Replies

1. 
   rdesigns | Aug 09, 2010 04:30pm | #1

   A chase or other conduit for air would be the key to making this work. An in-line, variable-speed duct fan would move the air. You want to size the fan and chase or conduit to minimize noise while still moving the air. If this condo had, say, 600 sq. ft on each level, then you could probably use a fan that could move about 500-600 CFM, which would mean the total volume of air in the building could be moved 2 or three times in an hour. The duct should be sized at about 8" x 12" or 11" round to allow easy, quiet air movement.

   How to distribute the air? That will depend on how the condo is configured. Is there an open stairwell that connects all 3 levels? Do you want every room on each level to have both a supply and return path? (More complex) Or will you be satisfied with moving the air in the common areas of each level? (Simpler)

   Assume a simple chase that "pulls" air from the lowest level and supplies that air to each of the upper levels. You'd mount the fan in the duct in the lowest level so that it pushes that air up to the higher levels. You'll want a damper-controlled opening at each of the upper level openings to balance and adjust the airflow. The air from the upper levels needs an unrestricted path to return to the lowest level--this could simply be the stairwell, if it has no doors separating the levels. Otherwise, you'll need transfer grilles or louvered doors to allow free passage of the air.

2. 
   Clewless1 | Aug 12, 2010 01:12am | #2

   rdesigns has some good thoughts. However ... you may choose to reverse his air flow. Take the warm air from the top and circulate it to the bottom ... assuming you are in a heating mode. Ducts and fans work fine. Anything that will move air from upstairs to downstairs. Yes, you do have to have a path for the 'return air' (e.g. the stairs as the other guy said).

   QUESTION: Why are you doing this? Is it that much higher temp upstairs? Why? Doesn't your heating system do a good job of distributing heat where it needs to go?

   Air [de]stratification systems work great ... but only if you have a problem. I've seen a lot of people jump on the bandwagon w/out really understanding whether they have a problem or not. And if you do have a problem, is this the right fix or should you simply better balance your existing heating/air system?

   While you may have checked for your problem, maybe you haven't, so my advice is to make sure the problem is really there and then make sure you don't have an easier solution with what you already have.

   rdesigns is right about the configuration of your space and the specific plan of your condo. Your 'fix' will depend a lot on that. Open plans can make things easy. Closed plans maybe more difficult.

   What kind of heating system do you have now?

3. 
   simplemind | Aug 16, 2010 08:54am | #3

   finally checked back in~

   I finally checked back here to find two really good posts, thank you!

   1) The condo is 1000 sq. ft., ~300 ft./floor. 

   2) Open stairway from bottom to top. 

   3) Bottom floor is 1/2 basement or 1/2 underground.

   4) Town is located at (10k elevation)

   5) Only heat sourse is hot water (boiler) w/ baseboard radiators.

   6) Temperature differential ~ 15-20 degrees from bottom to top in summer. Winter not that drastic.

   7) There appears to be ducting possibilites (space)

   I'm thinking a mini- forced air system bringing hot air from top to bottom would work, using an HRVS unit might work and provide fresh air, which would be a welcome benefit.  I am just clueless as to how to design.  Attached is a similar system to what I think would work.

   http://residential.fantech.net/residential-products/indoor-air-quality/hrvs-heat-recovery-ventilators/

   
1. 
   rdesigns | Aug 16, 2010 10:04am | #4

   The picture is much like what I had in mind--what I suggested about locating the fan at the base of the stack is best for cooling because it blows cool basement air up into the upper floors, and any drafts that you feel from the upper outlets feel good. Whether the flow is upward or downward will still result in de-stratification. Just be aware that a jet of air blowing directly on occupants will always feel cool--good in summer, bad in winter. Proper register selection is important; you can buy those with adjustable fins to direct air as needed.

   The heat recovery ventilator is a nice addition, but, by itself, is probably not going to accomplish de-stratification, because the flow of about 50-60 cfm is too small. At 50 cfm, it will take about 2-1/2 hrs to move the total volume of air in a 1000 sq. ft. condo.

2. 
   DanH | Aug 16, 2010 05:53pm | #5

   Depending on how the open stairway is configured, you might want to consider a fabric duct down the stairway between flights.  Basically, a decorative fabric tube is constructed (maybe 8" diameter) and is hung down the stairway.  Then a fan at the top forces air down (or possibly you could use a fan at the bottom forcing air up).  Well done, it's cheap, effective, and actually decorative.

   Someone here had some pictures of one of these a year or so ago.

4. 
   Clewless1 | Sep 17, 2010 08:58pm | #6

   This was done back in the 70s and 80s. A reasonable approach ... helps you think outside the box a bit more. Lots of ways to accomplish the same end.