Using attic heat for the house

[Daox]

Here are the said updates. I added an additional fan to the base, as well as attaching a heatsink to the SSR. It used to get pretty warm.

I got it installed yesterday. The attic got up to the upper 70s, and the fans turned on once. Then, as the sun was going down, the fans turned off... once. That is exactly how I'd like it to function, so I'm thinking things are pretty much done with this project now.


Here is the unit with the additional fan.

[Daox]

I plugged in the attic fan the other day since we had a week of highs in the 60s. It did its job, but I noticed it wasn't blowing as hard. So, I grabbed the unit, brought it down and sure enough, one fan was barely spinning and the other wasn't at all. I lubed up the motors with some silicon spray and they went as expected after being powered up.





My one complaint about this thing is it could be quieter. The fans I've always had are used and worn out. There is some unbalance going on, and they're really just cheap fans. So, there is vibration transmitted to the chimney and thus the entire house framing. When I went to reinstall the unit, I grabbed some adhesive backed foam, and put some around the outside edge. Its not ideal as it is open cell foam, but it did some good in quieting things down.






If the the fans keep dying on me, I'm thinking I'd like to swap out the 3 fans for probably a 6" or 8" inline centrifugal fan like the one below. I can hang it so it doesn't vibrate anything, and use flexible ducting to go to the chimney.

[Xringer]

That "inline centrifugal fan" looks like the type I'm using.
One to bring air down from the attic to the basement stairway and the second fan
lifts cool air off the basement floor and pumps it out to a 'dryer' vent.
I normally don't turn on the basement fan, unless we get over 4 pCi/L on the Radon meter..

Did a test this week on my kid's new home. Basement has 22.0 pCi/L (picocuries per liter), 1 foot above the sump pump hole.
Gonna do some testing on the 1st floor starting today and retest the basement at the same time.
It takes 3 days to get a reading, after resetting the old data.

22.0 pCi/L is worrisome to say the least..

[Daox]

Well, the one fan has already stopped working again... bleh. Not only does it not blow air, but it provides a great way for the air being blow to go out the wrong way.

However, when I lube it up good it spins fine. So, I'm wondering if you guys have any suggestions on a lube that may work better for me? I've used silicon spray thus far, and it just doesn't seem to last.

[Xringer]

My old in-wall 12k unit has small metal tubes plugged into oil-holes that lead to the bearings.
Inside the tubes is a cotton string-like wick, that you add oil to, once a year.
I used to put 20 drops of oil in each tube.. It was a gravity feed system, and it worked..

Which reminds me, I've got to get rid of that boat anchor! And close up that hole-in-the-wall.
Maybe turn it into a heat pump! Use it to make hot water!

[Daox]

The fan kicked on for the first time this year just yesterday. I think its time to bring this to the next step. I just ordered a 6" inline duct fan. This fan blows 440 cfm. The three 4" fans blow 120-150. So, this should be pretty equivalent to the three (only 2 working) fans that I have been using. It is also is an inline fan, so I will be hanging it and this will isolate a lot of vibrations and hopefully quiet things down which will be a great side effect.

This is the fan I got:

[Daox]

Alright, last night I got all of my bits for this project. This new version virtually replaces every part of the system minus the spring loaded damper at the bottom of the chimney.


I started out by making a new top plate to fit on the chimney. This replaces the board that used to hold the fans. Now, it just has a 6" round duct with flange. The flange came with adhesive foam on it plus a few started holes for screws. It worked quite nicely for fixing to the wood board. Not shown, but I also added adhesive backed foam to this plate to help seal it against the top of the chimney.







A few screws gets that attached where the old fan board used to be.





The new fan got mounted a bit farther south in the attic. I think it should be a bit warmer since it gets not only the top of the attic, but also the south side of the house getting hit with sun. It is also mounted up about as high as I could. Even last night working up there you could tell a temperature difference from the bottom of the attic to the top which is only about 5 feet.







I have a new temperature controller as well. I am hoping to simplify this design and only go with a controller in the attic, no temperature sensor to run to the room its blowing into. So, this version uses an attic fan controller with an adjustable temperature control. I still have to lookup the specs on it and double check its accuracy though.





Last night the attic wasn't cold, but it wasn't' warm. I didn't run it too long but so far I love this new setup. First off, its massively quieter. The hanging fan with flexible duct transmits no vibrations to the chimney at all. Downstairs, all you hear is wooshing air, no fan noise at all. Number two, it blows a lot more air than the previous setup. Especially since one fan had stopped working. Interestingly, the two setups pull the same amount of power, ~135W when in use.

[pinballlooking]

Being quiet is a very big plus. Hope this one last for you.

[jeff5may]

For these kinds of projects, I have found the perfect blower motor fan thingy. They're available everyday everywhere for next to nothing. Drum roll please...

Look on your local yard sale marketplace bulletin board and find a clothes dryer with a heating problem. It doesn't matter whether the thing is electric or gas, they use the same ultra durable blower. Depending on brand / design, the blower may be self-contained or have a housing that mounts separately. Either way, it's not a big deal, because the cabinet usually acts as the thing that keeps everything lined up. I bet anyone, given a few days of random hunting, can find one for around 20 bucks or less. For the scavenger types, they litter the dumps and scrap yards everywhere. While you're dropping off all the waste metal, throw one in the empty truck bed. The whole thing might weigh 5 bucks.

The fans and motors in these units are made to live a long life of blowing hot, dusty, linty air through a long lossy pipe. With 15 feet of corrugated or flex hose, they do around 200 to 250 CFM. 4 or 5 hundred CFM is not uncommon with a short smooth run. The only thing I don't like about these things is that they are not variable speed. They have a built-in centrifugal start / run switch, so once they drop below a certain RPM, they switch to start. Not good for longevity.

[Daox]

That does indeed sound like a good blower option. It would be interesting to get some specs and see what kind of CFM they flow.