Using attic heat to warm up basement - Page 2

Xringer · 10-26-13, 04:11 PM

Thanks, I'm going to change the system off time to 10PM!!

And we shall see what happens..

~~

I agree about pumping in some not-so-warm air.
If it's warmer than my basement, it's welcome.
I might just program the set-point for basement temp+5 deg F.

My wife and I have already noticed it's nicer in the basement today.
We can feel the difference. The log shows a 4 deg F gain,
but a lot of that is due to heat leakage from the hotwater tank(PV gain) and my wife ran the dryer..

Bad data day again! One of these days, we'll get a solid solar day!

The air the I'm pumping outdoors, is coming right off the floor (cold concrete slab)
and is slightly contaminated with a heavy gas called Radon..

So, recycling it isn't the cards.. I'm pretty sure that a really good filter
would be needed to clean it up.

Got a little bug in my logging for some reason..

Here's the plot for the day..

Got some hot water in the tank and a little hot air in the basement..

Xringer · 10-27-13, 07:51 PM

But you can see on this temperature plot, a bunch of little peaks in temperature,
between 8AM and 4PM.. When the clouds come, the air temp drops.

Temperatures displayed in F, without a decimal point. (Raw CAI data).
Today is the first time we have seen 80F in the attic, with the new setup.
I'm pleased to say we saw at least 2 deg F air temp increase in most areas of the basement.

Outdoor temp was pretty flat all day. Even with all the clouds, the water tank warmed right up nicely.

I might have to work tomorrow, so there may not be much data taken..

Daox · 10-28-13, 11:31 AM

Cool, looks like it is working out. Do you have any logs from the night to see how the temperature drops off?

Exeric · 10-28-13, 01:44 PM

XRinger, it sounds like things are working out for you. I'm a bit jealous of your peak temp differential between attic and outside temps on your latest measurement. 34 degrees is pretty good! I'm finding that the peak differentials that I recorded for those same parameters has gone down quite a bit from summer. Now its usually between 30 and 35 degrees, which isn't what I'd hoped.

Of course, my situation is different in that I still don't have ceilings yet! No insulation up there either. Plus, biggest of all, I still haven't closed the roof vent because I'm trying to keep a constant baseline for measurement.

Do you have a roof vent that is open? Inquiring minds want to know. If you do, then I'm definitely jealous.

Xringer · 10-28-13, 01:57 PM

You can see the west (left) side attic vent near the peak.
There is another vent on the east side, above the #1 Sanyo outdoor unit.
There is also a ridge vent along the top of the peak.. A lot of the heat escapes there.

The attic intake (for the blower) is very near the center of the attic..

I have not paid any attention to the late night attic temp, I think it depends on how fast and far it drops..

Early in the AM, the attic has been about 1 degree warmer than the outdoors..
Must be leakage from the Sanyos and the difference in altitude of the sensors.

~~Edit~~~
Started the logger at 10:34 this morning. Came back and it was still working!
According to the math for a 200cfm air flow, in 30 minutes, you can move 6,000 cubic feet of air!
So, all the air in my basement is being changed twice an hour..

We discovered that holding onto the hardwood banister on the way downstairs,
we can easily 'feel' the temperature change, as you near the middle steps.
Up top, the banister feels warm, but as you decent to the point where
the angled overhead meets the basement ceiling, the wooden rail becomes quite cold, to the touch.
That's the point where the warm air slides into the basement, along the basement ceiling.

Xringer · 10-28-13, 11:14 PM

Hot part of the day in the attic 80.2 @ 01:52:16 PM

The setpoint is 66F. With 200cfm being sucked out, I expected to see
a little negative jog on the plot.. But, it's not there in the AM
and might be there a bit in the afternoon (when the temp dropped below 66F).

Right now, it's 11:12PM and it's 42.4 F outdoors and 44.0 F in the attic..

PS: When the DHW hit 105F, my wife washed her hair..

Xringer · 10-29-13, 11:36 AM

Mostly sunny day at 11:30 and the fans aren't on yet..
The roof is hot, the inside roof planks are warming up..
But, the attic peak sensor is only showing 61.8 (outdoors is 45.5).

I looked at the ridge vent with binocs and I could see the heat wave effect.
Inside the attic, I measured the temp of the planks close up..
The lower planks were warm, the middle planks were warmer.
Higher=warmer.. Until the last plank at the peak.. 20 deg colder!
The ridge vent is sucking out the heat!

