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Started By
Message
Adding temporary HVAC supply vent to screened in back patio, thoughts
Posted on 7/27/20 at 4:31 pm
Posted on 7/27/20 at 4:31 pm
We have a roll up screen on our back patio that we use in the evenings to keep the bugs out. Only issue is during these hot summer nights, it gets hot and stuffy on the patio due to lack of ventilation (we have fans and it’s bearable). The screen blocks 95% of air flow so it does keep cool air in, so much so that we can open the windows from our living room to cool off the patio. Problem with that is it in turn warms up the inside of the house. I was in the attic today and noticed I have a duct running from the plenum to the master closet that passes right over the patio and got to thinking, what if I tapped into that duct, installed a motorized damper, and dropped a supply vent in the patio ceiling so when we’re out there, we could just open that damper and get conditioned air into that space. I could put it on a smart switch so it automatically closed after a certain amount of time.
The master closet is connected only to the master bath which also has a supply vent, is on an east facing wall, and has no other windows or doors (so it’s pretty isolated).
My worry is if we pulled air from the closet and pumped it outside, would it have a detrimental affect on my HVAC system and if so, how much.
Note, this would only be for cooling for a few hours in the evening from late spring to early fall. We shouldn’t need to pull any heat.
The master closet is connected only to the master bath which also has a supply vent, is on an east facing wall, and has no other windows or doors (so it’s pretty isolated).
My worry is if we pulled air from the closet and pumped it outside, would it have a detrimental affect on my HVAC system and if so, how much.
Note, this would only be for cooling for a few hours in the evening from late spring to early fall. We shouldn’t need to pull any heat.
10
Posted on 7/27/20 at 4:59 pm to Coon
quote:
My worry is if we pulled air from the closet and pumped it outside, would it have a detrimental affect on my HVAC system and if so, how much
That would be my concern as a HVAC usually isn’t sized by design with much reserve capacity, and even it it is, it’s almost a guarantee the ducts are not over-sized. Then you’d be have sweating and dripping of water at the patio HVAC register when the dew point temperature of the patio air is higher than temperature of the cooler conditioned air exiting the register - which in south LA is most of the year.
I’d look for another alternative.
This post was edited on 7/27/20 at 5:55 pm
Posted on 7/27/20 at 5:02 pm to CrawDude
I didn’t think about the sweating, good point there. I could probably live with that.
On this...
I would be sending air to either the closet or I outside, not both. So same volume.
On this...
quote:
That would be my concern as a HVAC usually isn’t sized by design with much reserve capacity, and even it it is, it’s almost a guarantee the ducts are not over-sized.
I would be sending air to either the closet or I outside, not both. So same volume.
This post was edited on 7/27/20 at 5:07 pm
Posted on 7/27/20 at 5:26 pm to Coon
I'm an incompetent moron who can't read.
This post was edited on 7/27/20 at 9:30 pm
Posted on 7/27/20 at 5:29 pm to Hopeful Doc
Yes...
quote:
The screen blocks 95% of air flow so it does keep cool air in, so much so that we can open the windows from our living room to cool off the patio. Problem with that is it in turn warms up the inside of the house.
Posted on 7/27/20 at 7:01 pm to Coon
You will be sucking air out of your house into the AC and depositing it outside. This will create a negative pressure in your house. The air will be pulled in from the attic or outside depending on the route of least resistance.
Basically what I’m saying is, opening the window is having the same effect. Save your money on the duct work modifications.
Side note: I had this problem when I bought an older house. Dust and black shite would build up around the light switches and outlets as dirty, hot, wet, air was being sucked out of the walls to make up the lost air.
Basically what I’m saying is, opening the window is having the same effect. Save your money on the duct work modifications.
Side note: I had this problem when I bought an older house. Dust and black shite would build up around the light switches and outlets as dirty, hot, wet, air was being sucked out of the walls to make up the lost air.
Posted on 7/27/20 at 7:13 pm to Coon
Just stick a mini split out there
Posted on 7/28/20 at 11:15 am to Cracker
quote:
Just stick a mini split out there
This...
