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Discussion Starter · #1 ·
Hello all,

I purchased a new home about 2 years ago with a bit of a troubled past. It took 4 years and two owners to get it 90% complete, which is where I picked it up.

The house is a 2540 sq. ft. cape cod with a walk-out basement. The foyer is open to the second story. There is a staircase in the foyer leading to the second story, ending in a small landing connected to a 6' x 15' loft at the top of the stairs. There is a 15' x 22' room on either side of the loft with a 6' x 6' dormer in each one.

I realized shortly after purchasing the house that there were no cold air returns upstairs. There is a grill on either side of the loft space upstairs at the top of the wall, and on the inside of each room there is a grill at the bottom of the wall in the same stud space. These do not connect to the HVAC system however.

The loft has a supply duct, and each room has two supply ducts in the kneewalls. It appears as if this supply ducting is flexible uninsulated ducting. The kneewalls are insulated with fiberglass batt insulation, as is the 1st floor ceiling behind the knee walls. There is a plastic vapor barrier between the insulation and drywall on the kneewalls.

It does not feel like there is much air coming from the supply ducts upstairs, and the air coming out does not feel especially warm. Without supplimental heat there is about a 10 deg. F. difference betwen the 1st and 2nd floor. The opposite effect occurs in the summer.

I would like to add some insulation to the attic spaces upstairs, since I know that is a big source of my heat loss. I plan to use blown in insulation. However, I would like to remedy my duct work issue before I bury it all in insulation.

Any suggestions on where to start? I would like to figure out if this is a supply or return issue first. If it is a return issue, how do I retrofit to install returns? Can I attach them to existing 1st floor returns or do I need to run all new lines?

Thanks
 

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I purchased a new home about 2 years ago with a bit of a troubled past. It took 4 years and two owners to get it 90% complete, which is where I picked it up.

Any suggestions on where to start?
I would like to figure out if this is a supply or return issue first.
It's both. Start with finding a way to get return air from the upper level down to the furnace. Insulation never hurts... but that's secondary.

...how do I retrofit to install returns?
you make a bloody mess opening up walls and floors for the duct to run.

Can I attach them to existing 1st floor returns...
Not likely. Depends on duct sizes.

Get a pro in there.
Tell them to pretend you have no drywall installed or sheet metal in place.
Use the prescription that provides as a guide.

hth
 

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If you can find a plumber willing to run a camera down the duct, and return cavities, that can allow you to get a film of what is going on inside down to the furnace.

You may be better off, just installing a second unit for the second floor, since the unit you have now, may be undersized, or more of a pain to get the second floor working, due to having to tear into walls and ceilings on the first floor. There should be blue prints of the hvac system, so if you can get a hold of those, it should give you something to go with, when trying to fix this nightmare.
 

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You need to check the load calculation report. If there isn't one you need to one. Check if your attic is properly insulated. You need 1 units for each floor.
 

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Adjust louvers on first floor registers or dampers in first floor ducts to close off the air flow a little. Be sure that the louvers and/or dampers for the second floor are open. This will send more air to the second floor.

This should show whether the system has adequate capacity (in BTU) for the house.

With room doors open you should get approximately the same performance without a return duct upstairs as with.

Adding louvers on both sides of a wall (or floor/ceiling) between a room with no return and a room with a return will substitute for an actual return duct. There is a disadvantage of loss of soundproofing between those rooms.
 

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Try leaving your furnace/ac fan on constantly for a day or two to see if temps even out. If so, then see if the controls can be configured to provide "fan on" on low/medium speedand then kick into high speed when stat calls for heating/cooling. Downside is...may feel drafty during heating mode. In any case, if temps even out then you may have enough capacity for heating but, can't be sure about cooling until you try in cooling season. Regardless, with a 2 storey home, I would leave fan on continuous for cooling because cool air is denser and requires more circulation to even out temps.
 

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I would bet you that your flex duct is not installed to industry standards!!! check out this site ( http://askweldin.com/Flex.html ) and then read up a little more on how to install flex... then get in the attic etc and see how yours is run.. again, I would bet you its not run right.

additionally, you can get yourself a manometer (0-2 wci) and check your static pressures in the ducts.. I would also be you that the static is way past your systems max static pressures !!!

or you can get a pro to check it out for you...
 

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Discussion Starter · #8 ·
My flex is definitely installed wrong.

I won't be installing a second unit since I heat primarily with a wood pellet stove. The furnace is used as backup and supplementary heat when its really cold. I want to get the system working properly however. I may at a later date add a wood pellet furnace to my existing system if it works.
 
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