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oxwife 2014-10-06 12:31am

Yet another ventilation concern! Help please!
Greetings! I've been absent from this site for years, took a long break from lampwork to get some other stuff done, and now I'm back at it and back here! And I have a question!

I have a big (ten inch diameter) squirrel cage fan with two settings. Even on the low setting, I know it pulls a massive amount of air; just for fun, we turn it on, close all the windows in the house but one (several rooms away), and can feel a serious breeze. I used to just rely on the fan sucking the air up and out, but I can tell that this time it wasn't cutting it (sore throat and chest achey-ness after a few days. maybe I'm getting more sensitive in my old age?). So we hooked up an old kitchen range hood, which can be seen in the photos. I did the incense test, and although I couldn't smell it from where I sit to work at the torch, a bunch of the smoke was wafting AROUND the hood and up into the backside of the squirrel cage fan! Obviously, the path with the greatest pull is to the backside of the fan, not up through the ducting.

Now, I have read a bunch of these threads, and it appears that I should be using smooth ducting instead of the flexible. Could that make so much of a difference that there would be more suction through the hole in the top of the range hood, rather than the back of the fan? AND/ OR is the problem that my fan is inside the house? I'm looking at a bunch of photos and not really seeing any squirrel cage fans inside.

I'm sorry if this photo is too small. I tried to post larger, but the site said I could only post up to 80 kilobytes. I suppose I could do a thumbnail and if you click it, it would get bigger? (not very computer savvy!)

Oh, some added information...

The bottom of the range hood is about 14 inches from the top of where the flame would be. It is completely over the torch and the flame and a couple inches from my head (it actually touches the top of my head if I lean forward). With the incense test, if I raised the incense up a few inches, it went directly up through the hole. But I don't want to lower the hood too much or I'll constantly be knocking my head into it.

I would love some input on this issue, please! Especially since it would be great to solve the problem before my husband has to do even more work with experimenting!

oxwife 2014-10-06 12:54am

And here is where I realize that I have a bad case of memory loss. I just decided to look at some of my old posts and realized that I posted something very similar to this several years ago! And apparently, I had hooked up this same range (which was in the basement) for a brief time, but with a much smaller squirrel cage fan. In that post, I was just about to get a much larger fan, which I did. But I must have not used it; must have been around that time that I put all my glass stuff away for a while!

Anyway, I had received some advice and one bit was that I really should use smooth pipe instead of flexible, so maybe my question is already answered.

Still wondering though if there should be so much draw from the back of the fan?

Dale M. 2014-10-10 6:31am

Look at fan.... Seriously, fans usually have one inlet and one outlet..... BUT some fans actually have two inlets.....Its all about the design of fan.... It could be the type of fan you have can actually draw air from motor side too and you do not realize it.... If so this type of fan needs to be in a box or plenum with exhaust plumbed to outside of box and beyond and intake to the box so it can feed both intakes (suction sides) of fan....

As opposed to this type of fan that only has single inlet which does not need to be inside a box but merely has ducting connected to inlet and outlet...


oxwife 2014-10-19 6:57pm

Oh my goodness, Dale, my fan DOES have that open back part; didn't even know that was a "thing"! That makes sense though, and I hadn't even considered it.

Well, my husband helped me configure something that works, even with the fan pulling some air from the back. We finished putting it together this afternoon, and I had a session. It seems good. I'll try to take some photos tomorrow, and post them!

killerbeedz1 2015-02-24 10:44am

I've been using a squirrel fan for years. It has two speeds and exhausts to the outdoors. However I don't have a hood. I was always thinking my replacement air was just around me and was drawing from upstairs due to the fact that I work in the basement. When it's on I can smell everything that's cooking upstairs and when my older dog had an accident. I'm now second guessing myself and just want to make sure I'm safe. Does this sound adequate?

Speedslug 2015-03-04 1:36pm

You could have a problem and not know it Patsy.

The replacement air that you are pulling down the stairs could also mean that the flue gases from your heating furnace and water heater might be being pulled down out of the chimney.

This could mean you are poisoning yourself and family with not only carbon monoxide but also with the other combustion gases from the burned fuel.

You really should look into making a dedicated source for your replacement air.

It could very well be that you have enough holes in the rest of the house to supply your replacement air to not be pulling fumes back in to the house but if something unrelated to your lampwork were to happen at your house and you had to file an insurance claim they could decide to deny your claim because you did not have every single one of your ducks in a row.

Heaven knows they will deny a claim for the slightest reason and you could be left owing a mortgage on a house you can not live in and you can not sell.

Speedslug 2015-03-04 2:56pm

You may not be as safe as you might think Patsy.

That replacement air that is bringing the odors from upstairs down into your basement may also be pulling exhaust gases back down your chimney from your furnace and your water heater.

That would be dosing the whole basement with carbon monoxide and other burnt fuel gases which have been known to kill people.
Carbon monoxide exposure everyday for months can become a major stressor on your body and could leave you vulnerable to other illnesses even if it does not actually accumulate enough to send you to the ER yourself.

I think they used to call it sick building syndrome.

Other than making you sick with a low grade undefined illness with mild headaches and body aches this situation can also leave you open to having any insurance claims denied because you did not have every single one of your ducks in a row and insurance companies start looking for reasons to deny a claim before they ever begin trying to figure out what happened in a claim investigation.

It really is that important to make sure you have a dedicated source of make up air that the kids won't close on you or the dog won't lean against or the wind can't blow shut.

I don't know what gas you are using but I feel I also have to point out that propane and basements can be a very explosive combination.

Propane gas is heavier than air and will sink down around your feet kind of like that fog they used in movies to make things look scary.
The problem is that will actually pool all over the entire floor until it gets high enough to find the pilot light on the water heater or the spark in the furnace when it turns on and then it will go off 'boom' just like in the movies.

It would be better if you are using natural gas for your torch. Natural gas is lighter than air and will not settle into a pool on the floor. It will try to go up and not get concentrated like propane will.

Speedslug 2015-03-04 2:59pm

Well fudge. I thought I lost that first post to the escape key. I am going to leave them both for now. My brain gets tired. :lol:

killerbeedz1 2015-03-07 9:49pm

I use natural gas Phil and have a carbon monoxide alert next to my lampworking station. I've worked this way for 15 years. No one has gotten sick. Thank you for your information! It sure is a small world. I can't believe you grew up in my neck of the woods. I'm sure we might have passed each other in the hallway of our high school. Maybe my older brother knew you. He graduated a year before you. It was a huge school. I graduated with about 600 students. It's hard to believe there were that many kids in one class.


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