ventilation installed but nothing but problems

murf · #1 2006-11-21, 5:33pm

installed my hood with the 650 cmf fan, the company supplied a ten inch flex pipe but do to my set up , i had to reduce it to 8". the pipe runs maybe 2 feet and is vented outside through a 8 in vent with baffle, this is a dead straight shot to the out side. turn on my fan, light a smoke and i watch the smoke curl up and over the hood. light a roll of paper and blow it out holding it at the torch head, the smoke comes straight back and into my face. holy smokes, should have stuck with a dust collector motor and a 6" pipe or a box fan at a window, From the moment i preassembled this unit, i had my doubts. baffle flange that one has to assemble to the unit, shows air light every where, the motor flanges are not tight(tape them?). so here i sit $400 in the hole, and what to do, SOB, really had hope this was a done deal, but now I have got to start all over and oh ya got a nice 8" hole out the side of my shop wall. Any suggestions? sorry maybe this was to be in the safety section.

Judi_B · #2 2006-11-21, 5:54pm

Do you have a window or door open for make-up air? The fan can't pull very well if there isn't adequate make-up air. I forgot to open the window one day

Starrr · #3 2006-11-21, 9:56pm

Sounds like you are going to have to install baffles down the sides and back of your vent hood to the table. I don't think that the diameter of the duct work is suppose to be reduced. I bought some furnace ducting for my hood because it comes in half which gives you 2 right angles for the hood. I screwed them in with self piloting screws and then just duct taped the bottoms that were on the sharp side. It didn't take too long and improved my ventilation alot, I have 2, 650cfm blowers.

Judi is right that you need to bring in enough fresh makeup air for the sysytem to work properly.

Renee · #4 2006-11-21, 10:52pm

Are you sure the baffle is opening when you turn the fan on?

Rose · #5 2006-11-23, 7:17am

I had a tabletop vent installed and it sounds a lot like yours. I have a ten inch hole in my wall, as I don't think you are supposed to reduce it. They used metal tape around the area the metal comes togther. Sealed it up tight! I had it professionally installed by the manufacturer.

I think you need to contact the people you bought it from. I LOVE my unit and never have to worry about breathing anything.

Rose

JavaGirlBT · #6 2006-11-23, 9:19am

Is your ducting smooth or is it ridgy? If it's the ridgy kind, change it to the smooth because a lot of turbulence can build up in the ducting, diminishing the sucking power of your hood.

Hayley · #7 2006-11-23, 11:22am

How far from your table top is your hood set at? If it's higher than 30" (from bottom of hood to top of table), you will probably need enclosure extending the back and sides. It's a good idea anyway - otherwise your fan is drawing air from your room instead of the fume from your torch.

I agree with above - adequate intake air, as well as rigid ducting and no reduction are critical to ensure your utilizing the maximum power of the fan . . . changing that reduces the power 30-50%.