Question Regarding Fan Speed, Humidity, Static Pressure.
Hello Everyone,
I recently installed this system below (Trane XR17 Condenser 4 Ton 18 SEER 2 Stage). The installer paired it with a larger 5-ton coil evaporator deliberately. From what I have been told and read, this can be done to increase efficiency in drier climates at the expense of dehumidification ability. I am not sure if this is 100% correct. We are having a usually wet monsoon month with humidity outside peaking over 45% on some days when it should be around 20%.
With humidity being higher than normal outside at 45% and peak temperatures lower than normal at 95f this month, I do notice that indoor humidity ratings have been in the lower 50% indoors and have uncomfortably peaked as high as 65% or 70% in the day sometimes when I leave the thermostat higher at 75 or so. Is this normal?
In case this is relevant information, this system kept us at a comfortable 70-75 at 40% humidity when it was 110f outside at 20% humidity earlier this summer.
Is this mismatch of having a larger evaporator ideal for this climate? Without having the ability to measure the external static pressure, Would it reduce humidity or operate more efficiently if I reduce Stage 2 to Tap 6 1554 cfm @ 0.5″ W.C?
Home Size: 1550 Square Feet 2 Story 3 Bed / 2 Bath
Home Build Date: 2006
Location: Southwest Desert
Temperature Peak: 105f Average July
Humidity Range: 17% July – 45% December Average
Equipment
- Trane XR17 Condenser 4 Ton 18 SEER 2 Stage
- Allstyle Coil 5 Ton Horizontal Coil 60000 BTU
- Trane S8X2 Furnace
- (2) 20x20x1 8 MERV Filters
Based on 350 cfm/ton required and assuming the average or ideal 0.5″ external static pressure
Trane Condenser Requirements
- Stage 1 = 2.8 Ton (70%) x 350 cfm = 980 cfm
- Stage 2 = 4 Ton x 350 cfm = 1400 cfm
Trane Defaults
- Stage 1 = Tap 3 = 940 cfm @ 0.5″ W.C.
- Stage 2 = Tap 7 = 1551 cfm @ 0.5″ W.C.