On Mar 29, 1:23*pm, wrote:
On Thursday, March 29, 2012 9:35:57 AM UTC-4, Robert Macy wrote:
So question: where is best source of good vent cover?

If you put a weight or a spring on the vent cover, the vent blower will not be able to blow it open.

Vent covers are designed to be blown open when the wind comes from the inside, and blow closed when the wind comes from the outside. No spring or weight necessary.

You're missing my point!

Look at a standard vent cover. When shut, it is vertical, which means
there is absolutely NO force holding it shut. When the fan comes on,
and the flap tilts, then [when you don't want much closing force]
there is closing force creating useless head pressure for the fan!

What I talked about was the OPPOSITE effect. Substantial force keeping
it closed, but when open almost no force trying to shut it.

I did not mention a spring, which if properly installed could be used,
but more likely it would be used in some stupid manner, making it more
difficult to open and keep open. Nor did I mention a weight that
would be like a 'heavy' flap, impeding the fan more, but rather a
cantilevered weight that actually HOLDS the vent flap closed when the
flap is in the vertical position.yet as the flap opens the weight
shifts to almost apply NO force in trying to close the flap. Thus,
you win twice. The flap is held shut until opened. And once opened
there is little force to shut it, so the fan runs steady state with
very little head pressure.

On Mar 29, 11:07*pm, Robert Macy wrote:
On Mar 29, 1:23*pm, wrote:

On Thursday, March 29, 2012 9:35:57 AM UTC-4, Robert Macy wrote:
So question: where is best source of good vent cover?

If you put a weight or a spring on the vent cover, the vent blower will not be able to blow it open.

Vent covers are designed to be blown open when the wind comes from the inside, and blow closed when the wind comes from the outside. No spring or weight necessary.

You're missing my point!

Look at a standard vent cover. When shut, it is vertical, which means
there is absolutely NO force holding it shut. *When the fan comes on,
and the flap tilts, then [when you don't want much closing force]
there is closing force creating useless head pressure for the fan!

What I talked about was the OPPOSITE effect. Substantial force keeping
it closed, but when open almost no force trying to shut it.

I did not mention a spring, which if properly installed could be used,
but more likely it would be used in some stupid manner, making it more
difficult to open and keep open. *Nor did I mention a weight that
would be like a 'heavy' flap, impeding the fan more, but rather a
cantilevered weight that actually HOLDS the vent flap closed when the
flap is in the vertical position.yet as the flap opens the weight
shifts to almost apply NO force in trying to close the flap. *Thus,
you win twice. The flap is held shut until opened. And once opened
there is little force to shut it, so the fan runs steady state with
very little head pressure.

Sounds like you want a very weak magnet-type defvice, the magnet has
just a little force to hold the vent closed, but weak enough that the
blower can overcome the force. Design one and sell it to the world
after you patent it.

On Mar 31, 1:15*pm, "hr(bob) "
wrote:
On Mar 29, 11:07*pm, Robert Macy wrote:





On Mar 29, 1:23*pm, wrote:

On Thursday, March 29, 2012 9:35:57 AM UTC-4, Robert Macy wrote:
So question: where is best source of good vent cover?

If you put a weight or a spring on the vent cover, the vent blower will not be able to blow it open.

Vent covers are designed to be blown open when the wind comes from the inside, and blow closed when the wind comes from the outside. No spring or weight necessary.

You're missing my point!

Look at a standard vent cover. When shut, it is vertical, which means
there is absolutely NO force holding it shut. *When the fan comes on,
and the flap tilts, then [when you don't want much closing force]
there is closing force creating useless head pressure for the fan!

What I talked about was the OPPOSITE effect. Substantial force keeping
it closed, but when open almost no force trying to shut it.

I did not mention a spring, which if properly installed could be used,
but more likely it would be used in some stupid manner, making it more
difficult to open and keep open. *Nor did I mention a weight that
would be like a 'heavy' flap, impeding the fan more, but rather a
cantilevered weight that actually HOLDS the vent flap closed when the
flap is in the vertical position.yet as the flap opens the weight
shifts to almost apply NO force in trying to close the flap. *Thus,
you win twice. The flap is held shut until opened. And once opened
there is little force to shut it, so the fan runs steady state with
very little head pressure.

Sounds like you want a very weak magnet-type defvice, the magnet has
just a little force to hold the vent closed, but weak enough that the
blower can overcome the force. *Design one and sell it to the world
after you patent it.

Clever!

On Apr 1, 7:30*am, Robert Macy wrote:
...snip...
Look at a standard vent cover. When shut, it is vertical, which means
there is absolutely NO force holding it shut. *When the fan comes on,
and the flap tilts, then [when you don't want much closing force]
there is closing force creating useless head pressure for the fan!

What I talked about was the OPPOSITE effect. Substantial force keeping
it closed, but when open almost no force trying to shut it.

