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blthomas 12-05-2007 12:15 PM

New poster, looking for advise on heating cooling in basement that is being finished
This may come off long, but I'll paint the picture best I can.

Bought the house in 05', started fixing the drywall already in basement. Got it cleaned up, did some painting, did some drop ceiling, got some carpet down.

One thing when repairing the drywall, was I blocked off 6 vents that were cut directly into the trunk line of the HVAC.

I know nothing about HVAC, my step father is a master plumber, electrician, and is very knowledgable on HVAC. He tried to explain how the system works with returns and these vents were just robbing the main level of air.

I would consult him on these issues, but he's not ven in my State. :(

So I blocked them and sealed them, then drywalled over the vent holes.

Now as I work through the basement, I want to do the system setup correctly, and what will work best.

The basement is used everyday, and is about 85% finished.

Please pardon the pics, I whipped them up in "paint" on the computer to help give visuals.

Lets start downstairs.....

Black squares (vents) are existing. The two to the left in the laundry room are closed. The single vent in the middle of the basement is open.

The red squares are where I thought the vents should go.

What is the best way to set it up? Based on dimensions of the rooms or overall house dimensions? Do I need to calculate anything for flow?

All ductwork is 6" flex, except the bathrooms which are 5" IIRC after looking.

Should the basement be 6"? Do I need more or less vents? Should they be in front of the windows and doors, or equally spaced along the exterior walls?

The vent in the middle and the two in the laundry are to be moved/reused somewhere.

For the upstairs.............

Again pardon the pic please.....

Black squares are existing vents. My first concern is what is the best scenario downstairs, will that affect my output and/or comfort upstairs?

Second concern upstairs is the great room.

Gets a bit cooler in there than everywhere else upstairs. I have a ceiling fan centrally located in the room, a BIG one.

I run it some, but it seems to have little affect on keeping the room evenly warm.

Is the four vents pictured enough? What can I do if anything?

I feel like I need more insulation in the attic, but money is tight right now. I can see the tops of the joists sticking through the old insulation.

I'd like to put what I have towards the ducting and HVAC setup.

The house has all new Pella windows and doors, with the foam in the spaces around the new installs (we did them), and fiberglass insulation in the larger spaces that the foam only expanded into partially.

I feel while the house is insulated somewhat well, and knowing the attic could use some more, (built in 88'), we are OK, looking for tips on flow and setup.

Many thanks in advance for help.

Blair in VA.

concretemasonry 12-05-2007 01:46 PM

New poster, looking for advise on heating cooling in basement that is being finished
I assume that when you say vents, you supply of air. Do you have any return air intakes?

blthomas 12-05-2007 02:08 PM


Originally Posted by concretemasonry (Post 78571)
I assume that when you say vents, you supply of air. Do you have any return air intakes?

Yessir. I labeled them vents, never thought about calling them supply....:no:

The returns on each level (1 per level) are labeled in the drawings. Upstairs is across from the basement steps on the edge of the Great room.

Downstairs return is cut into the side of the wall directly connected to the unit, kind of around the corner from the main area of the basement.

Hope that makes sense.


jogr 12-05-2007 03:24 PM

My Dad use to tell me "if it ain't broke don't fix it".

With that in mind what exactly were you fixing when you closed off the basement supply registers? You don't say if the basement was too hot or too cold so I assume the temp was fine and you just closed them off because.... why???

And now that they are closed off, what exactly is the issue you are trying to fix in the basement? Is it too hot, too cold, uneven??

And upstairs is the only problem that you want the greatroom warmer in the heating season? Is it ok in the cooling season? You just might need to rebalance the existing supply registers upstairs.

How far do you want to go to upgrade your system. Do you want Good, Better or Best? If you really want this done right an HVAC guy should run a manual J to determine if your furnace and A/C are sized right and a manual D to determine the correct ductwork. In a top notch system you'll have returns in nearly every room with a door.

But really, don't fix what isn't broken. Your comfort will tell you if anything needs changing. If your only complaint is the Greatroom needs a little more heat then try readjusting your registers.

blthomas 12-06-2007 08:58 AM

Thanks for the reply.

IN the basement, the ones I closed off, were 7 in a row, about 3 feet apart, cut into the trunkline.

I was told this was rediculous and robbing me of air upstairs. (It was really hot in the summer upstairs, and overly warm in the basement the first winter)

The basement is too cool, about the same temp consistantly throughout. I'd like to even it out as much as I can and warm it up.

