If a 1.5 ton cooled and dehumidified well but ran all the time, what in blazes are you doing over doubling the size? You had better be ripping all the ducts and putting over double the duct capacity in too. And increasing the number of supply & return vents.
I can't believe 2500 sq ft in CT needs 3.5 to 4 tons. You'll barely run and have high humidity, even the 2 stage since low isn't much less than high .Then you'll need a whole house dehumidifier.
You likely will never recoup the investment for 16-17 SEER either. Good for the salesman's commission which is likely why Mr. Trane was pushing them. Rheem is good equipment but 4 tons without changing the main duct size???? Wow, you have some real winners up there.
Somebody better find out what you have (if you can post model #s in & out we can tell you, somebody, even you, should do an accurate heat gain, then see what you need. But if you kept comfy with 1.5 ton and only complaint is higher than desired bill, you sure don't need those monsters being quoted. Short cycling and if they reuse that small duct system, you may not see much of a savings.
Well every single person has recommended a 3.5-4.0 ton unit. I was incorrect (rather one of the salesman was incorrect) on the outside unit being 1.5 ton - it's 3 ton and the air handler is a 3.5 ton unit. This guy is the only one who did the heat lost/gain and every single neighbor with a similarly sized house built by the same builder in 1953 has a 3.5 to 4.0 ton so I don't find the size shocking. Also, it's a ranch with a very large roof, lots of attic volume and lots of very large unshaded southern-exposed windows.
Originally Posted by BaldLoonie
He said going to a 4 ton from a 3.5 ton that the main duct will be fine (it is slightly oversized for a 3.5 ton system), he will need to add a return (there are already two) and runs may need to be added and sizes adjusted based on cfm requirements of the individual rooms.
Lastly where are you from? Don't discount how hot and humid southern CT can be in summer especially along the Sound where you don't get the ocean breezes - just the added evaporative humidity.
Click on http://hvac-talk.com/vbb/showthread....1#post15583161 and read the post again.
Originally Posted by idmd
If your 3-Ton ran steady at the worst conditions then it was sized right; though it may not have been delivering to & from the rooms near its Rated Performance. They can't size replacement units by un-performance tested existing units; the existing system may need work to improve its performance!
There is NO way you can go to 5-Ton on that duct system & Return Air Filter sizing, etc., don't even consider it; please don't make any equipment decision until the Home Energy Audit & any needed Retro-work is completed.
Please don't get the cart before the horse; You could make a costly mistake that you will regret for the life of the equipment.
Were it me, I would use a separate system for the distant room that is running the load-calc way up. The design conditions show that humidity is probably the biggest problem not temp; therefore, never oversize the A/C, as it needs long runtimes.
Check the duct system & return Air filter area sizing should be for 300-fpm velocity through a 1" deep fiber glass filter (Manual D, Bet they don't know that); you have to keep the pressure drops low...You make the call, you live with an efficient result or, with a very costly result...
Alright, I have his load form in front of me now.
Total sqft = 2510
Total required cooling 47602 Btuh @1600 cfm
Total required heating 75825 Btuh
The "sun room" in question is 192 sqft (bigger than I thought) and he calculates in needs 276 cfm. Some rooms like the dinning room have too much flow as is and some like the very large living room don't have enough. Interestingly the "sun room" is the most cooling intensive room in the house even compared to the 464 sqft living room that only has one externally exposed wall and one large window.
As always comments welcome.....
The reason the 5 ton would be significantly more is because he said all the duct work would been to be replaced....with the 4 ton he says we can use the main supply and since we're changing out all the runs anyway they can be properly sized.
Originally Posted by udarrell
Alright....in the middle of the change out. Air handler (Trane Tam7) and condenser (xl15i - 4 ton) is installed and now they are working on the duct work. Turns out main duct was internally insulated with a 1" fiberglass duct liner. Their plan is to keep this because it was done well and in good shape and then use 3" fiberglass duct wrap. Installer said it should give around an R11.
Any reason to question whether or not internal insulation should be removed?
So finishing an energy audit that could not be completed because the AC died. New AC is in but the audit guy made the following comments - overall they did a good job with the exception of:
1. There is 1/2" space between the air handler and supply duct around the bottom.
2. The 90 degree elbows that lead into the vents were not sealed with mastic.
As a consequence the system is not sealed properly and I don't qualify for a $500 rebate until that's done.
System is 2 weeks old. What do you think about these comments? How would you approach install company?
I grew up in belchertown ma, and didnt have ac untill a week before i left for bootcamp and dad bought "me" a window shaker. We used to hang sheets in the doorways n open windows at night... And the house never got above 78/58rh i love seeing the big ac boom up there though.
Southern coast of CT gets warm and particularly humid at night. Tonight for example it's only 64F out but the humidity is 95%. We have long stretches in the summer where the temp is 80F+ with high humidity at night - windows or fan I'd probably wake up in a puddle of sweat without an AC on those nights
Originally Posted by ReferYankee
Please review AOP Forum Rules.
So today is our first 90F day with 45% himidity and really the first day the AC has been "needed". Still have some improperly sealed ducts so things may get a little better. I set the tstat at 68F just to see if it could cool that low. My new system is a 4 ton which replaced a 3.5 ton and there was some discussion it maybe too big. With the tstat set at 68F the system has run constantly all day and has maintained 70F inside.
On a positive note the kitchen and sun room which have large windows and a southern exposure are much more consistent with the rest of the house. The sun room used to be 8 or 9 degrees warmer on a 90F day and today it's been 73.5F all day with full sun.
It's my understanding a properly sized system will lower inside temp 20F. Is this correct? Is this the type of performance you would expect?