? re: high SEER (Attn: Baldloonie)
In another thread, Baldloonie wrote:
"Ducts in the attic? That can kill performance right there. If the 1st floor unit has a basement furnace, that helps since the ducts are in a cold basement.
And as the boys say, high SEER especially with too much air, doesn't give the drop of an oldie. "
Does enabling 'high SEER' on an RGFD furnace (RARL a/c) boost airflow above that (400 CFM/T) set on the IFC? System with matching coil is rated at 14.7 SEER.
I'm not sure what you mean about enabling high SEER. The blower speed should be what it is set for. As I recall, it can be tweaked above or below 400 CFM ton.
As per the furnace manual:
Originally Posted by BaldLoonie
"To achieve high SEER operation, turn dip switch #6 of SW1 to the 'on' position. This will enable the furnace operation for 16 SEER. ....."
I ask this as a tech set this switch to 'on' which seemed to negatively affect overall cooling/dehumidification. It has since been restored to the original setting. Much better.
Last edited by ampulman; 08-05-2012 at 08:37 AM.
Reason: minor change
I believe I may have found the answer (partly, at least).
Reading on a little further, there are airflow tables. With standard cooling, "first stage airflow is 50% of high cooling on low stage" "This matches airflow of the original IFC". With HS cooling, "High SEER (16+) Premium Cooling airflow (SW1 postion 6 is 'on'."
Now, the only question remaining is whether in low stage, the a/c (RARL) first stage (which is about 72% of high stage) is reduced to 50%, or is airflow only, reduced?
During the last prolonged hot spell, the unit ran several hours in 2nd stage. Even with the increased airflow, the air did not feel as 'cool' as when running in low stage.
Last edited by ampulman; 08-05-2012 at 09:24 AM.
I'd have to study how the mod handles the RARL. The 50/100% staging was from the good old days when 2 stage A/Cs were closer to 50% on low, rather than the 70-80% with the unloading scroll. So if it is dropping to 50%, you should have some superb moisture removal on low.
Dehumidification comes at a premium. Enhanced dehumidification mode causes SEER to drop. On the upside, with the drier indoor air you can raise your t-stat setpoint a couple of degrees with no loss in comfort. This will help to regain some of the lost SEER.
Originally Posted by ampulman
True. I have to say that when I selected the system, I opted for the 'basic' coil (RCQD) as I wanted maximum dehumidification, rather than highER SEER. While we have raised the SP a degree or so, we need to keep it lower when the son visits (often).
Originally Posted by hvacrmedic
Baldloonie: Looking forward to your further input. I might add that DOD is NOT enabled.