Posted on 06/29/2011 9:50:55 AM PDT by JerseyHighlander
First off, sorry for the vanity. Second, thanks for reading.
Here's the situation, a relative in NJ just retrofitted her home with central A/C, the house did not have duct work so new flexible ducts were installed in the attic.
The house is about 50 years old. The insulation is double layered pink fiberglass, lower layer is probably 35 years old, second layer is probably 25 years old. Both still have decent loft and R value.
Since the A/C was installed, the "attic smell" of fiberglass and environmental dust has been pushing through the vents into the living quarters. It's causing burning eyes, ears, and throats.
The A/C contractor came back and taped up every seam he could in the attic, yet the smell continues to be pushed into the living quarters. I went up there and taped off even more joints and seams, still no good effect.
Are there any HVAC and general contractor or insulation guys on FR who could give me some options on remediating this situation?
Is it normal for leaks to occur like this? and is it fixable without basically gutting the insulation in the attic and replacing it with new fiberglass or one of the new spray on foams?
I'm trying to figure out if I do end up removing the fiberglass insulation is worth it, and if I do remove the insulation if I will need to vacuum out the entire attic space with a HEPA vacuum to actually clean up the space.
Also, does anyone understand the different new spray in foam insulation on the market and can point me in the right direction for further info ?
I have a few insulation contractors calling or visiting her in the next few days but I'm not sure what the options are, and which would fit her needs. Any suggestions?
Your contractor needs to fix the problem. It is not normal and removing the insulation is not a solution.
FYI,
This is an unfinished attic, without climate control atm.
The roof shingles were recently replaced, but not all of the plywood decking underneath was replaced.
I would take some burning sticks of incense and let it smoke all around where the cold air return joins the ac unit in the attic. You will see pretty fast if attic air is being pulled into the AC.
I don’t understand how the attic environment is making it’s way into the house. The unit should pull from the returns, through the unit and out the outlets. I don’t see how you would be getting attic smell in the house. It is basically a closed system unless no returns were put in. In that case it would pull air from the basement if that is were the unit is. Is the unit in the attic? I never heard of that being done in the NE before.
It sounds like you have been doing all the duct taping on the supply side. What you need to look at is the return ducting and how it is sealed. Also, you may need to have the dusting cleaned. Once you get a lot of dust or insulation material into the duct work it will take a long time to be blown out during normal use.
From the air handler to the vents you have positive pressure. From the return grills to the air handler you have negative pressure. Check the return ducts and make sure they are all taped. Applying mastic to all joints in the system in not a bad idea either.
It sounds more like the air supply/return problem, not the ductwork.Where is the air return filter?Is it in the celing or did they come down an interior wall?
Problem is more likely to be associated with the return ducting or the point where the return duct meets the air handler. Leaks at these points suck in attic air and pull it into the house. Leaks in supply ducting will usually not have such an effect.
Many power companies have a low or no cost program where they test the duct system for leaks. Mostly concentrate on the supply ductwork, though. In humid climates, especially, leaking supply or return ductwork causes huge problems, besides the energy wasted.
When ducts are installed, most of the time the interface between the duct boot and the ceiling is not properly sealed. Which can allow attic air into house, after all it’s not just the AC, there are a whole bunch of new holes in the ceiling. Seal with aluminium tape, caulk or foam.
Best approach I’m aware of for most climates is to turn the attic into a semi-conditioned space by moving the insulation to the underside of the roof with spray foam. Must be done properly and building science implications worked thru, or Bad Things can happen.
Excellent site for anybody with a home. Huge amounts of free information. Technical level varies.
www.buildingscience.com
For info on foam insulation.
http://www.icynene.com/
Probably should have replaced all of the older insulation as well.Since dust will collect on it through the years.Another issue would be to assure the ductwork was completely insulated or condensation would build up and ruin the ceilings.That could be what that musty smell is.
Good luck with the problem.
Get the HVAC contractor back. Problem sounds like it is in the return side not the conditioned side. I would start where it is pulling the air back. Suspect you will find it is being pulled through a unsealed wall or ceiling cavity somewhere.
Like to reinforce this.
All seams should be sealed with glass cloth and mastic, not tape, which is at best a temporary fix.
If you do use tape, use aluminum tape, not “duct tape”
Where is the return air routed? IF it is like some homes, it routes using wall space for part of the ducting (which is bad). That could be the source of odor.
If the ducting is all sealed properly (I hope “duct tape” isn’t what you and the contractor have been using it won’t last long even if you were to find the source of the air leak. Mastic is about the best thing to use. Lasts for decades.
But I echo the prior sentiment - the “stale” air is getting sucked into the system - that would require a fairly large air leak (actually, probably multiple large air leaks) in the delivery ducts. I would suspect the return Air (the air going TO the unit).
The other thought I had was that you may be using the wrong tape. Duct tape is not for ducts. You need special tape that is suited for sealing ducts. Duct tape will fall off and not make a proper seal.
Does the attic (unfinished and with new roof shingles) have enough external air vents? I live in a 50 year old house and got a new roof about 15 years ago. They had to add many roof vents when we did the roof. This was a complete roof tear off. I did not replace the insulation, but we need to. 50 year old insulation is (typically) not very good.
We added air conditioning about 4 years ago, but we are using the existing heating duct work, as we already had central heat. Everything works great.
That would be the 500 MPH tape and not the 100 MPH tape, right?
It is very common for retro0fitted air handlers to be installed laying flat in the attic, with the return just below it (usually in the ceiling of the 2nd floor hallway), while the compressor is installed outside, next to the house. The situation described here sounds like the handler is not getting its air through the return for some reason and is therefore drawing air directly from its surroundings, ie., the attic.
This situation is very unusual and something is definitely not right.
Sounds like the attic wasn’t properly vented, who was your roofing contractor?
Hoses are likely leaking in the attic creating positive air pressure in the attic and with the attic not properly vented you are getting the smell and dust coming in around your registers.
I had a new house and had a guy install satellite tv in my attic and crushed my hose to one of the rooms, you have to watch these contractors like a hawk.
You can get smoke sticks for that (no flame) at HVAC supply stores. Is the fan cabinet also in the attic? I would look there and the return duct as they are under a vacuum so there is where things (odors)get sucked in. The supply ducts are under pressure and any leaks blow outward.
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