HVAC Question

[AgronAlum]

With the coming new addition to our family, we had to move our oldest to the basement. It’s a 400 sq ft area with one vent. When the previous owners finished it, they routed the vent seen in the picture below. The trouble is, the T off the line produces almost 0 air flow into the room.

I believe the rest of that line only goes under the sink in our kitchen and spits out at the kick plate on the cabinet.

What should I replace that T with to get more airflow into the basement area but not completely cut off the kitchen?

 

[ISUCyclones2015]

We had a similar almost identical issue in my house growing up. Two things we did was install damper in the couple nearest vents and a booster in the vent going to the basement. Seemed to fix it for the most part

Booster vent example

 

[AgronAlum]

We had a similar almost identical issue in my house growing up. Two things we did was install damper in the couple nearest vents and a booster in the vent going to the basement. Seemed to fix it for the most part

Booster vent example

View attachment 82177

The damper is kind of tough to do with the proximity to the furnace. If you look at this pic, the main trunk to the left comes right off the furnace. The vent on that trunk is the only vent before this T into the finished area. There are a couple main lines coming off that trunk before it gets to that end but I don’t really want to dampen the airflow to the majority of the house.

A booster might actually work in this situation although a modification to the T would probably be a lot cheaper than a 50-80 dollar vent booster, especially because the vent area is unfinished.

 

[NWICY]

As long as the main line goes to only one place couldn't you put in a damper just past the room flex line and then adjust it right there just a simple flipper damper would work. 2015's idea might be easier though just replace the front instead of splitting the duct work. .

 

[AgronAlum]

As long as the main line goes to only one place couldn't you put in a damper just past the room flex line and then adjust it right there just a simple flipper damper would work. 2015's idea might be easier though just replace the front instead of splitting the duct work. .

I know almost zero about HVAC, so I didn’t know whether a damper on the line would do it or if they make something like an adjustable Y pipe for this.

 

[NWICY]

I know almost zero about HVAC, so I didn’t know whether a damper on the line would do it or if they make something like an adjustable Y pipe for this.

I was thinking of just a simple damper that way you could adjust it but yeah I think a Y would work ok also. Also not a HVAC person but have rigged some stuff up t o get by/make it work. LOL. Good luck with it!

 

[arobb]

With the coming new addition to our family, we had to move our oldest to the basement. It’s a 400 sq ft area with one vent. When the previous owners finished it, they routed the vent seen in the picture below. The trouble is, the T off the line produces almost 0 air flow into the room.

I believe the rest of that line only goes under the sink in our kitchen and spits out at the kick plate on the cabinet.

What should I replace that T with to get more airflow into the basement area but not completely cut off the kitchen?

View attachment 82176

How tight is the room? Maybe you need an air return to get more flow?

 

[cychhosis]

Does it have a cold air return? Hard to push air in if there’s no place for it to go.

 

[AgronAlum]

Does it have a cold air return? Hard to push air in if there’s no place for it to go.

Not directly but it wouldn’t be too hard to add. I just don’t want to upset the balance of the rest of the house. This is the return line going over the ceiling of the finished portion of the basement. The finished portion is to the left in this picture.

 

[Dopey]

Your kid could always get an apartment if he's going to ***** about being a bit cold.

 

[clone4life82]

Not directly but it wouldn’t be too hard to add. I just don’t want to upset the balance of the rest of the house. This is the return line going over the ceiling of the finished portion of the basement. The finished portion is to the left in this picture.

View attachment 82179

the return would probably help a lot and be the least noisy. You could pull the flex duct tap off the main line off enough that you could slide a damper in down stream of where that flex duct tape in and then reattach it. They have them at menards. It may take a little to shimmy it into place but it may help. The problem with it though is that it may rattle and be more of a nuisance when you do it.

 

[clone4life82]

Do you have a supply grille in your kick plate in the kitchen you could choke down?

 

[Tri4Cy]

What others have said. Return air is crucial. Just something in the wall allowing air to escape the room otherwise the positive pressure will prevent any new air from entering.