The greatroom upstairs is too cool in the winter and too warm in the summer.

Ideally, I don't want to fix what's not broken, I agree completely. The house was butchered by the previous owner with wiring and the silly registers 3 feet apart, shoddy drywall, yada, yada.

The tip about a pro coming in to do a manual J and manual D means alot. At least I know what to ask for.

I was close to buying a system last year, the inside of ours was hideous as the previous owners never changed the filter or had much maintenance done since they bought it.

ONe guy came in and recommended replacement right away. Second guy recommended a serious cleaning, duct cleaning, and run it.

Third guy, recommended same cleanings, fixed a blower switch that was keeping the blower on for too long at times, and really gave the coil a bath.

He mentioned that the unit itself was in good shape, (trane) and replacement was not nessecarry as of now.

I think the upstairs is OK, could maybe use some tweaking of the registers or something to help cool in the summer and spread the heat in the winter.

Downstairs I need help with the best solution to even the heat/cool (it can get real stuffy down there in the summer).

Many thanks,


KUIPORNG 12-06-2007 02:50 PM

no break, no fix is not apply here... original design for the vent in basement is for basement not as living space... now you change it to living space, definitely should do some work on the vent/return air thing properly if you want to have a healthy basement, having said that, you don't need to do rocket science calculation.... you aren't going to increase the basement air supply by 10 fold to affect the supply for upstairs.... what you need to do are simply:

close off the ceiling vent which you did.

brind the vent down to the floor level which you haven't done and is going be hard for you because you already drywalled... but this is the official way... the second way is to move around in the ceiling like the way you are trying, not the best but better than nothing... move them to window locations are correct approach....

the other thing is you need to move your return vent to the floor level and open it up to a larger hole as well consider you are going to supply more air in the basement.... which again is hard for you to do because you already drywalled....

the problem is you reverse the order, these things should have been taken care of before any drywalling....

anyway... do what you can to the best ....

blthomas 12-06-2007 03:23 PM


Yea, his drywalling definitely didn't help me earlier, and doesn't now with the situation.

I only tried to repair holes and do patchwork on shoddy jointing. Never knew about the vents in the walls.

Makes sense though, get them colse to the floor.

So the return in the basement gets bigger, currently a 16"x16". It's already at floor level, so I can just enlarge the hole and address that accordingly?

Yea the walls are done, so I guess it looks like ceiling vents are all I can do, without making a ginormous mess.

If I shoot for in front of windows/door, where shuld I place them in the section with no windows at all?

Simply space them accordingly?

Many thanks for the input.


jogr 12-06-2007 03:47 PM

At this point in the basement put adjustable registers in the ceiling. That way you can adjust the airflow to each room and also attempt to balance the upstairs and downstairs. You may need to rebalance when you go from heating to cooling seasons as the basement will cool easier than it will heat. Near the windows on outside walls is the best location for the basement registers, if no windows then yes, distribute evenly.

Don't enlarge your returns. They were already sized for your furnace and blower.

You may find that your furnace or A/C is not sized large enough to adequately control both the basement and upstairs and the airflow may not be enough with the additional registers. Time will tell.

KUIPORNG 12-07-2007 08:40 AM

if your return air is already 16" by 16" and is already at floor level, looks like you may not need to do much as looks like this is quite large already....

blthomas 12-07-2007 09:09 AM

Thanks guys.

I picked up some flex duct, more registers, and the (I don't know the proper name for them) connections at the trunk.

Going to add a total of 5 downstairs. Using 6".

After reading the replys, I'm thinking this will help my situation for comfort downstairs, but I was already wondering about my airflow.

If it matters, we keep both bathrooms and the master bedroom's registers closed. The bedroom gets constant sun, and the bathrooms get very warm.

Maybe this can help accommodate the basement, and we can flip flop the routine and close some registers down there in the summer and pull this off.

Many thanks.

KUIPORNG 12-07-2007 09:54 AM

flex duct is not really good idea for setting up ... as they are easily break and have hole ...etc... you should use solid metal duct... it is more work but unfortunately it is kind of required.

blthomas 12-07-2007 10:07 AM

The flexible insulated duct is a no-no?

The stuff I have is insulated and supported by wire inside of it.

I can take the flexible duct back.

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