DIY Home Improvement, Remodeling & Repair Forum

DIY Home Improvement, Remodeling & Repair Forum (
-   HVAC (
-   -   condensation troubles (

oldman55 08-26-2010 07:35 AM

condensation troubles
I just put in a new 80,000 btu Bryant furnace & 31/2 ton heat pump(new 410 freon). This unit replaced a fifteen year old furnace and 3 ton a/c. I wanted a larger unit this time because the 3 ton didn't cool the house on really hot days. Here's the problem the trunk line under the house is flooding with condensation. I have wrapped the trunk line with bubble wrap insulation and it has filled with so much water that it's:agree: sagging down. The blower speed is on high and the charge is ok on the heat pump. The duct start out as 10x18 and reduces down. The condensation goes about 15 to 20 feet before it stops. This thing really has me pulling my hair out. Any suggestions ?

kok328 08-26-2010 04:03 PM

warm, humid air being blown across cold coils creates condensation. This condensation runs down the coils and collects into a condensate pan that is plumbed to a nearby drain or outside. Check to see if the drain is clogged and that the pan remains relatively empty during a cooling cycle. It might be that the pan is overflowing into the ductwork and/or the blower is carrying the condensate into the ductwork.

budro 08-28-2010 05:08 AM

a question for kok 328. is the fan going to have less condensation running on high? i think it will but not for sure. his problem sounds like what happens when you put too large of a unit for the capacity you are cooling. did the a/c company warn you about oversizing? back to my kok 328 question, if he slowed the fan down to med or low would that just pick up more cold air or less? could a slower speed help out or hurt?

oldman55 08-28-2010 08:07 AM

Thanks for the ideas . The old unit was a 3 ton w/80,000 furnace and still had the same problems to an extent because I had to replace the bottom half of the plenum.I figured that if I insulated the plenum and trunk line it would stop it. (plenum is insulated with 1/2" blue board.) The heat loss\gain was calculated 3 ton but wouldn't cool the house when temps reached 90+. I wouldn't think that 1/2 ton would make this much difference, the first 15 to 20 feet look like they have been sprayed with a garden hose. there is actually some spots that are starting to puddle on the ground. I have put down new 4 mil. plastic on the ground, also ran an extra blower under the house to try to dry it out. There has to be an answer-I just can't find it. I was just wondering if anyone else has had any problem with the new R410 causing problems because of the lower temps? I also checked and drain is fine.

NitroNate 08-30-2010 01:23 PM

like kok328 said, did you look inside the air handler where the evaporator coil is to check that the pan is relatively empty while it is running? the drain my be fine but the unit could be collecting water in the pan due to a leveling problem. usually there is an access panel you have to take off or you have to cut an access hole in the plenum to see the drain pan.

oldman55 08-31-2010 07:40 AM

I haven't thought about that but I will check it today and let you know what I find. Thanks for the idea

oldman75 09-02-2010 10:54 AM

I am having the same prob with excessive moisture on everything within 6' or so of main trunk line in crawl space directly below Carrier down flow unit which sits in closet of living space. Unit was installed with minor company mod for down flow which works fine as far as managing condensate inside unit. Condensate from coils is properly collected by small pan and directed outside foundation wall. Interior of unit at fan motor and plenum/main trunk below is bone dry. Same for main trunk (10x20) leading away from unit in crawl space.
I believe condensation is coming from moist warm air in clawl space coming in contact with either cool conditioned air leaking from trunk line or from a poorly insulated trunk line or both. (Contractor that installed it is no longer in business, which is 'nother story)
Trunk line is sheet metal wrapped in maybe 1" insulation blanket.
Any help, please

oldman75 09-08-2010 07:04 PM

solved here
Have installed squirrel cage fan under house by access door and blowing directly at center point of main trunk. After several days of this improved ventilation, all moisture in area dried up. Now plan to include humidistat to control the fan. Have also ensured that all 8X15 vents are open and clear.

All times are GMT -6. The time now is 11:23 PM.