Adding a/c to a room

[andromeda]

Hello all! New here... home repair junkie with an a/c question

I'm hoping to buy a house within the next few months (once it gets out of probate ) and it has an interesting setup. The main part of the house has central air, the garage doesnt. In between the garage and main house there is a "florida room" which I believe was at one point a breezeway or a carport that they just closed off with sliding glass doors so they could call it an extra room.

If you're standing at the front of the house looking towards the back yard, the house is on the right, so the right hand wall of the room is the outside brick of the house. The left side of the room is the outside wall of the garage and is some sort of siding. The front and back walls are just sliding glass doors and the roof is an uninsulated carport type roof.

On the left and right walls, near the top, are vents which I assume used to be the attic vents to the outside.

Being that I live in Florida, having a room with no a/c is pretty much a wasted space. So, I'd like to bring the a/c from the main part of the house into the florida room.

Is it possible to just use the existing vents into the attic or would they have to break through the brick to put in new vents? And what do you think I would need to have done in terms of insulation? I assume the ceiling, but being that most of the room is glass and one wall is an uninsulated garage wall, it seems like more would need to be done or I'd just be cooling the great outdoors

I'm sure no one can give me specifics without actually seeing my house or knowing my a/c setup... so just some general info to get me started would really be appreciated.

Thanks!

[lonestarheir]

How is your system set up? Is it in an attic - being florida, I assume you dont have a basement - or is it in a closet in the house? Does you house have slab foundation, or peir and beam? If peir and beam, are your a/c ducts under the house? What size is the room that you are trying to heat and cool?


All of these things change everything I am about to tell you - If (I am assuming that you are probably set up alot like most things here in Texas) your ducts are in the attic, adding ducts to this room probably wouldn't be to hard. The best thing to do would probably be run the new duct back all the way to the plenum (The starting place for all ductwork). You want to tap it in on either the side, top, or bottom. You NEVER want to tap a duct at the end of the plenum. Doing so will cause the flow of a lot of air to that duct, but the rest of the ducts will suffer drastically. If you do not have room to tap on one of the sides, you will need to increase the size of another tap and then "Y" off of it to the new area.

Most of the supplies to do this type of job are available at your local home improvement supercenters (ie. Home Depot, Lowes, etc...) Make sure that you use a metal based tape to tape any connection points and make sure that everything is insulated - failure to do this will result in water spots on your ceiling (that can sometimes be mistaken for roof leaks).

If you let me know what size the room is I will let you know about what size of duct would be about right for you.

[andromeda]

Ok, I'm trying to do this from memory since I'm not in the house...

On the listing for the house, they have the Florida Room listed as 10x19... on the appraiser's floorplan, they listed it as 11x24 - so it's somewhere around there.

The a/c unit is inside in the laundry/utility room which is right off the florida room. I believe everything is in the attic. No basement. The house is concrete slab except for the laundry room and two bathrooms which are wood. I haven't ripped up the bathroom floors yet (which I have to do. they're old and starting to sag) so I don't have proof, but the inspector said they put all the plumbing/electrical whatnot under the wood parts of the house's floor so if I needed to do any work on it, I wouldn't have to break through the concrete slab. The florida room is concrete slab with really bad carpeting tacked on top.

I'm thinking I wouldn't have to add too much duct work to the current a/c - length wise. If you drew a straight line from the a/c unit to the Florida room, it would only be... maybe 6-10 feet.

Thanks for your help on this. I'm so excited about this project

[lonestarheir]

You will need at least an 8 or 9 inch duct more than likely - A duct of this size can cause loss of flow to other ducts as I said before. In order to spread the air out a bit you could use 2 - 7" ducts and a 9X7X7 "Y"

A 9" duct will give you about enough air to cool and heat a 300 sq. ft. room. That is without sizing it according to the Manual J heat load, but should be close. A 8" or 2 - 6" with a 8X6X6 "Y" will cool about 200 sq. ft.

Hope this helps a bit.

[SSN596]

You need to have someone look at the existing system to see if it would support more cubic feet of conditioned space. If not already insulated, I think it would be important to do that in the "Florida room".

[lonestarheir]

You need to have someone look at the existing system to see if it would support more cubic feet of conditioned space. If not already insulated, I think it would be important to do that in the "Florida room".

This is a very important point - your current system may be at its capacity already, adding duct will only cause alot of problems in the future

[Total Home Care]

Add a mini split system to the room. Adding additional duct and supply registers is only going to make the rest of the home not right.and the system will most likely run much too long...unless the exsisting unit was designed for that room to be added later,,,

[lonestarheir]

Mini splits are a good option for that situation