please help with ventilation

[Jaterwunky]

originally started with kitchen hood system fan 220 CFM. Vented to outside with flexible tubing I believe it is 4 inch. Also note I have my studio in my basement with washer, dryer, furnise hot water heater. I was getting terrible headaches and occasional chest pain. Needless to say stopped torching. Bought 800-1000 CFM in-line fan, took out kitchen fan and replaced with in line fan. Diameter is 12 in. as we narrow down to vent once we get down to 10 inch it seroisly dampens fan and fan starts to back blow. I don't know what to do. Please help. Still getting headaches but I miss my torch.
Thank you very much
Deb
Debsglassbeads

[bhhco]

What torch are you using?
Is your oxygen tank or oxycon, and if oxycon how many LPM?
Is the furnace and water heater gas?
Answer those... and if you can, post a picture of your work area with the hood.

Me

[Jaterwunky]

i am using a lynx torch with propane and oxycon at 5 lpm. Furnace and water heater gas ans sit approx 10-12 feet behind me. Okay stupid question. I have pic in upload manager but how do I post it. I am a virgin at this be kind. Thank you
Deb

[Jaterwunky]

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[IF-Designs]

you may not want to use the flex duct, every lil crinkle in that duct and bend reduces your flow alot, I would look at getting some straight duct and elbows (they have some adjustable elbows that are great) and try using that and see if it helps it should help alot...and I would not reduce more than the 10 inches you already have from 12 I would keep your duct 10 inches out to your vent outside....and make sure you have some sort of protected vent cap over the exit area. Also do you have sufficient make up air coming into your work area? That may also be conributing to your your back flow / headache problem. You need to replace the airflow you take out with fresh air from an area opposite of your exhaust preferably....

Mike A is better about the mathmatics of the ducting and all....but what I posted above should be a few lil helpful hints for yea.

[Jaterwunky]

My hubby is going to kill me. I keep sending him on errands for parts. So straight tube is the way to go. I have a total of 3 windows in my basement. One I keep closed because it is rigfht next to the exit for the fan. The other 2 are open as well as my door upstairs. So I think I get enough replacement air. Where would you get 10 or 12 inch duct. Home depot doesn't seem to carry it. They do carry 12 inch insulated flex duct tubing but I gather that won't work. Thank you
Deb

[bhhco]

Originally Posted by debsglass

...I keep sending him on errands for parts.....Deb

Well, don't send him out quite yet ... give me about 30 minutes to study this.

Great picture by the way... really helps. Good job.

Oh... and jsut a quick thing... that first 90 degree of the 'fan motor?', coupling is creating the major back pressure problem. More info later.

Me

[bhhco]

Homes with gas-appliances, on averge, show a 'background level' of 15-30 ppm of CO due to the appliances. These appliances are located in your work area.

As Dale and Mike will later tell you... it's possible you are adding to this by backdrafting the appliances if you do not have enough make-up air coming in to replace what is going out the vent hood. More on that later.

The Permissable Exposure Limt (PEL) for CO is 50 ppm... you may be starting out with as high as 30 (background) to begin with, in the basement. If you remain below 50ppm most persons (999 out of 1000) will have no symptoms or 'bad effects'... per the NIOSH.

If your ventilation is system is operating properly it will remove the combustion products the torch produces. Your specific set-up will, by itself, produce enough product to hit the CO PEL limit (50 ppm) in approximately 42 minutes of operation. If the ventilation system is not working properly, some or all will be retained in the room and within 2 hours you will be at 2 times the PEL limit, or over 100 ppm... plus possibly the 'background' CO of 15-30 ppm, and you will begin to feel the effects.

Now, given that the system does not appear to be 'pulling', then the volume of make-up air needed may be lacking -- and (from above) you may also be backdrafting additional CO from the appliances.

All this really means is that it confirms the system is not performing properly and strongly indicates the CO levels are above the PEL limit... and accumulating. So what's the ventilation problem?...

Here's what I see, and Dale and Mike I'm sure will be along too.

