Replies

1. 
   mike_guertin | May 16, 2004 11:58pm | #1

   I've installed both Fantech FR and Panasonic fans for spot and whole house purposes.  I usually select one or the other based on location / function / customer preference.....

   I'm never concerned about the Panasonic box being "buried in the insulation."  The motor and fan are accessable from the interior just by dropping the trim.  This makes 'maintenance' (which I've never been called back for on dozens of installs) simple.  The key is to seal the exhaust duct well to the housing and the housing to the drywall.  The duct can go right through the roof - just create a long sweep in the duct rather than a sharp 90 deg.  Look in FHB 157 for an article on my typical installation.

   I have a FR fan venting two baths in my house (and on several projects).  Just use a short piece of flex duct between the exhaust port and the fan to isolate noise.  Fantech doesn't list the sones because the noise is directly related to the duct installation so no two are alike.  There are a few tricks to ducting too.  First - always install a good gasketed butterfly style backdraft damper right at the ceiling level or just inside the attic - otherwise you'll get drafts.  Use a sideways 'S' in the duct run to create a thermal 'trap' to minimize the the stack effect drawing air out the duct when you don't want it.  This isn't necessary but some installers swear by it.  Use the rubber washers that come with the hanger and even go so far as to use a piece of foam or innertube to isolate the mounting bracket and screws from the truss web or other mounting support - I had one case where the slight hum of the fan transmitted through the roof framing to the ceiling and was noticable - not objectionable, just apparant to the owners.

   MG

1. 
   Taylor | May 17, 2004 06:43pm | #4

   Thanks that's more information than I could have expected.

2. 
   Taylor | Jun 08, 2004 01:10am | #11

   Sorry to bring up old business, I had a question about this (re installing a Fantech inline fan):

   > Use a sideways 'S' in the duct run to create a thermal 'trap' to

   > minimize the the stack effect drawing air out the duct when you

   > don't want it. This isn't necessary but some installers swear by it.

   I appreciate the purpose, but it seems to me there is a danger of condensation collecting in the valleys of the S and (a) increasing the friction on the air flow and (b) eventually leading to mold in the duct. It also seems unnecessary if one has a damper. I'm just curious if I've missed something here. I appreciate that you said you considered it unnecessary yourself.

1. 
   mike_guertin | Jun 10, 2004 07:24pm | #16

   Yup, could get condensation.  But hopefully the flow of air will dry it out.  Yup, could get mold.  But I'm not afraid of mold 'outside' the house.  Actually, I have mold in my house but my house cleaner keeps it under control.....

   Yup, a little redundent with backdraft damper.

   I've been in loads of attics on remodels where there are those slinky exhaust hoses with slinks and kinks and low spots.....  And miraculously I've never seen puddles of condensation or mold.  Who knows.  We guess about so much in this business.  And even when we follow building code and 'common sense' we still end up with problems....

   MG

1. 
   Taylor | Jun 12, 2004 02:23pm | #17

   Is there a way of finding out how much a backdraft damper contributes to static pressure? Looking at a default configuration of backdraft dampers in roof cap and ceiling vent, and perhaps a backdraft damper in the fan itself, one starts to wonder how the air ever gets out of there.... Tamarack makes a cape backdraft damper that is not as tight as butterfly but also quieter and not as much SP, perhaps that belongs at the vent, but I don't know what the numbers are....

   Thinking about the S, I guess backdraft dampers will only help with summer stack effect, they will not stop (though perhaps slow) stack effect upwards in winter.

   Edit: To answer my own question, I found this information at Tamarack's web site: http://www.tamtech.com/cape_damper.htm#test

   Edit: Now I'm wondering if backdraft damper on roof cap is a good idea, especially if it's a steel cap with alum damper. Aluminium has twice the thermal expansion rate of steel. Tamarack reports finding butterfly dampers stuck closed due to expansion in heat. I give up. What is a good backdraft damper? What is a good roof cap?

   Edited 6/12/2004 4:02 pm ET by Taylor

1. 
   mike_guertin | Jul 12, 2004 03:04pm | #18

   Sorry for delay - been on a 5 week trip with no connection.

   Trying to sort out the embeded questions you present.

   I always put the backdraft damper at the closest level to the ceiling rather than at the roofline - reason: duct gets cold (even when insulated) in attic, warm air rises into cold duct and condenses; mositure drips back down into house.  Only had this happen once.  Also, even if you don't have the condensation problem, the air chills within the duct and 'falls' back into house so client thinks there's an air leak in duct - and they don't like the cool draft in winter.

   Static pressure.  Uh - I took a whole day course 10 years ago to learn just how to install HVAC stuff.  Primary focus was HRV/ERV and ventilation fans for whole house installations.  Bill Rock Smith (he's written for FHB and JLC several times).  After doing loads of sample calculations and looking at examples of installations it became evident that as long as you don't go hog-wild with elbows or extended flex duct runs, you can get away with just about anything and not run into a problem loosing fan capacity.

   After installations, If I'm concerned there's low-flow I use the garbage bag trick.  Grab a bag and calculate the volume in Cubic feet.  Hold it over the end of the discharge pipe -just before you connect it to the roof vent - With the fan running and bag deflated, time how long it takes to fill (seconds count here so don't be sloppy).  Convert seconds to minutes figure in  bag  volume and you have CFM output.  Not precise but it gives you a handle on how well the system's preforming. 

