smoke tested my house looking for drafts. Found lots... - Page 2

MN Renovator · 02-24-12, 12:08 PM

I've seen a guy use thick painters plastic that was taped into place when I was watching a guy using a blower door to pressurize before with new construction before drywall was up. I think he was an energy rater or something, he also tested the ductwork for air leakage too. I've never seen a fiberglass job actually look good before, complete fill top to bottom, not wavy at all, completely straight with the studs without pocks, divots, compression, or buldging. The amount of time it looks like it took made me wonder how the extra labor cost of doing fiberglass right could possibly be cheaper than dense-pack cellulose. Anyway, thick plastic or even a sheet of cardboard taped in place, remove the fan grille first so you can get a flat surface and avoid taping it to the bumpy stuff on the ceiling.

S-F · 02-25-12, 09:56 PM

Unless your room leaks like a sieve you aren't going to need to worry about this stuff. You saw that strider managed to get a noticeable response all over his house with just two box fans in a fixed location. If you move them room to room the pressure will be enough. When I set up the blower door I'm always thinking that this tiny little fan can't possibly move enough air to effect the 2,500 Sq Ft house I'm working on. WRONG! When I'm upstairs in a 3,500 Sq Ft house I know if someone else fires up the blower door because my ears start popping and dust from every nook and cranny starts flying in a certain direction. It doesn't take as much as I'd think to pressurize or depressurize a house. Now imagine what your bath/range fan or you dryer/furnace are doing.......

MN Renovator · 02-28-12, 03:34 AM

So if I was at 1500cfm before I started renovating(this is with atmospherically venting furnae and water heater getting tons of air sucked through too), two box fans would pull or push enough for a DIY blower door? I was thinking of pulling my furnace blower(furnace rated for 800cfm on high for a 2 ton a/c) and sealing it around a window and pushing air into the house because I thought axial/blade fans weren't too good at generating/working against pressure.

It would be fairly difficult to generate too much pressure/vacuum on the house, wouldn't it? Considering 50 pascals is 0.00725PSI or about 0.2" water.

Also, where do you buy the smoke pencils? I've been having trouble working with following birthday candle flames against metal ductwork and incense just aren't making the smoke needed.

strider3700 · 02-28-12, 12:54 PM

local hardware store had the smoke pencils in the tools area.

02-24-12, 12:08 PM	#11
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	I've seen a guy use thick painters plastic that was taped into place when I was watching a guy using a blower door to pressurize before with new construction before drywall was up. I think he was an energy rater or something, he also tested the ductwork for air leakage too. I've never seen a fiberglass job actually look good before, complete fill top to bottom, not wavy at all, completely straight with the studs without pocks, divots, compression, or buldging. The amount of time it looks like it took made me wonder how the extra labor cost of doing fiberglass right could possibly be cheaper than dense-pack cellulose. Anyway, thick plastic or even a sheet of cardboard taped in place, remove the fan grille first so you can get a flat surface and avoid taping it to the bumpy stuff on the ceiling.

02-28-12, 03:34 AM	#13
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	So if I was at 1500cfm before I started renovating(this is with atmospherically venting furnae and water heater getting tons of air sucked through too), two box fans would pull or push enough for a DIY blower door? I was thinking of pulling my furnace blower(furnace rated for 800cfm on high for a 2 ton a/c) and sealing it around a window and pushing air into the house because I thought axial/blade fans weren't too good at generating/working against pressure. It would be fairly difficult to generate too much pressure/vacuum on the house, wouldn't it? Considering 50 pascals is 0.00725PSI or about 0.2" water. Also, where do you buy the smoke pencils? I've been having trouble working with following birthday candle flames against metal ductwork and incense just aren't making the smoke needed.

02-28-12, 12:54 PM	#14
strider3700 Master EcoRenovator Join Date: Dec 2008 Location: Vancouver Island BC Posts: 745 Thanks: 23 Thanked 37 Times in 30 Posts	local hardware store had the smoke pencils in the tools area.