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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22541
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I have a 7 ton closed loop Geocomfort split system with an

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I have a 7 ton closed loop Geocomfort split system with an air handler in my basement and one in my attic. The upstairs in my home is not getting adequately dehumidified in the summer. The house is cooling down but the air is still too moist. My contractor thinks I need more returns, but the previous central ac system worked fine with the existing single return (approximately 25x25 inches) for my 3000 sq ft home. Any thoughts?

was the previous unit the same tonnage?
was the previous air handler the same cfm?


Customer: replied 4 years ago.
The previous ac unit was smaller than my geothermal unit as I has 2 ac zones and now the Geothermal system does everything. I don't know if the air handler had the same cfm.
Thank you,

This is a classic sign of the ac being oversized. That is why I aasked about the cfm (cubic feet minute airflow) and size of the unit.

You are cooling too fast thus leaving humidity. An ac actually works better sized right or slightly under. This creates longer run times thus removing the humidity.

I do not know the particular set up in your case...but it is obvious you have too much cooling. More return will not help. This is a case of moving too much air with too much cooling which results in a "basement" type feel.

At this point since it is already may want to consider adding a central dehumidification unit to the duct.

If you have questions on this let me know.

Customer: replied 4 years ago.
a larger unit was put used in anticipation of an addition we hope to put on our house in the future, and to be able to handle added living space in the attic and basement.
Do you think the best option for now is to add a dehumidifier to the upstairs air handler?
It seems like adding returns was pointless.

Ok, I understand. This is just temporary then.

Yes to the dehumidifier. They are referred to as whole house as they go in the duct work. This pulls air and dehumidifies without cooling the air.

See link HERE

Actually the only other option is to dump the extra cooling somewhere else besides the living space...which is not real efficient.

If you need further help please let me know.


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Customer: replied 4 years ago.
Thanks for your help
You are very welcome.

You also see if the contractor can slow the blower down. This moves the air slower and gives it a chnce to remove more humidity. BUT these changes would have to be reversed once the additions are done.

I am betting if you utilize the dehumidifier you will use the central ac even less.