   Alternatively you can make a rim for a bag - fill the bag with air and hold the rim to the ceiling over the fan hole to see how long it takes to empty air out of the bag - same result.

   MG

2. 
   timkline | May 17, 2004 05:01am | #2

   Never used the Panasonic, but have used a lot of Fantechs.  I have never been able to hear the motor, only the air rushing through the ceiling mounted diffusers. 

   Love 'em.......

   carpenter in transition

3. 
   JDRHI | May 17, 2004 04:28pm | #3

   OK....I followed you just fine till I got to:

   "Given that I plan to use this fan also for whole-house ventilation...."

   What exactly do you mean by this? Are you planned on using a bathroom fan to exhaust your entire house or are you planing on buying a "whole house" fan by one of the manufacturers in question?

   J. D. Reynolds

   Home Improvements

   "DO IT RIGHT, DO IT ONCE"

1. 
   Taylor | May 17, 2004 06:46pm | #5

   I've discussed this before...I always get treated like a Martian when I do but whatever....I plan to seal up the air leaks in the attic, all that exhalation then needs to go somewhere when the windows are closed, vent out the bathroom as low-CFM background ventilation....intake won't be a problem, this is a 75-year old house, though I will have to take care to seal up the air leaks in the crawlspace and other unpleasant places....cheap alternative to whole-house ventilation....

1. 
   JDRHI | May 17, 2004 09:32pm | #6

   Well then, all I can say is, good luck....you will certainly need it.

   I suppose this thread answers an age old question...is there any length too great that some folks are willing to go in order not to do something in the proper manner?

   Apparently not.J. D. Reynolds

   Home Improvements

   "DO IT RIGHT, DO IT ONCE"

1. 
   Taylor | May 17, 2004 10:46pm | #7

   That was uncalled for....if you're referring to ventilation, I took this idea from the Taunton insulation book....I would say I'm going to great lengths to do things right (ventilate etc)...I've been advised against sealing up the envelope because "the house needs to breathe" and other such idiocies....

2. 
   Sphere | May 17, 2004 11:06pm | #8

   LOL..Bad Jaybird, Bad.

   View Image

   Spheramid Enterprises Architectural Woodworks

   Repairs, Remodeling, Restorations. 

4. 
   10D | May 18, 2004 01:55am | #9

    ". . .choice of bathroom fan. We are oscillating. . ."

   I know you probably didn't intend this, but it made me laugh.

   I am planning on having a Panasonic Whisper Fit fan installed in my bathroom, it has great reviews.  Any further comments on the "whole house fan" idea would be appreciated, too - I am wondering if it is necessary to install one in my badlly finished c. 1960s-70s attic/second floor of  my 90 year old frame bungalow.  

   10D

1. 
   Taylor | May 18, 2004 03:19am | #10

   It's the way I tell 'em.

   Edit: See message 42823.1 and the thread it started for whole-house ventilation.

   Edited 5/17/2004 8:30 pm ET by Taylor

5. 
   Virginbuild | Jun 08, 2004 05:43am | #12

   Hi Taylor

   I opted for the Panasonic fan It was really quiet. I looked at the Fantech fans and I could not find anywhere in the installation material anything about electronic dampers for each bathroom inlet. this is what I would expect for a whole house vent fan for more than one bathroom. Common sense thought, just why would I want bathrooms b and c to have vent suction when I am only using bathroom a. In the south it puts an extra load on the house AC system and in the north it puts extra dollars up the vent to heat the outdoors. If I marketed a fan like Fantech it would have variable speed controls and electronic dampers at each bathroom inlet all controlled by an onboard computer chip. Anything else is dumb for a company to market.

1. 
   Taylor | Jun 08, 2004 09:43am | #13

   Yes, Panasonic looks great, my consideration of Fantech is strictly aesthetic. That little 4" duct will be less obtrusive to the bathroom decor than a bathroom fan cowling. And I'll be using the smallest FR fan to vent a single bathroom, with a backdraft damper over the exhaust vent etc. I think Fantech does have variable speed controls, but your point about absence of electronic dampers is well taken. Well think of it as whole house ventilation :-)

2. 
   billyg | Jun 09, 2004 08:30pm | #14

   I have a Fantech fan venting two bathrooms.  I looked at electronic dampers for each bath and the controls, but I decided it was stupid to spend all that money for something that may break only to save a small airflow for perhaps 30 minutes per day.  Theoretically it would be nice but practically I didn't think it was worth it.

   These were the electronic dampers I looked at:

   http://www.smarthome.com/3080.HTML

   http://www.smarthome.com/307106.HTML

    

   The Panasonic fans are a nice option though.

   Billy

   Edited 6/9/2004 1:34 pm ET by Billy

   Edited 6/9/2004 2:41 pm ET by Billy

1. 
   Virginbuild | Jun 10, 2004 05:10am | #15

   Hi Billy,

   Thanks for the "Smarthome" hot link. Like they say "different ships, different long splices".

   I guess that if only one or two bathrooms are involved it is hard to see the advantage of electronic dampers in the system. The factors of how much volume the fan will pull per unit of time, and cost to heating the replaced air will vary for region along with seasonal temperature differences between interior and exterior environments.

   Then one has to consider that the sum of each "little" wasteful giveaway, especially in a larger house is synergistic to considerable waste and costs.

   One thing good about this forum is that with differing views and facts it helps others bite the bullet and make informed decisions with their biggest investment.

   Thanks for sharing,

   Virginbuild