 

[cyphoon]

Adding a cold air return, preferably on the opposite side of the room, combined with restricting flow a bit in the kitchen should do the trick. May need to supplement with electric heat you just cant get enough air in there.

If that room shares a wall to the exterior of the house, or can easily be connected to the outside, you could install a small, ductless mini-split just for that room. A bit pricey though. Probably $800 minimum. This would give them their own thermostat zone and ideal comfort. Do they deserve this?

H

 

[CYdTracked]

We had a similar almost identical issue in my house growing up. Two things we did was install damper in the couple nearest vents and a booster in the vent going to the basement. Seemed to fix it for the most part

Booster vent example

View attachment 82177

This is something I may need to consider trying on 1 vent. I have 3 vents in my basement, 2 are on opposite ends of the finished area and 1 in the unfinished storage area/utility room. Typically I only have the 2 open in the finished area in the winter and closed in the summer and it stays a pretty consistent 66-68 degrees but this past cold spell it dipped down to around 61-64 at times even after I opened up the 3rd vent and left the door open to the storage room so the air from all 3 vents could circulate the entire space but didn't seem to raise the temp at all. I don't mind it a little cooler in the basement but the 61-63 was pretty noticeable when coming from the main level where it is usually between 70-72 in the winter. I need to doublecheck but I don't think there is a cold air return in the finished part of my basement so maybe that is why. Unfortunately not sure there is a good spot to add one either because there is very limited area where the finished and unfinished areas meet and right behind that wall is the furnace and main trunks that good up through the house and go above the adjacent finished area.

 

[07Clone]

I would just cut in a new takeoff boot into the rectangular supply duct main, and run a new round duct in the adjacent joist space, then disconnect the flex from the tee, cap the tee, and move the flex to the new line you installed. You should install 8" dia minimum, 10" would be better (you can always damper down the flow if you have more than you need). Not knowing the room conditions (above/below grade, windows, insulation, etc., it is hard knowing exactly how much air you need)

Afterwards, I would make sure you have a return air path. You have panning over a couple joist cavities, so you know you have a return path - you just need to look up into the joists after you cut your hole to make sure they didn't install an end cap to block the end of the RA path.

 

[St810s]

HVAC engineer here....

A lot of the options mentioned could work but I would start with cheaper / easier options to begin with.

First option would be to close the damper on the grille below your sink if you have one. Then check for airflow in the basement room.

Next option (if you don't have a damper on the sink grille) would be to add a damper after your tee and then close it. Check to see if you feel air flowing into the basement room (which you hopefully should). If you do, then slowly open the damper until you have an acceptable amount of airflow in the room and at the sink. Remember, you are essentially just splitting the initial airflow for the sink between the two grilles now so don't expect a ton of airflow at either location.

Return / transfer grille above the door could help but I wouldn't mess with adding a new return tap right away. Not sure how your return air is set up so it's hard to guess.

If you close off the new damper after the tee and still don't get airflow, you would need to damper down the airflow to the rest of the house until you achieve the airflow needed for the room / sink. Not as fun of an option.

 

[swiacy]

HVAC engineer here....

A lot of the options mentioned could work but I would start with cheaper / easier options to begin with.

First option would be to close the damper on the grille below your sink if you have one. Then check for airflow in the basement room.

Next option (if you don't have a damper on the sink grille) would be to add a damper after your tee and then close it. Check to see if you feel air flowing into the basement room (which you hopefully should). If you do, then slowly open the damper until you have an acceptable amount of airflow in the room and at the sink. Remember, you are essentially just splitting the initial airflow for the sink between the two grilles now so don't expect a ton of airflow at either location.

Return / transfer grille above the door could help but I wouldn't mess with adding a new return tap right away. Not sure how your return air is set up so it's hard to guess.

If you close off the new damper after the tee and still don't get airflow, you would need to damper down the airflow to the rest of the house until you achieve the airflow needed for the room / sink. Not as fun of an option.

Agree with St810s. My experience is that static pressure due to poor placement of cold air return or lack there of is the culprit in many cases.