Home AC Retrofits

[RedScare]

I am in the process of collecting bids on retrofitting my 1920 bungalow with central AC. My house currently has 3 window units, so this project involves not only installing the HVAC system, but installing ductwork to all of the rooms. So far, ballpark bids from FRIENDS are running $6500 to $8000, not including electrical hookups.

Two questions....

1. Has anyone done a full retrofit on a 2/1 bungalow recently? Or gotten quotes? How much were the bids?

2. Has anyone looked into installing a mini split? A mini split is similar to central AC, in that it has a large unit outside, but instead of ductwork for the chilled air, a refrigerant tube carries the cold freon to a blower in each room. The blower often looks like the AC unit in a hotel room. The savings comes from not having to build and install ductwork in the attic. The link shows an example of a mini split.

http://www.minisplitsystems.com/

Ideas? Suggestions?

[jm1fd]

I am in the process of collecting bids on retrofitting my 1920 bungalow with central AC. My house currently has 3 window units, so this project involves not only installing the HVAC system, but installing ductwork to all of the rooms. So far, ballpark bids from FRIENDS are running $6500 to $8000, not including electrical hookups.

Two questions....

1. Has anyone done a full retrofit on a 2/1 bungalow recently? Or gotten quotes? How much were the bids?

2. Has anyone looked into installing a mini split? A mini split is similar to central AC, in that it has a large unit outside, but instead of ductwork for the chilled air, a refrigerant tube carries the cold freon to a blower in each room. The blower often looks like the AC unit in a hotel room. The savings comes from not having to build and install ductwork in the attic. The link shows an example of a mini split.

http://www.minisplitsystems.com/

Ideas? Suggestions?

In my opinion, you'd be just as well to stick with your window units if you're looking at mini splits. Mini splits would be cost prohibitive to install in every room to get the same balance that centrals will give you. Minisplits only in certain rooms will give you hot and cold rooms.

I had a 95% AFUE gas furnace with variable speed blower, and 15 SEER condenser/coil installed, plus new ductwork and a new return for $5600. All Lennox equipment, 10 year parts and labor. You need to wait a couple more months to get bids. HVAC companies lower their prices when nobody is running their A/C nor their heat.

Edited September 1, 2006 by jm1fd

[flipper]

6500 Sounds a little high.

We just put central air in a 2200 square foot 3/2 (4.5 ton I think) I believe it was around 6k-6500.

[wheels]

I am in the process of collecting bids on retrofitting my 1920 bungalow with central AC. My house currently has 3 window units, so this project involves not only installing the HVAC system, but installing ductwork to all of the rooms. So far, ballpark bids from FRIENDS are running $6500 to $8000, not including electrical hookups.

Two questions....

1. Has anyone done a full retrofit on a 2/1 bungalow recently? Or gotten quotes? How much were the bids?

2. Has anyone looked into installing a mini split? A mini split is similar to central AC, in that it has a large unit outside, but instead of ductwork for the chilled air, a refrigerant tube carries the cold freon to a blower in each room. The blower often looks like the AC unit in a hotel room. The savings comes from not having to build and install ductwork in the attic. The link shows an example of a mini split.

http://www.minisplitsystems.com/

Ideas? Suggestions?

Brian McIlwain with Chimney Rock Service, 713-782-0789, is hands down the best A/C man I know. Everyone I have referred him to raves about his service. Exceptionally honest; he has the keys and alarm code to my stepmother's house to do his regular service calls when she is out of town. He installed a system in the upstairs unit of a duplex in Riverside Terrace for one of my clients recently. It was less than the $6500, but price will always depend on accessibility, attic space, etc. Call him and he will take good care of you.

[JasonDFW]

What's the goal in putting in a central AC system? Convenience I hope. Window units can be incredibly efficient if run properly. Don't be fooled by the high SEER numbers of single cycle central air units, they're measured at 82

[RedScare]

What's the goal in putting in a central AC system?

Jason

To keep cool.

Seriously, I have had the window units for 2 and a half years. They were efficient for my needs until the last several months. As the cost to run them mounted, the noise and hot/cold spots became less tolerable. I don't NEED central AC like some people do. As you know, I like Houston weather, and I never ran Central AC below 78 degrees, even when I had it.

I like the thought of mini splits, since the labor to install them is much less, and they are quieter. I suspect that my window unit may just be old, but rather than just replace it, I thought I might upgrade a bit if the price is right.

BTW, mini splits are much more efficient than central AC as well, since there is no ductwork (30% of the air loss).

