Mark Furst
  • Fort Atkinson, WI
  • United States
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Mark Furst's Discussions

Bath fan weirdness

Started this discussion. Last reply by Bruce Fillmore Oct 11. 13 Replies

I recently measured disappointing bath fan flows at a project - both being below our program minimum of 50cfm. The builder had the installer come back to have a look and found nothing obvious but he…Continue

Tax Credit and the LTO test

Started this discussion. Last reply by Mark Furst Mar 10. 4 Replies

Anybody else super frustrated by the retroactive implementation of the tax credit?I have 2 big problems with this:1)Most all of the homes I rated last year did not pass the tax credit because I opted…Continue

Tags: test, LTO, Credit, Tax

 

Mark Furst's Page

Latest Activity

Bruce Fillmore replied to Mark Furst's discussion Bath fan weirdness
"In my opinion venting into any soffit is a bad idea, it usually requires a sharp bend to get into the soffit, and reduces insulation value where it crosses the top plate. (significantly)  Better going through the sidewall or box/gable, nice…"
Oct 11
Tray Biasiolli replied to Mark Furst's discussion Bath fan weirdness
"I'd agree with Sean - we get wind effects regularly when measuring ventilation fan intake at the outdoor hood. And there's a notable difference if the capture hood is flush with the wall (eg around foundation wall) or if there are gaps,…"
Oct 11
Charles Buell replied to Mark Furst's discussion Bath fan weirdness
"You would have to test the vent at the inside at a location the same diameter as the outside diameter to get the same CFM reading."
Oct 11
Sam Karpowicz replied to Mark Furst's discussion Bath fan weirdness
"What size is the exhaust vent?  I helped with a project in the past where the exhaust was vented out with 3-4" vent (forget which one).  But it wasn't reaching its stated exhaust flow rate.  The contractor had to come back…"
Oct 9
Sean Lintow Sr replied to Mark Furst's discussion Bath fan weirdness
"I will go back to how did you seal up tight / anything else that could impact the flows (just remember that those nice arrows we draw for flows... well nature has a way of screwing with you - especially with wind)"
Oct 5
Mark Furst replied to Randall Olsen's discussion How to measure room pressures
"Busy days "I have never seen an inside wall that did not leak to the exterior." I have noticed some top plate leakage at a handful of walls in some homes but certainly not enough to make a blanket statement about "all" walls. I…"
Oct 5
Mark Furst replied to Mark Furst's discussion Bath fan weirdness
"I use an Alnor flow hood which I know works both inside and out as I recently measured flows for an ERV installation. "
Oct 5
Brad Cook replied to Mark Furst's discussion Bath fan weirdness
"Maybe it is because at the fan, you are measuring negative pressure and at the soffit it is positive pressure. I am guessing that you are using the Energy Conservatory fan flow hood. Check with TEC about that."
Oct 4
Kent Browning replied to Mark Furst's discussion Bath fan weirdness
"Depends on the insulation. Batt insulation I would not expect much to be drawn in. Cellulose insulation would likely restrict the leakage to where my theory does not work. Blown in fiberglass could draw in some insulation but it might be a very…"
Oct 2
Sean Lintow Sr replied to Mark Furst's discussion Bath fan weirdness
"Was it at all windy - just how did you test / equipment? How did you seal tight on the exterior? I have seen interesting results on ERV's intake, exhausts, etc..."
Oct 1
Mark Furst replied to Randall Olsen's discussion How to measure room pressures
"Leakage, yes, but to where? The interior? These are only run in interior walls (exteriors have to be ducted) and, generally they work just fine unless they have the installation problems I mentioned above. Plus, the contractors are much getting…"
Oct 1
Mark Furst replied to Mark Furst's discussion Bath fan weirdness
"Yes, I should have stated: 6' straight run, all insulated flex insulated duct with tightish bends down to the soffit terminations which did yield a tad more cfm when we pushed up to relax the curve. But my confusion is how does it end up being…"
Oct 1
Mark Furst replied to Mark Furst's discussion Bath fan weirdness
"Reasonable theory, but if that was the case I'd expect to see some insulation (in which the fan is buried) drawn along with that airflow, no?"
Oct 1
Sean Lintow Sr replied to Mark Furst's discussion Bath fan weirdness
"Just to add on to common problems... Short - as in straight, pulled tight with minor bends (assuming flex)? Just what is short - 10', 20'? Most issues I see besides birds nest is hard bends, full 25' worth of material going only…"
Oct 1
Kent Browning replied to Mark Furst's discussion Bath fan weirdness
"I am guessing based on what you posted. I suspect the fan collar to exhaust duct is leaking. If my guess is correct, the fan is acting like an "ejector pump". as the airflow passes the leaking collar it pulls in more air thru the leak.…"
Oct 1
Mark Furst posted a discussion

Bath fan weirdness

I recently measured disappointing bath fan flows at a project - both being below our program minimum of 50cfm. The builder had the installer come back to have a look and found nothing obvious but he did get a couple of new fan motors and swapped them out and also double checked that the damper flap wasn't stuck. There was a slight improvement to both but it was not enough, still both below 50.These fans were routed - with a short run of duct - to soffit terminations which allowed us to look up…See More
Oct 1

Profile Information

Company
Grading Spaces LLC
Role in Home Performance Marketplace
Energy auditor / assessor / analyst
Professional Certification
BPI, HERS Rater, Home Energy Score Qualified Assessor, RESNET
Website URL
http://www.gradingspaces.com

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At 5:34pm on March 12, 2018, Diane Chojnowski said…

Hi Mark,

Welcome to Home Energy Pros Forum. Feel free to join the conversation in the Forum and Groups. And share your energy efficiency photos, videos, and upcoming events. If you're blogging about home performance, this is the place for you!

Thanks!

Diane, HEP Forum Moderator

 
 
 

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