Original message
| smoldt
 |  "2nd story returns"
, posted Fri 9 May 07:34  
I recently had a new Goodman furnace and air conditioner installed by a reputable local company. The salesman claimed his technicians could install two returns for my oddly-designed upper story three bedrooms.
On the hectic day of the install, the technicians found the returns too structurally dangerous and cut in a six inch vent to the attic in each bedroom with the good intention of removing hot air when the new temperature activated attic fan kicks in.
I presumed they would install some special vent designed for this purpose. Instead, the vents are in the ceilings and always open to a 6 inch round riser sticking above the insulation. The vents don't close.
The fist stiff wind that came along pushed a breeze down the vents, and the rooms now smell like insulation.
I'm now trying to decide what to suggest to the company when I let them know this field-designed workaround doesn't work. I just found this forum and would like opinions.
Returns will be quite difficult to extend up the walls but perhaps not as structurally dangerous as opined. The new furnace, which is in an unfinished basement, is 95% efficient so I have a 6 inch pipe to the attic that the installers used for cold air combustion after my suggestion of using that for a return was rejected as having insufficient area. (They also ran an electric line up the middle of that vent for the attic fan)
The old furnace flue is still used by a gas hot water heater and passes through the attic. I suppose something might be done with that, too.
I've considered using the two pipes and connecting the ceiling vents already now installed. That would require adding cold air pvc in the basement, which is feasible, and going to tankless hot water I suppose. I may have some other options on the returns that I haven't flushed out yet.
Any opinions?
Thanks,
Bill
Bill
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Replies:
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| dwcaveney
| "Re(1):2nd story returns" , posted Sun 11 May 16:26:
Don't understand why you would need returns on the 2nd story. The ducts to the attic are probably for HRVs (heat recovery ventilators, which you have yet to buy)
What is the location of your existing return air?
Is it sized correctly?
Do you have a door which closes off your stairs?
(might need a jumper duct to by pass door)
The 2nd story returns will add pressure drop to the system. Placement of returns don't have much to do with air circulation. (air won't you go through a duct if it's easier to go down the stairs)
The new codes are requiring 24/7 mechanical ventilation. One HRV would satisfy requirements for whole house.
EDIT: It takes four ducts, two in-door termination devices and two out-door termination devices to make up an ERV/HRV unit. The unit can locate in the attic, attached to a switch.
EDIT2: You could put Wyes in to serve more than one room, depending on available static pressure. Requires R-6 insulated duct 3-4 inch.
Mitsubishi makes one.
http://www.renewaire.com/for_your_home/what_product_fits_you.php
DW
[this message was edited by dwcaveney on Mon 12 May 13:21] |
| | smoldt
| "Re(2):2nd story returns" , posted Wed 14 May 05:29
dwcaveney,
I somehow missed your post - thanks!
I don't know anything about ERV/HRV but I've started reading about it based on your post. I don't know the local codes nor whether mechanical ventilation is required.
I see your point about the air going down the stairs instead of into the return ducts. And thanks for focusing me on air circulation instead of returns.
To answer your other questions, there are four existing air returns in the house, all 32x18 - one in the dining/living room, one in the master b/r, two in the great room (one low and one at 8 feet).
Is it sized correctly? I don't know.
There is no door to the stairs as they are open to the great room.
The house is very open to the second story in the great room, which includes the kitchen, family room, walkway bridge between bedrooms, and foyer. The great room has a lot of windows facing west which catch the afternoon sun - the previous owner covered these with 3M solar film but we decided that we weren't going to make it through summer without air conditioning.
One of the upstairs bedroom (my office and primary concern) is entirely isolated from the other two bedrooms across the bridge. I normally would have that door closed during the day for noise isolation, but it is typically otherwise open. It gets hot in the summer.
The attic fan came on last week for the first time when the outside air hit 88 degrees. But the attic fan kept running for hours when that happened.
Are you suggesting that I should connect the three upstairs bedroom vents to an ERV/HRV in the attic or consider that for the entire house? Sounds like that's what I should have instead of an attic fan?
