I'm guessing Advent might be 14 x 14 x 16 (maybe 18), not counting the vestibule.  Probably want around 250 to 300 cfm.

Looks like a BlueAir 311 or Coway Mighty would be appropriate CFM.  Wirecutter likes both, and looks like they rate Coway higher principally on price.
BlueAir might be quieter - I didn't find dB ratings for the Coway.

I'd be in favor of going ahead with the BlueAir 311.  I'm happy to order one and be reimbursed sometime.

On Sat, Nov 13, 2021 at 3:22 PM Cally Perry <cally.perry@gmail.com> wrote:
We’re pretty happy with our ridiculously quiet Blueair filters, recommended
by David Wilson that day the air quality dropped into the red here. There
have since visited multiple venues en masse.

On Fri, Nov 12, 2021 at 6:55 PM John Schreiner <jeschreiner17@gmail.com>
wrote:

> My envelope calculation says 315 m^3/hr can cycle the air 5 times an hour
> in a space 15x15x10. 10’ is probably not the ceiling height in your
> mother’s house, and also not in either tower, but it’s an understandable
> amount.
>
> John
>
> On Friday, November 12, 2021, <lauradi@rcn.com> wrote:
>
> >    What we have in our bedroom and in two rooms in my mother's house is
> > this one
> >
> > https://www.smarterhepa.com/products/smart-health-s
> >
> >   At the lowest level, it's very quiet.  When one looks at the specs, it
> > states that it has a "Clean Air Delivery Rate (CADR) of 315 m3/hr." I
> think
> > for maximum virus protection, this is what one is supposed to have per
> > *minute* not hour, but we're hoping it's better than nothing for viruses
> as
> > well as allergens.
> >
> > Laura Dickerson
> >
> > ----- Original Message -----
> > From: Cally Perry &lt;cally.perry@gmail.com&gt;
> > To: Austin Paul &lt;austinjpaul@gmail.com&gt;
> > Cc: Andrew Tyler via Boston-change-ringers &lt;boston-change-ringers@
> > cosmos.phy.tufts.edu&gt;
> > Sent: Fri, 12 Nov 2021 16:53:25 -0500 (EST)
> > Subject: Re: Annual Meeting
> >
> > As promised, I sorted out where the square dancers got the idea that Hepa
> > filtration was super useful.
> >
> > If you go to the microCovid site  (Google will find it, but this site
> > strips links), and put in an approximate scenario  (indoors, 10 people
> > total, 3 feet apart, talking normally, etc., very approximate, but
> there's
> > no setting for One Person is Yelling at a time) and select the
> Environment
> > menu, one of the dropdowns is "Indoors with a HEPA filter (flow rate 5X
> > room size per hour) [1/4th the risk]
> >
> > I haven't researched the microcovid site, but it does seem as though we
> > might want to pony up for an air filter.
> >
> > Best,
> > Cally
> >
> >
> >
> >
> > On Sun, Oct 24, 2021 at 1:35 PM Austin Paul &lt;austinjpaul@gmail.com
> &gt;
> > wrote:
> >
> > &gt; Hi everyone,
> > &gt;
> > &gt; Our Annual Guild Meeting will be Monday November 8th at 7:30 pm
> > online (in
> > &gt; stead of handbells).
> > &gt;
> > &gt; I will send out a zoom link closer to the time.
> > &gt;
> > &gt;
> > &gt; Best,
> > &gt; Austin
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> --
> John E. Schreiner
> Vice President of Special Projects and Maintenance
> C. B. Fisk, Inc.
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