Duct Replacement

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Duct Replacement

Postby CraigE » Thu Apr 30, 2009 5:59 pm

Hello everybody! 1991 Palm Harbor DW with Mortex inside AC/Propane Furnace (Only 3 years old). Ok here we go. Last summer we kept smelling a funny smell from the vents when the AC came on. So I finally removed the cover to get to the A coil and found black looking spots all over it about the diameter of a pencil. Cleaned with coil cleaner and then bleached. Reinstalled cover and finished out the rest of the summer, but their was still a small hint of that funky smell. During the winter was not as bad but figured it was due to the lack of moisture in the system. So, I tried the AC a few days a ago before the Texas heat hits and folks I'm here to tell you it smelled horrible. This is not a dead mouse (animal) smell it smells really musty. So, I go under remove the crossover and collar stick my head into the vents and see that the insulation inside the vents are black looking from one end of the trailer to the other. This stuff is very hard to remove even with a shop vac but you can rub your finger over it and it becomes a air born powder. I will admit that I let my drain pan run over twice due to clogged drain line and had to replace section of flooring under unit when it was replaced. Just wondering if the extra water could have sent small water vapors up my trunk lines and now I have something in there that I don't want. My trunk lines seem to be made of metal/tin (16X4) with roughly 1/2 inch insulation on the inside. Any info would be very helpful. Thanks
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RE: Duct Replacement

Postby tritontr » Fri May 01, 2009 10:45 am

Craig it sounds like it could be mold I would suggest you have a licensed HVAC tech. come and check it out. You don't want to take a chance if it is mold that it could effect your health.
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RE: Duct Replacement

Postby CraigE » Sat May 02, 2009 11:21 am

I really hate the idea of the insulation being inside the ductwork, It seems it allows anything to collect on it. I called around about having it cleaned but no one really wanted to tackle trying to clean rectangle ductwork. They said they could not clean it properly and it probably just needed to be replaced. (Atleast they were honost with me).I really would like to replace it all with round but I do understand that round will not fit where the current rectangle is located. Since I live in North Texas and cold is not a large factor, I was wondering if anyone out there has dropped below their black matting(vapor barrier) and run new. I really hate to cut my underbelly from one end to the other. I know there are other questions such as diameter, new plenum, crossover but maybe this is a good place to start just to see if any has had this done or better yet DIY. Please anyone chime in, any thoughts or helpful hints would be appeciated.
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RE: Duct Replacement

Postby CraigE » Sun May 03, 2009 12:59 pm

Upon more inspection with the old trusty mirror and flashlight (as you guys suggested) found holes at the end of each trinkline. I new something was going on because the air did not flow from the vents as it did when the trailer was new. These holes had to be made by mice because the holes are perfectly round and the insulation seems to be torn away around the hole.
As for the ducts being dirty the ducts are not as dirty on the opposite side without the furnace. Possibly could patch holes but I guess they would just start new ones somewhere else.
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RE: Duct Replacement

Postby Robert » Mon May 04, 2009 4:09 pm

Hi Craig,


Running new duct under home is done often, it allows for better duct as mh ductwork is dismal at best.


It ends need for mh duct rated motors, gives balanced airflow, etc., etc.


IF cold temps are not a problem, easier done. IF cold temps are a problem, have to make arrangement for keeping water pipes from freezing.


That is definately mold as any time your drain pan overflows, it will go in the duct.



Best time to do the duct change is when replacing the furnace , then you can go with furnace to meet duct specs.


Still have to have a mh rated venting/combustion air for furnace if gas though.



Will need an hvac tech with mh experience to come out and consult on it.



Thanks,
Robert
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RE: Duct Replacement

Postby CraigE » Mon May 04, 2009 10:13 pm

Thank you Robert for your response.
Please bear with me because I want to make the right choice on what to do, and not to have to do this twice. So, you have seen this done, run new round ductwork under the underbelly if freezing is not a problem?
I do not plan on replacing the furnace since it is only 3 years old but the current ductwork is 16X4 throughout the house and that converts to 8.27" in diameter (Roughly).
I have talked with the local Air Conditioner Supply house and they can order most anything I need as long as it is round. I also talked with the local sheet metal business and they can build me a new plenum to drop below the vapor barrior to begin my new trunklines.
Sorry once again for all the questions but no one around here (In town) seems to have any ideas or answers for my problems.
If you or anyone else has a better suggestion please remit.
I have lived in this Double Wide for almost twenty years and plan on for many more. Thank you Craig
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RE: Duct Replacement

Postby Robert » Mon May 04, 2009 10:50 pm

Hi Craig,

I haven't had any dealings with doing this while keeping a MH rated furnace.

Keeping the furnace may mean replacing current duct with same, minus the inner insulation.


Get an hvac contractor with MH experience and have them consult on this issue.


Match duct to the furnace/blower/airflow specs and run it where current duct is or below belly.


It can be round or rectangular as long as it matches furnace and blower specs.


This is done often, but needs someone who understands MH systems.


Thanks,
Robert
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Postby Johnny » Wed May 06, 2009 9:29 am

I think you will have to open the under belly any way to remove duct-work that goes to your registers in home so you can attach new duck-work to the registers.
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RE: Duct Replacement

Postby CraigE » Thu May 07, 2009 6:10 pm

Yes sir you are right but hopefully this will eliminate from having to cut it from one end to the other on both halves. I guess just alot of smaller holes. Thanks for the input. I sure wish there was a way to put round back up into the underbelly because falling below it sure is going to cut down on crawling capabilty under the house.
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RE: Duct Replacement

Postby Robert » Fri May 08, 2009 1:04 am

IF you remove the current trunklines from both halves, you can usually replace with round duct of same size as the rectangular.


You can also get most any sheetmetal shop to make you new rectangular trunklines.


Thanks,
Robert
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RE: Duct Replacement

Postby CraigE » Sat May 09, 2009 10:40 am

On this particular style of MH I have cross braces welded between the I beam main frame about every 10ft apart(angle iron). The current rectangle duct is between the welded angle iron and the floor joists. I guess the angle iron is for extra support and it also helps hold up all the insulation and vapor barrior. Did I see somewhere in a thread that there is replacement vapor barrior? Mine is black in color and seems to be a tarp type material but very sturdy.
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RE: Duct Replacement

Postby Robert » Sat May 09, 2009 6:34 pm

Hi,


May have to go back with new rectangular duct or go beneath the underbelly.


Find reputable hvac contractor with mobile home experience and go from there.


We sell the underbelly and underbelly repair materials in top blue toolbar at Books & Parts, then go to Belly Repair.





Thanks,
Robert
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RE: Duct Replacement

Postby Crazy X » Wed Jun 24, 2009 6:35 pm

I am having the same problem with mine. It seems as If every time I go underneath the home I find another leak.I have a 1987
palm Harbor and I want to replace the trunk line. Is it possible to build a plenum and feed each register Individually ?
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RE: Duct Replacement

Postby Robert » Thu Jun 25, 2009 12:10 am

Please start a new thread with your question(s). Keeps down confusion by keeping one poster per thread.


Thanks,
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RE: Duct Replacement

Postby burnerr22 » Fri Aug 21, 2009 10:26 am

I live in Wisconsin,so,my water pipes are in the underbelly,I am having a hvac guy coming for an estimate on replacing the current ductwork.My home is a 1988 wausau with a coleman heat and air unit 5 yrs. old.Has anyone had an estimate to do this?,just wondering if there was a ballpark figure that i might use as a referrence,thanx.
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