Need a little HVAC help

[dgreen1069]

I'm in the process of finishing my basement and I'm about done with the framing. I need to run about 8 vents into 4 rooms and a bathroom. What is the best type of duct material to use? What size ducting should I use? Am I allowed to tap into the end of the main duct work that runs the length of my basement? Do I have to have a cold air return in my basement? Any help is greatly appreciated.

 

[1985buickttype]

R-6 is the best way to go. R-8 is better but bulkier so there might be clearance issues, and yes install a return air. You need away to pull the unconditoned air out. (forgot) duct is duct just dont that **** from lowes or home depot there stuff is worthless.

 

[jhef83]

Tapping into the existing ductwork may be ok if your systems large enough. I would use 6" metal pipe if your runs aren't too long or 8" if your going more than 20 feet. Never come off the end cap. The ductwork is pressurized so if you come off the end you'll kill the airflow. You may not need 8 runs, basements aren't that hard to heat or cool. The cold air return is a good idea but if its too close to the furnace the other one upstairs won't pull much air.

 

[Dwayne]

Tapping into the existing ductwork may be ok if your systems large enough. I would use 6" metal pipe if your runs aren't too long or 8" if your going more than 20 feet. Never come off the end cap. The ductwork is pressurized so if you come off the end you'll kill the airflow. You may not need 8 runs, basements aren't that hard to heat or cool. The cold air return is a good idea but if its too close to the furnace the other one upstairs won't pull much air.

Good advice here, and as he stated, do not pull a run off the end cap. If you do, you'll kill the pressure to all your other runs. I just recently replaced the furnace and all runs in my house and basement. I used only four runs in the basement and that was more than enough. I only drew my cold-air return from upstairs. Works fine. The only other suggestion I could give you is to buy the most efficient furnace and condenser you can afford within your budget and insulate EVERYTHING, including your cold-air return....Good luck

 

[turbojimmy]

I put 3 supplies and one return in my 800 SF basement and they don't even begin to heat the place. I tapped into my existing system which should be able to handle it. I did what the builder did and put the vents in the ceiling - that could be why. I was told that the most effective way to do it is to put the heat vents down low and position the return(s) where it will draw the most air across the space. As I look around my house I can see that's what the builder did. I put electric baseboard heat in the basement - two 4 foot units and a 3 foot unit (total of 7500 watts) and they work great. Heat is nice and even. I insulated every square inch of wall and ceiling, too.

In the summer the basement stays plenty cool. I actually have to shut off the vents because it gets too cold. I usually keep the one farthest from the return open so air circulates down there. Doing this keeps it from getting humid down there.

Excellent move putting a bathroom down there. I wish I had and am now faced with tearing the place up in order to jam one in there. I'll probably get started in the spring.

I'm by no means a pro, but I did document the whole process here:
Basement Finishing Project

The people at Do It Yourself Home Improvement, Repair, and Remodeling Information at DoItYourself.com are a big help, too.

Jim

 

[BandAid]

I put 3 supplies and one return in my 800 SF basement and they don't even begin to heat the place. I tapped into my existing system which should be able to handle it. I did what the builder did and put the vents in the ceiling - that could be why. I was told that the most effective way to do it is to put the heat vents down low and position the return(s) where it will draw the most air across the space. As I look around my house I can see that's what the builder did. I put electric baseboard heat in the basement - two 4 foot units and a 3 foot unit (total of 7500 watts) and they work great. Heat is nice and even. I insulated every square inch of wall and ceiling, too.

In the summer the basement stays plenty cool. I actually have to shut off the vents because it gets too cold. I usually keep the one farthest from the return open so air circulates down there. Doing this keeps it from getting humid down there.

Excellent move putting a bathroom down there. I wish I had and am now faced with tearing the place up in order to jam one in there. I'll probably get started in the spring.

I'm by no means a pro, but I did document the whole process here:
Basement Finishing Project

The people at Do It Yourself Home Improvement, Repair, and Remodeling Information at DoItYourself.com are a big help, too.

Jim

Awesome job,looked at every pic from start to finish.....WOW...

 

[turbojimmy]

Awesome job,looked at every pic from start to finish.....WOW...

Thanks! I'll never take something like that on again! But I'm glad I did it. I've since had a fire down there (long story: Dragonfly King) and replaced all of the carpet with MUCH better stuff.

Just a correction, too: the heaters are 3,500 watts, not 7,500. I have 2 1250s and one 1000 watt heater on a single 240V circuit.

Jim

 

[dgreen1069]

Thanks for all the advice. I picked up all the materials I need today and I have installed 3 vents so far. I've decided to scale back to 6 vents from the original 8 I had planned.....I just don't think the basement really needs it. It hasn't been too bad....my back is killing me from standing on a stupid ladder for the last couple of hours. I've been playing around trying to find the best tool for cutting into the main duct. So far I've used my Dremel, tin snips, and an angle grinder. The grinder produced the cleanest cut, but it was a for a square fitting. I wanted to buy a ductwork hole saw, but the 90 degree takeoffs I bought are oval instead of round at the base. Oh well, hopefully the other 3 won't take too long tomorrow.

 

[dgreen1069]

Thanks again for all the help. I finished up yesterday with all the vents. It wasn't too bad a job, but it did take a while. I probably spent as much time sealing the original ductwork as I did installing new stuff. I couldn't believe none of the original stuff was sealed off on top of the main trunk. The tabs were bent to hold the 90's on, but there was no tape to seal the air in. Builder's contractors really do crummy work a lot of the time.