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Ermagerd - another A/C question - my system is pulling in a lot of outside air...
Posted on 8/10/23 at 11:17 am
Posted on 8/10/23 at 11:17 am
So I mentioned awhile back in this thread that I was seeing alot of moisture in the my vent hood...
Well it turns out I'm having issues in other places as well.
Then I realized my A/C system is drawing in A LOT of outside air through any nook and cranny it can.
Anything to look for in particular or just go straight to calling in a pro?
Well it turns out I'm having issues in other places as well.
Then I realized my A/C system is drawing in A LOT of outside air through any nook and cranny it can.
Anything to look for in particular or just go straight to calling in a pro?
6
Posted on 8/10/23 at 11:54 am to Meauxjeaux
Do you have super- dehum equipment?
What is the % humidity inside ?
What is the % humidity inside ?
Posted on 8/10/23 at 12:03 pm to Meauxjeaux
quote:
Then I realized my A/C system is drawing in A LOT of outside air through any nook and cranny it ca
They are always going to do this. Do you mean into the system through the ducts or do you mean into your house from the exterior?
Eit
Posted on 8/10/23 at 12:07 pm to Meauxjeaux
If it's pulling in air from somewhere, it's also blowing air out somewhere, most likely your fireplace.
Posted on 8/10/23 at 12:23 pm to EF Hutton
Not anything special for dehumidifying.
I haven't measured, but our humid % is probably pretty normal.
I haven't measured, but our humid % is probably pretty normal.
Posted on 8/10/23 at 12:23 pm to baldona
Pulling in from outside air.
Posted on 8/10/23 at 12:25 pm to TeddyPadillac
quote:
If it's pulling in air from somewhere, it's also blowing air out somewhere, most likely your fireplace.
Going to keep looking.
I did some experimenting and when I have all of the bedroom doors shut, it pulls in outside air like crazy. (2 upstairs, 2 downstairs).
But when I open them all, the system seems to re-circulate it's own air better... IE, if I open an outside door just slightly, there is way less air pulling in to the house with all of the inside doors open.
This post was edited on 8/10/23 at 12:26 pm
Posted on 8/10/23 at 2:54 pm to Meauxjeaux
Sounds like you might need a blower door test - puts interior of house under negative pressure and they assess overall house air leakage/infiltration, and while is under negative pressure they can use a smoke pen to check where major sources of air infiltration are. When I had it done a few years ago cost was $350. Some utility companies may coverall or part of the cost of this test - you can check your utility’s website.
You can also have a HVAC duct leakage test performed - they use the same equipment - and the cost is about the same.
LINK
Beaucoup articles and Y/T videos on both tests if your not familiar with them.
You can also have a HVAC duct leakage test performed - they use the same equipment - and the cost is about the same.
LINK
Beaucoup articles and Y/T videos on both tests if your not familiar with them.
This post was edited on 8/10/23 at 2:56 pm
Posted on 8/10/23 at 5:02 pm to Meauxjeaux
quote:
I did some experimenting and when I have all of the bedroom doors shut, it pulls in outside air like crazy. (2 upstairs, 2 downstairs).
But when I open them all, the system seems to re-circulate it's own air better... IE, if I open an outside door just slightly, there is way less air pulling in to the house with all of the inside doors open.
So what is happening is your return air from the bedrooms is being restricted by the closed doors. While the unit is running, if you had sensitive enough measuring devices, you would see lower pressure in the main part of your home and higher in the bedrooms with closed doors.
Posted on 8/10/23 at 5:35 pm to mdomingue
Please explain how you know air is being pulled from the outside?
If this is true ---- then the air blower must be blowing air out of the house. The only way I can think of is air is somehow coming out of the air distribution box or an air duck has come apart and is blowing cold air into the attic.
If this is true ---- then the air blower must be blowing air out of the house. The only way I can think of is air is somehow coming out of the air distribution box or an air duck has come apart and is blowing cold air into the attic.
Posted on 8/10/23 at 6:07 pm to gerald65
quote:
Please explain how you know air is being pulled from the outside?
I don't know that for certain. I am just explaining why he is seeing the difference in the air coming into his house at his cracked open door when the bedroom doors are closed. The closed-off rooms don't allow airflow so unless the ducts are closed in the rooms, you will have a higher pressure in those rooms and lower in the main part of the house, especially at first. I'm not sure that wouldn't even out after a few minutes with the rooms reaching a pressure where the airflow there is impinged and more dumped into the main area.
quote:
If this is true ---- then the air blower must be blowing air out of the house. The only way I can think of is air is somehow coming out of the air distribution box or an air duck has come apart and is blowing cold air into the attic.
The air pressure in the portion of the house where he feels the inlet airflow would have to be lower than it is outside. How would that happen? I could see two things contributing to that. First, if multiple rooms are closed off, the restriction of the return air can cause a drop in air pressure in the rest of the house while the unit is running. Second, the combined gas law tells us the P1V1/T1=P2V2/T2 so since the volume of the room is constant as the temperature drops the pressure will also drop.
Is that drawing air in from the outside? I don't know. I would definitely check the ductwork in the attic as well or call a pro.
