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2006-10-09, 11:53am
This is going to be my fourth winter lampworking and I've decided that I can't go through another one opening a side door for makeup air. I'm sick of freezing and the snow blowing in through the screen so after reading some of the threads on alternative make up air, I'm going to try and reconfigure a solution.

My studio is a room in the back of my house, with a door to a patio to my back and right. All my venting goes out in front of me to the top a a window, the window is sealed closed except for where my exhaust goes out. There is also a doorway to my left that opens to the dining room, bath, and another bedroom that is directly behind me. I have rigid ducting to the outside, 2, 650cfm blowers, and my propane is hard piped in through the brick wall that the outside door opens to. I am happy with my system and confident that it works correctly, as long as I open the door.

I was wondering if I could run a rectangular furnace duct up through the wall, from the basement, and then bring that ducting up to my table for make up air. It is a large basement, (almost 3,000 sq ft house), with the furnace and hot water tank way on the other side, but the ducting would come from the basement above my washer and dryer. The door way from the basement to our hallway is always open, and I could open a window over the washer if need be.

Can I use the basement for make up air or will it cause a problem with any appliances in the basement? I could, if need be, just run one of my blowers, because I am pretty sure just the 1, 650cfm blower would do the job. Or would it be better to bring in fresh air from the bottom of the vent window, but make sure the duct opening outside was more that 10 feet from the vent exhaust. I would prefer the basement solution because the makeup air would be warmer. The furnace vent in the room is behind me, but can't keep up with the heat loss when the door is open. I have tried space heaters and even bought one of those expensive heat/air conditioner units with no luck.

Oh yeah, the closest cold air return vent in the house is in between the downstairs hall and dining room, one room away from me, but has a door inbetween, less than 20 feet from my torch.

Any suggestions would be appreciated!


2006-10-09, 11:57am
I'd consult with a mechanical contractor if I were you.
Sounds complicated.

2006-10-09, 11:59am
You should only bring in air from your basement if your basement also has an open window or other source of outside air. Otherwise, what will happen is the draw created by your exhaust fan will create a vaccuum and air will flow in from the easiest route to the outside, which is your furnace and hot water exhaust. If these appliances are on, this will draw carbon monoxide into the basement, and from there into your studio.

Ultimately, your makeup air HAS to come from the outside. It's just a question of how it gets in.

2006-10-09, 12:12pm
Maybe I should have mentioned that the basement has 9 windows along with the door that opens to a hall. The window nearest to where I could have my make up air duct would be about 2 feet away.

I thought if basement make up air was possible, it would be the least complicated way to go. Simply install furnace ducting from basement directly up to studio wall, a straight 3 feet maybe.

What gave me the idea, was that this room also has a laundry shoot, the run is 3 feet to the basement. If something gets stuck, I can simply stick my hand in and push it through!

2006-10-09, 12:26pm
You can duct up from the basement to your workstation PROVIDED that the duct from the basement is attached to an open window.

You absolutely cannot use internal air as make up air without an open window or door to the outside.

You will draw down the air pressure in the basement, where all of your gas-using appliances are. This will create several problems - back flow on the exhaust stacks for the furnace and hot water heater - sucking carbon monoxide and aother noxious fumes into the basement. It may also draw back on plumbing vents, sucking sewer smells into the house.

The best way to try to overcome the air cooling effects of fresh air makeup is to duct the fresh air directly into either backside or bottom of your work station. This can be done very simply by cutting an opening in the back of the workstation or the top of the workstation bench top, and ducting straight up from the fresh air ducting. Cover the duct opening with a floor register (I use 4" x 12" for the best amount of air) and you are set.

Additonally, be sure that the fresh air intake is at least 10 linear feet from the exhaust ducting. This ensures that you do not draw in exhausted fumes.

To reiterate, you cannot use inside air from the house for your make up air - it has to come from outside.

2006-10-09, 12:28pm
I'm with Kalera on this one... It's a bad idea.

In another thread Mike brought up the idea of ducting the make up air into the work zone in someway meaning you won't chill the whole house, although you may still need your long (natural fiber) undies on.


2006-10-09, 12:28pm
You beat me to it Mike!

2006-10-09, 12:31pm
LOL Jeff!

2006-10-09, 1:07pm
Ok, so no basement for makeup air. If I go out the bottom of the window, the same window that I exhaust out of, can I just bring the make up air ducting down, and to the right, as long as it's at least 10 feet away from the souce of my exhaust? Do I need rigid ducting, I was thinking of just using regular furnace venting, what about a turn or elbow in the ducting, will it still allow the air in. I got the cutting the hole in the table with the vent and register, that should be no problem. My table is about 18 inches from the window with a back and side baffles. I'm thinking that with the wind blowing the exhaust is going to be pulled away rather quickly anyway, correct?

Thanks for your input all


2006-10-09, 1:10pm
You can go out of the same window as the exhaust, but I would make the ducting to be the same size (in area) as the exhaust or the next size up. You want as low of resistance for the fresh air as possible.

No problems with the bends as necessary, as long as the sizing is there.

The wind will take care of the exhaust, that's the reason for the 10 feet - when there is no wind.

2006-10-09, 8:15pm
Thanks Mike, that was all I need to know! This is going to be way easier than I thought, and warmer.