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Old 05-02-2011, 10:57 AM   #1
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Newbie needs advice on ducts/insulation and more

We have a 1993 York 3.5 ton split unit in southern OR. We moved here in 2007. We would like entire new duct under the house as home inspection in 2007 found it broken apart in two places plus other issues. Seller had it fixed. It is CertainTeed fiberglass ductboard. How long it was broken is unknown. We have had a blower door test which showed lots of air leaks: can lights, outlets, ABS plumbing, stack vents, etc. Also floor registers and air return have gaps. Loose cellulose insulation in the attic is entering house and collects as fine dust.

We would love to get a new split unit with the new ducting. Can't afford the $16K to $20K bids we have had for 16 SEER, variable speed A/H, new ducting, 2 zones, additional air return (we have one) and a super-duper whole house air cleaner. We are all-electric and our power bills are $400+ in winter.

Two HVAC licensed contractors did Man J and D for their bids. 4 others quoted for 3.5 tons with no new ducting. We are 2200 s.f., single level. One bid was for 5 tons (or 2 tons with zoning). Other bid was for 3 tons, no zoning.

I wanted all new duct work and an additional air return, to run with our existing unit but that has been pronounced dumb until a complete new split system is installed with various calculations.

Current thinking is this: blower door and duct blaster test followed by air sealing (everything possible) and additional blown-in borate cellulose in attic. Another blower door and duct blaster test.

Also a flex camera to inspect the 11 flex duct runouts as we think rotating brush duct cleaning had been done before we got here and there could be internal damage. I did spot one damaged flex about a foot down from the register with fiberglass showing. I taped it over. If camera shows damage, we would want new flex ducts installed and leave the main trunk as is (even if the camera shows bad stuff). No bids on this yet. I looked online for insulated 8 inch flex duct and took a rough guess of $1000, parts and labor for 150 feet of new flex duct. How does that sound ?

Finally, a new CleanEffects or AccuClean air cleaner.

Hope this is not too confusing but I am learning on the fly and probably know 25% of what I should know and should have done this years ago, but here we are........

Thanks in advance for any and all comments.


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Old 05-05-2011, 06:22 AM   #2
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lets start off with with the duct sealing you said you have duct board trunk line and return you should be able to buy mastic duct seal at a local supply house .take plenty of rags wipe off seams and joints and apply with paint brush .on the flex if it is not torn you you can wipe it down and tape as needed that shoul save you a few hundred off the bill.opinions vary on air cleaners on older systems .i have not seen blower motors fail because of air cleaners but i know guys that say they have .the system is 18 yrs old you may have to change it today .we installed alot and havent had any issues .however be ready to pull a clean cells and pre filters every 60to 90 days if home and ducts are dusty.cost in my area is around 800.oo for the cleaneffects its self .the 3 ton sounds about right by rule of thumb 2ton even with zoneing is under sized at least for the area im in the local contractors that did mj calc would be who to listen to .you may check on breaking the job up in to phases start with duct work and end with new unit and air cleaner.this is becoming more comon gives you time to pay it off as you go good luck


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