Excess Condensation
mperry_metroservices
| Posted in General Questions on
I have a property of townhomes that is having excess moisture in the floor space between the first and second floors. The exterior envelope is sealed and the ducts are insulated. The condensation is so high that there have been times of standing water being found in the flex duct, along with microbial growth on the drywall ceiling directly underneath the supply lines. No signs of draftstopping issues and the hvac company has confirmed their levels are correct.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Do those condensation spots follow ductwork overhead?
What’s the flow rate at HVAC air handler. Is it throwing water off coil into duct.
Is there a humidifier running on this HVAC system? Sound like “yes”. You have to be careful with humidifiers and excessive moisture levels. Since you found standing water INSIDE the ducts, that seems to indicate the air from the HVAC system is probably the source of the moisture, which is why I’m thinking you have a humidifier that is running way too much. The moisture under the supply lines on the drywall is probably condensation from inside the duct that ran out since ducts are usually not water tight.
Bill
Image 2 says this is in Georgia? The ducts are completely within the conditioned envelope? If so, why are they insulated? The humidity is too high. I'm also betting that floor cavity acts as the return 'plenum' meaning it's under negative pressure when the air handler runs pulling in humid outside air through leaks. 'Sealed' is never 'sealed enough' when you have negative pressure. Try a ducted return.