Using attic heat for the house

[Daox]

I am currently testing the new controller. I'm not sure how its working out so far. The fan has only kicked on twice. The first time it worked nearly perfectly. It kicked on at 80F attic temp, and off around 74F. However, the second time it kicked on at 76F, and off at some unknown temperature above 73F. I need some more cycles to make sure, but it seems to be a bit on the inconsistent side.

[jeff5may]

Your thermostat looks like the type I had in the greenhouse in the past. They're super reliable, but not so precise. Mine used to drift around 5 degrees total, depending on it's mood. It outlasted the fan it controlled and the next one that took it's place.

The can fan you're using is awesome! They move a ton of air and are very unimposing. Might be too much for the attic though.

[Daox]

Thanks. The new fan is really nice. On top of being so much quieter, it really does blow a LOT more air. We have yet to really get a good day for it sun and temperature wise, but we'll see how long it stays going a bit later in the season.

I also ordered a new digital controller. I didn't like the bimetal one. I would like something more accurate to better take advantage of the available heat.

[Daox]

Here are some pictures of the new digital controller I am using. It has been working very well so far.

[Daox]

Time for another update. I noticed some real bad sag early in the season. So, I went to feel it and the vent line was actually full of water. I can only imagine this was from condensation. Fast forward to today and I went up in the attic to drain the water out. However, the attic fan has run numerous times since then and the water was already gone. It was a fair amount of water too. In any case, I shortened up the vent line so that there isn't nearly as much sag.

Before:



After:




I also had printed up a fan guard to go on the front to avoid any possibility of putting your hand into the fan. After a year of use it does have some dust build up, but really not that bad at all.





That all being said I am still absolutely loving the new attic fan design. The new setup moves so much more air, and its so much quieter than it was before. I'm very glad I updated the setup.

I also have one more update that is pretty slick and I'll add that when I get a minute.

[solarhotairpanels]

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.

Best idea yet... for sure.
Been reading about your project all morning here 1/3/21

Great project and updates along the way.

I use 6 inch duct work booster fans and 6 inch insulated flexible duct hose on a couple of hot air collectors I have installed which work out fantastic.

Couple of things..
You mentioned water inside the hose.. condensation
Would insulated ductwork similar to A/C ductwork eliminate the condensation rather then the hose you are currently using? Just a thought.

Next, why not run the insulated hose all the way down the chimney to the kitchen?

Right now air is being pushed down the chimney and could be blowing past your kitchen opening bouncing around inside your chimney before finding it's way to your kitchen.

Next, Backdraft dampers
I tried the dampers you purchased but found that too much cold air was getting by the litthe openings. I ended up building 2 of my own using collapsable cloth when fan off.

The cloth blocks the entire opening once the fan shuts off.

Next, can you fill me and others in?
How's your attic to kitchen forced hot air thermostatically controlled heating system doing?
Are you happy where you are with the system as of today?

again, just my tid bits on your great project! :-}

[solarhotairpanels]

Just wondering... maybe someone has tried this before and if so chime in with your results please.

What about a cold air trap rather then relying on the dampers to totally stop cold air from dropping back down in to your kitchen?

Cold air trap meaning...
Could you arrange / refasten that hose in the attic so intake end remains where it is but then have the hose drop down from your attic ceiling about 4 ft. then turns and goes back up to the attic ceiling before continuing down your chimney to the kitchen outlet.

Hot air rises / cold air drops right? so if the cold air gets trapped in the hose because of the loop in the hose / when the fan is OFF / would it stop the cold air from dropping down into the kitchen?

If this hose was insulated from the intake end of the hose in the attic all the way down the chimney to kitchen outlet I think that might work pretty good to stop cold night time attic air from penetrating the hose.

just some thoughts

[Daox]

Originally Posted by solarhotairpanels

Best idea yet... for sure.
Been reading about your project all morning here 1/3/21

Great project and updates along the way.

Thanks. Its been a fun thing to tinker on over the years.

I use 6 inch duct work booster fans and 6 inch insulated flexible duct hose on a couple of hot air collectors I have installed which work out fantastic.

That is a good setup if you have a closed loop system (like a solar hot air panel). If you need any pressure, a centrifugal fan will do a lot better at pushing air into the house.

Couple of things..
You mentioned water inside the hose.. condensation
Would insulated ductwork similar to A/C ductwork eliminate the condensation rather then the hose you are currently using? Just a thought.

I'm sure it would help some, but not totally eliminate it. Warm air is still going to get inside the duct and the temperature swing of the attic is fairly large. A bit of insulation around the ducting will help reduce the temperature swing, but without any thermal mass it'll still vary in temperature quite a lot. If you are in a milder climate, this might help eliminate the problem completely though.

Next, why not run the insulated hose all the way down the chimney to the kitchen?

Right now air is being pushed down the chimney and could be blowing past your kitchen opening bouncing around inside your chimney before finding it's way to your kitchen.

I'm fine with it warming up the chimney brick as that'll radiate into the house eventually. Running the hose down to the opening would be a pain in the butt for me as access is quite limited.

Next, Backdraft dampers
I tried the dampers you purchased but found that too much cold air was getting by the litthe openings. I ended up building 2 of my own using collapsable cloth when fan off.

The cloth blocks the entire opening once the fan shuts off.

That's very cool. I'd love to see pictures of your setup.

Next, can you fill me and others in?
How's your attic to kitchen forced hot air thermostatically controlled heating system doing?
Are you happy where you are with the system as of today?

Of course. The system is working great. I'm very happy with it. If I had to think of what I'd like to do next it would be add additional ducting and possibly get an even larger fan to scavenge even more heat.

What about a cold air trap rather then relying on the dampers to totally stop cold air from dropping back down in to your kitchen?

Cold air trap meaning...
Could you arrange / refasten that hose in the attic so intake end remains where it is but then have the hose drop down from your attic ceiling about 4 ft. then turns and goes back up to the attic ceiling before continuing down your chimney to the kitchen outlet.

Hot air rises / cold air drops right? so if the cold air gets trapped in the hose because of the loop in the hose / when the fan is OFF / would it stop the cold air from dropping down into the kitchen?

If this hose was insulated from the intake end of the hose in the attic all the way down the chimney to kitchen outlet I think that might work pretty good to stop cold night time attic air from penetrating the hose.

I don't see any reason why that wouldn't work. You would probably want a way to drain it as I imagine condensation would be an issue in the trap though.

[solarhotairpanels]

Originally Posted by Daox

That's very cool. I'd love to see pictures of your setup.

Daox unfortunetly I don't have pictures of my backdraft dampers I built. My computer dumped on me, had to get a new one, lost a ton of files.

I made it out of a plastic for sale sign I picked up at Lowe's and some left over cloth material my wife had in her craftroom.

All you do is shape the for sale sign into a circle (in my case a 6 inch diameter to fit in the end of the pipe)

After taping the sign into a 6 inch diameter circle I just duct taped the cloth to the sign so that it overhung the end of the sign by about 8 inches. Very light cloth material.

I stuck this thing in the end of the pipe and bingo wingo! It worked beautiful.

When the fan was on the cloth opened allowing hot air to enter room.. Fan OFF the cloth collapsed stopping cold air backdraft. Worked great.

[jeff5may]

The spring loaded check valves work pretty well. The ones without a rubber seal are cheaper than the ones with the seal. Easy peasy breezy. Any orientation installation for quick and simple.