Thanks Kam - I will check to see if something as simple as that will suffice. Whatever damper my HVAC guys were going to install on the furnace was a no-go.

Totally different situation, we are in Florida. It is just now getting cool enough to open the windows and turn off the a/c a few mornings per week.
I have a 1200 cfm hood and the rangetop is my only non-electric appliance. I use "high" rarely, and only when a window is open. My house volume is over 30k cubic feet because we have high ceilings, and it is one story.
I think I've read that using a recirculating kit is code compliant, and some people choose to vent after final inspection. If you are going to skirt the rules, know what they are, why they exist, and what consequences your family could face for creatively interpreting them.

We also have the Broan unit, but in the 6" size and we do not have a Broan hood. Our stove is near our refrigerator and we have the make-up air coming in under the refrigerator, so it is "pre-warmed" before it gets into the kitchen.

Appreciate the info Kksmama - recirculating is another option that hadn't crossed my mind. I'm fairly comfortable with my situation - I have two windows in the kitchen that I can use to pull in outside air and I don't anticipate using max capacity on a regular basis. I'm all for a makeup air solution, but I need options that are more reasonable.

Hi,
I am in Michigan too. There is an in between option also. If you are above 400 cfm up to 600 cfm you can have a modulating make up air damper that only opens when the hood is on. This costs way less than the full separately heated makeup air system for hiids over 600 cfm. For example my builder charges 3000 for the over 600cfm mu air system but 600 for the damper system. That cost is for the damper and larger (8") piping (vs 6" standard piping). Then obviously whatever your hood equipment us costing you.

Good luck!

Illinigirl - that's interesting. Your solution sounds like the same as the Broan unit mentioned by Kam and Dekeoboe. Do you have the name of the manufacturer? I'd love to do more research. I was quoted 13K for makeup air, but your quote sounds more in line with what I was willing to pay. I can't imagine the difference is new build versus retro-fit.

Dekeoboe - thanks for the fridge warming tip...may come in handy.

Mgoblue,
I don't know if there is a specific manufacturer for the damper itself. I can ask.

My understanding is I can use whatever brand hood will work with the 8" vent tubing that is going to be externally vented from our house. At this early point in our build I'm not sure if it's chicken or egg that comes first (Does the builder work with the hood we choose to make the venting to code, or do we work around what we're willing to pay for in a MU air system and find a hood to fit that code as we are not even willing to spend the 3K on the MUA system to get a 1200 cfm hood)

I'll try to find out more.

Mgoblue--$13K for make-up air? That sounds ridiculous to me. We live in VA and there is no code dictating MUA. I am putting in a Blue Star cooktop with 720 CFM hood. I chose to add MUA after researching here on GW and other places. I had an HVAC engineer at the house for something else and he said that with 720 CFM I definitely want MUA--it will pull so much from the HVAC system when on it will affect efficiency. I purchased the 6" Broan MD6TU. We ran a vent to the outside and installed an inline filter. I would say $1000 installed (by my contractor) including parts. We did not tie to the HVAC system as the engineer advised against it. I like the idea of running it under the fridge to gain warmed air for cooler climates--very smart. Good luck!

ok - good...glad I'm not crazy to think 13k is a bit on the extreme side to pay for make up air!!!

Sum - do you also have a Broan hood or just the MD6TU equipment? I have 10" venting and it looks like they make a 10" as well. I would love if I could make something like this work.

Appreciate all the suggestions!!!

Blue, are you required to have venting at all?

Appreciate the check Illinigirl - makeup air solutions don't appear to be very widespread - either that or I'm not plugging in the right words for good hits. Hopefully this thread will help others as well.

Thanks all!!!

Mgoblue, no, our hood is not by Broan. You can use the Broan MUA damper unit with any hood. I know they make 6" (was what we needed with our hood) and 8". If they make 10", go for it! Seems to be an easy system. We are partially installed--the MUA system is in but the hood is not up yet. Waiting for tile to go up first. ;).

