Help Think This Through - Hanging A Grease Hood

[vash]

i would screw a 2x4 along the wall, right at the perfect elevation as the bottom of that vent hood. that way you and your helper(s) can lift it up and hook it to the board and brace the front edge with something at the ready. like a cheap screw jack.

then insert fasteners fastidiously. then remove 2x4 and brace.

does it come with a template to line up fasteners to the wall?

wait. 400lbs? forget what i said.

[908/930]

Keep in mind that you need a large hole in the house for make up air to enter the building, you could likely reduce that 12" duct to 8" and still have lots of flow out, depends how badly you burn things. Still means you need at least 8" duct or larger for make up air. You are in Nor Cal, at least the outside air is warm.

[jyl]

Originally Posted by 908/930

Keep in mind that you need a large hole in the house for make up air to enter the building, you could likely reduce that 12" duct to 8" and still have lots of flow out, depends how badly you burn things. Still means you need at least 8" duct or larger for make up air. You are in Nor Cal, at least the outside air is warm.

I'm in Portland OR, but its not usually too cold here - not like some other parts of the country.

I haven't figured out how to do MUA yet. Thinking about a floor vent, to make it easier to run ducts (below the kitchen is a basement, easy access). I think that if I place the floor vent under the range, I may be able to skip heating the MUA since the cold outside air will flow up around the hot range and more or less directly into the exhaust hood.

[jyl]

Originally Posted by greglepore

Really like the high cfm fantec inlines for this application, along with their muffler...

I found this CFM calculator which suggests about 2,000 CFM (based on total range BTU 168K and ducting 6' / 2 elbows). I've used other calculators which give lower numbers.
I suspect I will not have anywhere that much CFM - it would be terribly costly and involved, and I never have all six burners and oven raging at the same time. It is a commercial-type range, but I'm not a restaurant. I think I'll aim for around 1,000 CFM.

https://kitease.com/range-hood/cfm-calculator

It is this range

https://www.ajmadison.com/cgi-bin/ajmadison/ARROB636N.html

[908/930]

At 1000 CFM I would plan on having a VFD on the fan so you can slow it down, having the MUA from under would probably be a good idea. At least you are thinking about the MUA, I think many people do not.

[Zeke]

Originally Posted by jyl

I'm in Portland OR, but its not usually too cold here - not like some other parts of the country.

I haven't figured out how to do MUA yet. Thinking about a floor vent, to make it easier to run ducts (below the kitchen is a basement, easy access). I think that if I place the floor vent under the range, I may be able to skip heating the MUA since the cold outside air will flow up around the hot range and more or less directly into the exhaust hood.

Which is exactly what you want. And a damper on that, for sure. AFA the variable speeds go, that should be built in to the package. Might not hurt to double check. You don't need full tilt all the time.

[jyl]

Made some progress. Installed two 1 5/8” strut rails using 5/8” lag screws (structural screws too small for rails), checked pullout strength tables, looks like at 100 lb/screw I’m at one-third of “rated” loads. I’ll add a big-ass cleat on the wall too, and probably more support as well.

Re-measured ceiling height, head clearance and height to grates (39”, I was totally wrong before), and clearance needed for a hypothetical 100 qt stockpot on grate and a small under-hood shelf, determined ideal hood height and outlet, light switch, fan control locations.

Cut away some sheetrock and lath & plaster, measured, realized I can’t do the ducting with off-the-shelf 12” round. Not enough clearance given ceiling and stud location. Will have a sheet metal shop make the necessary ducting using 10” square, in a few pieces for ease of installation.

Recalculated cfm using the Greenheck formula, still coming up that 1,000 cfm will be more than sufficient. That lets me use a small fan (“small” by commercial standards) on 120v, so I won’t have to run a 240v circuit.

The future issue is that this is going to be a rather massive expanse of stainless steel hood in a medium-sized kitchen, which may not entirely please the wife. So eventually - like, after months or years of marital discord - I may have to figure out how to make it attractive. That’s for later. I’m thinking copper sheet. She looooves polished copper.

[jyl]

Rails



Rods



Cutting for duct.



Rough design for ducting.

[jyl]

She just bought a bunch more copper stuff . . . plus the dozen copper pots hanging from the ceiling . . . so I’m thinking if the hood gets wrapped in copper she’ll see its massive presence as a feature not a bug.

[greglepore]

Yeah, 1000 cfm would probably be fine, but due to the size of the hood I might upsize it slightly as the draw at the edges will be weaker than with say a 48 in hood pulling 1000 cfm. Think maybe 1250 or so. And makeup air? If you're in an old leaky house, you may not need a dedicated source, but I'd default to some sort of damped mua setup, maybe with a solenoid damper tied to the fan switch so that its not open unless the fan is on. But I overthink this stuff.

[p911dad]

It sounds well planned out, but I can offer one suggestion- if you can a sheetrock jack you could lift it up level into place with no stress and move it around until you have it just right. I am not sure of the load rating of those jacks but it seems 300 lbs should be within limits. I used to get one from the lumberyard where I shopped. Good luck!

Oops - 86 this idea. I just checked load capacity on these jacks and it is less than you need to safely lift the unit.

[908/930]

For lifting check if any local rental places have a portable material lift, sort of a manual fork lift usually good for about 500lbs and easy to transport.

[jyl]

Making very slow progress, too much other stuff to do.

Finally figured out how to hoist a load to within 13” of ceiling. 1 ton chain hoist, recessed into ceiling, upper hook on a 5/8” bolt through upper 1/3 of 2x10 joist. $65 at Harbor Freight, cheaper than renting anything for a day.

[jyl]

[jyl]

Many thanks to herroberst! hood is up, still need cleat, spacer, all the ducting and fan etc. but the part that was stressing me out is done.

[jyl]