Daox · 10-29-13, 11:45 AM

Yep, I've noticed on windy days the fans stay on for way less time and take a lot longer to start up too. If you could control how much vent is open or something, you could really harvest a lot more heat.

Xringer · 10-29-13, 12:31 PM

I don't think my end-vents are effected much by wind, but it's possible that wind
hitting the ridge vent is causing a vacuum effect to suck out the heat.?.
(See drawing pic of garden sprayer).

Theory #2:
I think that my air intake is creating a low-pressure-area a few feet around it.
Air is going to rush to the intake, to fill the vacuum.
But, it's going to take the path of least-resistance.
So, instead of coming in from the end-vent (as I wished for), air is being
sucked in from the outdoor air, (1" above the roof) passing thru the mesh in the ridge vent..
The air being sent down to the basement is a Mix of warm attic air and cold outdoor air..

If Theory #2 is correct, I need a way to block up the ridge vent for about
10 or 15 feet on either side of the air-intake and temp sensor..

I just took some plastic shopping bags up and stuffed them into the slots in the attic peak.
Got 3 or 4 feet blocked off on each side of the intake.. Might help a bit..

Exeric · 10-29-13, 01:47 PM

Yeah, I've noticed the same thing. When the wind is above 10 mph or so the peak temps in relation to outside air temp never gets to where I expect them to. A gable roof seems like it might be very difficult to work with compare to a hip roof. Hip roofs, like mine, have other disadvantages in that you don't get much laminar flow up the roof sheathing, but it has the big advantage that the air moves up and concentrates in a relatively small area. Big advantage there if you want control it with a damper like the one I installed on my roof.

I've been trying to think about a good way to control that flow in Xringer's roof. That ridge vent seems like a real problem for accumulating heat. So far I haven't thought of a way around that doesn't seem like a bit of a kludge that would be expensive in terms of labor and maybe even materials.

10-26-13, 04:11 PM	#11
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	Hi Guys! Thanks, I'm going to change the system off time to 10PM!! And we shall see what happens.. ~~ I agree about pumping in some not-so-warm air. If it's warmer than my basement, it's welcome. I might just program the set-point for basement temp+5 deg F. My wife and I have already noticed it's nicer in the basement today. We can feel the difference. The log shows a 4 deg F gain, but a lot of that is due to heat leakage from the hotwater tank(PV gain) and my wife ran the dryer.. Bad data day again! One of these days, we'll get a solid solar day! The air the I'm pumping outdoors, is coming right off the floor (cold concrete slab) and is slightly contaminated with a heavy gas called Radon.. So, recycling it isn't the cards.. I'm pretty sure that a really good filter would be needed to clean it up. Got a little bug in my logging for some reason.. Here's the plot for the day.. Got some hot water in the tank and a little hot air in the basement.. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 10-26-13 at 06:59 PM..

10-27-13, 07:51 PM	#12
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	Sunday wasn't too cloudy.. But you can see on this temperature plot, a bunch of little peaks in temperature, between 8AM and 4PM.. When the clouds come, the air temp drops. Temperatures displayed in F, without a decimal point. (Raw CAI data). Today is the first time we have seen 80F in the attic, with the new setup. I'm pleased to say we saw at least 2 deg F air temp increase in most areas of the basement. Outdoor temp was pretty flat all day. Even with all the clouds, the water tank warmed right up nicely. I might have to work tomorrow, so there may not be much data taken.. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

10-28-13, 11:31 AM	#13
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Cool, looks like it is working out. Do you have any logs from the night to see how the temperature drops off? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-28-13, 01:57 PM	#15
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	You can see the west (left) side attic vent near the peak. There is another vent on the east side, above the #1 Sanyo outdoor unit. There is also a ridge vent along the top of the peak.. A lot of the heat escapes there. The attic intake (for the blower) is very near the center of the attic.. I have not paid any attention to the late night attic temp, I think it depends on how fast and far it drops.. Early in the AM, the attic has been about 1 degree warmer than the outdoors.. Must be leakage from the Sanyos and the difference in altitude of the sensors. ~~Edit~~~ Started the logger at 10:34 this morning. Came back and it was still working! According to the math for a 200cfm air flow, in 30 minutes, you can move 6,000 cubic feet of air! So, all the air in my basement is being changed twice an hour.. We discovered that holding onto the hardwood banister on the way downstairs, we can easily 'feel' the temperature change, as you near the middle steps. Up top, the banister feels warm, but as you decent to the point where the angled overhead meets the basement ceiling, the wooden rail becomes quite cold, to the touch. That's the point where the warm air slides into the basement, along the basement ceiling. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 10-28-13 at 05:11 PM.. Reason: Update for Monday 10/28?13

