Air Conditioning - How do I cool hot rooms better

I would appreciate your advice, experiences, suggestions regarding my following problem:
I live in New Jersey in a 2 story colonial house. Cooling works very good in 2nd Floor, Master BR (even with 1 of the 2 regisers closed). Cooling in Loft attached to MBR works very little but I do not care about it at all. It cools very little in remianing 3 BRs on 2nd Floor which I want to cool better. Total square foot being cooled on 2nd floor is about 1600-1700 SF. There are two seperate AC/Heating systems, one for 1st floor and one for 2nd.
Furnace and cooling coil for the first floor is in basement whereas furnace and cooling coil combo for the 2nd floor is in the attic. All ductwork for the 2nd floor system is also in the attic. Cooling/Heating on first floor works very good and no change is needed. Other details are as follows:
1) Condensing unit for 2nd floor is located outside of the house and is a 3 Ton (as per Contactor) Trane unit (High efficiency model XE1200) replaced about 7-8 yrs ago. Whole system is 17 years old. Volts: 200/230, Min. Circuit Capacity: 23.0 amps., Circuit Breaker 40 amps.
2) Cooling coil in attic is 4 Tons (per Contractor) non-name brand name as supplied by builder as original installation.
TO IMPROVE COOLING in 3 BRs on 2nd floor
a) Should I ask contractor to run 3 additional round ducts from the main rectangular duct to the 3 rooms that do not cool well right now to improve cooling. Do I need to replace the main rectangular duct with a bigger size duct also ( I prefer not to do that)
b) Should I ask contractor to relace 17 yr. old mismatched 4 Ton coil with a new 3 Ton cooling coil to match the condensing unit. I do not want to replace the Trane condensing unit with a higher (or lower) tonnage unit unless absolutely necessary.
Do I need to do a) or b) or both.
Any advice/comment will be appreciated. Thank you very much.

i am not an ac service man but i do know that the duct work size matters, the size duct has to match the ac unit ton and number if ducts so you get enough flow, the slower your air moves the warmer it gets by the time it gets to the duct outlet. I would guess that the room that cools the best is closest to the unit, if that is true then it is just a problem with duct work, is the duct work insulated enough or at all. The small amount of ins. that most install is not good enough, you can add to the ins. by wraping it with an additional 3.5" of ins. This would let the air stay cooler while traveling through the duct.

1. Where is the t-stat located?

2. Have you checked the ducts in the attic? If it's flex duct, it hasn't collapsed has it?

3. Do you have good airflow out of the diffusers in the questionable rooms?

4. Do you have returns in all the rooms?

You may want to have them run a "Manual D" calculation and a "Manual J" calculation. The "J" will give you the heat load/loss on the home and the "D" will calculate the ducting needs to meet the load.

Call a good licensed contractor have him come out and give you an estimate on what needs to be done. Then post back

Im with Matt What is the AC load on the upstairs there. Why did they take away about 1/2 ton of AC there. With that 4 ton old coil and new 3 ton condenser. Did they cut the blower speed down some when they put that 3 ton condenser in????


ED ;)

I do not know the tonnage of the old unit. But it must be be less than 3 Ton because it was much smaller than the current unit in physical size. The old unit was a Rheem product per contractor.

AIR FLOW IN HOT ROOMS IS GOOD.

The main rectangular duct is made of fiber board, so I do not think insulated or not, does matter much. Also I remember, in my previous house, which was a Bi-Level I had put in a brand new air-conditioning system. The brand new house had a water heated base board heating system. I think some contactors had offered to insulate the metal duct but others said, it was not important. So my system was non-insulated and it worked fine till I sold the house. The a/c system cooled only the 2nd floor. First floor did not need any cooling. House did not have a basement.

For the current house, one contractor 1 day ago came and said that 3 ton unit is more than enough. Since the cooling coil is 17 year old, it may die soon in the future. So he will repace old cooling coil with a new 3 ton coil to match the condensing coil. He will put in a new metal duct which will be bigger in size than the current one and will move 1200 cfm of air (much more than currently being moved). He will also replace the existing furnace (as it is 17 years old) with a Lenox 2 stage variable speed, 80 % efficiency Furnace.
He will leave condensing unit as is.

I think this solution will work, but it is a expensive solution. He will submit his proposal in few days. DOES ANYBODY HAVE SUGGESTION FOR A CHEAPER SOLUTION. Does anybody have any comment about performance of Lenox Furnaces.
Contractor also said that attic cannot take a 90 % efficiency furnace as water from furnace may freeze. Is that true.

Another contractor who came 3 days ago said, he will do load calculations and let me know the correct size of the condensing unit needed.
I will post again when I hear from the contactors. Thank you very much.

1) One 14 by 30 return is located in the Foyer. One small return is located in the loft (I do not care about cooling Loft well). Contractor #2 (who came in 1 day ago) said he will put in 1 extra return in one hot BR that will help it cool better. He will also put one extra return in Loft.
Can some one give me pointers on importance of returns, proper location and size of returns.

2) Themostat is located in the MBR directly under one Register. Contractor #1 (who came in 3 days ago pointed out that) and said that he will move it.
How important is that ?
I do not think that, it is very important, because even with the register above thermostat closed and air coming out of the 2nd register only in MBR, MBR gets very cool and other rooms stay hot.