Fori - the Bluestar manual indicates ventilation with a minimum of 300cfm hood, which is interesting given the btu power. Are you thinking of a non vented option?

Thanks Sum!!! Good to know.

search for an HRV heat recovery ventilator

I know YOU need a hood, but does the inspection require one that functions (instead of just being "cosmetic" and lights)?

Mgoblue85, spending 13k for mua is nuts, there has to be a better way (or a misunderstanding and that money includes a gorgeous hood, installation, the motor, mua and is still too pricey). But please don't think I was suggesting recirculating instead of a real vent, I'm really sorry I didn't have a real vent until I remodeled, I had no idea it was a health hazard.

Here is a link that might be useful: NYT article on kitchen as health hazard

Fori - got it. Thanks for the clarification. I'll double check that but it may be pretty obvious that something is missing. Definitely worth checking.

Julie - thanks. I will expand my search! I'm a Julie too.

Kks - crazy isn't it. That's why I put out the APB to the helpful GW folks. There has to be a better alternative than what I was told.

No, 13K is about average to add enough heated makeup air to your home to counteract the CFM of your fan. That's a LOT of cold CFM coming in to the home to have to heat.

What goes out, has to come in from somewhere! Back down through your chimney, furnace vent, or water heater vent is where it will come if you don't give it enough air from another source. Meaning carbon monoxide poisoning for your family, not just a code inconvenience to be skirted around. That amount of CFM can completely suck all of the air that is in your home out of it in less than 10 minutes. Meaning all of the heat that you just paid to keep warm with is now outside.

I don't suppose you would give up the high BTU range that's requiring the high CFM fan that's forcing you into the heated makeup air situation? If not, then do your best to comply with the requirements. It's for your safety and comfort that it's required.

And yeah, you should be searching for HRV. That's part of the MUA requirement in cold climates. MUA IS required in all locations in all states if the vent is over 400 CFM. It's part of the 2012 IRC, or the International Residential Code. It's just not enforced in the more temperate locations, or those locations still on the 2009 IRC, or in locations that have few ways to enforce anything. You're still required to comply with the code, even if your location doesn't have the means to enforce that compliance.

Here is a link that might be useful: Code Adoptions

We had a home energy audit last week and found out a couple of thought provoking (scary) things. We are in a place that currently doesn't require makeup air and went with a 715 CFM hood without makeup air. We have a 1912 (single paned and no insulation) bungalow that failed the audit. A score of 8 when passing is 5 and 3 the best we could hope for. Drafty would not be an understatement :-). Getting to my point here, when we put the hood on the 2nd highest and highest level, the not sealed combustion furnace failed to the tune of over 2.75 minutes! And the not sealed water heater missed not failing by 2 seconds. Yikes. We will be replacing the furnace (1945 BTW) with a boiler next summer as well as the water heater, but it was truly unnerving. We DO use the higher levels so if you never do you might not create the perfect storm, but after seeing, and smelling, I'm a believer!

hollysprings--thanks so much for the detailed info. Very helpful! Glad we decided to do it anyway and that we are temperate enough to not need HRV. Your wisdom is so helpful. The HVAC engineer noted that the 720 CFM hood could pull 2 tons of air. Not something to ignore...

clueless--validation of all holly's info! Sorry for your situation but so glad you are aware and can make the needed adjustments to ensure your safety.

I am in MI as well and just had to do this for our new build. We used the MUA by Zephyr. Damper only opens when fan is running.
HVAC guys connected it to the cold air return ducts. It was about $600 installed.

Good Luck!

Here's a link to Zephyr

I'd sure like to know what 13k includes, I guess there must be some kind of second furnace? And would having a furnace for the purpose of heating make up air really be justified over the cost of using one's primary furnace a little more? I don't understand.

I do understand back-drafting, and the dangers of CO, but we don't have a fireplace and all my other appliances are electric. I think I've correctly calculated that it would take nearly 30 minutes on "high" to replace all the air in my house, and I'm looking forward to opening windows and doing so more often when the weather allows.