10-28-13, 11:14 PM	#16
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	12 hours of data on a partly sunny day Hot part of the day in the attic 80.2 @ 01:52:16 PM The setpoint is 66F. With 200cfm being sucked out, I expected to see a little negative jog on the plot.. But, it's not there in the AM and might be there a bit in the afternoon (when the temp dropped below 66F). Right now, it's 11:12PM and it's 42.4 F outdoors and 44.0 F in the attic.. PS: When the DHW hit 105F, my wife washed her hair.. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 10-28-13 at 11:28 PM.. Reason: PS:

10-28-13, 01:44 PM	#14
Exeric Apprentice EcoRenovator Join Date: Aug 2012 Location: California Posts: 274 Thanks: 19 Thanked 37 Times in 28 Posts	XRinger, it sounds like things are working out for you. I'm a bit jealous of your peak temp differential between attic and outside temps on your latest measurement. 34 degrees is pretty good! I'm finding that the peak differentials that I recorded for those same parameters has gone down quite a bit from summer. Now its usually between 30 and 35 degrees, which isn't what I'd hoped. Of course, my situation is different in that I still don't have ceilings yet! No insulation up there either. Plus, biggest of all, I still haven't closed the roof vent because I'm trying to keep a constant baseline for measurement. Do you have a roof vent that is open? Inquiring minds want to know. If you do, then I'm definitely jealous.

10-29-13, 11:36 AM	#17
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	Mostly sunny day at 11:30 and the fans aren't on yet.. The roof is hot, the inside roof planks are warming up.. But, the attic peak sensor is only showing 61.8 (outdoors is 45.5). I looked at the ridge vent with binocs and I could see the heat wave effect. Inside the attic, I measured the temp of the planks close up.. The lower planks were warm, the middle planks were warmer. Higher=warmer.. Until the last plank at the peak.. 20 deg colder! The ridge vent is sucking out the heat! __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

10-29-13, 11:45 AM	#18
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Yep, I've noticed on windy days the fans stay on for way less time and take a lot longer to start up too. If you could control how much vent is open or something, you could really harvest a lot more heat. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-29-13, 12:31 PM	#19
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 115 Thanked 250 Times in 230 Posts	Low pressure I don't think my end-vents are effected much by wind, but it's possible that wind hitting the ridge vent is causing a vacuum effect to suck out the heat.?. (See drawing pic of garden sprayer). Theory #2: I think that my air intake is creating a low-pressure-area a few feet around it. Air is going to rush to the intake, to fill the vacuum. But, it's going to take the path of least-resistance. So, instead of coming in from the end-vent (as I wished for), air is being sucked in from the outdoor air, (1" above the roof) passing thru the mesh in the ridge vent.. The air being sent down to the basement is a Mix of warm attic air and cold outdoor air.. If Theory #2 is correct, I need a way to block up the ridge vent for about 10 or 15 feet on either side of the air-intake and temp sensor.. I just took some plastic shopping bags up and stuffed them into the slots in the attic peak. Got 3 or 4 feet blocked off on each side of the intake.. Might help a bit.. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less.. Last edited by Xringer; 10-29-13 at 01:43 PM..

10-29-13, 01:47 PM	#20
Exeric Apprentice EcoRenovator Join Date: Aug 2012 Location: California Posts: 274 Thanks: 19 Thanked 37 Times in 28 Posts	Yeah, I've noticed the same thing. When the wind is above 10 mph or so the peak temps in relation to outside air temp never gets to where I expect them to. A gable roof seems like it might be very difficult to work with compare to a hip roof. Hip roofs, like mine, have other disadvantages in that you don't get much laminar flow up the roof sheathing, but it has the big advantage that the air moves up and concentrates in a relatively small area. Big advantage there if you want control it with a damper like the one I installed on my roof. I've been trying to think about a good way to control that flow in Xringer's roof. That ridge vent seems like a real problem for accumulating heat. So far I haven't thought of a way around that doesn't seem like a bit of a kludge that would be expensive in terms of labor and maybe even materials.