Kitchen exhaust hood time!

ChrisJ

Sort of unrelated to heat but I need some opinions from those I trust, the people of heatinghelp.com



I'm replacing a 200CFM exhaust hood in our kitchen and need to know some good brands.  Its an undercabinet style which connects to a 3 1/4" x 10" through the wall directly behind it.   Currently I have a Broan 76,000 series rated 200CFM @ 6 sones and it only works on high and its LOUD.  Stove has 40,000BTU worth of burners + oven.



I'm considering a Zephyr brand as they appear to have good ratings, but I know nothing about this other then in my opinion more is better.  The one I'm looking at is a model called the Typhoon and I have several concerns one of which may be a very valid concern as far as safety.  This fan is rated, at least they claim, 850CFM @ 5 sones.  Now 850CFM seems like a lot to push through a 3 1/4" x 10" connector, no?   My only concern is I don't want to risk causing downdrafting from my boiler.  My boiler is vented via a 6" B vent down in the basement and to be honest my house is drafty, very drafty.  I'm assuming I won't have a problem, but what risk does such a fan pose as far as this?  Over time as I start to seal things up how likely is an 850CFM (if its true) exhause hood to cause a downdraft issue? Kitchen is on the 1st floor above a crawl space, but the crawl space is connected to the basement and of course I'm sure there are tons of leaks all over the house.



My house is a 150+ year old building which needs a lot of work on the windows which are 90% original, currently has an unvented attic, no insulation, clap board with no sheathing. 



So to recap, my questions are :



1: Is Zephyr a good brand of exhaust hood, if not what do you like?



2: How many CFM do I really want?  There are also concerns regarding how low the hood can go, the Zephyr Typhoon I believe goes to a minimum of 275CFM, seems like pulling a lot of air out of the house when only boiling a pot of water.....



3: Will 600-850CFM risk causing a downdraft issue without a makeup air supply.  Again my home is REALLY drafty but I plan on correcting this over time to some extent.



Thanks for your time and look forward to ANY replies both good and bad.  Everyones opinion matters both pro and homeowner.  I'm also willing to bet many guys here will have an opinion on how well a 3 1/4 x 10" connector will handle X amount of CFM.



Link to the Typhoon : <a href="http://zephyronline.com/products/essentials_power/typhoon_under_cabinet">http://zephyronline.com/products/essentials_power/typhoon_under_cabinet</a>

SWEI

kitchen exhaust

I'm not a fan of the fans in residential exhaust hoods.  A small roof-mounted ECM commercial exhaust fan like a Greenheck CUE VariGreen will perform better, run quieter, and be easier to clean.  You can select the right fan for the application and get the CFM range you need with the installed ductwork.



850 CFM needs an 11" round duct at 1500 FPM.  500-700 is better if you can do it.  That makes your duct good for a max of about 340 CFM.

ChrisJ

Cost

Hi SWEI, thanks for responding.



  I understand your dislike for this style hood, however the construction of my house would make installing anything on the roof a nitemare and I can't afford it by a long shot at this point in my life.  There is nothing I would like more than to put the fan it self somewhere else.



 I find it interesting you said the 3 1/4" x 10 connector is only good for about 340cfm.  This explains why Broan fans anything above 440CFM or so they go to a 3 1/4" x 14" connector and being 440 isnt much above 340 I'm thinking your 100% right.  This is what made me suspicious of Zephyrs specifications being so much higher (2+ times?), yet still with the smaller duct.

SWEI

duct capacity and fans

The fan will have a specified airflow at some static pressure value (often 0.25") but the actual airflow it produces will depend on the size, length, and configuration of the duct on which it is installed.  Fans, like pumps, have curves.  You need to look at the curve (or at least a chart) to see what airflow the fan will produce with your duct.  A so-called 440 CFM fan might well pull only 250 CFM when it is installed.  Proper fan sizing is unfortunately rare in residential applications.

ChrisJ

Curves

I agree, however I have not seen a chart for any of these fans.  I understand they are all $300-$600 fans but I would still expect something.  Broan gives CFM ratings for horizontal VS vertical flow yet nothing specific on duct length.  Zephyr gives nothing other than one single rating which seems way too good to be true.  They tell you you can use a 3 1/4" x 10" connector horizontal or vertical or I think a 7" round duct vertical which still sounds way too small for 850CFM.  As you said earlier, it would need at least an 11" round duct.  Perhaps it does 850CFM without any duct connected to it.  I do have to wonder though, how restrictive is that 3 1/4" x 10" connector I have going through my wall?  Its only 5 inches long or so plus the two dampers.



