Duct replacement in low clearance attic

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  #1  
Old 07-27-03, 10:21 AM
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keleng
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Duct replacement in low clearance attic

I have a 60s ranch and a roof slope of 2:12 which creates a VERY low clearance attic. In the attic there is old rigid metal duct work that has deteriorated insulation.

The problem is that the ducts are producing condensation that drips from the vents and water damage is developing on the ceiling around the vents. Also, we have never had good air flow. The air is good and cold put it comes out of the vents about the same as if you were blowing in your sweetie's ear!

I had an ac company take a look and they said we need to replace the ducts with new duct work because the old stuff we have was made for hot air and not cold. Also, because of the low clearance attic, we would have to rip our our ceilings to replace the ducts (or even to fix with new insulation).

Does any of this sound right? Do they want to rip into my ceilings because they don't want to bother with crawling around in a hot shallow attic?

I plan on getting more estimates, but I wanted to get some feedback first so that I'll know better what questions to ask.

Thanks for any help you can offer!

kelly
 
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Old 07-27-03, 10:32 AM
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Duct work

You dont say how much room is there in the attic? Duct just for heat?????Is this duct insulation inside the duct work what we call a duct liner? did some of it come lose in the duct and you dont get air???? ED
 
  #3  
Old 07-27-03, 10:48 AM
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keleng
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The tallest point in the attic is about 3' and the duct insulation that has deteriorated is on the outside (I don't know about duct liner on the inside). Also, the ac company said that the ducts are very narrow and that the unit itself is in good working order (coils clean, good pressure, compressor size is just right and clean).

Thanks!
-kelly
 
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Old 07-27-03, 11:11 AM
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Duct work

You know it hard when you dont see the job. But 3' can do. you dont say how big the home or how many runs here. So some ifs here. The whole job could be done maybe with whats called duct board up into the attic and the runs off this duct with flex round pipe it has insulation in it. About all the homes down here are that way. A duct board plenum up into the attic and round flex pipes off it to the outlets.Yes I can see where the water is comeing from with what you have now ED
 
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Old 07-27-03, 04:04 PM
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Check out www.unicosystems.com. The head or working space is no problem with this product. It's a high pressure system with small insulated main ducts (7"ID and 9" OD) and insulated branch ducts (2" ID and 3 1/2" OD). The supply diffusers are hardly noticeable and it uses one common return air register for the whole house. The up front cost for the equipment is higher than a typical ducted system but the labor costs will be lower. You'll love it, but make sure it's sized properly!
 
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Old 07-30-03, 07:28 AM
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keleng
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follow-up

So far I have had three HVAC contractors take a look at my system. Good news is that all three agree that there is enough working room in the attic - however the labor costs will be more due to the tight squeeze.

Bad news is that they disagree on what I need.

#1 says that I have a good quality galvinized hard pipe duct system, it just needs to be re-insulated because there are places where the insulation is completely gone and where there is insulation, it is only 1" thick and just stapled together.

#2 says that although it is a good quality metal duct - it is sized for heating requirements only and that to meet a cooling airflow we need larger ducts.

#3 says that we need new ducts and a new 4 ton unit. Currently, we have a 3 ton unit and he ran a load calculation (using industry software calculator) to determine the 4 ton unit size. We have a 1400 sf house built in '62 with virtually no insulation (we did the blown in cellulose insulation in the attic ourselves but no insulation in the walls based on bathroom remodel) and 20 large wood uninsulated windows and oh yeah, we live in central Texas (don't think I mentioned this before: the a/c during the late afternoon stays at least 2 degrees behind).

I feel that to be safe we can go ahead and spring for new ducts, but a new larger unit scares me because I know that we could be adding to the problem if we get a unit that is oversized. I also thought that we could just get new ducts and then later, get a new larger unit if it's still not cooling properly.

All three contractors are licensed, well establised local companies with no problems with BBB.

Anyway, I'm very confused. Should I get more estimates? Should I go with one of the above? PLEASE HELP!

Thanks,
kelly
 
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Old 07-30-03, 08:45 AM
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A/C

Ok first here is what is your time frame for this home??
How long will you stay there? Think about this.If its a long time.

Your #3 sounds ok ,new insulated duct work and 4 ton if he ran the load. If you go with this 4 ton ac I would get a V/S blower on it for sure. This will help with the humidity. stay with the R22 freon now you have to 2020 before they start to stop making the units and 2030 when they stop making the freon. Right now Id say dont go for a 410a freon set up they cost to much to work on. Where you are Id get ac with a SEER about 14. One other thing does this attic have good vents all around. You might look into a attic vent fan for it. Will help on the heat load. Also you could look into a hot water recovery unit on this new AC. it would give you free hot water and help kick up the SEER on the AC unit ED
 
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Old 07-30-03, 01:34 PM
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keleng
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Got an estimate

Okay, received my first estimate in writing.

-Bryant 3.5 ton 14 seer (model 597C) central air conditioner
-Gas furnace (The Plus 80v, model 315 multi-poise)
-new refrigerant lines because existing are undersized
-any sheetrock repair due to vent changes

$7357

what do you think?
 
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Old 07-30-03, 04:42 PM
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Cost

lets get the 2 other bids here first. I think you will find here that most like a Trane or Rheem furnace and AC. But if the company has been there a long time its ok. For where you are Id stay with just a 80%furnace but go for that 14 seer AC. Did you look into a hot water recovery unit thats free hot water.
This sounds high But I cant see the job from here. Did he run a load for the AC? You said that the old 3ton AC was just a little light. the 3.5 ton could be just right. He said new lines Ill go with that but ask them if your electric is ok if you go 3.5 or 4 ton on this new AC. ED
 
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