Anyone done this who has Steam or hot-water heat? Most of what I read talks about how to do it into a forced-air system. Not what we have--and there is no way I'm willing to stick a fan--even 300-400--into my house with the furnace, the hot water heater and the radon system and risk getting CO AND radon up into my living spaces. Opening a window is a lovely concept, but the risks involved with someone who doesn't know doing it aren't worth discussing. Am in the Boston area, so not as bad as MI but still certainly cold.

Hollysprings - thanks for the enlightenment. I've been trying to find as much info as possible on mua, so I can be in the "know" and make the right decision. I'd not heard of anyone paying that much for mua, so it's interesting that you think this is average. Not giving up the range, so I'll search until I find a good solution that includes safety - don't want anyone reading about me on the news!!!

Clueless - thanks for the reinforcement. I'm not opposed to mua at all, just to the cost, which I thought was pretty steep.

Hough - thanks for the link. Good to know this worked in MI. Will research further.

Kks - at this point I'm hoping I don't have to find out what 13K covers by finding another SAFE alternative that isn't so costly.

Megan - good luck. If I come across anything applicable I will post.

Again - thanks all. Really appreciate the advise and options!!!

MGoBlue - Yup - Mi for you.
A2 is enforcing strictly but the code doesn't require any ventilation. Read between the lines. We didn't have a hood at inspection. We then installed afterwards.(prewired and vented)
I put in one that is 350 CFM with a boost to 450. It is a Broan as well but not happy with it as there is one fan on the left side.
I did find a baffle hood which has a low setting of 350 and also a higher setting.
Remember - no charge for fan under 400 but go to 401 and you have to make up all of it...
Now as others pointed out - think safety first. Our house is not tight enough to cause a problem with our 350-450 and we also have a CO monitor installed.
Can't wait to see your reveal

Is there any truth to the claim by Vent a Hood that their products act like they are higher CFM because of their "different technology", but they are technically rated as lower....therefore you don't need MUA?

Mgoblue85, just wanted to clarify that I wasn't trying to be a scaremonger, but was really surprised by the audit results and wanted to share. It was an orchestrated example to show what COULD happen if the furnace or water heater kicked on while the vent hood was on high. Will that happen? Maybe, probably. I tiptoe around our 70 year old furnace as it is, now I'm even more aware :-( Unlike kksmama all of our appliances (water heater, dryer, range, furnace) are natural gas so carbon monoxide is never far from my thoughts in winter. We have detectors all over the house, but those are for danger levels.

If it were me, I'd probably try to find a 36" 400 CFM hood and avoid the makeup air issue - unless you can live with unheated makeup air.

Old Thread but perhaps some of you are still receiving comments. Planning on doing the Broan or some other MUA damper system. Is it working well for those of you who went that way? Hough2012, any issues with condensation? If your HVAC unit isn't running at the time you use the hood and Mua unit, does the hot or cold air just leak out the nearest vent? Summerstuff, what type of inline filter did you use? Brand?, You indicated your engineer said not to connect to cold air return, what was the reasoning? Kam76, Dekeobee, Summerstuff, Hough2012, would any of you do it differently now?

I use a Broan 10" damper with a Vent-a-hood. No issues, and low cost. I run it through a pantry cupboard, and when I turn the VaH on full blast, I can really feel the air come through the open cupboard doors. The only issue is with the Broan exhaust--the louvers stay open. If I was doing it again, I would use a damper on both the intake and exhaust side. That would fix the louver staying open issue.

I have a Broan MUA damper and it works great, opens and closes within seconds of turning the hood on. In the winter it can get a little chilly in the rest of the house but we have a 48" Capital Culinarian that puts out a lot of heat so it evens out eventually. Ours is not hooked up to the HVAC, the outside air just dumps in the basement right under the kitchen.

When I was research MUA, I came across articles that indicated dumping it into the HVAC could potentially damage the HVAC due to the temperature differences between outside and inside air.