The cooktop is 36".

The xo hood comes with mesh filters, but baffles are available.

The Zephyr hood is about $850, the MUA they offer is around $200.

The XO hood is $1000, their MUA is $350, and the baffles would be another $150, but then I would have both types of filters and I could alternate.

Your microwave oven's fan may be rated for 300 CFM in free air; I would be surprised if more than 150 CFM were actually realized in practice given the pressure losses.

You can find a lot of messages here by myself and others about the requirements for adequate air flow, and the requirements for adequate MUA. However, the planning time needed far exceeds your schedule. So you can only do something as limiting as your candidate hoods plus some MUA scheme acceptable to the AHJ.

MUA need not be by the same company, but does need the attention of a HVAC person familiar with MUA if you don't have the time to study the subject. In any case, the Zephyr does not come with an integrated MUA, so some MUA planning is necessary, seemingly in too little time. You may be able to adapt something to your house that does not delay the kitchen reno directly. In other words, the MUA need not be introduced into the kitchen via its walls or ceiling if it can get there another way.

kas

So my HVAC guy came out to the house this past Friday. He said that my monday he would have an estimate for me on the MUA. He believes that the MUA should be installed near the furnaces which would mean that it is in the basement. The benefit of this is that I wouldn't be introducing cold NJ winter air into the main living area of my home, nor any unsightly vents (which I guess I could live with the vents, not the cold air rushing into my home.)

The Zephyr says it has hybrid baffle filters, which I guess means that it looks like baffle filters, but has mesh behind it. There is no real explanation as to what a hybrid baffle filter is. My other issue with the Zephyr is that the area of filters is relatively small, there is a lot of border around them. But it is quite a bit less than the xo, especially considering that I would have to buy the baffles separately.

Re the cooktop. The reviews I read have been mostly positive, but I haven't read every review out there. The cooktop was a floor model (that was in a drawer, so nearly never actually touched, and I got it for a steal. Although at this point, since I can't get a decent hood in, it looks like it being underpowered might be a blessing for me. Ugh.

I am hoping that I can talk the township guy into letting us start the other work in the mean time until we iron out the hood situation. My plan is to tell him that i would like to proceed with the makeup air and higher cfm hood, but if we can't work it out, I will go with a 400 cfm hood. And hopefully he will be generous and allow demo and electric and plumbing rough to start in the meantime.

I don't like the sound of the "hybrid" filters. They are after all mesh filters with some kind of cover over them. I'd cross that off the list, now that I understand that they are "hybrid".

Have you checked Kobe? They make two styles of hoods, one has an "oil cup", which I do not recommend, and the other is traditional baffles.

I will have a similar issue and started a similar thread in the home building forum. We will install a 60" 1200cfm hood over our range when we are at that stage in our build. I learnt that anything over 600cfm requires a heated MUA; we will need a 1200cfm MUA with a 20KW heater that will be installed in the mechanical room, feeding heated air (when applicable) directly into the return air duct system. The MUA needs to be connected to and activated by hood fan speed controls, feeding as much air into the home as the hood is exhausting. I'd be most interested in hearing what estimate your HVAC guy comes up with; depending on size, it can get quite expensive.

Hey Pinebaron. The quote for the MUA was $3500, so that I can get a stronger $800 hood. Needless to say, I am going with the 400cfm hood and no MUA. If I have problems with it, I might upgrade to a 600cfm hood when the town is no longer involved.

mayasmommy: $3500 is reasonable if it includes installation; the first HVAC guys estimated $6K for an MUA. Here I selected a new HVAC company for the somewhat complicated HVAC install per my specs, estimated at $50K+, crazy when my builder allocated $28K for a basic system. I will purchase and provide the HVAC company an MUA, rated at 1200cfm with 20KW heater, directly from manufacturer for around $2300; installation and material will likely cost another $1000 hence close to your #3500. I am also considering modifying a 1200cfm hood to run at 400cfm since I have knowledge on how to do that, delaying an MUA installation for a later date if I need more cfm. I have time to think, since HVAC installation is several months away; as yet they installed two plenums for the two HVAC systems and that was less than $800.

Don't you need a 42" hood for a 36" cook top?

Dream - a 42" hood over a 36" cooktop would be an improvement, but is not strictly required. Many people don't want to lose the additional 6" of upper space, or, they have pre-existing cabinetry with a 36" space. Many of the experts feel it's more important to have the depth to the hood so that the front burners are covered. I.e., there are so many hoods that are only 20-21" deep, but 24" is better.

So, in the end, I went with the 36" XO hood over a 36" gas range. I didn't do the MUA because the cost was prohibited at the time. My reasons for going with XO over Zephyr were:

I liked that it projected 24" vs 21" for the Zephyr. I am short, so I mostly use the front burners.

Also, XO offers the same exact hood in a 600cfm version and it would also use the 6" ducts that I have. So, this means that if I did ever have to change it to the stronger one, it would be a lot easier since the cabinets were custom fit to the hood.

Now, it has been almost two years, and I must say at this point, I have no intention of making any changes. I have not had a single issue of the alarm going off while I was cooking/grilling on the stove top. Usually, I don't need the hood at all, but when I grill I use it, and it manages everything without a problem.

Two things come to mind in retrospect:

(a) What is the length of your duct from hood to outside? Or, more simply, is this hood directly vented through a wall to outside, or does the duct take a significant path length to a roof?

(b) Just because the local authority sets a 400 CFM (rated, not actual) limit for MUA, doesn't mean that a sealed house with unsealed gas combustion appliances won't have a combustion back-draft potential, and hence a safety hazard. If your household includes combustion appliances that do not have their own MUA, I would put a carbon monoxide sensor in their vicinity.