[Guest danax]

Anyone know if placing the ductwork and coil etc under the crawlspace has merit in Houston?

[gnu]

Anyone know if placing the ductwork and coil etc under the crawlspace has merit in Houston?

I think your house would need to be raised higher or you would need a sump pump if you dug out an area under the house for the evap unit.

I saw some new houses in south carolina on a teevee show that raised the homes up high enough to do it.

They looked about the height of a lot of galveston houses.

I wanted to do it on my 2 story house so I wouldn't have to make a chase from the attic to the first floor and for better positioning of the ducts. Alas, in the end, i didn't pursue it.

Edited September 1, 2006 by gnu

[Northwood]

The house I rented in Charleston, SC was about a foot above grade (no crawl space) and it had below floor hard ducts. The system worked great but the cost of adding hard ducts is certainly more expensive.

RedScare - I have always heard that A/C companies in the suburbs are considerably cheaper than in town companies. I have no proof but it is worth the call.

MiniSplits (or P-Tac units) are great for a large garage office/workshop or loft but I think you will find Central A/C better for your home.

[Scharpe St Guy]

RedScare,

Act quickly!!! http://houston.craigslist.org/tls/201788555.html

Craigslist Listing for RedScare

Scharpe St Guy

To keep cool.

Seriously, I have had the window units for 2 and a half years. They were efficient for my needs until the last several months. As the cost to run them mounted, the noise and hot/cold spots became less tolerable. I don't NEED central AC like some people do. As you know, I like Houston weather, and I never ran Central AC below 78 degrees, even when I had it.

I like the thought of mini splits, since the labor to install them is much less, and they are quieter. I suspect that my window unit may just be old, but rather than just replace it, I thought I might upgrade a bit if the price is right.

BTW, mini splits are much more efficient than central AC as well, since there is no ductwork (30% of the air loss).

[ricco67]

I am in the process of collecting bids on retrofitting my 1920 bungalow with central AC. My house currently has 3 window units, so this project involves not only installing the HVAC system, but installing ductwork to all of the rooms. So far, ballpark bids from FRIENDS are running $6500 to $8000, not including electrical hookups.

http://www.minisplitsystems.com/

Ideas? Suggestions?

I'll pray for ya.

and i'm agnostic!

[Scharpe St Guy]

Is $700 for a unit a good price? When I first read the ad on craigslist this topic came to mind and I thought it was $700 for all three units!!! When we went to Granada Nicaragua last the home we stayed in had these units, they did a great job and I was impressed.

Scharpe St Guy

RedScare,

Act quickly!!! http://houston.craigslist.org/tls/201788555.html

Craigslist Listing for RedScare

Scharpe St Guy

[jm1fd]

Anyone know if placing the ductwork and coil etc under the crawlspace has merit in Houston?

I would think there would be major issues with mold, putting cold ducts in a humid environment like that...plus critters getting under there and destroying the ducts....plus it would cost more because the local A/C folks would charge more just because it is different.

I'd rather put them in the attic, and then have the attic sealed with iceynene foam.

[TheNiche]

Ideas? Suggestions?

I'm glad you brought this topic up. If you hadn't have, I would've within a month or two of today (assuming that I ever am able to close on this deal).

The space that I'll be needing to cool is about 2200sf with two stories. Of that, about 300 to 400sf is in an addition that may as well be its own structure if it weren't for the shared crawlspace/attic between the first and second floors.

It would seem to be very efficient if I could lay ductwork in the attic crawlspace that could cool the first floor from above and the second floor from below using a single duct. [Disclaimer: I'm not an HVAC guy, so I may be very very wrong]. On the other hand, I've always personally liked window units and the ability to very easily zone a home so as to only provide A/C to rooms that I'm using...of course, that's just me.

What I'm not sure about are two things: 1) how well does mini split/ductless do in the market compared to central A/C, and 2) many insurance companies won't write policies for homes without central A/C--what about mini split/ductless?

Edited September 1, 2006 by TheNiche

[jm1fd]

6500 Sounds a little high.

We just put central air in a 2200 square foot 3/2 (4.5 ton I think) I believe it was around 6k-6500.

Maybe a little high, but there isn't much difference in equipment cost as the size goes up, and there isn't much difference in labor for a larger house...just a couple more ducts.

[RedScare]

Thanks for all the replies.

Niche, I am like you. I don't need central AC. If I did, I probably wouldn't live in an old house. Besides, central AC makes you fat and lazy. jk However, mini splits are MUCH quieter than window units, so that upgrade is attractive. The guy coming out next week works for a company that installs central and minis, so I should have a much better idea of the pros and cons and relative costs by then.

