Adding air

[gfretwell]

Since in other threads you are talking about insulation and an attic you have the same options as you would have in most homes.

In Florida with poorly insulated houses, big windows and lots of sun they usually use a quick rule of thumb as a ton (12,000 BTU) per 500 sq ft. With no windows and R-11 insulation in the walls (3.5" fiberglass batts) you should be OK with a ton and a half. The Bard wall hanger somebody mentioned is an option. That is the tall package style unit you see hanging on the side of a building. Another option is a regular split system with the Air handler hanging in the attic or below the ceiling near the center with some duct work distributing the air to the ends of the building.

Are you planning on installing this yourself, do you have a buddy in the trade or are you just calling someone? Other choices are the package unit on the ground with ductwork similar to the split system. This can be DIY since you are just supplying the ducts and the power. It comes fully charged and ready to go in that "package", or the big mini-split which may not be the best air mover but it is the easiest to do and they sell DIY setups for the mini. Move the air with some fans.

[stryped]

I will be doing this myself. I found a guy that has a Bryant 2 ton

2005 model that will deliver it for 500 dollars. How much shoudl I expect to pay in ductwork?

[clare]

They are designed for "sleeve mountable" or "through the wall" conditioners - NOT window units - and the through the wall units are not very common - and are relatively expensive.

Standard window units will NOT work in an apartment sleeve - at leat not MOST of them.

It takes at leat 3 inches to get adequate airflow, and it has to be properly baffled so the heat shed from the back of the unit is not drawn back in the sides.

[gfretwell]

If you can get an HVAC supplier to sell you the stuff it is certainly less than $100 but that can be hard to do. They really like to protect their commercial customers. To do it right you need a few tools, a couple sheets of duct board, a box of flex duct, a roll of silver tape (not duct tape) and some fittings. The coolest tool for working with duct board is the cutter that makes a "V" shaped groove without breaking the outer paper for a perfectly mitered corner you don't have to seal. You need a wiper to seal down the tape, they might give you one but it is a dollar deal. The best way to seal the joints where duct board meets flex duct is mastic (gooey stuff that hardens) You need metal collars for that joint and metal boots for the duct grilles on the other end. Keep the flex duct tight and support it so it doesn't sag. It will perform virtually as well as metal duct. You can usually size the ducts based on the size of the hole in the unit and be OK. Do a little geometry and get the round flex ducts to equal or exceed the sq/in of the duct you build. As short as the ducts are it is not a huge problem if you are a little off but don't choke it.

I have a duct wheel I can run the numbers if you want to actually engineer this (a rotary slide rule deal). .

[stryped]

Would you go outside the building or inside?

One thing I am having trouble invisioning is how the supply and return air both are positioned on the unit? I mean when I drive down the road and look at houses with a package unit, all I see is a "metal square" going into a crawlspace. On metal businesses I see one square duct going up the side of the building into the roof. Are both the supply and return lines in that one duct?

I would look at my house but it has a split system.

I also found a guy selling split systems. He said the coolant is still in the condensor like the factory. ALl that is required is brazing a copper line from the condensor to the evaporator. It seems there are alot of these air units around.

The package unti I qoted earlier sounds like it was a good deal. WOuld

2 tons be enough for a 30x30x10?

[gfretwell]

2 tons should do it if you insulate the place some. Usually the return port is on the bottom and the supply is on top. Take the return straight through the wall and duct the supply up the wall, inside or outside. Just be sure you have an insulating chase over the ducts if it is outside with the vapor barrier on the outside. (where the warm moist air is) Personally I would put the unit tight to the wall and run the ductwork on the inside.

As for he guy who says the freon is still in the compressor on a removed unit, what remains there is not as much as the "precharge" from the factory. You will be adding some. I would not trust it anyway. I would replace the dryers, draw it down and recharge any old system. Legally they were supposed to recover all of that freon before they broke the old machine apart.

[jamesgangnc]

The ducts are side by side on your typical package unit. If you go under the crawl on a house that has one you'll see. Typically a couple big pieces of flex run from there. If you are putting a package unit against the side of your garage you could pretty much butt a return vent right up against the unit. You would still need a log piece of square duct to get to the attic from the outlet. That'll be $100 or so from a sheet metal shop that specializes in duct work.

The refreigerant is inside the condensor but to install it properly you braze or solder the lines, pull a vacuum on the lines and evaporator. See if it holds to check for leaks. Then open the vavles on the compressor to let the refrigerant inot the rest of the system. A brand new system will have enough charge for an evaporator and x feet of line. A used systemor longer line will require you to add refreigerant.

