Garage exhaust system

[493mike]

Hello fellas,
I thought you might like to see my in floor engine exhaust removal system. I used an old heating boiler air fan to create the necessary "vacuum". The entire below grade system is schedule 40 PVC-4" size, all pitched like a sanitary plumbing drain to a sanitary tee draining into the soil. The air flow has to reverse direction at that point, allowing any condensate to flow down, and fumes to flow up into the fan and get pumped out through the garage wall.
I placed 2 inlets in each of my 3 working bays near the overhead door, each with a SS cover. I only need to place rubber exhaust hoses over the tailpipes and into the inlet holes. This has worked well for 15 years to date.The system pulls so strong it makes removing the covers somewhat difficult!
Mike

 

[Carl_WI]

I wish I would have seen this before I built my shop. Very nice.

 

[txvwnut]

And friends this is how you properly plan ahead when building your shop.

Awesome idea you did there, really blows my wall mounted exhaust fan away.

 

[ALinCarolina]

Nice. Do you have a photo of the hose you use? Does the OD of the hose fit snugly into the PVC opening or do you use a coupling?

 

[lakeroadster]

15 years of operation would seem to prove this as a moot point, but wouldn't there be an inherent danger of explosions due to concentrated gas fumes being evacuated by an electric motor driven device?

 

[38Chevy454]

15 years of operation would seem to prove this as a moot point, but wouldn't there be an inherent danger of explosions due to concentrated gas fumes being evacuated by an electric motor driven device?

Unless your car is significantly out of tune, there would not be enough carbon monoxide to be explosion hazard. Even somewhat out of tune my gut feel is you would be a lot of safety margin. Plus the blower motor is outside the exhaust gas flow and blower assy.

OP, good idea and thinking ahead there.

 

[pmiranda]

CO is not flammable... but if you're running rich without a catalytic converter you'll have some unburned fuel in the exhaust. Using an extractor fan suitable for flammable vapors would be a good idea and also let you use it for a temporary paint booth... which was my thinking for floor drains.

 

[38Chevy454]

CO is not flammable... but if you're running rich without a catalytic converter you'll have some unburned fuel in the exhaust. Using an extractor fan suitable for flammable vapors would be a good idea and also let you use it for a temporary paint booth... which was my thinking for floor drains.

...uhh, CO is flammable. I looked it up, lower explosive limit is 12%, upper explosive limit is 75%. Values for in air.

 

[493mike]

The hose I use is available from auto parts stores and is a commercial product. It fits very loosely in the floor inlets but that doesn't make a difference. The system fan suction prevents any leakage. If I'm careful I can run a snowmobile with the muffler outlet over a floor inlet and not have too much leakage!
Mike

 

[jimindm]

I will let you guys work on how flammable what is going through the system.

That motor looks to be very near the floor, and that is where any gas fumes would collect. Is it a fire proof motor, or brushless, or any other kind that would limit a spark at start up.

I would be more worried about the fumes around it, than what is going through it.

 

[Iroc-Z]

Wish I would have done this too. We had the same type of set up in a previous shop. I would recommend a squirrel cage fan driven by a motor via belt to avoid any dangers.

 

[Scottwi]

I will let you guys work on how flammable what is going through the system.

That motor looks to be very near the floor, and that is where any gas fumes would collect. Is it a fire proof motor, or brushless, or any other kind that would limit a spark at start up.

I would be more worried about the fumes around it, than what is going through it.

If he did have issues with fumes in that are, wouldn't the furnace or water heater that are on either side ignite and fumes before the motor?

I think it is a great idea and wish I had done for working on snowmobiles.

 

[404]

15 years of operation would seem to prove this as a moot point, but wouldn't there be an inherent danger of explosions due to concentrated gas fumes being evacuated by an electric motor driven device?

This is perfectly safe and will not ignite the CO in a meaningful way. Meaning that the CO concentration will be fatal by inhalation long before we reach the lower flammable limit.

 

[lakeroadster]

15 years of operation would seem to prove this as a moot point, but wouldn't there be an inherent danger of explosions due to concentrated gas fumes being evacuated by an electric motor driven device?

This is perfectly safe and will not ignite the CO in a meaningful way. Meaning that the CO concentration will be fatal by inhalation long before we reach the lower flammable limit.

When I wrote "gas" I was referring to gasoline, not CO. All my "classics" have carburetors that run rich when cold, due to the normal choke operation.

 

[LS6 Tommy]

This is perfectly safe and will not ignite the CO in a meaningful way. Meaning that the CO concentration will be fatal by inhalation long before we reach the lower flammable limit.

X2. My Dad got minor CO poisoning working in the garage when I was a kid. He had a propane heater running in the garage the whole time.


His in floor system is really nice. I'm used to the "old school" setups with the ports on the garage doors. Someday I might even put a pair in my little garage so I can give Madge a little mid winter run time without having to back her out or open the roll up door once she's on the road.

Tommy

 

[csargents1546]

Exhaust systems such as this pull so much ambient air into the system that co concentrations are next to nothing. As one of my coworker who is from the navy would say "You are nuking it" meaning over thinking it.

 

[rebelranger]

So I'm a little confused on this. How is it preferable to simple exhaust tips vented outside? Think wall vent that only opens when venting.

 

[493mike]

It works better (no leakage) and I did it because I wanted to.
Mike

 

[bad_idea]

Welcome to Garage Journal 493Mike. I think it's a cool idea. If you have an idea that is different, expect to be slammed by the safety nazi's on the board. This is a great forum, but some of the guys are over the top with safety.

DOn't even mention PVC in a thread about air compressors.

 

[kaymccampbell]

More bait. I've been using a 1974 vintage furnace fan for the same purpose in my shop. Perforated case. Big visible windings. Running right over a bench with lots of flamable use and paint mixing and spraying.
For over 30 years and I still haven't blown up. Oh. Imagine it sucking fumes of a monthly auto repaint for 20 of those years.
FEEDING FRENZY!

 

[404]

More bait. I've been using a 1974 vintage furnace fan for the same purpose in my shop. Perforated case. Big visible windings. Running right over a bench with lots of flamable use and paint mixing and spraying.
For over 30 years and I still haven't blown up. Oh. Imagine it sucking fumes of a monthly auto repaint for 20 of those years.
FEEDING FRENZY!

LOL the visible windings are fine. The potential problem is a motor with an internal switch for capacitor start. When the switch moves there is a spark.

 

[redmondjp]

LOL the visible windings are fine. The potential problem is a motor with an internal switch for capacitor start. When the switch moves there is a spark.

Yup. Or a universal motor that has a commutator and brushes - definitely an ignition source there as well.

 

[gnpenning]

That is a nice cheap simple solution to a problem. Way to think ahead on the drain.

If that was mounted high on the wall couldn't you use blast gates and have a leg going over a welding table as well? Trying to kill 2 birds with one stone.