Or maybe one of those "portable" AC units depending on area you are trying to cool.
FWIW, I have an LG unit and it's been great for over 2 years now.
Posted on 7/28/20 at 12:04 pm to skidry
i appreciate all the insight, guys. not really interested in adding another unit independently, would rather deal with it as is...
question on this:
Looking at my HVAC calculations, that room gets 120CFM; so that would be what i'm pulling from the house and dumping outside. The lowest setting on my vent hood over my stove is 280CFM. How is it different?
question on this:
quote:
You will be sucking air out of your house into the AC and depositing it outside. This will create a negative pressure in your house. The air will be pulled in from the attic or outside depending on the route of least resistance.
Looking at my HVAC calculations, that room gets 120CFM; so that would be what i'm pulling from the house and dumping outside. The lowest setting on my vent hood over my stove is 280CFM. How is it different?
Posted on 7/28/20 at 12:54 pm to Coon
You said you would have a damper and close when not in use but I wouldn't trust that to keep bugs, dust, mold, wild animals, etc out of my A/C ducts. There is no way I would want a path from outside directly into my ducting.
Posted on 7/28/20 at 1:10 pm to Coon
quote:It's not different, range hoods, bath vent fans, and dryer exhaust all do the same thing, as would running a duct outside, none are ideal.
How is it different?
When you open the windows the negative pressure is no longer there, it will stay balanced within the screened in patio, and make up for it through the screen positively or negatively, but forces your inside unit to work harder.
I personally think you're asking for trouble running a duct on a motorized damper to outside, you will have loss from leakage even when its not open all the time, and it will likely make up the difference from a less desirable area than your patio window.
The best solution is an independent on demand unit, whether portable, or mini split.
Posted on 7/28/20 at 1:45 pm to Citica8
All great points, guys. Thanks for sharing y’all knowledge.
Posted on 7/29/20 at 11:09 am to Coon
The portable AC units are perfect for this. They are not terribly expensive, you can roll it out into a closet and get it out of the way if needed, and most importantly, take about 5 minutes to get going. There is no need to crawl and work in the attic.
We have used a unit to cool garage spaces, and even semi enclosed tailgates...they work.
It is a $120/150 unit that if it breaks down, you buy another one. No need to alter you $6K home AC.
We have used a unit to cool garage spaces, and even semi enclosed tailgates...they work.
It is a $120/150 unit that if it breaks down, you buy another one. No need to alter you $6K home AC.
Posted on 7/29/20 at 11:43 am to Geaux Frogs
How to you dump the heat from a portable unit?
Posted on 7/29/20 at 2:31 pm to Coon
You can put it close to the screen so it exhausts out, they make ducts to get even more separation, and if you're feeling crazy and just want to cut some holes in your patio roof, you can duct the ac exhaust out through the attic, assuming its not a conditioned attic.
Posted on 7/29/20 at 6:11 pm to Coon
We just built a house in Thibodaux, we did the same thing however it has its own trunk link with a return and also we have dedicated switch to open or close the damper. Also have 3 separate zones on that ac unit, we just go to that zone just temp and open damper. When we done we turn off zone and close damper. We also have ez breeze on our patio. HVAC works awesome.
Posted on 7/29/20 at 10:16 pm to tbrud
What EZ Breeze are you referring to? I found an EZ Breeze porch window company and a portable A/C type deal.
I am curious how the windows work if that is what you are talking about.
I am curious how the windows work if that is what you are talking about.
Posted on 10/9/20 at 11:04 pm to Jj283
Posted on 10/9/20 at 11:24 pm to Coon
Just thinking old school here, do you have ceiling fans on the patio?
We had then in our old house on the patio and sitting under them on hot nights was not bad.
We had then in our old house on the patio and sitting under them on hot nights was not bad.
Posted on 10/10/20 at 6:42 am to Coon
Don't mess with your ductwork. Just go get one of those portable roll around a/c units and plug it into an outlet on your patio.
We have had a Shinco for 5 years and it is still chilling like a boss.
We have had a Shinco for 5 years and it is still chilling like a boss.
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