The trick to dealing with hvac supply houses is to do your research ahead of time. You go in and know what you're asking for they will usually not question you. As long as it's not systems. You need a certificate and in most states a contractors license to buy a system. But if all you're after is duct work or boots or somethingthey won't hassle you. Also good to go middle of the day. Most ofthe pros hit them first thing in the morning to get ready for a job. You want to visit when they are not busy.

[stryped]

Thanks so much for the good advice! WOuld you guys run the duct up the inside wall into the attic, then protrude the registers in the ceiling or, like in come commerical buildings, would you just hang the duct and registers below the finished ceiling?

[jamesgangnc]

A lot depends on the exact nature of your situation. I'd probably try to go for a corner where I could box in the vent going up and run the distribution above the finished ceiling. But I like to get professional looking results and you might not care so much about that in your garage.

[stryped]

I like professional results too, I just hate to have an odd blocked corner. Going on the outside seems easiest but not sure.

I just went to my local Lowes and they have all kinds of duct material. They dont have the "square duct" like I see on the outside of building sometimes.

Does a plenium usually come with the air conditioner?

[stryped]

One thought, can all this ductwork touch a combustable surface?

Also are the ports out the back of the package unit typically round or square?

[stryped]

One last thing, I am learnign alot here. When I went to lowes I saw duct that would fit inside a 2x4 wall. Would it be better to put registers in the wall as opped to the top of the 10 foot ceiling?

[jamesgangnc]

Lowes only has the bare minimum. The bigger square stuff is usually built to a specific application. Measure and do a rough sketch of what you need. Find out who's building duct work around you. Sometimes it sheet metal fabrication places. One of the local hvac supply places near me also does sheet metal work. I'd stick with the ceiling vents. Running it back down the walls just addds more resistance to the whole system..

[gfretwell]

No the package unit will just have 2 rectangular flanged ports on the back. You have to make or have made the plenum and the rectangular ducts. Duct board is usually the easiest way to go and if you are out of conditioned space the best way to go. Metal ducts will sweat like a pig. The duct board comes in different thicknesses with different R values. You use that "V" tool to define the corners and fold it up, taping the final corner. Then you cut the holes for the round ducts going out and the rectangular flange coming in.

It might actually even be worth going to a guy and having these built if you can find someone who will do it. It might not be that much more to just have it all installed. When you get the whole thing done, build a chase around it with 2x4s, insulate it and sheath it with whatever suits your fancy. The weather will kill that duct board pretty quick. It is a good idea to build a platform for the unit up off the ground if flooding or snow are a problem. In Florida it has to be above the FEMA flood plane.

[stryped]

I planned on pouring a concrete pad myself for the unit. SO there is no way to attach just regular duct to those two ports on the unit you were describing? So the plenum has to be in conditioned space?

[stryped]

I learned alot reading this:

All a plenium seems to be is a square of metal or duct board. I have seen panels at Lowes that look like they snap togther. I am wondering if I could make one? I could even mig weld it.

Could I make a metal one then line the insife with duct board to insulate it? Go up to the attic with 14 inch metal pipe, a 90 degree elbow then the insulated duct inside the attic? I think someone said I would need to insulate this 14 inch metal duct somehow. Is there insulation that is rated for outside exposure?

Again I appreciate it!

[gfretwell]

Metal is really more appropriate for heat. It will sweat when you have A/C going through it. Just use the duct board and round flex duct. That is insulated too. If you pull tight so it runs straight and supported so it doesn't sag it performs as well as metal and a lot easier to deal with. I bet if you call around you can find an AC guy to do this for a couple hundred bucks if you build the chase (after) and have the slab ready.

[Evan]

The heat drawn back in the sides ?

On a motel PTAC: Packaged Terminal Air Conditioner there are no "sides" exposed... On the exterior all that is exposed is the flat face with the louvers on it... The "sides" are inside the wall and the rest of the unit is sticking out into the room on the interior...

~~ Evan

[Evan]

Man, I would look at a motel model PTAC like a GE Zoneline...

They don't cost all that much more than what you are looking at spending on this used package unit which would require ductwork to be installed (which will cost money to do right) and a heavier duty electrical feeder which will have to be installed in rain tight enclosures and with rain tight flexible metal conduit...

Is that used Bryant 2 ton unit from a commercial building ? Does it need 3-phase power ? It is not something that will be plug and play into a standard power outlet...

For just a about a hundred dollars more than you are looking to spend on the huge outdoor unit and all the tools, ductwork and electrical supplies you would need to install it, you could buy a brand new 14,700 BTU PTAC unit which will cool, heat using reverse cooling cycle and have a 5KW electric booster heating element for when it is too cold outside to use the reverse cooling cycle for heating; all fed from a unit which only requires a 30amp 240v power outlet...

Simpler electrical install since it would all be inside wiring, simpler unit install and it would serve you year round rather than being summer only...

Just my thoughts man... Good luck...

~~ Evan