I wouldn't expect anything but the best conceptualization as well as installation work from you, kas. Thank you for sharing the specific details of your heated MUA construction and implementation. I'm wondering if you might wish to share this for publication on http://www.greenbuildingadvisor.com, as so many of their readers as well as Martin Holladay would find this very helpful given the engineering complexity of residential heated MUA and green building of homes.

My own Broan Universal Make-Up Air Damper installation project was much simpler: a hole cut through side of house exterior brick with 8" round rigid ducts connecting to our main HVAC return. A Braun MUA unit on the return connects via 24V wiring to our Wolf vent hood (900 cfm) such that when it is turned on, the Broan damper is opened to pull air into the return and distributed through the house. Exhaust from the Wolf vent hood is to roof exterior, driven by a compatible Wolf exhaust fan. I haven't had any kinks in two years, minus recent fixing of a small opening in the exterior MUA duct. The MUA duct are in a conditioned crawl space in which I have installed lighting, as well as easy access, so as to keep an eye on the system. I also have a remote hydrometer in the crawl MUA duct area and check every so often on consistency of humidity/dew point (this is how, I believe, I picked up there was a small exterior MUA rigid duct separation and went and closed it). As to the metal screening over the exterior intake duct hole, I check that every couple of months by visual inspection and it is fine without holes and firmly attached. And there is draw. No filter further down the line so not to mess with the airflow dynamics. All in all, while tempered MUA is preferable, I feel I did well working with my permit office, with Broan and my kitchen GC to get a substantial 900 CFM MUA system installed. Btw, thank you, kas, for all the knowledge you have offered us. I have enjoyed reading every morsel and am glad to see this post.

So when the hood is running, the air flow direction in the HVAC return is (potentially) reversed by the MUA flow and air flows out of the HVAC return registers? (This is a clarification question, not a thinly disguised criticism; the likely distribution of return registers through the house should greatly minimize any cross drafts near the hood. Not knowing what the air flow rate of the furnace is, net direction of flow when the furnace is running is unclear.)

Before considering any publication, completion and testing are required. In particular, the purported ability of the Fuji computer module to self-optimize its PID parameters (where the complex-plane poles and zeros of its transfer function are located) is yet to be demonstrated, at least in the context of my application.

kas

OMG. you are so hard core. I only understood about a tenth of that.

Don't need the info, but it somehow makes my day to know it is out there and that someone understands it.

kas: I had my CS prof spouse review your post and he said it was "beyond my abilities to comprehend"! Wow.

We will be needing MUA in the kitchen, but before that, I need to pick an external blower with continuously variable speed for max 600 cfm (36" induction cooktop). Could you please suggest best options or point me in some direction? Thanks very much!

Continuously variable external blowers are available from Broan/NuTone, Wolf (probably a spec'd Broan), abbaka, Prestige, Fantech, and others. A global search on "kitchen hood roof blower" or similar phrases will yield many options. What you want to select will depend on what your roof is like, your preference for efficiency vs. low visibility, and how the fan curve versus the pressure losses in your system yields the desired air flow.

Noise could also be a factor. In this case, large and slow beats small and fast.

You need to ensure that the control on the hood is compatible with the fan. For those not wanting a research project, this requirement is most easily met by choosing a roof blower that the hood manufacturer has selected for use with the hood. (See the Wolf design guide for an example of designating blowers compatible with hoods.)

In general, I do not recommend particular products unless I have used them.

kas

kas: Thanks very much -- VERY helpful "laundry list" of points to consider. Much appreciated!