I'm curious how Broan is viewed in the professional world as far as vent fans in general?  Decent company? Homeowner garbage?

SWEI

fans

Call and tell them your engineer needs curves or a table.  They have to have something.



Broan makes a lot of value priced stuff that's OK.  They also make some really nice stuff like the new Broan Ultra bathroom fans.

NH03865

Makeup air

Even if the job won't be inspected, it is a good idea to keep in mind the code requirements.  There are usually good technical reasons that they are there.

You are wise to consider the downdraft issue, take particular note of the makeup air requirement at the end

The following section is from the IRC:2009 (I don't have the 2012 electronically to copy from)

SECTION M1503

RANGE HOODS

M1503.1 General. Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.Range hoods shall discharge to the outdoors through a single-wall duct. The duct serving the hood shall have a smooth interior surface, shall be air tight and shall be equipped with a backdraft damper. Ducts serving range hoods shall not terminate in an attic or crawl space or areas inside the building.

Exception: Where installed in accordance with the manufacturer's installation instructions, and where  mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.Where installed in accordance with the manufacturer's installation instructions, and where  mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.

M1503.2 Duct material. Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.Single-wall ducts serving range hoods shall be constructed of galvanized steel, stainless steel or copper.

Exception: Ducts for domestic kitchen cooking appliances equipped with down-draft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe and fittings provided that the installation complies with all of the following:

1. The duct is installed under a concrete slab poured on grade; and

2. The underfloor trench in which the duct is installed is completely backfilled with sand or gravel; and

3. The PVC duct extends not more than 1 inch (25 mm) above the indoor concrete floor surface; and

4. The PVC duct extends not more than 1 inch (25 mm) above grade outside of the building; and

5. The PVC ducts are solvent cemented.

M1503.3 Kitchen exhaust rates. Where domestic kitchen cooking appliances are equipped with ducted range hoods or 488 down-draft exhaust systems, the fans shall be sized in accordance with Section M1507.3.Ducts for domestic kitchen cooking appliances equipped with down-draft exhaust systems shall be permitted to be constructed of schedule 40 PVC pipe and fittings provided that the installation complies with all of the following:

1. The duct is installed under a concrete slab poured on grade; and

2. The underfloor trench in which the duct is installed is completely backfilled with sand or gravel; and

3. The PVC duct extends not more than 1 inch (25 mm) above the indoor concrete floor surface; and

4. The PVC duct extends not more than 1 inch (25 mm) above grade outside of the building; and

5. The PVC ducts are solvent cemented.

M1503.3 Kitchen exhaust rates. Where domestic kitchen cooking appliances are equipped with ducted range hoods or 488 down-draft exhaust systems, the fans shall be sized in accordance with Section M1507.3.M1503.3 Kitchen exhaust rates. Where domestic kitchen cooking appliances are equipped with ducted range hoods or 488 down-draft exhaust systems, the fans shall be sized in accordance with Section M1507.3.

M1503.4 Makeup air required. Exhaust hood systems capable of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be automatically controlled to start and operate simultaneously with the exhaust system.Exhaust hood systems capable of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be automatically controlled to start and operate simultaneously with the exhaust system.

ChrisJ

codes

NH03865, thank you for posting this.  As you said codes are in place usually for a good reason. 

BillW

Kitchen exhausts

Be careful that you do not put your house under negative pressure with too much exhaust and not enough make-up air.  If you do, you can pull products of combustion (carbon monoxide) out of your other combustion appliances and into your living space with possibly deadly results.  The code excerpt that was posted spells this out very carefully.  This is a common IAQ problem, especially when someone puts a commercial restaurant-type range hood fan in a home. Make sure you have access to clean the ducts and a critter screen on the outside exhaust. Greasy, dead rodents are not fun to remove. Isolating the fan from the duct with rubber connectors may help cut down the noise, and facilitate the removal of the fan for cleaning. ER/HR ventilators can help with the the makeup air.  You can test to see if your house is under a negative pressure by starting all the fans, like the dryer, range hood and any others, then going into the basement, and opening a window partially.  Hold up a strip of facial tissue, and if it blows inward, you are under a negative pressure.  Outward, you are under a positive pressure, and that isn't good either.

vaporvac

Vent-a-Hood

I can't really speak to the specs, but I've had a Vent-v-Hood for many

years and it's worked GREAT! Quiet, easy to clean and easy to put in.

