfm)........................................................2,000 1,208 rpm, 1,130 watts.
External static pressure - ESP (in. wg) ................................. 0.4 NOTE For PQ units or RQ units with plenums, use PQ fan
Heating load........................................................... 60,000 Btuh fable at required ESP.
Outdoor temperature (winter design)............................. —10 F ESP IFM Kvy
Air entering indoor coil (Heating).......................................70 F 2,000 cfm *.2 83
Power supply .............................................................. 230-3-60 .66 1.13
_ . . . (Diff in Kw) = 0 30
etermine unit size. ^ *NOTE Use motor Kw from RQ fan tables for .2 in ESP at
Select unit on cooling capacity. specified cfm for all plenum applications.
Enter the cooling capacity table at the given air quantity Adjust all capacities for additional IFM heat at higher
and evaporator entering wet bulb (2,000 cfm, 64 ewb). statics than .2 in. wg.
Read across table for net total capacity (TC) and net Diff (Btuh) = 3 413Btu/Kw x Kw
sensible capacity (SHC), under the condenser entering air ^ 3 413 x 30 = 1 024 Btuh
temperature (95 F) to find by interpolation TC of 56,000 rnni INC
and SHC of 47,400 at 2,000 cfm, 64 F wb for the , ,
RORonnK Adjusted TC = TC — Diff (Btuh)
, , , , = 56,000-1,024 = 54,976 Btuh
Since these net capacities have been calculated at 0.2 in. wg Adjusted SHC = SHC — Diff (Btuh)
external static (ARI condition), for any additional static — ^ 4 qq _ ^ Q24 = 4g 375
the net capacities must be adjusted to reflect the resulting Adjusted power input = Kw* + Diff '
IFM heat. To obtain the total required static,all accessory ^ 7 g + g 30 8 1 Kw
pressure drops must be calculated. Therefore, calculation *Kw-unit total from 'cooling capacity table at selected
of heater requirements must be made since pressure drop conditions
varies for each size of electric heater. HEATING
III Heating requirements — number of electric heaters required. Adjusted heating capacity = 18,000 -1- 1,024 = 19,024
Enter instantaneous/integrated heating ratings at 006 size Adjusted power input = Kw** -t Diff (Kw)
and 2,000 cfm. Under temperature at air entering outdoor = 4 2 - t 30 = 4 5 Kw
coil, -10 F, the Integrated heating capacity is 18,000 Btuh. **Kw from heating capacity tables of selected conditions.
The heating load is 60,000 Btuh, therefore, 42,000 Btuh V Corrections to SHC for dry bulb above or below 80 F - see
additional electric heat is necessary. Enter electric resist- SHC correction factor table. For this example, no correction
ance heater capacity table at 006 size and 230-3-60. The is necessary since the entering dry bulb is 80 F.
.754 heat ratio/or 13 Kw electric heater most closely Therefore, the final net capacities are
satisfies the electric heater requirement. SHC = 46,376 Btuh
13Kwor — 44,400 Btuh (from Electric TC = 54,976 Btuh
Heating Capacities Table) The 50RQ at the required design conditions has enough
44,400 -t- 18,000 — 62,400 Btuh sensible capacity for the job application.
Performance data
ARI CAPACITY RATINGS
COOLING HTG (Hi -Temp) HTG(L o-T emp)
UNIT CFM Cap. .
(Btuh)
EER
Cap.
(Btuh)
C.O.P.
Cap.
(Btuh)
C.O.P.
50RQ
006
2000 59,000 7.5 62,000 2.8 35,000 2.0
50RQ
008
3000 88,000 7.8 91,000 2.8 51,000 2.0
SORQ
010
3Ó00 108,000 7.7 11 2,000 2.8 61,000 2 0
SOPQ
006
2000 59,000 7.4 62,000 2.8 35,000 1.9
SOPQ
008
3000 87,000 7 6 92,000 2.8 52,000 2 0
50PQ
010
3600 1 07,000 7 5 113,000 2.8 62,000 2 0
Rated in accordance with
ARI Standard 240-75.
Ratings are net values, reflecting the effects of circulating fan heat
Supplementary electric heat is not included, Ratings are based on:
Cooling Standard: 80 F db, 67 F wb indoor entering air temperature
and 95 F db air entering outdoor unit
Hi-Temp Heating Standard: 70 F db indoor entering air temperature
and 47 F db, 43 F wb air entering outdoor unit
Lo-Temp Heating Standard: 70 F db indoor entering air temperature
and 17 F db, 1 5 F wb air entering outdoor unit