3) I do not think that they cut the blower speed when they replaced the condensing unit. Because Contractor #1 was saying that speed of the Blower is fixed. I think they put in a replacent unit of 3 Tons as old unit was 3 Tons or smaller. I do not think that they bothered to check the coil size when they replaced the condensing unit.
Thank you very much.

1) One 14 by 30 return is located in the Foyer. One small return is located in the loft (I do not care about cooling Loft well). Contractor #2 (who came in 1 day ago) said he will put in 1 extra return in one hot BR that will help it cool better. He will also put one extra return in Loft.
Can some one give me pointers on importance of returns, proper location and size of returns.
You need to return at least as much air as you are trying to put out. Return location should be toward the inside walls. Returns need to be at least as big as supplys. I always go 10-20% larger.

2) Themostat is located in the MBR directly under one Register. Contractor #1 (who came in 3 days ago pointed out that) and said that he will move it.
How important is that ?
I do not think that, it is very important, because even with the register above thermostat closed and air coming out of the 2nd register only in MBR, MBR gets very cool and other rooms stay hot.
Normally I would say it's very important but in your case???

l would appreciate very much if some one can tell me what is the "expected Average Life" of a non-name brand Gas furnace installed in 1987 by the Builder, like one I have. Most probably it is not a variable speed or any other kind of fancy furnace.
Is it 20 years, or is it less or more than 20 years ?
Thank you very much.

If installed properly & with a little care, any furnace should last at least 20 years. Depending on your heating season, it might pay to look into a 90%+ efficient unit.

Contractor #1 has done load calculations. He calculated the area to be 1471 to 1475 SF. He came up with a condenser size of 2.5 Tons. He says duct size is fine. However contractor #2 and contractor #3 (who came in today) based on their experience say that 3.0 Ton unit is fine. Also the size of original condenser put in by the builder was 3.0 ton (I verified this, from the original contact signed with the builder. If the correct size is 2.5 ton, then also it should not make much difference, as hot rooms may stay humid but they should cool down). Contactors can replace either cooling coil or furnace (with a two stage/variable speed or regular furnace) or both at a reasonable price. Cooling coil does not have a label and does not seem to ever have a label attached to it. So I do not know the manufacturer or tonnage of the coil. Is cooling coil supposed to have a label. My guess is that seers of coil should be 9 or less as coil was installed in 1987. Furnace is 95,000 BTUH Rheem, Model No.: RGUF-095A-GR. Label also shows the S. No. of the furnace. Furnace and cooling coil were installed in the end of year 1987. Considering all this I have following questions:

1) Contractor #2 and 3 said, they would replace it with a 13.0 seers Rheem compatible coil (per contractor #3, Rheem does not make cooling coils. Somebody else make coil for them. Does anybody know, if this is correct ? ) . #2 said that 3 ton Trane XE1200 condenser for the system (manufactured in Feb 96, installed in 1997 or 1998) is 13.0 seers. Does anybody know if this seers is correct ? If it is then I have a matched system. Difference between seers 13 and seers 10 coil is only $50.

2) Cooling coil was installed in 1987, so it is old. If I replace it with a new coil, would that improve cooling in hot rooms at all ?

3) If I replace 18 year old 95,000 BTUH Rheem furnace with a Trane or Rheem or Lennox furnace, would that improve cooling in hot rooms at all. If I replace the furnace, would choice between Two Stage/variable speed or regular furnace would make any difference at all, as far as improving the cooling in the hot rooms is concerned. Contactors want to replace the furnace with a 75,000 BTUH or 80,000 BTUH two stage/variable speed furnace. If I replace furnace with a regular furnace, should I go with 95,000 BTUH or less BTUH furnace. Any thoughts on this.

Any thoughts, comments, suggestions, advice on above issues will be much appreciated. Thank you very much.

Iam sorry I forgot to ask one question in the last post (please see my previous post also). Iam asking too many questions. I think I will stop asking questions soon.
I know, when A/C system is operating normally then it is fully charged with freon. When the system is fully discharged, (i.e. there is no freon in the system, because freon was discharged due to a leak), system cannot produce coolness, even if system is running for few hours. So my questions are as follows:

1) Is it possible for the system to be partially charged, even though there is a leak in the system (and A/C system is running). With a leak in the system,
how many hours of continous A/C operation would it take for the sytem to be completely discharged (maximum number of hours), i.e. freon to escape from the leak and A/C stop producing coolness ?

2) I had following scenario in my house on 2nd floor, yesterday at around noon time. outside temperature was around 55F. So I started running heat around 11:00 am. I set the thermostat at 80F (actual temp. probably was between 75 to 77F). Heating system maintained that temperature. Thermostat was showing a temperature of 80F. At 12:00 noon I decided to test the A/C syetem. I checked the attic. Attic fan was running because temperature in attic kicked it off. I turned the A/C and set it at 65F. After running for 1 hour continously, thermostat was showing a temperature of 67F and cool air was coming from the registers. Based on this information is it possible to say that there is no leak in the A/C system ?

I thank you for reading my posts. Thank you very much.

If there is no frost or ice on the lines by the indoor coil .And the big copper line outdoor at the compressor is cold and wet. Then sounds like the units charge is ok
Makee sure the air filter is clean.

ED ;)

Contractor also said that attic cannot take a 90 % efficiency furnace as water from furnace may freeze. Is that true.



That is true. A condensing furnace cannot be exposed to freezing temps. You must build an insulated room in the attic.

Refrigerant leaks can be large or very small. There is no way to tell how long it will last.