1. I see the thermal plume of combustion products is flowing past the back edge of the hood and is not being captured while the torch is in idle mode -- even if the exhaust fan was operating at the rated level. I suspect that when you are working in the flame, a similar problem occurs, but this time off the front leading edge of the hood -- due to hood placement and height. Additionally, your body position may be placing you, and your breathing zone, in the working mode thermal plume before it ever reaches the hood. Essentially these are all 'placement problems'... and are distinct from fan, duct, and makeup air problems.

a. a back plate needs to be placed on the back of the venthood, extending down to the table top, to stop the thermal plume from bypassing the back edge of the vent hood. A sheet of galvanized metal will work, 30" wide.

b. the vent hood should be lowered to 22" above the table and moved such that the leading front edge is aligned 4" back from the torch face.

c. Ensure as you work than you do not place your face (nose) further forward than the leading edge of the vent hood (the lowered 22" will help prevent that).

2. Outside make-up air must equal that removed by a ventilation or the ventilation can 'rob' the gas appliances (backdraft), and/or it will simply slow down... it cannot move what it cannot get. The outside makeup air must be looked at very closely. Please post how that is done... Dale and Mike will need to know.

3. The fan and ducting need 'adjustment' to ensure better movement of the air. Again Dale and Mike will be here to guide that.

Now... before you do any of this, wait until Dale or Mike post... they may have different ideas that will work and may be easier to do. They may see things I did not see. Get a total picture of what's wrong, and how to best fix it. Then send DH to the home improvement store... tell him it's last trip
Me

[Jaterwunky]

OMG!!!!
Okay there are a few things killing my brain cells. Thank you so much for all the valuable info. I am enclosing some more pics so you can get a full idea of what I am working with.
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Once agin thank you for your expertise

[Jaterwunky]

There is slao a window on the opposite side of the basement about 20 feet away. The handrail near furnace leads up to lower level. I usually keep this door open when I am torching.
Again thank you.
PS ignore the mess basement is least priority on the cleaning list.
Thanks
Deb

[Paul Ewing]

As was mentioned, Mike and Dale are much better at this, but I'll throw out a few suggestions. First you definitely want to get rid of the flex vent. I have heard that it reduces your vent efficiency by 50% or more. My Home Depot carries 10" and I think 12" smooth wall vent. It is sold in I think 4 foot sections and is flat. You need to roll it up and clip the edge into the slot on the other edge to make the cylinder. If they don't have it on the shelf, ask and see if they can order it for you. They might have to do that through the contractor desk. If not, check and see if there are any AC/Heating supply businesses in town. The Home Depot people should be able to point you to one.

Just looking at your pictures, I would probably try running your vent out the window instead of cutting a bigger hole in the wall since it is so close to where you are planning on venting anyway. Maybe split the window in half and put one side glass for light. On the other side I would take a piece of plywood and cut a hole for the vent to go through. Another option is to get a piece of plexiglass for the whole window and then cut the vent hole in one side. This would give a bit more area for light and may be easier to fit into the existing frame.

It sounds like you should be good for makeup air if you keep the two windows on the opposite wall open. They look like they are around 16 inches x 3 or 4 feet wide. You might get the measurements for them and post so Mike can verify the calculations based on your fan size.

Also as was mentioned, it looks like your torch is too far away from the hood. The torch face should be at least even with the edge of the hood. Also is the hood all the way to the wall?

[bhhco]

Originally Posted by debsglass

OMG!!!!
Okay there are a few things killing my brain cells. Thank you so much for all the valuable info. I am enclosing some more pics so you can get a full idea of what I am working with.
.
Once agin thank you for your expertise

Thank you for the additional pictures. The gas furnace shown above is a Cat 1 natural draft furnace. It uses room/house air for combustion; and vents the combustion products using draft air from the room.

The indicated CO levels being experienced could be from the torch or the furnace, or both. I would suggest having the furnace checked to ensure the flame is properly adjusted and the draft is working.

However, even if the furnace is working perfectly, I see no way to use a torch ventilation system in basement with a natural draft furnace -- just a fireplace somewhere else in the house can throw off a natural draft at the furnace... and we are talking about several hundred cubic foot per minute torch ventilation -- IMO it simply cannot be done safely in a basement with a natural draft furnace.

Perhaps you could move your studio to the garage, versus inside the home. The torch ventilation system, if placed inside the home, could create a backdraft on the furnace, even if the set-up is in a very remote room.

