No, not Washington DC fans... Are there any of those?

I'm looking for a fan that I can use to inflate my greenhouse. I can
find AC inflation fans aplenty. Heck, I already have two of them...
But a DC fan would be more efficient, and work well with my backup
greenhouse power. Anybody ever seen something that would work?
Googling is getting me nowhere.

Thanks

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

Rob Halgren wrote:

Check he

http://www.allelectronics.com/

They deal in surplus, you never know what they will have listed.

cheers

On Tue, 07 Dec 2004 18:32:59 -0500, Rob Halgren
wrote:

No, not Washington DC fans... Are there any of those?

I'm looking for a fan that I can use to inflate my greenhouse. I can
find AC inflation fans aplenty. Heck, I already have two of them...
But a DC fan would be more efficient, and work well with my backup
greenhouse power. Anybody ever seen something that would work?
Googling is getting me nowhere.

Thanks

Rob

Try Grainger - www.grainger.com Bet they can fix you up, though you
might have to buy a DC motor and hook it up to a squirrel cage blower.

deg

Anybody ever seen something that would work?
I use old car radiator fans, they're often free :-)
jc


--
http://mysite.wanadoo-members.co.uk/jc_atm/



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Rob Halgren wrote:
No, not Washington DC fans... Are there any of those?

I don't know about fans, but there are plenty of Washington DC units
that blow plenty of air, both hot and cold. I don't think they run on
electricity though, they're very difficult to turn off and they tend to
be high maintenance.


But a DC fan would be more efficient, and work well with my backup
greenhouse power. Anybody ever seen something that would work?
Googling is getting me nowhere.

Have you tried looking in the RV/camping area, or maybe boating?

A couple of random thoughts: I don't know what the capacity of your DC
power source is but keep in mind that a lower voltage appliance draws
proportionately more current than one that runs at higher voltage. (And
apart from the capacity of your DC source, you may need much heavier
gauge wiring than the rest of your existing circuitry.) A 200W fan
that would draw a "mere" 1.5 amps at a nominal 125V would draw 8A+ at
24V and 16A+ at 12V.

Have you tried looking in the RV/camping area, or maybe boating?



No, but I can..

A couple of random thoughts: I don't know what the capacity of your DC
power source is but keep in mind that a lower voltage appliance draws
proportionately more current than one that runs at higher voltage. (And
apart from the capacity of your DC source, you may need much heavier
gauge wiring than the rest of your existing circuitry.) A 200W fan
that would draw a "mere" 1.5 amps at a nominal 125V would draw 8A+ at
24V and 16A+ at 12V.



Actually I'm pretty sure the DC fans are substantially more
efficient in terms of total watts per CFM than AC fans. But I could be
full of BS too (AC/DC BS). And these greenhouse inflating fans aren't
that big anyway. I think my AC blowers draw 34W (actual measured
amount). I am planning to run everything at 24V.

I suspect I could create a inflating fan with a little ingenuity and
off the shelf parts. I wasn't really looking to replace my regular
overhead fans with DC. Those are 150W (3 speed, maybe 50W at low
speed) big old loud cyclone fans. I can find DC equivalents for
those, but far more expensive than just keeping the old ones. If the
power goes out I don't need those to run. I do need the poly inflating
fans to run, if it rains and the plastic isn't inflated my greenhouse
goes squish. Or that is what the greenhouse people told me, something
to do with my big roof vent.

Of course I can always run my AC blowers off of DC power, I have an
inverter for that purpose. Seems a little inefficient though.


Rob


--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

Rob Halgren wrote:
I am
planning to run everything at 24V.

You may have better luck finding DC fans that run best at 48VDC. Most
telco facilities, and many data centers run off of 48V battery power. I
don't think that they generally invert their cooling to 12VAC, and
facilities like this have to move a lot of air around.

--Matt

All AC here so not that much help. I think you need a blower more than a
fan. The blower must be powerful enough to still have flow at some static
pressure, but not so powerful as it will damage the plastic. I use a
Grainger 4C440 for a 30' by 100' greenhouse. It has a 1/125 HP motor and
produces 39 CFM at .4 inches static pressure. You might want to look at
Grainger 4C814.

Pat


"Rob Halgren" wrote in message
...
No, not Washington DC fans... Are there any of those?

I'm looking for a fan that I can use to inflate my greenhouse. I can find
AC inflation fans aplenty. Heck, I already have two of them... But a
DC fan would be more efficient, and work well with my backup greenhouse
power. Anybody ever seen something that would work? Googling is getting
me nowhere.

Thanks

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

Pat Brennan wrote:

All AC here so not that much help. I think you need a blower more than a
fan. The blower must be powerful enough to still have flow at some static
pressure, but not so powerful as it will damage the plastic. I use a
Grainger 4C440 for a 30' by 100' greenhouse. It has a 1/125 HP motor and
produces 39 CFM at .4 inches static pressure. You might want to look at
Grainger 4C814.


Now that is getting me somewhere... Thanks!

