Home AC installation

[look 171]

Originally Posted by red-beard

You can get systems with a single outdoor unit which handles three or four indoor units. These units also use variable frequency drive technology which ramp the outdoor unit up and down with need. Each indoor unit has an indivdual control, so you only cool where you need at the time you need. And many of the better units have SEER rating of 24 or better.

Mike, how much cooling do you need? How "hot" did it get in the summer? My Parents installed a 3 ton A/C unit in upstate NY which was fine for 2800 sq feet. I have 3300-3400 here in Houston and 7 tons of cooling with 2 separate A/C units.

A good professional A/C person will evaluate your insulation, cooling requirements, etc. I would get a few people too look.

In Texas, the price of electricity means the super-duper efficient units won't pay back enough in energy savings. California, with the much higher price of electricity, you will need to evaluate the operational costs vs. installed cost.

a 3 ton unit for over 3000sq' ain't gonna cut it. I don't care how you look at it. But then what do I know, I have never done any work outside of CA, SoCal for that matter.

[look 171]

Originally Posted by Baz

If it's just a couple-few months out of the year - I wonder if a couple window units would accommodate your needs, Mike. That would be easier and less expensive than trying to retrofit an existing central system.

Yes, but they look like crap and not efficient. I would suggest against it.

[red-beard]

Originally Posted by look 171

a 3 ton unit for over 3000sq' ain't gonna cut it. I don't care how you look at it. But then what do I know, I have never done any work outside of CA, SoCal for that matter.

In Upstate NY, you needed AC for maybe 3 months. Generally, maximum temps mid 80's July, with some 90's in August. 3 tons was fine for 2800 sq feet.

[BK911]

Originally Posted by red-beard

You can get systems with a single outdoor unit which handles three or four indoor units. These units also use variable frequency drive technology which ramp the outdoor unit up and down with need. Each indoor unit has an indivdual control, so you only cool where you need at the time you need. And many of the better units have SEER rating of 24 or better.

Is this a poll? If so, I vote for this.

For a house without central conditioning, ductless is definitely the way to go. Easier install, better zone control, and more energy efficient.

My house already has (2) ducted units. I will add a ductless VRF system for the bedrooms so I dont have to heat/cool the entire house at night. One outside condenser and mulitple indoor cassettes.

[mikester]

To be honest we don't need an AC system to get us to 68 degrees in the summer. We just need something to keep the house 'comfortable'. Which translates to lower humidity and around under 78 degrees. I would like less than 78 but that probably isn't very 'energy efficient'.

Seriously though - over the last few years we are pretty used to having a few weeks in July/August that are uncomfortable but this year it's been pretty much the entirety of July, August and so far most of September. If I'm going to have 1/4 of the year like this I'm going to have to do something about it. It's affecting the quality of my sleep as well as the rest of us which is making my wife and I both pretty damned irritable. The kids handle it better but I know it is shortening their fuses too.

The ductless systems are interesting but I really don't have the wall space for them to be honest and I don't really have the window space for window units. Our house isn't very big and we need all the space we can get. Unless there is something systemically wrong with our existing duct work I would like to leverage that.

[KaptKaos]

I think a decibel reading should be your first step

[red-beard]

Mike, most of the discussion here is theoretical. The reality is you need to get someone out to your place to do a review. You aren't cooling THAT much space. I've been to your place a few times. You aren't dropping the temp as much as I have to do here in Texas. I expect that your ducting will be adequate and the most straight forward system will be a standard "split" AC system.

I live in a permit free zone. You do not. You need to get this work done by a licensed AC person. Use Angies list or get one of the pelicans here to help you find a good AC guy.

The main thing to understand: a 13 SEER system is a good system. A 15 SEER system is more efficient, but will only save you 13% in electrical cooling costs. You need to do the cost to payback evaluation.

I was quoted replacement of both of my AC systems to 15 SEER units for about ~$10K. The same system quoted to 24 SEER was $30K. This will never pay back at $0.089/kWh.

If my electricity was $.25/kWh, it might pay back. You will need to work this out.

FWIW, I went with replacing just the condensers with 13SEER units, total cost $3K. It was impossible to even pay $10K for updated system for the slight energy efficiency improvement.



James

[mikester]

Originally Posted by KaptKaos

I think a decibel reading should be your first step

If you're referring to the FAA/LAX sound abatement project we have already had that done. At that time they were not doing AC installs (which seems to come and go with the program) but that is when we had the central air upgraded to what it is today.

We got new windows and new heat which is fantastic in the winter. All of it is useless in the summer though because we have to open up all the windows of course. We of course mentioned this to the program directors at the time and they basically shrugged. The FAA and LAX got my feedback though - it is a pretty crappy program in that regard but outside of that we got a much better noise situation.

The AC upgrade that they offered us was over $8000 which I declined and the contractor they were working with doing the HVAC work was pretty lame and I'm glad I didn't have them do more than they did.

[mikester]

I have an well recommended HVAC guy coming tomorrow. My first order of business is still probbly to do the whole house fan thing. That's where I'm looking right now at least but I want to know what my options are from an AC perspective too. Over the phone they seemed to think adding in the coil and compressor might be all that is needed (over simplifying maybe though).

[red-beard]

A whole house fan will help when you can open the windows, otherwise no. You need AC. Get'r done.

[mikester]

I don't care about having the windows open or not. The Jet noise doesn't bother me. I grew up on Air Force Bases - modern jets are quiet compared to a KC-135s or an F-4 or something like that...

Whole house fan works if it keeps the house cool.

[red-beard]

If it is hot outside, how will it cool the house?

[mikester]

Yeah, it's actually not that hot outside it's just the heat build-up in the house over time. By late afternoon it'll be 82 degrees in the house and pretty humid but outside it's already cooled off 5 or 6 degrees and it's quite nice. So...there's that.

[look 171]

Mike,

Tricks we have used over the years is to install a bathroom fan just to remove the stale heated air from the highest part of ceiling. We install a remotely mounted inline fan in the attic and pipe the hot air right into the attic. The remotely mounted location makes the fan super quiet. the grill is usually a 4" round vent in the ceiling. We sometimes run two or four in various part of the house with just one fan. An electronic timer switch is hooked up to the fan. I have had people forget to turn them off (regular on/off switch)and they run for weeks because they are so quiet. Most people don't even notice they are on. The whole house fan works well but you still have to get rid of the hot air up near the ceiling.