Cold Air Return on Dist Blower

Okay, I know that this has been covered in detail. I am pretty much convinced that I need to run a cold air return from the farthest point of the coldest room directly to the distribution blower of my Harman Magnum Stoker. I can't believe how much information I found on this topic, but I couldn't find answers to a couple of questions:

1. Is roughly 50' too far to run the cold air return using just the distribution blower? The duct will have to make quite a few turns as it will pass through a finished basement.
2. I have two rooms that are always cold in the winter as they are over the cold (uninsulated, unfinished) 1/4 corner of the basement. Any reason why I couldn't pull the cold air out of both? Doing so would increase the length by roughly 20'. Would this require an in-line duct fan?
3. I found 4" flexible aluminum ducts. Has anyone found anything cheaper? It's really not that expensive ($1/foot), but I would hate to spend the money on something that only might work.
4. Might I get comparable performance if I merely ran a duct from the floor of the cold room into the warm, finished portion of the basement but not the whole way to the distribution blower? It would run only around 12' and I could slope it down to basement floor level. Or will this merely put more cold air on the basement floor (it would have to travel the remaining 38' to the stove on its own)?

This is going in a ranch house, stove in the basement. Three-quarters of the basement is finished and insulated. The remaining 1/4 is under the cold bedroom and cold bathroom in the far corner of the house.

Any input is greatly appreciated. I can draw plans if that helps.

You built in blower probably doesn't have enough power to move and/or suck air over a large distance, Most of the blowers are 250-250CFM and you furnance is lke 1500+ CFM

Can you hook it to your existing furnance cold air return anywhere close?

As long as you have some air circulation, it should work..

flow
Run a 6 " pipe from the stove to the coldest rooms in the house.
If size is a issue reduce from 6" too two 4" lines one for each of the coldest rooms.
Install a 6" inline fan and a t stat to cycle it on and off.
make sure there is adquate air supply to the rooms in question

BDD

WNY: I should have explained myself a little better. The old furnace, and its ductwork, was torn out long before I bought the house. I have plenty of holes in the floors of all the rooms, though, so the hardest part is done. I was thinking of piping the hot air from the basement to the cold rooms, but given the run I believe that it will cool long before it gets there.

BDD: That's pretty much how I saw it working. I really want to get the temps more even between the two. Basement is usually 77 with the bedroom/bathroom is 67.

Thanks for your replies and advice.

I would use an 8" to go to far rooms, they make 8" flexible insulated ducting, but the strait snap pipe would give you smoother flow, and insulating that would probably be the best. 8" inline duct fans have 500 cfm while 6" inline duct fans are only 250 cfm. Tap off of the 8" to split it to the rooms. Register boots are generally 6" then go to a rectangular dimension like 4"x10". This is what I picked up from doing my little hvac work, I am not anywhere near being a pro. All the stuff I mentioned was what I could find at lowes or home depot.

All good advice, smooth pipe instead of flex pipe, larger diameter will also help. But most important is to get the air circulating.. any amount of cool air removed from the cold rooms will be replaced with warm air from the more central parts of the house.. but you will probably need to leave the doors to the rooms open to let the air circulate..

Greg L
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My design is a work-in-progress and I've spent a bit more money than I'd have liked. I researched the cheaper inline fans and found that they are not too efficient with moving air due to pressure drops in the plenum. Blower "cfm ratings" do not typically equal "actual cfm flows" once they are installed in the ducting. Adding an air filter, which I recommend, will also create an additional pressure drop. My attic is completely open and I decided to run all ducting up there. I read that it is recommended to size the blower for 1 cfm/square foot or area being heated. I purchased an inline vortex blower on ebay, 8" flexible ducting from home depot with register boxes. Each register has louvers so that I can balance the air flow. I purchased a 14"x14" filter return box and filter back grill at http://www.valueac.com/reairbor6.html and http://www.valueac.com/reairgr.html. One other thing that I found out. Its ok to use flexible ducting on the blower discharge, but you need to use rigid on the suction to keep it from collapsing.

My stove is located in my family room, downstairs at the rear of the house next to a circular stair case that allows heat to naturally come up. I installed my return at the top of the stair case and and pull hot air from the rear of the house and blow to all the rooms in the front. Since my house is a ranch, I am able to create good circulation and found that the return is sufficient to pull the air back from the front of the house essentially mixing it with the hotter air in the back. I still have some problems in that the rear of the house is about 75 degrees, the front is 67 and the family room downstairs is about 85. Again, its a work in progress. I think that I need an additional return downstairs to help pull the heat out of that room forcing more heat to the front. I'm also going to add a thermostat and relay to control the blower based upon temperature. Since I'm a bit cheap and don't have central ac, I'm hoping to use this setup to cirulate air from my window units this summer.

Has anyone had success with ducting a Keystoker 90KBTU, Bottom Direct Vent, into the cold air return of the furnance and run the furnance fan to distribute the heat from the stove throughout the house? I have the stove hooked into the cold air return now but when I run the furnance fan it just blows cold air. I can't seem to get the stove hot enough to keep warm air in the duct work. The house is a 2000sq ft colonial.

The stove is being run by a coal-trol module which also has a dry switch installed so I can wire my furnance fan directly to it. Any help would be appreciated..

Paul