Mine went into a wooden enclosure ie. it's an insert so you can match it

to any thing you want. It has the "magic Lung" squirrel cage

configuration, that's supposed to help prevent the spread of fire. One

can put in different configurations depending on your need. Did I say

quiet and easy to clean, plus very efficient at extraction!? Check them

out at ventahood.com.

icesailor

Broan Fans:

Broan makes repair parts for all their fans. Unless you want to go through a discouraging process, have you considered replacing the fan and motor?

If the old fan didn't back draft the boiler, it won't if you replace the old with new.



JMO

icesailor

Broan Fans:

Broan makes repair parts for all their fans. Unless you want to go through a discouraging process, have you considered replacing the fan and motor?

If the old fan didn't back draft the boiler, it won't if you replace the old with new.



JMO

ChrisJ

replacement parts

Hi icesailor,



Unfortunately the previous owner of the house felt it was necessary to paint the entire hood with a latex paint using a brush.  If that wasn't the case then sure I'd replace the blower and control board to fix the variable speed. 



I've been considering a Broan 88000 series or 89000 series because they appear to be almost identical to my 76000 series except stronger.

Another brand I'm looking at is Fujioh which has a 3 year warranty which to me, suggests a better build quality.  It appears they are owned by Fuji Industrial.



 

icesailor

Warranties:

Warranties are like the paper you find on a roll in the bathroom. They are good for what they are advertised for. Warranties are factored into the cost of sale. Its like electric water heaters. They will last as least as only as the warranty. After that, it is indefinite.

The difference between an electric 80 gallon water heater with a 5 year warranty and the ten year warranty is the initial cost for the insurance policy the manufacturer has with an insurance company. There is no difference between the two tanks. Just a different label and usually a different tank color.

Buy what you like. Forget the warranty. It won't matter. I've hardly ever collected on a warranty replacement and when over, it was almost not worth the effort.

ChrisJ

Water heater

I thought water heaters with longer warranties had larger and often two anode rods?



I've collected on two warranties, one was a 19 year old Bryston audio power amplifier which had a 20 year warranty, yes, they covered it.  The other was my Kitchenaid Dishwasher blew a hole in the calrod heater when it was like 8 months old.  Of course that heater would've been cheap enough for me to replace my self but it still counts. 

SWEI

19 year old Bryston audio power amplifier

A 4B?

ChrisJ

Bryston

Ah I see you know your Brystons! Yep an older 4B from the mid 1980s.

SWEI

4B

A great sounding tank.

ChrisJ

4B

Yep, the 4B was one of the best amps I ever had my hands on, and hundreds of amplifiers have passed through my hands, though mainly 1950s-60s Fisher tube stuff. I later sold the 4B to a good friend who is using it with a 2B in a biamp setup.



These days I'm more into building my own amps which doesn't happen to much lately due to the house sucking up all of my money. Not sure if you're familiar with them but I have a pair of late 70s Powered Advents that I built new amplifiers for due to the originals burning out too often for no reason. I drive them with a late 70s APT Holman preamp.

SWEI

veering off track a bit

APT Holman was a nice box.  Still have a Fisher 500 and a Mac MC275 out back.  Embarrassed to say I haven't fired them up in about 15 years.

icesailor

Warranties:

I have been told for years that there is no difference between the two. There are so few that buy 10 Year tanks that it isn't profitable to tool up for the few sold. The only people that use them are architects that specify them. Manufacturers buy insurance against losses. Its part of the cost of the item. Its the luck of the draw. Like derivatives that blew up the Wall Street Crime Syndicate.

I have three Ruud water heaters in my customer base that were installed in 1977. That was a very bad year for Ruud and their water heaters. They still are not leaking. If you buy a 10 year water heater and it fails under warranty, they give you a new one. The warranty is only good for the remainder of the first warranty.

Its my opinion that warranties are written on the same paper that is on the roll in the bathroom.