Just Moved In and Miserable

Anthony42

Hi, everyone,

We just moved to the Memphis area and MAN is it humid. We’re from Michigan, so maybe we just need to acclimate.

One of our children is receiving cancer treatment in the area, meaning that we had to find a home quickly and we don’t know how long we will be here. Home prices are much cheaper here, so we decided to buy an older home with a 10-year-old 4-ton unit. The couple we bought it from mentioned that the unit replaced a 2.5 ton unit, but that none of the ductwork had ever been replaced. It felt comfortable when we toured it.

I’ve cleaned the outdoor coils myself, and the indoor coils look clean. We used a recommended HVAC contractor to come and check the system out. He noted some leaks in the ductwork, but said the pressure looked good and the unit was in proper working order. He offered to come out to fix the ductwork and measure the static pressure to see if we needed larger ducts. At present, we have two returns total (both in a hallway) that connect the plenum with 2 10” rigid ducts, one that runs 2 feet with one bend, and another that runs 8 feet with two bends. We also have condensation coming from two of the vents, and the contractor said we needed a whole-home dehumidifier. We paid him $2,300 up-front, and he has disappeared. We are trying to track him down, but in the meantime, my family is roasting.

I can fix the duct leaks myself with mastic and screws. Unfortunately, my wife is still looking for a job, so we are in a lurch until we get our money back or can borrow money from family.

I guess my questions are 1) should I try to add another return to the unit? The return plenum has two sides available to cut into. 2) Are there other things I should be looking at? 3) I’m concerned about the condensation causing air quality issues because of my child’s immune system. Are there other reasons a vent might drip condensation?

Sorry, I know I’ve probably left a LOT of useful info out, but I can answer any questions and take as many photos as needed. These last 2 months have just been really stressful for our family, and I’m hoping I can at least make the house comfortable in my own.

Other (possibly helpful) information:

When it’s over 90, the unit will run all day to keep the house at 78.

I feel a lot of air leaking out from the supply plenum where the ducts connect.

My filter is 20x25x1. I’ve tried several brands and MERV ratings

mattmia2

Is the condensate draining properly? Can you see the coil? Does it all get wet with condensation? Is it freezing because of lack of airflow? If the system is oversized it won't dehumidify very well but the ductwork sweating is extreme.

Where is the condensation coming from the vents? Is it on the surface or is it running out through the duct? If the condensate pan is plugged it could be running through the ductwork. (it can get drawn through the ductwork by the airflow under some conditions too)

EBEBRATT-Ed

Sealing up air leaks in the ducts can make a huge difference. When you lose supply air to an unconditioned space (attic, basement or crawl space) warm outside air is forced to leak into the ouse to make up for what was lost also bringing in excess humidity.

Since you feel a lot of supply air leaking out of the supply ducts at the plenum start their. Use duct sealing mastic available at an HVAC supply house. The big box stores may have it as well. Use the water based type and stay away from duct tape. Apply it with a cheap paint brush.

I question why a 4 ton unit was installed where a 2 1/2 ton unit was there before. How many square feet are you trying to cool??

Hope this move works out for you and your family at this tough time.

Anthony42

https://forum.heatinghelp.com/discussion/comment/1806917#Comment_1806917

The condensate is definitely draining. I can see water exiting the unit and flowing into a pump reservoir, at which point it is carried to a sewer stack above our front bathroom. A lot of water is moving through. The coil itself has condensate drops around the edge, where the refrigerant lines are visible. There is a lot of it.

So far I haven’t seen it freeze at all. The condensation collects along the side of the ductwork and drips out of the vents, sometimes in a very light, yet steady stream. Only the vents closest to the unit seem to have this issue.

Thank you for responding!

Anthony42

Thanks! I will go ahead and try mastic around the plenum leaks as a next step. I did not think about warm outdoor air needing to make up for what had been lost. That makes a lot of sense.

We are only trying to cool 1,600 square feet. I wish I knew why a 4-ton unit was deemed necessary. When I talked to the previous homeowner, they couldn’t remember, but just went with what their service person recommended at the time.

Thank you for your response and kind words.

mattmia2

If the condensation is on the outside of the ductwork in the attic then the only way to fix that is to insulate it. The insulation has to have a vapor barrier on the outside and it has to be well sealed or water will condense in the insulation and cause a bigger problem.

Mad Dog_2

I'll leave the AC advice to the AC guys, but good luck with your child's Treatments. You all are in my prayers 🙏. Mad Dog 🐕

EBEBRATT-Ed

1600 square feet. 2 1/2- 3tons would be more than enough. Don't know why they went with 4 tons.

My next question is I hope they changed the indoor air handler and did NOT put a 4 ton condensing unit on the original 2 1/2 ton indoor coil.

ratio

What's the temperature of the air going in to the return and coming out of the supply?

HVACNUT

I hope things go well for your family. This is the last thing you want to deal with.

The Tech said pressures were good but that doesn't tell us anything. If the system went from 2.5 to 4 tons without massive duct modifications, that's ludicrous. So we don't even know if the system is sized correctly.

The best starting point for you would be to tell us the Supply air temperature, Return air temperature, and outdoor air temperature in the shade, after the system has been running at least 30 minutes. If they use Fiberboard as opposed to metal duct, a piercing thermometer at the inlet and outlet of the air handler would be best for accurate temperatures.

Sootmaster

System sounds like a "do over". Could you get by with some $100 window shakers until you know if this is a forever home? Is it a heat pump supplying heat as well?

It sounds like a mis match and the condenser is way oversized and not breaking the humidity.

Manual J, Manual D would be the first step to getting it right. Then a "blower door" test to see what condition the sheet metal is in. $$$$$ when you least need the expense. You're in my prayers

HomerJSmith

I'm sorry to hear that one of your children has cancer. It must be devastating for your family. I'll say a prayer for your child.