Vent System Estimate - Comments Please?

lindag · #1 2009-03-18, 12:11pm

I got this estimate from the HVAC guys. This is in my garage, the area for the hood is 34" wide and I asked for 20" deep. I did ask for specific info re cfm's and hood dimensions and this is what they provided. I also asked for rigid ducting, not sure what the spiral duct is. I don't think they really understood my application yet they knew better than I what I needed...grrr. Any comments please? Is the information provided enough to make a decision? What else should I ask them?

- Install hood above work area
- Install sides and backing as required
- Run 8" spiral duct through roof
- Cut in flashing
-Install a Twin City exhaust fan on a roof curb. The fan will have a 3 speed motor and a back draft damper.

Total cost material and labor: $1425.

Deb Hopeful Journeys · #2 2009-03-18, 12:13pm

Wow, I put mine in myself with a total price of $150

Hayley · #3 2009-03-18, 12:39pm

I bought a glasscraft hood but replaced the fan - contractor got rigid ducting (about 5') and baffles (enclosure), did the install (cut hole in the wall and added flashing, etc.) and the costs were approximately:

hood - $400
CAN 1200 CFM fan - $300
contractor labor and materials - $200

So I would say that your estimate may be a bit on the high side.

RSimmons · #4 2009-03-18, 12:52pm

Spiral duct is a rigid duct product that looks like this:

(The ports are a special ap that I use at work, not usually there)

The outline that you've got is pretty labor intensive, especially cutting though the roof to install the exhaust port. It's pricey, but it's a lot of work and you probably won't find a much lower price from someone that you'd want to work with. Be sure you get a guarantee that the roof doesn't leak! I did my own install on my roof-vented system and it was a booger, but then I'm getting to be an old fart

.

Robert

lindag · #5 2009-03-18, 1:09pm

This is a local company, in business for 60 years so I trust them to do the job right but good idea, I will ask for a guarantee on the leaking issue.

Do I need a fan in the hood? The only one they listed was at the roof. I read the vent info here (etc.) all the time but now that I'm doing a serious system, I'm confused, lol, but I thought a fan to draw away fumes was needed lower than the roof.

Would it be better to go out the wall than the roof?

Oh, and this estimate does not include any electrical installation (my dh is an electrical contractor) but does include fabricating the hood.

Maybe the Glasscraft is the way to go and dh can do the rest. When he gets around to it is the problem.

RSimmons · #6 2009-03-18, 1:29pm

It's the getting around to it that can be expensive, time-wise. I had assumed that the electrical was part of the price. Having the hood fabricated is probably more expensive than the Glasscraft hood, but don't know for sure. I spent a lot of time getting mine assembled and installed.

Here's what I did: Got the Glasscraft hood (extended version in my case) and a squirrel cage blower through Grainger. I built a vacuum plenum (big box) for the fan and hung it from the ceiling. The hood connects to the bottom of the box (cut the hole in the hood myself) and the exhaust duct goes out the top and through the roof. I don't think it matters if the blower is in-line or on the roof so long as it pulls enough air. On the roof will generate less noise in your work area. Make up air comes in through the window/table top using the Glasscraft in-line fan.
It looks like this:

Robert

lindag · #7 2009-03-18, 3:03pm

That looks great Robert! I'm going to have to show it to DH and see what he thinks. Thanks for your advice everyone.

Hayley · #8 2009-03-18, 3:53pm

Make sure that the CFM of your fan is adequate for your hood. Based on what you indicated, I think you will need one that's at least 600 CFM.

AVC-Ed · #9 2009-03-19, 6:38am

Quote:

Originally Posted by lindag

I got this estimate from the HVAC guys. This is in my garage, the area for the hood is 34" wide and I asked for 20" deep. I did ask for specific info re cfm's and hood dimensions and this is what they provided. I also asked for rigid ducting, not sure what the spiral duct is. I don't think they really understood my application yet they knew better than I what I needed...grrr. Any comments please? Is the information provided enough to make a decision? What else should I ask them?

- Install hood above work area
- Install sides and backing as required
- Run 8" spiral duct through roof
- Cut in flashing
-Install a Twin City exhaust fan on a roof curb. The fan will have a 3 speed motor and a back draft damper.

Total cost material and labor: $1425.

Mike says using a Twin City Fan & Blower exhaust fan is perhaps a level higher than your contractor needed to go. TCF&B is a manufacturer of industrial and commercial air movement equipement and they make higher end units. A fan out of the Grainger catalog will work just as well, and perhaps save you a couple of hundred dollars.

All that being said, however, the quote is actually quite reasonable given all that they are going to do for you. Can you get it done cheaper? Perhaps, but will the quality of the work and materials supplied be equivalent? If you do it yourself, you will certainly save some labor dollars, but will you do the exact same job as a contractor, especially when cutting through a roof? Probably not, as roof installations are best left to professionals!

Mike says that when he build his last studio, with 5 workstation enclosures, he supplied the fan, had a roofing professional prepare and install the roof curb, and a HVAC company do all the sheet metal hook ups to the sheet metal he installed. By the time it was all said and done, the price tag was around $1800, not including the fan and shutter assembly.

You can shop around for a better price, but honestly, is it really worth the time you will spend, especially if you are waiting to turn on your torch?

squid · #10 2009-03-19, 11:29am

I would want specification on the fan they are using.

ruca · #11 2009-03-20, 12:10pm

i haven't read this whole thread.. but i think if you posted a thread in the family room or something with a call for help for someone to call you & walk you through it & do it yourself, you could save somewhere from $600 - $1000.

if i was better at this stuff i'd help you, for sure, but i'm not good at installing things. or explaining things.

alphamare · #12 2009-03-20, 2:16pm

I went to the local heating/cooling guy with all measurements for my 36"x20" hood. He built it out of heating duct sheeting (we covered it with wood later) which made it light weight. We screwed plywood to the wall and mounted the hood to it. I also added a steal plate against the wall below the hood.

The heating guy charged us $90 for the hood including the pipe and he built a flange for easy mounting of the squirrel cage fan. All we had to do is stick the pipe on the hood and the fan on the pipe. My fan sits on the main roof but under the porch roof so I don't have to worry about leeks. We did the electrical our selfs.

I have photos uploaded, how do I display them in my post?

Lorraine Chandler · #13 2009-03-20, 2:36pm

OOPS! My mistake..I see that is just the hood part and not bench. Disregard this post please...

20 inches deep is not very much. I had 36" inches originally and now switching to my horse trailer I set up with 24" and I am finding it cramped...do-able for temporary but still cramped.

My box is 48 wide and that gives me enough room for tools..last bench was 6 feet..even better. I used every spacious inch of it too.

Lorraine

alphamare · #14 2009-03-20, 2:53pm

My 20" hood covers the area to where the glass hits the flame. It also sits only 22" above the table or 14" above the face of the torch. The pipe is only 3 feet long and attached to a 495cfm fan.