Hi All,
As I told Kostas above I did build a new HRV using a heatexchangercore I
ordered readymade. It's the exact one some commercial brands are using
in their commercial HRV's and the specs look impressive, it wasn't too
expensive either.
I didn't take a lot of pictures and they aren't the best quality I am afraid
but they do tell the story nicely.
Bare cabinet with the core in it, playing with dimensions here.
Here I added a roster in the top left to put a filter on, it's 30x40cm (12"x16").
One of the fans will be internal, like this. I also added the holes to connect
the tubing.
My first HRV didn't have a bypass for when it's hot, I had to remove part of
the plates and block the rest, rather clumsy.
In this one i created a bypass inside the cabinet, this is in the 'open'state.
The two pieces of styrofoam on the fan are used to block it.
Like seen in this picture.
This is the finished product, working.
It is a bit larger than my first one but it is 16" less tall so hanging close to
the ceiling there's still a lot more room underneith.
Then I took some temperature readings inside the cabinet:
Code:
FAI OAO OAI FAO Eff IN Eff OUT
T1 T2 T3 T4
18.3 18.6 22.2 21.8 90% 92%
15.2 15.6 20.2 19.8 92% 92%
16.0 16.4 20.1 19.7 90% 90%
(degrees celcius)
One (luxury) problem I have calculating the efficiency is that the
temperatures are so close to eachother. The middle one is recorded in
the morning when it was freezing a few degrees all night. I get my supply-air
from my crawlspace which acts as a 50m^2 (550SQF) geothermal heating
surface. Also the supply-air is heated a bit while travelling through the tube
in my shed.
With supply-air this warm you could debate wether I even need an HRV... /grin.
After turning off the central heating (20,5C in the evening) at 11PM the next
morning it's still 18,5C in the livingroom and the floor doesn't feel cold (I
added extra insulation underneath it last year and the windows stay closed
now so the bottom half of the livingroom stays warm.) Most of the time we
don't turn up the heat untill after noon.
This plastic HX-core is performing very good, which works fine for me. If your
intake-air is very cold though an HX-core this good creates extra challenges.