[franleck]

I want to boost the air flow from my HVAC to the second floor. I have already tried closing vents on the lower floors. Have also made sure that all dampers are open to second floor. In our home the higher you go the hotter it gets.

Will a more powerful blower motor improve airflow ?

Currently have a 1/3 HP blower.

 

[beenthere]

Probably not.

Turn the power off to the furnace.

Remove the blower door.
Hold in the blower safety switch, and have your or some else turn the power back on.
And run teh blower. See if you get more air to the second floor like this.

If so, your return is not enough.

 

[franleck]

Any tips to improve the return air ?

Thanks !

 

[beenthere]

Need a lot more info.

Size of system. A/C and furnace.

Size of both supply and return duct.
number of supply and return registers, and size of return grilles and supply registers.

To determine what problem the return is having.
Is it the entire duct work. Or just the return drop.
Is it the return registers themselves. or not enough of them.

What type of air filter are you using.

3M makes a terrible air filter if you want good air flow.
Best not to use them.

 

[Yoyizit]

In our home the higher you go the hotter it gets.

http://en.wikipedia.org/wiki/Stack_effect

A duct booster fan may redistribute what air you do have.

 

[Chemist1961]

What about the attic

Franleck,
I have had an old furnace replaced recntly with huge improvements in circulation and with BT's and others advice have improved return air flow on second floor, but you might also want to consider checking your attic for insulation and proper ventilation.
Hot air trapped in a poorly vented attic will radiate down especially with poor insulation. Check out both your rooftop venting and soffit venting as well. Go to www.buildingscience.com to understand how they all tie in. We had our roof redone 1 1/2 years ago, with new venting added prior to the furnace. We saw a huge change in top floor heat buildup, far more comfortable now during summer and proper warmth in winter.
Now I am in the process of upgrading attic insulation and improving soffit venting as well, but venting was key for our scenario:thumbsup: One key indicator for me was ice dams forming in the winter.

 

[Yoyizit]

One key indicator for me was ice dams forming in the winter.

I've never had a chance to try this out, but I wired my t'stat controlled attic fan so that it can be switched on in the winter, the idea being that ice dams could be prevented by ensuring that the attic air is the same temp. as the outside air.

 

[sweaty]

In addition to sealing, ventilating, and insulating the attic, try adding a radiant heat barrier to the underside of the roof. That will cool down your top floor in the summer.

 

[sweaty]

Also, remove the register covers and use foil tape to seal the gaps between your ducts and the drywall. Reach into the duct and see if you can feel seams and/or gaps where pieces of ductwork fit together. Seal those with the tape, also. NOT DUCT TAPE. Do this for the return ducts, too.

On my second floor, I found big gaps in a duct that had very little air coming out. After sealing it, a lot more came out.

This is much more cost-effective than installing new ducts and possibly ending up with the same gaps.