I've included a couple of links to better explain Cat 1 furnace operation, back-drafting, and the CO problem.

http://www.achrnews.com/CDA/Articles...100000f932a8c0

http://www.homesafe.com/coalert/bkdraft.htm

Me

[Jaterwunky]

thank you, thank you, thank you. Well my adorable hubby is finishing with my vent hood. He suggested turning off the furnace while I am torching as a temp messure. We have a porch that He is willing to finish with the enclosure and turn it into my new studio now. Actually that would be better because my view from the backyard is gorgeous, not to mention more room for glass. He-He Thank you again for the info. In the end we need a new furnace. Probably as old as house. But why fix it if it ain't broke.
Again I owe you
Deb
PS
Interesting articles. Now I want a new furnace!!!! My hubby thanks you

[Dale M.]

I guess I'm old and cranky today, but with all the words written in this forum on ventilation....

Just to run a few thing by, for one to think about....

In almost every case use at least 8 inch rigid duct and turns for exhaust... Keeping runs as short as possible and as few turns as possible

One needs to have at least 100cfm of air flow for each square foot of hood opening...

Use a squirrel cage type blower, avoid in line (propeller) type blowers...

Make up air volume has to equal exhaust air volume.

Make use fresh air source has to be at least 10 feet away from exhaust point.

IF there are gas appliances (gas furnace - gas water heater) in studio there has to be enough make air for their proper operation and venting along with fresh air requirement for torch ventilation (prevents back drafting furnace or water heater). Keep in minds these appliances vent by convection and forced ventilation (suction) in basement can reverse flow pulling bad gasses into your studio.

Basement is hardest space to properly ventilate because of many of the above reasons....

Please anyone, dont my rant personally!

Dale

[Jaterwunky]

Thank you paul for your info re home depot. We went and got some 12 inch flat venting that we rigged into a cylinder and wrapped around in line fan. So the venting looks okay although haven't flipped the switch yet. Although sounds like need to relocate studio to porch from the compliments of our antiquated furnace.
Thank you all for your wisdom.
Deb

[Jaterwunky]

your not cranky. Believe me I have read this forum numerous times and had thought I had it down. But kept having problems. Didn't realize about furnace. I thought I had enough coverage with inflow air to make up for it. Thank goodness for this forum, many very knowledable people with excellent info.
Thank you again from the person recovering her brain cells.
deb

[bhhco]

Originally Posted by debsglass

your not cranky. Believe me I have read this forum numerous times and had thought I had it down. But kept having problems. Didn't realize about furnace. I thought I had enough coverage with inflow air to make up for it. Thank goodness for this forum, many very knowledable people with excellent info.
Thank you again from the person recovering her brain cells.
deb

Yes he is... he's just a cranky ol' meany

Thanks Dale -- 8" minimum and rigid -- I can remember that .

Me

[Ro]

i was having some issues, i too am in a basement. i just used plexiglass on sides and glass in the back to bring my 'hood' down to my table on 3 sides, HUGE improvement, i cant even keep foil on the table anymore. it starts about 7", i think from the torch face so i can still work large tubing/puntys no problem. i also changed which window is open, instead of behind me its infront, fresh air from 'under' your table brings it between you and torch , that really helped too i have a fan at the fresh air window blowing in and under my table too.
good luck
ro

[MikeAurelius]

In looking at the picture of the furnace, you already have a problem...see the rust marks on the exhaust duct? That's from a build up of sulfuric acid from not enough fresh air being provided to the furnace.

I suspect that you have never had enough fresh air coming into the basement to begin with.

You need to get a HVAC professional to come in and check out your furnace first of all -- any time you have rust marks on the exhaust ducting you need to have the furnace checked to see if the heat exchanger has been damaged or is leaking combustion by-products into the the household air stream.

The HVAC professional can then determine the amount of fresh air that your existing appliances require and plumb in the proper ducting to provide for them, and at the same time the necessary air for your torch workstation.

Now, as others have commented -- you definately need smooth sided ducting for the vent hood. It should be a minimum of 8" in diameter, and run that same diameter all through the system -- do not decrease the diameter at all anywhere in the system. It can be increased in the direction of air flow, but not decreased. While it may be easier to use flex ducting, it can decrease your air movement by as much as 50% or more.

[Jaterwunky]

Ro,
Looks like you have a huge basement. How did you attach the plexiglass to the hood???? Is your vent made or did you purchase it from somewhere???
Thanks for the pics and advice.
Deb