Again, thanks for your help and patience with my ignorance.
Bill
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| | dwcaveney
| "Ventilation - Circulation" , posted Wed 14 May 11:21:
Bill,
Glad you are dialed in on the "problem".
I think the attic fan is a good idea, to exhaust hot air from the attic, not the house.(a whole house fan would do that)
Attic and it's associated AQ issues should be isolated from conditioned space.
Edit: It is not unusual for the attic temperatures to reach 135 degrees on a hot day.
Sounds like you have plenty of return air grills/ducts.
That leaves the office. If you don't feel you have enough ventilation or good air flow, you may consider locating a jumper duct to an area where you have adequate air circ.
Normally a one inch under-cut on the door would be adequate.
The HRV/ERG may cost more than you would like to spend. In your situation, it seems that the office would be an exhaust location, an upstairs bathroom might be another.
An upstairs hallway could be one HRV outside air inlet location, a bedroom an other.
Try to get a mental picture of how the system pressures would function: with the MAIN CIRCULATOR FAN ON;OFF, HRV ON;OFF, combinations thereof, before deciding how to configure your HRV, jumper duct, or door undercut.
EDIT: Consider running these options by the installer, to see if he has any ideas to commission (tune-up) the system.
DW
[this message was edited by dwcaveney on Wed 14 May 20:59] |
| Jojo98
| "Re(1):2nd story returns" , posted Sat 10 May 01:01
You said reputable, but didn't mention what type of reputation. This is insane on your part and idiotic on the contractors part. I feel for ya.
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| learner
| "Re(1):2nd story returns" , posted Fri 9 May 09:49
Hi,
Logic is return vent has to go back to the air handler. Couldn't they run it between studs in the wall? You mean upstairs never had return duct work? I don't think your idea is good one. It is like air circulation vs. air dispersal to outside. Make cold air and sending it to outside.
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| | smoldt
| "Re(2):2nd story returns" , posted Fri 9 May 11:09
Right - no returns built into the 2nd story and no simple way to run them in studs due to structural issues.
I'm sure I'd have to use insulated tubing in the attic for the returns through the ceiling - but I see your point of putting the air right back into the environment I don't want it in for either the heating or cooling. I'm still looking for a way to get put the air returns in the walls and I may have a way for one of the bedrooms, but not the other two yet.
Bill
Bill
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| | mechacc
| "Re(3):2nd story returns" , posted Fri 9 May 23:29
An option would be is to cut returns in the same wall stud. One in the room either high or low and the one in the hallway at the opposite heighth and install grilles. This will allow privacy. Basically you have made a hole in the wall allowing a path for air to flow out of the room while supply air is pumping into the room. The other option would be to cut off 1 to 1-1/2 inch off the bottom of the door.
MechAcc
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| | theduke03
| "Re(3):2nd story returns" , posted Fri 9 May 18:58
That is brutal. So brutal in fact that if I went to your house for a service call I would take pictures, then show pictures to my coworkers and laugh about it. If you are willing to sacrifice space you can run a duct into attic thru a closet or build a chase in the corner of a room. I definately do not recommend open vents to attic.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | smoldt
| "Re(4):2nd story returns" , posted Sat 10 May 21:22
Thanks for the replies.
My home is custom and the upstairs rooms are disjointed. It wasn't air conditioned as most houses in Colorado in the 80s and there isn't really a problem with the heat, so I suppose the lack of returns hasn't been an issue.
I believe I've discovered a way to get returns to three of the rooms, albeit with some difficulty.
Now, I just need to decide how to effectively use the vents the contractor put in to some good use in removing hot air in the summer without losing hot air when it's cold. Any ideas for doing that?
Bill
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| | mechacc
| "Re(5):2nd story returns" , posted Sun 11 May 09:03
If heating is okay but cooling is not consider a mini split system. One condenser can be used to up to three evaporators which means that each of your 3 rooms can maintain the cooling that each occupant desires. If one wants 78 while others want 72 this type system can do it.
MechAcc
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