Sealing Old Ducts

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  #1  
Old 12-14-04, 06:26 AM
MomFor2Gifts
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Sealing Old Ducts

I hope this is the right place to ask this question. Moderator if not please advise and I will gladly remove. I am about to undergo the installation of new heating system. The old system has unbelievably small duct work however the 2.5 ton unit would of been sufficient had the duct work not been so small and had there been proper outlet for the air flow. This means we have to have all new duct work installed as well as a second air return. My question is how do I seal the old duct work. downstairs it is in the ceiling which I would assume would be no mroe than cutting sheet rock and then tape and mud. But the upstairs has floor registers how do I remedy this? We are in the next 12 months going to have the entire upstairs recarpeted so I would like to tackle the sealing of old duct work on the floor prior to this. Any ideas how to go about sealing a hole cut in the flooring for the old duct work?
 
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Old 12-14-04, 09:57 AM
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Though any good contractor can tell just by seeing the ductwork if it is adequate. However it does very little to assure the homeowner. Duct sealing may sound good, but how do you know you need to seal it? Measurement and verification is what the true professionals use today. The most common type of equipment used is known as the DUCT BLASTER.

Basically all this equipment is a fan that is temporary attached to the furnace blower compartment and all the vents are sealed temporarily with a sheet of plastic like saran wrap. The fan is turned on and the meters attached to the fan are read. ASHREA has a manual for this equipment in which the reading are found. Once this is determined, the real good contractors do pan testing. What this does is measure at each vent register. This means it may not be your entire system, just one duct may be the culprit.

I was part of a program that developed the Energy Star Homes certification procedures. This particular test is done for all new homes that have forced air systems in order to receive certification. I can tell you with all do honesty that I have installed ductwork and then tested it only to find out I missed something. So having all the knowledge and experience or being in this industry so many years or having the reputation is one thing, but having measurement, verification and documentation is another.

As far as the holes on the second floor, since it is going to be carpetted, I would install nailers on both sides of the opening and fill in with plywood the same thickness as the original floor. Then lay down some floor flashing to make the transition seamless. Any good carpet installer can do this for you.
 
  #3  
Old 12-15-04, 04:26 AM
MomFor2Gifts
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They already spent 3 hours doing the testing

We had a person come out already who spent 3 hours doing all types of testing to our system. I assume what you speak of is the test he did with a type of machine that made like a fog, while running the fan. The reason we are having the duct work replaced is that upstairs the registers are in the floor now and downstairs in the ceiling the only way to remedy our problem would be to rip out the sheet rock on the walls to install larger duct work and that is not feasible honestly. So we are having two trunk lines installed one under the house so the downstairs registers will now be on the floor instead of the ceiling and one in the attic so the upstairs registers will be in the ceiling instead of the floor from now on. This is a 20 year old home where the contractor spent very little on the heating system and to make matters worse it has had a total of 3 furnaces already because of the small duct work problem, it is causing back up of the air into the units and prematurely aging them. Currently the heat strips are running daily because the system defrosting every 30 minutes, it has burnt out 3 defrost timers in 8 months, and the system has been depleted of 3 lbs of freon just so it won't reverberate and still continually freezes up with the defrost set at 30 minute increments. The funny thing is the previous owners went through the expense of replacing the system 2 times themselves without ever being informed the problem lies in the duct work and no matter what type of system they put in they would of had the same problems unless they remedied the duct work problems. The only remedy would be to replace the duct work. We also are having a second air return installed because currently there is not one upstairs. Our smallest room upstairs is 12 x 14 and it has 3 windows yet only one register currently, running a 10 seer unit. So the system is far from adequate at this point. My main problem is getting those old register openings covered at this point as we have decided to go with zone system with a second return installed and a damper system with a 13 seer unit. I am hoping this all resolves our problem, we have had 3 separate heating contractors take a look at this without informing them anything about what the last contractor said and basically they all said the same thing so I am assuming we are getting the legit information on this. I will leave the closing off of the upstairs duct work to the flooring guys since you said they should be able to do that, honestly I was unaware they did stuff like that, I just assumed they would lay the carpet but it is nice to know that is one thing I don't have to do lol. Thanks for the input, let me know based on the info above if you think our plan of action is a good one.

Thanks Again
Angela
 
  #4  
Old 12-15-04, 11:10 AM
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http://www.eere.energy.gov/RE/geo_heat_pumps.html

The site mentioned above discusses Geothermal Heat Pumps. It also compares the different types of systems. The one that I would like you to read is your type of heat pump (air to air) compared to Geothermal Heat Pumps. It also should explain to you the most common cause for the outside units freezing up.

It is apparent that you have spent a great deal of time trying to resolve your problem with these units. Hopefully you haven't spent as much money as you have with your time. Since I cannot see your systems or where you live, I can take an educated guess that you problem stems from the type of systems you have and the area in which you live, especially the climatic conditions, rather than your ducting system.
 
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