I did not mention a spring, which if properly installed could be used,
but more likely it would be used in some stupid manner, making it more
difficult to open and keep open. *Nor did I mention a weight that
would be like a 'heavy' flap, impeding the fan more, but rather a
cantilevered weight that actually HOLDS the vent flap closed when the
flap is in the vertical position.yet as the flap opens the weight
shifts to almost apply NO force in trying to close the flap. *Thus,
you win twice. The flap is held shut until opened. And once opened
there is little force to shut it, so the fan runs steady state with
very little head pressure.

Sounds like you want a very weak magnet-type defvice, the magnet has
just a little force to hold the vent closed, but weak enough that the
blower can overcome the force. *Design one and sell it to the world
after you patent it.

Clever!

Ok, that's two forms. one totally passive using a cantilevered weight.
The other, uses a gravity wedge that absolutely does not allow the
flap to open unless/until a solenoid is powered to lift the wedge up
out of the way of the flap. Thus, power fan, power solenoid.

..
..
..
..
SERIOUSLY. Where do I get a high quality 8 inch vent fan cover for my
stove top vent?

responding to http://www.homeownershub.com/mainten...er-691111-.htm
Kevin Crotty wrote:
Did you every find a cover? My vent cover for my cooktop is rattling and driving me nuts. I may try felt weather striping. Thanks. Kevin
Robert Macy wrote:


On Apr 1, 7:30=A0am, Robert Macy wrote:
i...snip.../i
i Look at a standard vent cover. When shut, it is
vertical, which means/i
i there is absolutely NO force holding it shut. =A0When
the fan comes o=/i
n,
i and the flap tilts, then [when you don't want much
closing force]/i
i there is closing force creating useless head pressure
for the fan!/i
i/i
i What I talked about was the OPPOSITE effect.
Substantial force keepin=/i
g
i it closed, but when open almost no force trying to
shut it./i
i/i
i I did not mention a spring, which if properly
installed could be used=/i
,
i but more likely it would be used in some stupid
manner, making it mor=/i
e
i difficult to open and keep open. =A0Nor did I mention
a weight that/i
i would be like a 'heavy' flap, impeding the fan more,
but rather a/i
i cantilevered weight that actually HOLDS the vent flap
closed when the/i
i flap is in the vertical position.yet as the flap opens
the weight/i
i shifts to almost apply NO force in trying to close the
flap. =A0Thus,/i
i you win twice. The flap is held shut until opened. And
once opened/i
i there is little force to shut it, so the fan runs
steady state with/i
i very little head pressure./i
i/i
i Sounds like you want a very weak magnet-type defvice, the
magnet has/i
i just a little force to hold the vent closed, but weak
enough that the/i
i blower can overcome the force. =A0Design one and sell it to
the world/i
i after you patent it./i
i/i
i Clever!/i

Ok, that's two forms. one totally passive using a cantilevered weight.
The other, uses a gravity wedge that absolutely does not allow the
flap to open unless/until a solenoid is powered to lift the wedge up
out of the way of the flap. Thus, power fan, power solenoid.

.
.
.
.
SERIOUSLY. Where do I get a high quality 8 inch vent fan cover for my
stove top vent?



--

On Oct 14, 8:44*pm, Kevin Crotty
wrote:
responding tohttp://www.homeownershub.com/maintenance/where-to-get-high-quality-ex...Kevin Crotty wrote:

Did you every find a cover? *My vent cover for my cooktop is rattling and driving me nuts. *I may try felt weather striping. *Thanks. Kevin


Here are the ONLY two sources I found
from this URL:
http://www.copperlab.com
Email:
Phone: 651-341-4931
Fax: 651-204-6844
stucco flush vent 8 inch diameter with louvres $270 !!!

EXACT COPY OF Copperlab,!!!!
VentsUSA
St. Paul, MN
tel: 612 293 7083
fax: 651 646 0917

=-=-=
Very easy to work with, I ordered from these people: $180 copper
stainless tube

Thunderbird Wall Vents (800) 658-2473
1148 North Marshall Ave.
El Cajon, CA 92020
Tel: (619) 448-3567
fax: (619) 448-9072
http://www.thunderbirdproducts.com

They cut the tube length from 8 inch down to around 6 3/4 inch with no
additional charge

The item was heavy. Went right in and absolutely disappears on the
wall.

Looks great.


Our stove top vent has a builtin spring damper [butterfly flaps] right
at the fan. Then the louvres at the exit point provide a 'double' stop
if you will

All in all, I'm very disappointed in the design of damper valves. They
are completely wrong. There is NO real positive pressure to keep them
closed. As the vent opens there is more and more resistance to the
vanes opening, which impedes air flow. The vent should be designed so
that there is positive pressure to keep it closed, but once it starts
to open there should be less and less impediment to the vanes opening.

Two ways to do it. One uses gravity and the other uses better spring
locations.