Ducts replaced, Increase in temperature

[Dumb_Homeowner]

We live in Florida just south of Tampa. Yesterday we had all of our metal ductwork replaced with new flex duct. They also replaced our merc stat with a digital one. So far so good

My wife likes to keep the house frigid, stat stays pegged at 70 year round. Since we had our ductwork replaced temperature has not gone below 76.

Any thoughts on why the temp would increase?
We have a 2 1/2 ton Janijunk as they fondly refered to it.
Any questions you can think of I can ask?

I am just a dumb homeowner, actually an Irrigation contractor , but I know virtually nothing about ac, I would think by removing the old metal ductwork with holes and leaks and such and replacing it brand new flexible duct, you would get more air into the home which should be cooler not warmer.

When I called the tech this afternoon, and explained the higher temps, I was told they would stop by and check the pressure. This is a father / son team, and yesterday when the father asked the son what the static pressure was his response was 75 then walked away. I don't think he ever got the other half 75 over what?

And to top it off, he fell through the living room ceiling so their drywall guy is coming out today. It is currently patched with cardboard and silver tape.


Any thoughts are welcome.

Thanks,
John

[beenthere]

Did they replace the metal duct with the same size flex. If so, it decreased the amount of air your getting.

[obxtech]

Flex duct should be larger than the original sheet metal ducts as beenthere stated. also did they replace the register boxes / boots? if not then they probably used the same size flex as the metal they pulled out, or they reduced back to the original size, either way means less air delivered to each run out. how about the main trunk duct did they check it to make sure it was sized properly?.

[captube]

The system was off while ducts were replaced it's possible that it is using most of it's power removing humidity from the house and contents.

[Dumb_Homeowner]

They used the same size flex as the metal. 5" 6" and I believe 14" r60 for the main run. They left all the original vents in place, added 2 triangle shaped boxes and inserted the appropiate sized rings. I do believe the main metal duct was larger, but I did not measure, only going by eye.

[beenthere]

A 6" flex, is more restrictive to air flow then a 6" metal pipe.
So your air flow is reduced.

[Dumb_Homeowner]

Captube -
I thought the same, but the system was only off for about 2 hours while they made the final connections to the air handler. I figured 20 hours was enough time to remove the humidity from my 1400sqf home.

[BigJon3475]

Your low on air flow......

[papa_jo]

I hate them triangle things

[obxtech]

I hate them triangle things

[hvaclover]

Fell thru the cieling?

The Three Stooges come out of retirement?

[hvaclover]

You got an undersized duct system. Those six " runs should be a minimum of seven. And r6 seems a little slim for Florida.

A static of 75? The worst it should be is .50.

Sorry to say you didn't get what you paid for.

[captube]

Yeah, your probably right. It looked good from here

Airflow and the added heat gain from the cardboard is my new guess

Captube -
I thought the same, but the system was only off for about 2 hours while they made the final connections to the air handler. I figured 20 hours was enough time to remove the humidity from my 1400sqf home.

[geodude]

And to top it off, he fell through the living room ceiling so their drywall guy is coming out today. It is currently patched with cardboard and silver tape.


Beside the obvious undersized ducts/reduced airflow problem, I agree with cap tube, there will be added infiltration and heat gain from your temp. ceiling repair.

[forcryinoutloud]

I have to agree with everybody that said poor duct design and added heat through your cardboard ceiling.

Also concerning R-8 flex in Florida (atleast West Central), good luck finding it in stock anywhere around here, if you want it it is considered special order every place I have asked.

[hvaclover]

I have to agree with everybody that said poor duct design and added heat through your cardboard ceiling.

Also concerning R-8 flex in Florida (atleast West Central), good luck finding it in stock anywhere around here, if you want it it is considered special order every place I have asked.

Phfft...it's common as water around here. Bet if you called a Johnstone in Mi you could get it next to nothin'.

[catmanacman]

sounds like they pulled out a good duct system and installed a crappy one why did thet not just seal up and re insulate the metal duct they also could have a big air leak somewhere

[forcryinoutloud]

R-8 seems to be code for attic installations in quite a few states. The first time I asked for it at a supplier I got the 'deer in the headlights' look.

[addamsmasher]

I just talked with a buddy of mine who took a duct design class. He told me that when you're using flex you have to go up one size (for example 6" hard pipe would be 7" flex) because you have more frictional loss in flex. Sounds like you're return is undersized and return is where you get moisture removal, I mean if the unconditioned air can't get to the system it's going to stay unconditioned.

[dash]

"They also replaced our merc stat with a digital one. "

Could it be the old stat was inaccurate?

How does it feel,comfortable??


1400 sq ft,2.5 ton,not likely that it ever got to 70 degrees before,but it's possible.

14" and a larger trunk,if it's the case sounds large enough,but you know we can't tell from here.What size and type of return duct??


Can you get the sizes for sure and post some pics??