Posted on 8/10/23 at 6:16 pm to Meauxjeaux
Your return air is either too small or restricted
Posted on 8/10/23 at 6:49 pm to Meauxjeaux
When your doors are closed there is just less return air available. Gotta get air from somewhere, so your living area (if that’s where the return is) will be more negative than when bedroom doors are open. Air will get through most wall assemblies if the interior is negative enough.
Posted on 8/10/23 at 7:13 pm to AyyyBaw
Posted on 8/11/23 at 10:10 am to gerald65
quote:
Please explain how you know air is being pulled from the outside?
Well, mainly my lack of proper home maintenance showed up with moisture buildup underneath my kitchen counter and in my dryer.
Also, as noted in the OP, there was moisture buildup around my range hood vent, but that wasn't lack of maintenance, that's a new addition in our kitchen.
But I've got damage around my sink cabinets because so much moist air has been pulled in these last few months that some of walls inside there swelled up, then I noticed moisture on the inside of the sink cabinet doors, then I felt it.
Posted on 8/11/23 at 10:14 am to mdomingue
quote:
Please explain how you know air is being pulled from the outside?
I don't know that for certain. I am just explaining why he is seeing the difference in the air coming into his house at his cracked open door when the bedroom doors are closed. The closed-off rooms don't allow airflow so unless the ducts are closed in the rooms, you will have a higher pressure in those rooms and lower in the main part of the house, especially at first. I'm not sure that wouldn't even out after a few minutes with the rooms reaching a pressure where the airflow there is impinged and more dumped into the main area.
quote:
If this is true ---- then the air blower must be blowing air out of the house. The only way I can think of is air is somehow coming out of the air distribution box or an air duck has come apart and is blowing cold air into the attic.
The air pressure in the portion of the house where he feels the inlet airflow would have to be lower than it is outside. How would that happen? I could see two things contributing to that. First, if multiple rooms are closed off, the restriction of the return air can cause a drop in air pressure in the rest of the house while the unit is running. Second, the combined gas law tells us the P1V1/T1=P2V2/T2 so since the volume of the room is constant as the temperature drops the pressure will also drop.
Is that drawing air in from the outside? I don't know. I would definitely check the ductwork in the attic as well or call a pro.
This is all 100% spot-on and a big help.
I didn't know the reasons (pressure et all), but intuitively figured if the bedroom doors were all closed (which restricted the bedroom vents + bathroom vents + closet vents), the not enough volume was returning the the return (which is located on the second floor at the top of the stairs) and the sustem was making that up with outside air.
Going to check attics for open duct problems.
Posted on 8/12/23 at 2:52 am to Meauxjeaux
OK, I reread all these post.
You talked about when the bedroom doors are closed, this cuts off air flow in the house.
You also talked about finding moisture... mostly in the kitchen area, I believe.
If you have the bedroom doors closed, and then just crack open one door, do you feel or maybe hear air flowing out of the room? If the answer is yes... the door is fitting too tight. The door needs to have about a 1/2" gap at the bottom to allow good air flow out of the room.
It sounds like you usually have bedroom doors closed. If so, try keeping all doors open for at leased 24 hours and check to see if the moisture goes away.
Someone asked if you had checked humidity ... I suggest you get a thermometer which also shows humidity. You can get them at Walmart for about $20. Sometimes knowing the humidity is just as important as the temperature.
Check the humidity in several areas of your house. Humidity should be below 55%. Readings above 60% indicate there is a problem.
You talked about when the bedroom doors are closed, this cuts off air flow in the house.
You also talked about finding moisture... mostly in the kitchen area, I believe.
If you have the bedroom doors closed, and then just crack open one door, do you feel or maybe hear air flowing out of the room? If the answer is yes... the door is fitting too tight. The door needs to have about a 1/2" gap at the bottom to allow good air flow out of the room.
It sounds like you usually have bedroom doors closed. If so, try keeping all doors open for at leased 24 hours and check to see if the moisture goes away.
Someone asked if you had checked humidity ... I suggest you get a thermometer which also shows humidity. You can get them at Walmart for about $20. Sometimes knowing the humidity is just as important as the temperature.
Check the humidity in several areas of your house. Humidity should be below 55%. Readings above 60% indicate there is a problem.
This post was edited on 8/12/23 at 12:04 pm
Posted on 8/12/23 at 3:21 am to gerald65
Everything in post above this one is spot on.
Posted on 8/12/23 at 10:30 am to gerald65
Thanks all. Working on it this weekend.
Yes these doors have rushing air when slightly cracked open.
When I closed them all and then open the front door, there’s a massive amount of air sucking in. When I open them all and then open the front door, a lot less air sucking in.
Yes these doors have rushing air when slightly cracked open.
When I closed them all and then open the front door, there’s a massive amount of air sucking in. When I open them all and then open the front door, a lot less air sucking in.
Posted on 8/12/23 at 10:37 am to Meauxjeaux
Sounds like you have a leaky supply duct. I'd let it run and shut those doors then go up and start feeling and listening around in the attic.
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