That would most likely have been me.  I tried a few different options with
limited success.  The U-Haul Dish Pack stuff worked pretty well (it's been
in there for about ten years now.  I recall trimming it a few times before I
got the seal and feel I was looking for.

BTW, the original foam was soft, compliant, quite friable.  It also was not
two dimensional.  The center was only a couple or three mm thick, but there
was a bead around the edge that was maybe 4-5mm.

Karl Wolz

|-----Original Message-----
|From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]
|On Behalf Of David Beierl
|Sent: Tuesday, December 11, 2012 9:38 AM
|To: vanagon@GERRY.VANAGON.COM
|Subject: Re: Is it open-cell foam if it doesn't say
|closed-cell? (heater flap material)
|
|At 11:21 PM 12/10/2012, Mike South wrote:
|>Synthesizing these comments with what I read in the archive, I think
|>the softer stuff is preferable because you don't want too
|much friction
|>or they will be hard to close.  One message in particular speculated
|>that for the ones that blow down, they are activated by differential
|>force of air flow or something like that, and possibly won't even be
|>able to function with something on there that's too stiff.
|
|All the flaps need soft (compliant) foam.  The free-swinging
|ones IMO don't need any at all; the original stuff was
|extremely thin and may be hard to duplicate.  There is a tiny
|loss of fan efficiency from them not sealing tight, but I did
|not experience any whistling resulting from them not having
|new foam on them.  They do make a slightly louder clack if you
|suddenly turn the fan from off to full, but to me that just
|makes it easier to verify that they're working correctly.
|OTOH to the extent they fail to close properly the fan
|operation will be seriously compromised or rendered null.  The
|other flaps only need seals to stop airflow from their
|respective outlets and to prevent whistling at small openings.
| I think both those functions are important.
|
|The issue with compliance isn't friction but compressibility:
|if the foam is thick the flaps have to compress it near the
|hinges in order to get the outer edge to make contact at all.
|
|Someone mentioned thin closed-cell polyethylene packing foam
|-- I've used that (probably doubled) at least once with good results.
|
|Yours,
|David
|-----
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