Quote:
Originally Posted by KKNgroup
Hello!
This was great read. Still I was not able to read all the posts of this thread yet..
I am thinking of making heat recover at my flat (~60 m2/645 ft2)
Still I have only one hole in the wall where I could get air and where I can push air out aprox 0,15 m2 / 1.29 ft2 large. As it is 5 level building, it would not be so easy to drill just another hole in the wall. There would be needed different procedures and special permisions, which costs few hundred euros. 
So I was thinking how about making recuperator which blows out air from flat for some time, heats the inside radiator and then blows air in taking back that from radiator. Therefore there would be only one tube out of the wall and only one tube inside my flat. So I could make fan to change rotation direction. Do You think such a model would be possible? What do You think would be best efficiency, if I could get best timing for in/out air blows? Are there maybe already blueprints for such solution? |
You should be able to push and pull enough air through that size hole for the living space you describe. A typical clothes dryer moves 150 cfm through a 4 inch diameter duct. The hole you describe could move upwards of 1000 cfm before you would start hearing whistling or whooshing noises. Dividing that figure in half gives you 500 cfm of flow each way. This assumes a fairly short duct run to and from the hrv and the hole.
A quick Google search yields an easy formula:
"HRV Capacity in Cubic Feet Per Minute = 0.01(Sq footage of home) + 10(#Bedrooms+1)
Multiply your square footage by 0.01 and add the number of bedrooms in your home plus one times 10.
So, for a 1,700 square foot, three bedroom home:
CPM = 0.01 x 1700 + 10 x (3 + 1)
CPM = 57
The sizing number assumes that the HRV will be running 24 hrs per day."
(robbed from
DIY Heat Recovery Ventilator Project)
So for your size of home, a constantly running hrv would only need to move around 50 cfm to be highly effective. A pair of 4 inch dryer hoses could easily handle this airflow. Beware of over-ventilating, especially if you live in a climate with high humidity.