HVAC opinion needed

[andyb15]

I'm finishing off two bedrooms in my basement. I have run a heat duct to right in front of the egress windows in these bedrooms. Will I need CA return vents in these rooms as well?


The red boxes are the bedrooms and the green boxes are where i placed heat ducts in the ceiling. Any help is appreciated!

 

[deleted member]

i am not expert. but, i say no. is that whole floor one zone?

 

[andyb15]

my house is a rambler with a basement. I only have one thermostat in the house, so i'm assuming that the entire house is on the same zone.

 

[deleted member]

where are your CARs now?

 

[Obi-Wan]

Yes each room will need its own return. If the door is closed the room will pressurize and not get adequate airflow. If you can not get at the return duct you could just put transfer ducts through the wall, one high outside and one low inside in a stud cavity to get to the main area if that has a return vent.

If you have floor trusses the truss system may already be a wild return which is used sometimes but not very often

If all else fails you could use the old mobile home trick and keep your doors 2 to 3 inches off the floor.

 

[sierra1995]

yes, put cold air returns in each bedroom.

I would put them behind the door of each room.

 

[andyb15]

thanks for the help guys. the bedroom next to the furnace room will be easy to get a CAR as there isn't any intrusion behind the wall. the other bedroom may be a bit more challenging.

 

[eyexer]

yes absolutely put them in. you can use 8" flex duct if it's easier. most houses now are being done with all flex duct back to the return on the furnace itself. seeing it more all the time.

 

[andyb15]

is it best to run oval ducting in the wall cavity and then attach flex ducting from there?

 

[eyexer]

is it best to run oval ducting in the wall cavity and then attach flex ducting from there?

you user the wall cavity as a duct. install a boot on top of the wall cavity and then flex.

 

[LBrandt]

^^^^^^^this should work.

 

[muzzyhunter]

hvac opinion needed

In bed #4 I would run a passive jumper one high one low,as mentioned by obi earlier,same would work for #5 if door to caz(furnace room) left open,if not diffuser mounted on ceiling and dropped into furnace room should work.Rooms look to be large enough were room to room pressures shouldnt be great,we strive for less than 3pa difference between room and main body of house.Even with return the bathroom will have signifantly high pressure(smaller volume).If you have an atmospherically vented furnace you could open door to caz while running the air handler and if it is pulled in,alleviate pressure to caz.With the air handler runninng and dryer going could make caz go negative and possibly backdraft atmo vented appliances typically waterheaters.
I spend alot of time trying to backdraft appliances with worst case draft testing,for work.

 

[andyb15]

you user the wall cavity as a duct. install a boot on top of the wall cavity and then flex.

So is there anything actually in the cavity besides the boot? Or is it a boot connected to my grate at bottom of the wall cavity and then just flex coming out somewhere towards the top??? Thanks for all the help, haven't don much HVAC type work

 

[dust in the wind]

Andy - what eyewear mentioned is how the hvac guys did my basement. The boot is at the top of the stud cavity. Flex or rigid pipe from the boot to the cold air return channel. They notched out the top plates for the airflow. The stud cavity is the ductwork once the Sheetrock is on. Then it is just the grate at the bottom.

 

[andyb15]

Andy - what eyewear mentioned is how the hvac guys did my basement. The boot is at the top of the stud cavity. Flex or rigid pipe from the boot to the cold air return channel. They notched out the top plates for the airflow. The stud cavity is the ductwork once the Sheetrock is on. Then it is just the grate at the bottom.

ok, so the boot just goes at the top and my grate goes to the bottom. anyone have a picture or link to the boot I would need to get?

 

[sierra1995]

https://www.menards.com/main/heatin...ght-end-boot-duct-fitting/p-1444432272336.htm

We used something like this in my two bedrooms in the basement. We notched out the top plate and screwed this in place, then ran flex to the return air duct. Just keep in mind how you will run your flex, because this boot may not work for bedroom #4, but may work for #3. all depends on how your joists or floor trusses are laid out. I am not an expert by the way, i've only done one basement.

 

[andyb15]

ok, that helps a ton!

 

[Retired-Guy]

Yes each room will need its own return. If the door is closed the room will pressurize and not get adequate airflow. If you can not get at the return duct you could just put transfer ducts through the wall, one high outside and one low inside in a stud cavity to get to the main area if that has a return vent.

If you have floor trusses the truss system may already be a wild return which is used sometimes but not very often

If all else fails you could use the old mobile home trick and keep your doors 2 to 3 inches off the floor.

What Obi said!

 

[eyexer]

there are several different boots pending on the situation. sometimes you have close quarters in the joist area and a different boot works better.

 

[dust in the wind]

ok, so the boot just goes at the top and my grate goes to the bottom. anyone have a picture or link to the boot I would need to get?

Yep, I can take a picture of it when I get home tonight. I haven't started sheetrocking yet as I have a few little things to do yet.

The link posted by Sierra is similar to what was used on mine - just a different situation for the type of boot on mine.


eta - LOL I just noticed my phone autocorrected eyexer to eyewear! Sorry eyexer nothing intended by that.

Andy - what eyewear mentioned is how the hvac guys did my basement. The boot is at the top of the stud cavity. Flex or rigid pipe from the boot to the cold air return channel. They notched out the top plates for the airflow. The stud cavity is the ductwork once the Sheetrock is on. Then it is just the grate at the bottom.