Residential AC unit Not keeping house cool

[catmanacman]

call micheal and son they are pretty good from what I hear

[ryanxo]

Nevermind im thinking too much

[ryanxo]

OK i know that on most thermostats there is a hookup for heat pump mode and non heat pump. Could it be that someone hooked it up wrong? Could that cause an issue? This house was a repo so nothing is known about the previous install or system.

[udarrell]

I have no idea what is impeding the airflow. Both outside coil and inside fan have been supposedly cleaned. I have another tech coming out Friday. Until then I guess I'll replace 1 of the ducts and see if it makes it any cooler out that 1 vent. The air is 52 in the main trunk but its not getting out to the vents. Has to be the duct work right? It's just 6 inch insulated flex duct. I don't get how that could mess things up so badly. It just seems like it doesnt have enough air pushing out the vents

If 6" flex duct is not stretched tight that could be reducing the airflow fpm velocity & CFM, but there could also be other problems.

Get a good digital thermometer meant for taking air temps.
With the flatter headed one's you could take refrigerant pipe temps at turns.

Even an A/C supply house might sell you one.
Don't know if Home Depot or other stores have them.

I doubt those temps you took were correct.

[man from trane]

Re-reading the first few posts, 76 Degrees is not bad for a 2 ton system cooling 1300 SF with not much attic insulation at 90 Degrees outside temp. My system runs continuously on a Saturday afternoon to maintain 77 degrees. I doubt it would hold it much lower than that if I cranked it down. Remember, you don't want your house cold; you want it dry and comfortable. If it's 90 outside and 78 or so inside it should feel comfortable. Also, my duct guy tells me that there is a night and day difference between R-6 and R-8 flex duct. You probably have R-6.

[ryanxo]

Had another AC person out on Friday who also checked the duct work. Well he said that there is nothing wrong with my system except that it is not big enough for the house. recommended a 2.5 ton instead of my 2 ton. He said the temp going from 50 in the trunk to 68 at the vents is perfectly normal. IMO that's ridiculous for a 6 year old system. Figures the day he came out it was a nice cool 73 day outside so the AC didn't even need to be on.

Now this week its gonna be back in the 90s again. My ac runs constantly from 9AM to after 7PM. My parents 20 year old system didn't even run that often. Guess the system is fine... must be an insulation issue.

~Frustrated

[whoward]

Sounds to me as you have a couple of issues with the system. i would look into the fan speed being too low. Thus not moving the air fast enough through the system to keep the cool air flowing. Also, would double check the return for any air penetrations being pulled in from your attic causing a higher temperature at the evaporator.

[54regcab]

68 supply air with it 73 in the house is ridiculous.

[ryanxo]

68 supply air with it 73 in the house is ridiculous.

I agree. 2 different AC people seem to think it's normal.

Thanks whoward. I'll research the blower motor speed. Didn't see any issues with the return. It runs out of my ceiling and directly into the system. Maybe a 2 foot run haha

I know this isn't a DIY forum so I won't even ask about how to change the speed.

[skibme]

Flex duct has various R values.Also did you try killing all the attic fans? Maybe your pulling in too much nasty outside air.There is a big debate about attic fans,whether they help or hurt.

[ryanxo]

With the attic fans it's 100 up there...without it was hitting 130 so I'd vote to keep them. I went back up in the attic and got the dets off the air handler I guess it's called.

trane TWE024C140A0

Doubt that helps anything but whatever. Is there a way the wires could have been crossed when it was installed that would make it blow out too slow?

[man from trane]

Ryanxo, it sounds like the problem is the house. It sounds like the insulation in the walls, attic, and the windows themselves are just not very good. The system sounds like it's working fine. Every house is different. You can't compare your parents' house to yours.

Homes where I live don't have insulation. If your house were here it would have a 3 Ton system, minimum. My 1200 SF concrete condo has a 5 Ton system that runs balls out on a sunny afternoon to maintain 77 Degrees. 2 Tons is nothing. I put (2) 2 Ton mini splits in the small house across the street just for the great room.

2.5 Tons might cool your home down another 1-2 degrees. The difference between low and high speed on the fan might make a half-degree temp difference. How cool do you want it? You never said what the temp is and what you want it to be.

You're probably going to have to invest in windows, insulation, and probably some exterior shading if you want to make a significant difference in the temp inside.

And there's no way the temp at the diffusers is 68 with a 50 degree plenum temp. If those numbers are right, your ducts are in need of re-insulating.

[ryanxo]

I'd be perfectly content if it kept my house at 74 without running constantly. I'm gonna try to work on the duct work i guess. The way they ran the one to my room is has 2 90 degree turns in the stupid thing and goes over a rafter. on the other side one makes a 90 degree turn and goes over another duct. These people were on crack. I'm gonna replace with R-8 on a couple and see what happens. As far as the windows and insulation go. The windows are brand new and for the insulation its about 10 inches thick in most places blown fiberglass. I think I'm gonna move it all and put down about an inch of spray foam to seal everything up then put the fiberglass back on it. Or maybe take out all the fiberglass and put cellulose on top of the foam... after it cures of course

[man from trane]

Running continuously is usually a good thing. Cycling causes energy losses, and during the off cycle there's no humidity being removed. But I wouldn't think it would begin running continuously until around 11:00 or so.

[ryanxo]

Running continuously isn't a good thing for my electric bill haha. Its just weird to me that the air barely comes out. I just don't get it. I was up there again today checking ducts and they are all sealed up. besides my room which has 2 90 degree turns I am not really seeing an issue that would cause the crazy loss of air speed.

[54regcab]

Are you sure there isn't some sort of blockage? It's very odd to have cold air with good pressure at the air handler while barely any airflow at any of the registers. With the A/C off an the fan running how hot is the air coming from the registers?

[ryanxo]

I'll check it tomorrow when it's warmer because that is when it will show. I just checked the register and the temp coming out was 52! Granted its only 68 outside right now and it's night time. I think the temp goes up so high in the ducts during the day because of the lack of airflow. How would i be able to tell if there is a blockage? A blockage in every line???

[54regcab]

If air is just trickling out of the registers you have a blockage or disconnected duct somewhere. Odd that it's in ALL of the supply lines.

[ryanxo]

If air is just trickling out of the registers you have a blockage or disconnected duct somewhere. Odd that it's in ALL of the supply lines.

Yes air is just trickling out. It is very odd. I've been up there more than 8 times to check and can't find anything major. Should i rent a thermal imager!?

[snowbertca]

Just wondering if your attic fans are depressurizing the house and pulling in outside air. Since you mentioned fans. Try turning them off for a while. You can put passive vents in, soffits and roof and not pull cool air out of the house to the attic.