Attic Ventilation

[jmed999]

Is anyone using the ISY to control their attic ventilation? How can this be done?

 

Thanks!

[TJF1960]

Hello jmed999,

 

I have two roof mount attic fans which are each controlled by their own Switchlinc Relay. Once the attic temp reaches a set temperature I have programs which turn them on one at a time. I have them run for about a half hour each at a time then cycle off for a bit. Still trying to play with them to get the most benefit (air flow/cool down vs electric use). Haven't drawn any conclusions just yet.

I did bypass 1 of the attic fan thermostats so it is directly controlled by its SL relay switch at all times, the other attic fans thermostat is still active but was set pretty low so when its warm in the attic its thermostat is on at which point the SL relay is in full control of the fan operation.

 

Tim

[apostolakisl]

Hello jmed999,

 

I have two roof mount attic fans which are each controlled by their own Switchlinc Relay. Once the attic temp reaches a set temperature I have programs which turn them on one at a time. I have them run for about a half hour each at a time then cycle off for a bit. Still trying to play with them to get the most benefit (air flow/cool down vs electric use). Haven't drawn any conclusions just yet.

I did bypass 1 of the attic fan thermostats so it is directly controlled by its SL relay switch at all times, the other attic fans thermostat is still active but was set pretty low so when its warm in the attic its thermostat is on at which point the SL relay is in full control of the fan operation.

 

Tim

 

 

Are you monitoring/logging/graphing your attic temp relative to fan status? I would be curious to see if the temp drops and by how much.

 

Also!!!! be advised that if you do not have the attic/house interface tightly sealed, you may be sucking conditioned air out of the house with your attic fan and thus shooting yourself in the foot! You must have every crack sealed up (and that is hard to do) and you must have very adequate vents for air intake (so that the attic has minimal relative vacuum and is less inclined to suck from the house).

[TJF1960]

Are you monitoring/logging/graphing your attic temp relative to fan status? I would be curious to see if the temp drops and by how much.

No but you know what, that is a very good idea. I am going to check into doing that. I have sat and watched the temp in the attic drop when the fans turn on, but its been a while and I don’t remember by how much. When I get some time I am going to look into it again.

 

Also!!!! be advised that if you do not have the attic/house interface tightly sealed, you may be sucking conditioned air out of the house with your attic fan and thus shooting yourself in the foot! You must have every crack sealed up (and that is hard to do) and you must have very adequate vents for air intake (so that the attic has minimal relative vacuum and is less inclined to suck from the house).

Knowing the builder of these homes - I wouldn’t be surprised that I have at least few leaks into the attic and I am going to have to address them the best I can. In the mean time there are at least plenty of intake vents in both the soffits and gable ends.

 

Thanks,

Tim

[apostolakisl]

Of course the price point is very different here, but you might consider forgetting about venting the attic at all. Close up all the vents and spray foam the entire under side of the roof deck. This works awesome. I have both my house and office that way. If you have any hvac equipment/ducting in the attic it will work far better. Your attic will be much more temperate (mine goes from about 60 when it is 20 outside to about 85 when it is 105 outside) so you can actually use your attic for storage or have electronics operating in there. I promise you will see a sizable drop in your hvac bills. Also, no more fiberglass! Man I hate that stuff.

 

And it seals way way better than any other technique. And when you do the roof deck you don't have to worry about leaks around all your ceiling fixtures.

 

But back to the temp. I use a cai webcontrol unit and ioguy's program to log the temp readings every 5 minutes. It's a nice way to gather that data. You can also use some of the lacrossetechnology thermometers with a logging function and download that to a graph. Those are pretty cheap and work pretty well, I have one in my wine cellar, keg, and outside. I used it extensively to evaluate and adjust the hvac equipment in my wine room to optomize the tev settings.

[TJF1960]

Did you have the foam put in during new construction or existing construction. I haven't heard of it being done...will have to do some surfing to find out more about it. That’s a huge temp differential.

 

I too am using the webcontrol boards along with the caiwc program. I keep finding more reasons to buy them and implement them around the house.

 

Thanks,

Tim

[apostolakisl]

My house was new construction.

 

My office was a remodel which I just finished 3 weeks ago. My office had a bunch of roof vents which we mostly just boarded over. I had some of them boxed out with duct-board so the hvac guy could tap into them for fresh air and exhaust.

 

I have one of those temp reader laser gun things. Last summer, I pointed it at a west facing roof at 6pm when it was 105 outside and sunny. The roof was 150 degrees. I went in the attic and pointed it at the same spot on the under surface and it was 87.

[GregE]

I paid extra when I built my house too so I could have Icynene insulation sprayed everywhere. Love it. Kind of strange that the attic is sealed. I should have checked it out this summer when it was really hot out but didn't.

 

What are you guys using to remotely monitor temperatures?

[TJF1960]

Using the CAI WebControl boards http://www.cainetworks.com/products/webcontrol/index.html and using the 1 wire temp sensors from Maxim DS1820/DS1822 http://datasheets.maxim-ic.com/en/ds/DS1822.pdf

I am using the CAIWC program on a Pogoplug http://forum.universal-devices.com/viewtopic.php?f=81&t=7998 or you can also use WCLink http://forum.universal-devices.com/viewtopic.php?f=77&t=6612. Both programs work very well. The programs send the temps to variables in ISY.

[apostolakisl]

I paid extra when I built my house too so I could have Icynene insulation sprayed everywhere. Love it. Kind of strange that the attic is sealed. I should have checked it out this summer when it was really hot out but didn't.

 

What are you guys using to remotely monitor temperatures?

 

I have cai webcontrol boards monitoring some stuff. I also have some of the lacrosse technology weather stations that log data. The version I have allows you to download the data and import to excel where you can do all kinds of fancy stuff with it. The latter choice is easier and cheaper, but the cai choice lets you put the data into the ISY as variable values in essentially real time.