Scharpe St, thanks for the tip. Those minis are still available, but might not be the right configuration. The guy did say that the one he uses is extremely efficient and quieter than a box fan.

For those that are curious, here's what the DOE says about them...

http://www.eere.energy.gov/consumer/your_h...m/mytopic=12630

and, here's an example of one. They can be multi-zoned to be even more efficient.

http://www.minisplitsystems.com/cgi/displa...tem_num=CMH3172

[TheNiche]

Thanks for all the replies.

Niche, I am like you. I don't need central AC. If I did, I probably wouldn't live in an old house. Besides, central AC makes you fat and lazy. jk However, mini splits are MUCH quieter than window units, so that upgrade is attractive. The guy coming out next week works for a company that installs central and minis, so I should have a much better idea of the pros and cons and relative costs by then.

Please pass along any additional information you come across. I'll be very interested in knowing what your A/C guy says.

Thanks.

[musicman]

In my opinion, you'd be just as well to stick with your window units if you're looking at mini splits. Mini splits would be cost prohibitive to install in every room to get the same balance that centrals will give you. Minisplits only in certain rooms will give you hot and cold rooms.

I had a 95% AFUE gas furnace with variable speed blower, and 15 SEER condenser/coil installed, plus new ductwork and a new return for $5600. All Lennox equipment, 10 year parts and labor. You need to wait a couple more months to get bids. HVAC companies lower their prices when nobody is running their A/C nor their heat.

I'd agree that it is costprohibitive. My uncle has been in the a/c refrigeration biz for 50 yrs and one thing that he always mentions is the length of the copper runs. The longer the length, the less efficient. Seems like this configuration would have extremely long runs. Another thing would be the drainage situation. Each unit would require a drain thru the wall and under the house (plus an overflow drain). Seems like a LOT of labor costs. if you had a 2/1 bungalow...i can see you'd need 6 units (2 bedrooms,bath, living, dining, kitchen--maybe no dining unit if large living room unit). More maintenance would be required in this configuation.

placing ducts under house is a feasible option and is done but it is aluminum duct with the insulation interior to the duct. These are special order ducts similarly made like the plenum (the piece where ducts connect to in attic). THis is expensive compared to flex ducting. There has to be room under house for this to be feasible. Many of the multistoried townhomes i've seen should be using metal ducting whenever it goes thru a wall. In all of the new construction i've seen, home builders are using flex duct which is bad cause it WILL deteriorate. the metal duct doesn't so you won't have to tear out sheetrock for replacement.

My dad and I installed my unit 14 seer...I think i spent 1200 on the a/c and ducting and about 600 on the heater/blower. I my case, I chose not to install metal ducting due to cost and labor. For those worried about heat losses due to flex duct, you can install one duct inside of another fairly cheaply. Flex ducting is CHEAP.

Also make sure and install the condenser (the outside unit) where it is shaded if at all possible. Do NOT install on the west side of the house unless there is shade because during peak cooling times, the sun will be on the west side which causes unit to work harder. also keep shrubbery away from unit.

definitely wait til the attic is cool before you hire this job out. they do charge more during hot months.

I will say this....if you do hire a contractor and want some specific items, you MUST specify it when you hire them so it will be accounted for in their bid.

Edited September 2, 2006 by musicman

[cwrm4]

For 2007 all A/C units have to conform to new noise and efficiency standards...so, it may be worthwhile to wait until those models hit the market, or try to pick up a 2006 unit on the cheap at the end of the year.

There is some engineering effort involved in central A/C installations; I've seen some really crap retrofits (including my bungalow), so cheaper isn't always the best idea. Key things to watch out for are

1) ducting size used (bigger is better)

2) sealing of ductwok against the ceiling (in my bungalow there were pieces of the orginal wood shingles jammed under the ductwork, creating nice leaks. The lumpy ceilings of old houses aren't always the easiest to seal).

3) positioning of ducts and returns, i.e. you don't want the cold air blowing down by an exterior window.

4) sizing of returns...most installers put in too little return, as return ducts are a pain to install. In general you need at least 1 sq ft of unrestricted return for each ton of A/C. (note that with a filter, you get less than 1 sq ft of return for 1 sq ft of filter). Most Heights bungalows I've seen will have a 3 ton unit but only a 1 x 2 filter, which is about half what is needed. You can never have too much return air.

A/C is an investment in a house, and will contribute positively to resale value. I think a central A/C unit would be a smarter decision from the perspective of padding the value of the home, regardless of when you think you might sell.