Author Topic: Whole House Filtered Ventilation  (Read 2878 times)

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Offline WooferHound

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Whole House Filtered Ventilation
« on: April 09, 2012, 11:41:17 pm »
I have been using Whole House ventilation in place of air conditioning ever since I moved out of my parents house in 1976. It works by basically forcing out the heat that normally builds up in the house from electrical appliances and body heat. This is not cooling the house down but it is keeping the Inside temperature from getting any higher than the Outside temperature. I've never been a big user of Air Conditioning because of the high electric bills and I don't care to keep the air inside the house recirculating it. Plus I really don't mind the heat, till it gets over 90 degrees or so. The biggest problem with Blowing the Outside air into the house is the Bugs, Dust, Pollen and Rain.



When I moved into this house in 2004, I built this hood to go over the open window in the utility room. You can see a slot in the side where a filter slides in. There are strips of wood mounted around the opening that the filter lays against, and another set of wood strips around the back of the filter to keep it in place real good. I was planing to put a little door hinged over the slot to keep the filter dry, but we have had heavy windy thunderstorms and the filter stayed dry so, no door for now. I used the same filter Size as the one on my air conditioner unit, so I only need to remember one filter size. It looks like an airgap between the hood and the window frame but it's not, everything sealed up nicely with a tight fit. This takes care of all the problems with the Bugs, Dust, Pollen and Rain.



When I first built this I used a Box Fan in the window. I had Cardboard cut-outs fit around the fan to help seal it off and pull more air in. This is a picture of the old fan, without the cardboard sealing. It was loud, pulled a small amount of air, and used lots of power.



In 2006 I replaced the box fan. The new system is a set of three DC 48volt 20w DC fans that I got for $20 when a local electronics dealer that went out of business recently. There is a 4th fan at the top that is a 120vac 20w fan. For some reason DC fans are extremely more efficient than AC fans, so any vent fans that I use in the future will be operate from DC. This is a double window and the fans are sealed to the Outside window with the 1/4 inch blue plastic sheets that I cut out.



It's all plugged into a thermostat box containing a power relay so the fan will turn off when it cools down outside. The transformer next to the thermostat is powering the 48vdc fans with a rectifier/capacitor circuit mounted onto the fan housing. There is a 4 pin XLR connection for the power. I can disconnect this to close the inside window without mashing the wires or I can easy take the whole unit out and close all the windows for the Winter cold. The switch has 3 positions: On, Off, and Thermostat control.
This thermostat works great in the Spring and Fall when it gets too cold at night to pull in the outside air. I can go to bed at night when it's hot, and the fan will turn off later that night when it gets cold, and of course it will turn on in the morning when it starts warming up. In the Spring & Fall, if the house is running a slightly higher temperature than the outside air, the thermostat will cycle and actually maintain a steady temperature inside.



When I moved in here I rearranged the plants in the back yard so they would grow up and shade the area where the filtered intake hood is. I want to keep that area as cool as possible. I've been watering and fertilizing them to help them grow big and fast. In a few more years those plants should be able to shade an area that is a 10 foot (3meters) radius from the intake.



 I've been using this system for 8 years now and the wife and me love it. We like the fresh air, the LOW electricity bills, and the Clean, almost free, fresh air, automatically controlled, flowing through the house . . .

W o o f -={(
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Offline Wolvenar

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Re: Whole House Filtered Ventilation
« Reply #1 on: April 10, 2012, 12:02:42 am »
Nice planting idea, what are those?

How many watts do the fans pull ?
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline WooferHound

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Re: Whole House Filtered Ventilation
« Reply #2 on: April 10, 2012, 01:56:41 am »
They are Burford Holly, I looked them up last week and they are a type of small tree.
Really pretty in those pictures with the red berries and green leaves.

I put a Kill-a-watt meter on the setup and it pulls 95 watts, about 25 watts less than the Box fan and a LOT more air.
It is a Trilevel house, the Fan unit is in the utility room on the bottom floor and the windows are opened on the top floor.
There is a 4-step stairway that goes up to the second level, all of the forced air must travel up that opening. I can stand in that stairway and feel a significant breeze created by all the air moving.

I also have converted a box fan to run on 12 volts and I have a 12v muffin fan under the computer desk for personal cooling. those items run from my solar power system

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Offline rossw

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Re: Whole House Filtered Ventilation
« Reply #3 on: April 10, 2012, 03:27:21 am »
It is a Trilevel house, the Fan unit is in the utility room on the bottom floor and the windows are opened on the top floor.
There is a 4-step stairway that goes up to the second level, all of the forced air must travel up that opening. I can stand in that stairway and feel a significant breeze created by all the air moving.

We call that a "split-level" here :)

If you have a non-trivial vertical separation from the air inlet at bottom, to outlet at top, you should also get useful chimney (natural convection) currents. I'd be surprised if you can readily feel the air a few 4" muffin fans will move, through a void the size of a stairwell.

I recently got some "in-duct" air fans (I want to move some moist air from an atrium out into a glasshouse area - to both dry the atrium, and humidify the glasshouse) - I got some quite nice 6" axial duct fans. Intended to run on 240V AC, I'm able to reduce their flow rate a bit, and their power consumption quite a lot, with series capacitors. Still playing with optimum values, but around 10uF looks pretty good at the moment.

<RossW> !cap 10 50
<RossBot> 10.0 uF at 50.0 Hz has a capacitive reactance of 318.3 Ohms

They're super quiet, and designed to fit inside a standard 6" duct like a joiner. (I got some at a clearance sale for a few bucks each)

Offline WooferHound

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Re: Whole House Filtered Ventilation
« Reply #4 on: April 10, 2012, 09:30:00 am »
If you have a non-trivial vertical separation from the air inlet at bottom, to outlet at top, you should also get useful chimney (natural convection) currents. I'd be surprised if you can readily feel the air a few 4" muffin fans will move, through a void the size of a stairwell.

These are Not 4 inch muffin Fans. They are 6 inch 48 volt fans that originally were in some kind of Mainframe computer system. They are quite thick and have a mean looking Blade Profile on them.  The metal frame they are mounted to had an interesting slit pattern cut into the metal to make it look better and help prevent stuff from getting into the rotating blades. But I cut all that out and there is a freely open hole for the fans. The top fan is a 7 inch 120vac fan.

The 48v fans are surprisingly powerful, and the 120vac fan at the top is not so much.
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Offline tomw

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Re: Whole House Filtered Ventilation
« Reply #5 on: April 10, 2012, 11:54:32 am »
Woof;

You are probably getting an "enhanced" chimney effect.  I know of a couple houses with a tallish, large diameter, black heavy gage pipe stuck up out of the attic with a T on top to shed weather. They open low windows and the attic entry hatch and that stack heats up and draws air through the whole house with no fans at all. Beats opened windows and a fan it seems. Foliage around the intake is extra good.

Nice set up and whatever works, works!

We run the AC a few times a year but the close in overhanging trees keep us cool most of the time and in summer we live on the screened porch a lot of the time.

Tom
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Offline rossw

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Re: Whole House Filtered Ventilation
« Reply #6 on: April 10, 2012, 05:57:42 pm »
These are Not 4 inch muffin Fans. They are 6 inch 48 volt fans

Ahh, optical illusion. A stack of 6" fans, yes, they can move a decent amount of air. (But I still think there's some degree of natural convection/chimney effect helping you out there)