HVAC Systems: Electronic Dampers?

[Cajungaltx]

The house is 1503 sq. foot - last year, we built out 1/2 of the garage for additional square footage of 180 or so. Bringing it to 1683...

The air conditioner was builders grade when we bought the house - the additional square footage pushed it right over the edge - to the point that it was ridiculously hot.

The floor plan - and the return vents are in stupid places as well - per the a/c guy friend.

We installed a window unit to provide relief through the summer, and to give us time to figure out what to do to. Well - my husband was dealing with that particular issue, and as of right now, I have the issue dumped in my lap.

I've spoken with a friend of ours who is an a/c guy - he walked through the house with my husband and gave him some suggestions on what to do to 'balance' the air a bit more - because the bedrooms are cool/cold while the living area is way warmer...

Brad didn't get a chance to do much of anything - mainly due to the job issue and lack of income until just before he deployed. So I am going to have to address this issue while he's gone.

The goal is to do it over the cooler months - mainly cause I think we could probably get it done for less.

The options seem to be:

1.) Install a larger A/C Unit - long term, this is probably the better choice - but the cost is around 800-1K from everything I've researched.

2.) Install damper units - this was suggested by the a/c guy who came out and looked at the house. He said the unit we have is almost brand new (4 years old) and is in great shape, it's just too small. He said that would be the most cost effective.

Anyone have any experience with this?

I'm leaning towards the dampers - simply cause I think they make more sense. I don't use the bedrooms during the day, but I cool them all day. I don't use the living areas at night, but I cool them all night. Kind of like a programmable thermostat to me.

[kenw]

Yes the dampers make sense. We are planning to use them instead of adding a 2nd system.

Did you add insulation to the garage?

[Cajungaltx]

Ken - have you talked with anyone about doing it?

Definitely! Had them add it in the attic (the entrance to the attic is in that room) - and we had them insulated the walls, and sheet rocked on both sides.

[kenw]

Sorry for the brevity of the previous post, typing from an iPhone doesn't lend to detailed reports.....

Actually I've thought about it some more and considered your situation and how it is different from ours.

In our case, we are planning to block off the upstairs since those areas (~1100 sf) isn't occupied much anymore. Rather than install 2nd unit (furnace, condenser and evaporator, $$$$$), it makes more sense to simply redo the ducting and add dampers.

For eons we've done it manually: closed off the upstairs vents in the winter, closed most of the downstairs vents in summer. Dampers would make this simpler to change-over and allow us to replace a lot of the old ducts at the same time.

But realize that in our case, we've got enough AC to handle 100% of the space already, we're just throttling it back to gain efficiency.

In your case, you're trying to make a now-too-small unit work in a now-larger space it really can't handle. If you ever need to have all of the zones open, your AC will still struggle to keep up. For the dampers to work best, you'll need to cool EITHER the new space or the old space. If you can live in this either/or world, it would work fine. But something tells me that might be tough. The less your relatively new unit has to work the longer it will last, period.

In your case, the wall unit in the new space could be a lot more cost effective (and you already have it!) and isn't really all that much of a detriment. It might be your best option considering the cost involved. Beyond that, a separate and very small split system for the garage would be my 2nd choice. It would be more elegant, quieter and more palatable when you sell. (You've seen some ads on TV for them by Mitsubishi or Panasonic) But the window unit does the same thing from a capacity standpoint already, so it remains my 1st choice.

[Cajungaltx]

Ken,

The problem is my new french doors, quite honestly.

The window unit is in my office - which works great with the wide open doorway.... I have a ceiling fan, and then we keep another fan to circulate the air - but I just installed french doors in to close off my office. *grin*

Oops!

The garage area is enclosed - and we did it the long way. Usually when people convert their garage - they convert one 'bay' - i.e. where one car would fit. We did it exactly the opposite because it gave more 'head room' - where as converting one 'bay' would have meant 1/2 the room had the lower ceiling to accommodate the garage door opening.

The problem is that there isn't a way to get the wall unit in there.

Plus - window units are electricity hogs... lol.

I'll look into the split system. That may be the way to go. I could actually do the office/garage area on that one maybe.