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

Pat Brennan wrote:

All AC here so not that much help. I think you need a blower more than a
fan. The blower must be powerful enough to still have flow at some static
pressure, but not so powerful as it will damage the plastic. I use a
Grainger 4C440 for a 30' by 100' greenhouse. It has a 1/125 HP motor and
produces 39 CFM at .4 inches static pressure. You might want to look at
Grainger 4C814.


Now that is getting me somewhere... Thanks!

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

What kind of auxilliary power source puts out 24VDC?
Just curious.


J. Del Col

jadel wrote:

What kind of auxilliary power source puts out 24VDC?
Just curious.


J. Del Col



Just the battery bank. I have a Trace DR1524 (1.5kW @ 24 V) inverter,
that charges the batteries when the power is on. And if the power goes
out the theory is that the inverter draws DC from the batteries and
converts it to AC at the nominal 110V. Of course if I hooked the DC
fans up to the battery bank directly, then I wouldn't have to mess with
the inverter, but my vents and furnace run on AC so I need the inverter
anyway.

The DR1524 is old technology, but sufficient to my purposes. Wouldn't
work for sensitive electronics, it doesn't put out clean enough AC power
for that. Would need a more expensive inverter for that. You can get
inverters that run off 48V too, at more expense.

Now this is mostly theory. My inverter came in today. I'm hoping to
hook that up next week.

Rob

--
Rob's Rules: http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
LittlefrogFarm is open - e-mail me for a list )

I know a couple of guys back in Albuquerque that ran their
emergency backups off of national labs surplus. For example, big honkin'
power supplies designed to keep mainframes running for a few minutes
eventually become outdated and replaced- and surplused. If you ever want
to see some real lab surplus, Albuquerque is the place to be.

Albuquerque is also the place to be if you want to suffer heavy
plant losses if the power goes out in, say, August. Here in the Phoenix
suburbs, it's much worse, but the power is more stable- excepting the
occasion massive transformer fire at an APS substation, of course.

Anyway- buying big, old emergency backup supplies, swapping out
the lead/acid batteries (which are recycled) and putting in new ones
solves a sticky problem in a very short period of time. The nice thing is
that the capacity of your battery bank is limited only to the size of your
wallet. Provided one does not exceed the power limits of the backup in
terms of amps, you can put pretty much as many deep cycle or marine
batteries in parallel as you wish- and even that is a function of demand
(fans, blowers, pumps, etc.), rather than supply (12 VDC cells). You just
have to remember to wrap the handles of your long tools in electrical tape
when working in the ol' battery box.

Companies are now selling evaporative coolers and fans that run on
solar power, which makes them darned near uninterruptable here in the
desert, so long as the sun is high in the sky- and, for evap coolers, the
water line is intact.

I've also seen some clever "failsafe" systems- one in which a
solenoid opens when the power goes out, and a large gravity-fed tank of
water is allowed to spray through open jets through the greenhouse,
keeping the temperature low enough that the paging system can contact the
owner. It would be interesting to use a similar principle to cut loose a
spool of shade cloth from the crest of the greenhouse so that it unfurls
down the side of the glass to shade the plants.

I'm sure Rube Goldberg would be proud.

The address in the header isn't valid. Send no email there.

Cheers,

-AJHicks
Chandler, AZ

I know a couple of guys back in Albuquerque that ran their
emergency backups off of national labs surplus. For example, big honkin'
power supplies designed to keep mainframes running for a few minutes
eventually become outdated and replaced- and surplused. If you ever want
to see some real lab surplus, Albuquerque is the place to be.

Albuquerque is also the place to be if you want to suffer heavy
plant losses if the power goes out in, say, August. Here in the Phoenix
suburbs, it's much worse, but the power is more stable- excepting the
occasion massive transformer fire at an APS substation, of course.

Anyway- buying big, old emergency backup supplies, swapping out
the lead/acid batteries (which are recycled) and putting in new ones
solves a sticky problem in a very short period of time. The nice thing is
that the capacity of your battery bank is limited only to the size of your
wallet. Provided one does not exceed the power limits of the backup in
terms of amps, you can put pretty much as many deep cycle or marine
batteries in parallel as you wish- and even that is a function of demand
(fans, blowers, pumps, etc.), rather than supply (12 VDC cells). You just
have to remember to wrap the handles of your long tools in electrical tape
when working in the ol' battery box.

Companies are now selling evaporative coolers and fans that run on
solar power, which makes them darned near uninterruptable here in the
desert, so long as the sun is high in the sky- and, for evap coolers, the
water line is intact.

I've also seen some clever "failsafe" systems- one in which a
solenoid opens when the power goes out, and a large gravity-fed tank of
water is allowed to spray through open jets through the greenhouse,
keeping the temperature low enough that the paging system can contact the
owner. It would be interesting to use a similar principle to cut loose a
spool of shade cloth from the crest of the greenhouse so that it unfurls
down the side of the glass to shade the plants.

I'm sure Rube Goldberg would be proud.

The address in the header isn't valid. Send no email there.

Cheers,

-AJHicks
Chandler, AZ