DIY ventilation heat exchanger

[diyEthic]

@ Drake:
I like the long tube-in-tube contraflow idea, I've thought of doing something similar. How do you plan to suspend the 4" intake tube inside the 6" exhaust?

[Drake]

I have a very coarse rubber coated fiber material that is about 1" thick that is 90% open to air flow that i can cut into rings. Outer tube air will have to pass thru it. I salvaged it from a dumpster.

[ham789]

Haven't seen much going on here lately.

Garage sales have been good to me.

I picked up a Holmes HAWF3030T window fan.
Dual Centrifugal blowers on one shaft and one can be mechanically reversed to blow out.
Perfect for a new semi-permanent HRV.
Thinking about building a bigger coroplast unit, counterflow, maybe a foot square
and 4 feet long, but haven't been
able to figure out how to support it mechanically without it
sticking out 5 feet from the house or having two right-angle bends
in the air path. One option is to stand the fan on its end, but I'm
concerned about the reliability of the bearings in that configuration.
It's always something.

Oh well, a project for cooler weather.

Also picked up a Dylos DC1100 air particle counter with computer
interface. Should be able to evaluate air filters for next pollen season.

[Fornax]

Hi All,

I started reading this thread a few months ago. I came across this while googling for a DIY HRV. There is a lot of information in this thread and even more in all the external links provided over time.

I took some time to think things over for my situation and look around for parts to use.
The ideas condensed, I found my parts, today I ordered sheets of aluminum (Or aluminium as we call it over here) so the building will start next week.

Since this is my 2nd post I'll need a few more posts before I can post pictures, so I'll spread more information over several posts.

Fornax

[Daox]

That sounds great Fornax. We look forward to seeing your build. I'd recommend starting a new thread about the HRV build. This is already a pretty big thread and it'll get buried eventually.

[AC_Hacker]

Originally Posted by Fornax

Hi All,

I started reading this thread a few months ago. I came across this while googling for a DIY HRV. There is a lot of information in this thread and even more in all the external links provided over time.

Good to have a new voice!

There is a post you should also look at that contains these pages:

Page #1...

Page #2...

Page #3...

Page #4...

In this post, many of the coroplast issues have been worked out, and also 'dwell time' of the exchanging surfaces has been thought out.

Regarding posting to a different thread, I have a different opinion from Daox, in that I believe that most people come across these threads via Google, just as you did, and I think the information on a topic should stay in one thread, even if it becomes unwieldy.

In fact, the information I am leaving for you in this post came from an 'unrelated' EcoRenovator post on clothes dryer heat recovery. Now I ask you, who would have known?

Best of luck with your new project... we all need a breath of fresh air.

Best,

-AC_Hacker

[kostas]

Hello guys,

I'm following this interesting thread for quite a time now.
Back here in Italy we are also aware about the in-house air quality, so i tried to give it a try on my own.
You can see my work-in-process project here:

cercaenergia.forumcommunity.net/?t=52867443

Sorry, only in Italian for now, if you wish to have some specific info about it I'll be glad to share

[Mikesolar]

Why all these spacers between layers of coroplast.......when it can just be turned 90deg. With enough plates the efficiency will be high enough.

this is more interesting though.......It is the LUNOS from Germany. 2 are used per area, one pulls air in for 70sec and the other does the opposite. Exhaust heat is stored in a ceramic or PCM core, then the cycle is reversed. No ductwork needed, just a central controller.

[Daox]

Originally Posted by Mikesolar

Why all these spacers between layers of coroplast.......when it can just be turned 90deg. With enough plates the efficiency will be high enough.

Less material between the hot/cold side will promote faster heat transfer. This allows less material to be used and a cheaper and just as useful product.

[Fornax]

Daox, I'll continue posting about my project in this thread. I agree with AC_Hacker that regulars of this site can find it and others using Google can, erm, find it. Also we can easily refer to post #xxx in this thread when needed.

for example, one of the more usefull links for me was the one AC-Hacker posted in post #60, 2.5 years ago (www.fahrenergy.co.uk/FAHR_Installation.pdf).
- Short ducts are good.
- a small HRV covering a part of your house is good, use more if needed to cover other areas.
- A good way to beat radon is ventilation.
- and more

I'll build an HRV that basicaly only covers our groundfloor. I'll connect it to the existing ducting to draw air from the toilet and bathroom but heated fresh air will only be blown into the livingroom.

So FAI will be 100% in the livingroom. OAO will be roughly 80% from the kitchen and the other 20% from the toilet and bathroom.
The exhaust hood above the furnace will be stripped of it's motor etc., exhaust will go via the HRV (yes, with some extra filtering).

Where other houses in my street have a shed in front of the house I have the shed in an odd triangel shape next to my livingroom and kitchen. I can have the HRV in there, out of the way, and connect it with 2 short ducts with 2 relatively simple holes to the kitchen and living. In the kitchen a small duct of about 4m (13') will connect it to the existing ducting to both the toilet and bathroom.

In the lowest setting it will move about 50-75 cubic meters per hour, ACH in the livingroom will be roughly 0.6 which is quite high.