New Carrier System Issues
Just need some advice. We recently upgraded our old low efficiency and lousy cooling 1984 Goodman 4 ton system with a 5 ton Carrier 17 Seer system and Infinity controller. We have a well insulated one story 3300 sq ft home and another 3 ton HVAC unit.... so a total of 8 tons. Unfortunately, our home is still too hot. The 5 ton Carrier end of the house is not able to meet temperature even at max cool ( vs dehum). There are high static pressure errors each day ( reading about 1.2+) . Our Carrier installer assures me that he has enough supplies and returns. He calculated 6.5 tons of ducting in each direction. He is stating that Carrier knows there is a problem with the software and it is too sensitive, and that Carrier has already revised the software twice. From what I have read, the static pressure is indeed too high. Is there anything else that I should be doing to resolve? The installer says it's not a real issue, but I am concerned...especially since I'm still too hot.
We have not had any problems with the software that I know of, and I have not read any service bulletins. You have duct issues.
We like the static to read .5 in high speed.
We will allow .7 on some replacement jobs where if can not get to the ducts.
Did they do a manual J to figure the load, or just "bump 'er up a ton" because the other system was not cooling enough?
Model numbers of the indoor and outdoor equipment, and a location (city/state) would be helpful.
Last edited by davo; 06-16-2008 at 06:00 PM.
Reason: spelling error
Ah, you contractor my be grossly mistaken about the size of your ducts.
The controller is probably correct.
Don't recall contractors installing 4 ton systems with duct work big enough for 6,5 tons.
I have some prime swampland for sell though.
The new system I have is:
The installer added two returns so I now have (4) 16x16" return grates ( not sure on duct diameters). He added a few supply registers as well. But he did still "bump it up" since the 4 ton was not doing the job. He said 4 ton would be at the edge of not enough and 4.5 tons would have been about right. We went with 5 tons since we like it cool. It is 101 degrees today and the system has been running continuously for the afternoon and it has only reached 75 with 73 set-point. Am I asking too much? The last system (4 ton ) would reach only 78-80.
You might have a 5 ton unit. But with that high of a static pressure, your not moving 5 tons of air flow.
Sounds like your old 4 ton, wasn't moving enough air.
If he says that the controller is reading false, have him come out and test the staitc himself.
I would ask the installer to see the manual J and manual D results where it says you needed 5 ton system.
carrier only makes 2,3,4 and 5 ton cond units in infinity as you contractor to check sys pressures and make sure he checks it by subcooling ask him to tell you what subcooling is running i think 5 ton runs 15 to 16 F of subcool.....since your house doesnt cool your coil could be freezing up and acting as dirty filter......control sees the diferents in static pressure
Originally Posted by DanW13
Standard rated sensible capacity is reduced for each degree you set the indoor temperature below 80°.Your comparison sounds about right,between the old and the new.
Originally Posted by zz4x4
No software issues,and we install a lot of Infinity Systems .
Static should be reduced ,regardless,and will likely improve indoor temps a little.Ducts could be leaking ,as well as many other things.
It is a real chore to deliver 2000 to 2250-cfm for a 5-Ton A/C.
I am just guessing or, hypothesizing here!
The 4-ton 'probably' had low airflow.
Depending on the latent load, if they had installed the new ducting for a 4-ton with 1800-cfm, 450-cfm per/ton of cooling it may have done about the same as the 5-ton is doing. For the 5-ton, the 1800-cfm would be 360-cfm per/ton.
I am very concerned about 5-ton equipment in most homes, too many seem to have problems. - udarrell
They did 2 years ago have a small issue with series A controller. Just pull thermostat off bracket and look for series A or B. 1.2 static is definetly a problem. What is the model # EX- 58CVA155 -_ _ That will tell you cfm rating. Also furnace Has to be put up on return stand, so return air comes into bottom of furnace or both sides of furnace. Anything over 1600 cfm. Make sure filter is not to dense. Post pictures so we can show you what is wrong. Now when this is correct then you can charge unit properly.
Do it right the first time.
The Furnace model number is 58CVA110
What is the model # EX- 58CVA155
The installer did say that too. He said we were getting maybe 3.5 tons worth of flow on the old system. He did bump up the ducting but is this enough to move 5 tons...
Sounds like your old 4 ton, wasn't moving enough air.
I went to the attic and found
(3) 12" return ducts and (1) 10"
On the output side I see (6) 7" ducts and (3) 8" ducts.
I will try to get some photos.
According to the controller the handler is moving 1650 CFM with 1.18" Hg pressure. Shouldn't it run at 2000CFM on max cooling or has it dialed itself back due to the high pressure?
Could be the supply ducting that's giving you problems. Not sure, though, 'cause I don't have my duct-u-lator on me.
21degrees, could you elaborate on this? The furnace is laying on it's side with the input plenum connected to the end. Are you saying this is incorrect for a 5 ton system with 2000CFM?
Also furnace Has to be put up on return stand, so return air comes into bottom of furnace or both sides of furnace. Anything over 1600 cfm.