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Gas Hot Air System in a home.....HELP!

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I'm trying to help at my daughters house with her hot air system. two rooms on an upper level are not getting heat. I opened up the ceiling on the lower level last night to see if I could find any ducts that may have been damaged / apart, what I did discover was, at the corner where the ducts would make a turn the trunk line (12" x 8", approx:) was tapped into by 3" round ducts that went to the upper rooms. now, there was sufficient heat (I cut open the main trunk with shears) at the main trunk where these other lines were tapped in at, but not much heat going up. I ran a snake through these 3" ducts going up and they seemed to be clear.

Is there anyway to remedy this low to no heat going up? is there a buster blower that could be installed in the duct system? the rest of the house is fine, there is another zone that goes to the third floor and there is plenty of heat up there, but that is a different duct altogether.

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inline duct booster fans are pretty useless.

 

you can try closing down the vents that blow the strongest to force more air into those rooms.

 

if that does not work larger ducts may need to be installed, 3" is very small for forced hot air systems.

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inline duct booster fans are pretty useless.

you can try closing down the vents that blow the strongest to force more air into those rooms.

if that does not work larger ducts may need to be installed, 3" is very small for forced hot air systems.

 

most of the heat systems that are done are done wrong, most people use the flex lines for the runs off the main trunk, there's mistake number 1, they should always be hard pipe so the air will have no restrictions, 2nd, all feed lines should have in-line dampers about 2ft off the main trunk so you can damper down certain heat line's during the winter and during the summer, sounds like you have some trunk issues,

 

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first, thank you for a quick response. the ducts that are in there are hard ducts, there are no dampers anywhere. I drew a rough diagram of how it laid out, there are three registers from burner to this bend (where the 3 - 3" ducts connect) closing any or all of these registers does not change the force coming out any of the three ducts, but yet I can't see anything apart. (hidden in drop soffit) I ran a snake through and didn't feel any clogs.

480

 

vent #1 hall bath - good heat, #2 vent is the upstairs bathroom 2nd fl. - good heat, #3 vent hallway- good heat, now these three 3" ducts are tapped into the same duct from the hall, I cut open the duct in this area and had good heat, so as it is divided to the three 3" ducts the heat dies. ( these are hard pipe, not flex tubing)

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are the 3 registers you closed down the only other ones in the system?

 

if there are other registers try closing ALL of them a little bit, what you are trying to do is raise the static pressure in the whole duct system.

 

how hard would it be to run larger ducts to replace the 3" ducts?

 

i don't remember EVER using 3" supplies for any ductwork we did in over 40 years....:huh:

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yes, those are the only registers before the three that go up which aren't getting any heat. yes I am trying to raise the "static pressure" in this leg of the system, this is the only two rooms upstairs which are cold. as far as changing the ducts, it is possible, on the first floor there was a drop made to enclose the ducts (3-3" ones) which runs the length of the living room. it's sheetrock, minor demo, but I'm not too familiar with this duct work. the house was just purchased by my daughter about 3 years ago, she's been cold and she is due with a new baby in 4 months, I'd like to get this fixed for her. thank you for your help!!!

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yes, those are the only registers before the three that go up which aren't getting any heat. yes I am trying to raise the "static pressure" in this leg of the system, this is the only two rooms upstairs which are cold. as far as changing the ducts, it is possible, on the first floor there was a drop made to enclose the ducts (3-3" ones) which runs the length of the living room. it's sheetrock, minor demo, but I'm not too familiar with this duct work. the house was just purchased by my daughter about 3 years ago, she's been cold and she is due with a new baby in 4 months, I'd like to get this fixed for her. thank you for your help!!!

 

I think you might be better off to call in a HVAC specialist, they should be able to help you out, sounds like you have a un balnced system,

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do you think if I took the three 3" ducts out and ran a 8" x10" duct down and made short off shoots to the upstairs wall registers, do you think this would work?

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if it was me I would rip all of it apart to see what's going on, you can only improve on it, without seeing hands on it's hard for me to tell, like I said before something is wrong, like someone taped into it and screwed up the air flow for the whole system,

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yes, those are the only registers before the three that go up which aren't getting any heat. yes I am trying to raise the "static pressure" in this leg of the system, this is the only two rooms upstairs which are cold.

 

 

 

you can't raise the static pressure on one leg of the system, the air will just go out the vents with the easiest path.

 

before you go tearing stuff apart try closing down all vents on the system to see if you get enough air to the cold rooms.

 

if that fails you can run a larger trunk to the area of those rooms then run new take offs to the registers.

 

 

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installing dampers within the 1st 2' of each individual run is much better than closing the registers.  and you cannot.  CANNOT just take ducts out and replace them with largers sizes.  expecially further down the truck line.  its all about CFM's.  your furnace blows x amount.  that is the very begining of your trunk line.  each individual run takes away some of your cfm's depending on what size they are.  when you get the the end of your trunk, where you seem to be having your issue.  and you add a larger duct,  there is not enough volume at that point to have any sort of volocity in your system.  think of it as blowing through a straw as hard as you can.  you can move some air with force.  now try it in a paper towel tube.  some air comes out but not as strong.  now try it in a garden hose.  lucky if anyting comes out the other end.  hope this can clear things up a little.  you should have dampers installed anyway.  mostly b/c you have 2 stories.  its your least expensive and easiest fix.  damper down the rooms that blow air good, rooms that are too hot for you, rooms that you dont have a great need for heat in.  if you just close a register you still have to pressurize up to that point.  a damper cuts a lot of that volume out and redirects it where you want it immeadiately


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thank you for this information. where are you located? I'd like to get this fixed for my daughter in the near future, new baby on the way. I do not know anyone in this field locally I could trust. I'm pretty handy and could do some work, but if I do not know something ... I ask for help.

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Good points so far, also remember in this case  with each feed/room there needs to be a return duct,  can't get air into a room if none can come out very easily.



 



Al



 



 


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