View Full Version : Adding another AC unit or installing dampners, help....
04-28-2008, 02:27 PM
I hope you folks can shed some light on this for me. For 3 years now i've been in my house, it was new when i bought it. I've got a 3 ton unit outside that runs both the upstairs and downstairs, my whole house is only about 1600 sq feet. I live in the South and of course in the summer my upstairs get really warm, my upstairs consists of 2 small bedrooms of about 121 square feet each, a small hallway that is about 50 sq feet and a full back about 50-60 square feet for a total of about 350 square feet total upstairs. I've gotten 3 quotes and each one of them suggests installing a new 1.5 ton unit and none of them have mentioned anything about dampners. The other day i got a quote from a friend of mine who told me that this space is too small for a 1.5 ton unit and it would not get rid of all the humidity in the upstairs and he recommended dampners. This is somthing new for me and he explained to me that he would install a second thermostat upstairs and it would control the opening and closing of the dampners. My biggest question is why didnt the other 3 quotes i got mention something about dampners and also can someone tell me if they have dampners do they work fairly well?
Thanks in advance.
04-28-2008, 02:31 PM
Presuming he's talking about zoning your house. Yes, they can and do work well. If its designed and installed properly.
The others may have felt the upstairs zone is too small for a zone system to work right. Thats just a guess on my part.
Check with your friend, if he's installing a zoning system, or just motorized dampers.
04-28-2008, 03:05 PM
What is the difference between a zoning system and just adding motorized dampners?
04-28-2008, 03:16 PM
Adding just motorized dampers, turns the one area into a slave of the other. As in it only gets heat or cooling if the other one is calling for it.
04-28-2008, 03:34 PM
In your opinion, adding dampners or zoning it, would that help quite a bit as those rooms get pretty warm in the summer here in Mississippi? Or would you have another recommendation?
04-28-2008, 03:52 PM
if the area is to small for a 1 1/2 ton unit how is he going to cool it with 3 tons and a damper system??
i think the small seperate system would be the way to go, maybe dump off some of it down the steps if not needed upstairs.
04-28-2008, 04:06 PM
That is actually not a bad idea of putting in a 1.5 ton unit and running some of the additional air downstairs. The guy who mentioned the dampners is supposed to give me a call and give me a quote on it tomorrow and i will mention this to him. Thanks for the idea. Is the 1.5 ton unit the smallest unit the the well know carriers make?????
04-28-2008, 04:28 PM
York makes a 1 ton unit.
04-28-2008, 05:40 PM
Yes, York does make a nice little 1 ton!
Zoning is not a cure-all. If the ducts to the upstairs are undersized, zoning won't help especially on a hot day when the system is running maxed out to cool the whole house. We had to put a 2nd floor cooling only system in 2 years ago for a zoned house. Had the main duct to the 2nd floor been large enough he might have been OK. But it wasn't so despite zoning, he was hot upstairs.
In this case, could be the same way. Then there's the short cycling of the 3 ton trying to cool 2 rooms. If a cheap panel is used, you'd probably freeze the coil in short order. With a good panel that has a thermistor to monitor supply temp, the A/C would cycle off after a few minutes of running leaving the upstairs humid. Regardless putting 1200 CFM through 2 or 3 registers would be NOISY!!! You could put in a bypass but dumping 800-900 CFM of cold air straight in the return would really shut down the A/C fast!
I'm thinking mini split w/ 2-3 evaps:cool:
04-28-2008, 08:12 PM
First thing I should do is a load calculation for the house, if 3 tons is fine, then you can use a zoning panel wiht motorized damper and a bypass. But if you make the load calculation and 3 tons is not enough then tha load calculation will tell you how many tons you have to add.
I hope this help.
04-29-2008, 02:33 PM
Thanks for all the replys. I have the same guy coming back toward the end of this week and i am going to show him what you all have recommended and see what he says.
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