Just wanted to bounce this off you. I just got a Dust Collector for my
garage shop. Unfortunately the only place in the garage to fit it is on the
opposite side from where most of my tools are. So i started thinking I
could build a small bump out on the side of my garage to house my DC. then
i could just punch through the wall and shorten my runs. I would also quiet
down the shop some.
My only question is, would it be better to then just vent the bump out to
the outside, or put a filtered return back into the garage? Seems like the
DC probably wouldn't suck that much air out of the garage so it would be a
Hopefully the DC is sucking boatloads of air ( > 600 CFM). I'd say have a
filtered return to the garage.
This is discussed somewhere on this site.
People put DCs in another room and couldn't open the door while the DC was
running because of the pressure difference. Putting a filter in the door
was the solution, IIRC.
Kinda depends on your locale. Mine's outside, but I'm in southern Arizona. In
the summer, I run a swamp cooler that puts out a lot of air, so I'm not sucking
out too much cool air to the desert. Tom
Your DC would not remove much air...
Lets think about that!
Typical two car garage, say 24 x 30 feet, 8 foot ceiling. Just a tad over
8,000 cubic feet of air inside. 1200 CFM dust collector. 8000cuft/1200 cfm 6.67 minutes to change ALL the air in the shop. Not a problem unless you
plan on heating or air conditioning the shop!
I've been sitting on the side lines following this thread. I thought
I would offer the following information to help determine the hourly
cost to heat the air exhausted by a dust collector.
-Dust collector will exhaust approximately 1500 CFM (Based on 2 hp
-Outdoor air temperature is 10 degrees F, indoor air temperature is 70
-However the air is being replaced, i.e., by leakage in structure,
open window, etc. it will be heated to 70 dgrees by some heating
-The average efficiency of a gas fired furnace is 80%
-A direct resistance electric furnace or electric baseboard is 100%
-One CCF of gas contains 100,000 Btu's and cost $.70 (approximately)
-One kWh of electricity contains 3,412 Btu's and cost $.09
The formula to calculate the heat required to raise air temperature
Btuh (Btu's/hour) = CFM x (indoor temp - outdoor temp) X 1.08
1500 cfm X (70 - 10) X 1.08 = 97,200 Btuh (The heat required
to raise 1,500 cfm of makeup air (10 degree outdoor air) to 70
degrees) (The 1.08 constant contains the conversion factors to convert
CFM into Btu's per hour.)
If an 80% efficient gas appliance is used,
97,200 Btuh / (100,000 Btu/CCF X (80%/100)) = 121,500 Btu of gas
will be burned to produce 97,200 btu of heat.
121,500 Btu / 100,000 = 1.21 CCF X $.70/CCF = $.847
$.847 is the hourly cost to replace the heat exhausted from one
hour of operation.
If an 100% efficent electric appliance is used.
97,200 Btuh / 3,412 btu/kWh = 28.48 kWh
28.48 kWh X $.09/kWh = $2.56
$2.56 is the hourly cost to replace the heat exhausted from one
hour of operation.
Hope this helps
If you put in a filtered return, that is a differant story, no heat loss, no
Make is so you can block the return in the summer and just let it blow
outside, it will move some air through the shop if you don't have AC!
I don't think so. I think we're paying more than that in Bedford, VA...with
fuel factors and such, it is 14 cents per KWH, according to the most recent
bill.Some wide variations around the U.S., though, as you can see.
"Take care of the luxuries and the necessities will take care of themselves."
On 15 Jan 2004 16:46:32 GMT, firstname.lastname@example.org (Charlie Self)
Canada is even cheaper. Here in the Yukon, in one of the highest
priced areas in Canada (Only the NWT, Nunavut, and parts of Alberta
are higher), the basic residential rate is 10.5 Canadian cents per
kW-h. Quebec, Manitoba and BC are about 6 cents per kW-h, IIRC.
Note the new email address.
Please adjust your krillfiles (tmAD) accordingly
Replace "nonet" with "yukonomics" for real email address
My last electric bill for Standard Residential service (200A) was US $61.80
898 kwh or $0.0688/kwh.
Hard to say how the power is being produced, could be fossil fuel, nuclear,
Niagra Falls (hydro obviously).
I live in NE Ohio.
Other discussions have indicated that US$0.085/kwh is about average for the
I agree with your numbers, but don't forget to add heat loss of the building
to start with! If it takes 50,000 BTU just to heat your building you will
need to add this to the numbers. Now if you do not have a large enough
furnace to over come the heat loss, its gonna be cold in your shop! Period!
Now all of a sudden you will need a 170,000 BTU gas furnace, or 150,000 BTU
electric to maintain the temps in the building. I doubt few here have that
large of heat source in their shop!
You mention the cost to replace the heated air removed by the dust
collector, sure it is not much, but if the furnace is not large enough, will
not keep up with the heat loss, and you will be cold.
You probably can get by with short bursts of use from your dust collector,
but with long usage you better wear your thermal underwear!
This is all easy to test. Just stick your dust collector out the door with a
hose to the inside, and run it for a while, then decide which way you want
Or as was mentioned in the archives: If you use fossil fuels for your
water heater or furnace (I have natural gas in my garage), you would
end up pulling the exhaust fumes into the garage because of the
negative pressure. Not a good idea, so filtering it back into the
garage in that scenario would be a must.
I had no idea this thread would generate so much traffic.
My basic premise for the fact that the DC would not suck that much air out
of the garage is this.
My DC is not like my air cleaner. The air cleaner gets plugged in and
basically runs runs runs
My DC turns on when I use a tool. And turns off when done. Since most
cuts probably take probably less than 45sec, that isn't all that much air.
Am I missing something? Do most people turn on their DC and run it the
entire time they are in the shop?
I start my DC a few seconds before starting the tool and turn it off a few
seconds after turning off the tool. With the electricity in this 1960's
house, turning them on at the same time is likely to trip a breaker -- maybe
even on separate circuits. <g>
When I had a bench saw, I could run the shop vac and the saw on the same
circuit, and it didn't matter which was turned on first. With my 1.5 HP
Griz contractor saw, if the shop vac is turned on and on the same circuit,
pressing the switch on the contractor saw trips the breaker. That's why I
have an extension cord along the ceiling from the laundry room to the shop.
The TS gets its own 15A circuit from the laundry room when the washer is
Gotta rewire this house from the panel up.
It depends on the job at hand. I jointed and planed a pile of boards the
other day. The DC ran for about two hours straight. I will also let it run
if I am doing multiple cuts that require little time in between.
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