Howdy,

I'm getting ready to tackle finishing my basement. The existing system is only 2 years old and was installed by code to accommodate a finished basement, so I don't have concerns about capacity, but honestly, I don't know much of anything about hvac.

What I do know is the concept of how warm air and cold air returns work and which is which in my system, but other than that, I know nothing of tapping into trunk lines and planning for vent placement and spacing. Also, I have a concern about "unbalancing" the system---in other words, ending up with a 90 degree basement and 50 degree bedrooms.

Is there anyone out there who has some experience who might be willing to give some general advice? Even if the advice is to leave it to a pro, I'm fine with that. On this topic, I know nothing.

Thank you in advance.

 

I say in cases like this if you live in a neighborhood that has a bunch of houses that
are the same floor plan, Talk to your neighbors and see how theirs was set up and
if they are happy with the performance and vent temps at their house. I would rig
up a cutoff so you didn't have to waste energy to cool a basement that isn't occupied
and be sure to do a RADON test if you are going to be pulling air out of the basement
for the rest of the houses air.

 

Bluebeast,

Some good ideas. The development is pretty new so I'm not sure how many people have finsihed the basements yet.

I'm not really worried about the radon. Up here, there is a code-required air exchanger that changes the whole house air every so many minutes, plus there is a fresh-air vent from the outside that is piped into the mechanical area. Still good to think about though.

 

My high-dollar neighbor (great guy, great family, his equally high dollar brother across the street from me is also finishing his mcmansion) showed me some of his hvac for a 5000ft house with a 1600 ft basement. Don't know where you are in Tx but you probably have some similar climate issues to CA, hot in the summer being one. So, the neighbor has his set up to change the air back and forth between the basement and the upstairs. Cool air up in the summer, warm air down in the winter. It is also possible to zone the system so you don't send much if any to the basement when you aren't using it.


For our house, we have about 2900 ft single level, with one 5 ton unzoned system. If I did it over, I'd use two separate systems instead of a single zoned system....I think. Would two systems make any sense in your case?

Consider using larger returns than needed, with filters at the returns (the $7 ones are a good compromise) and the really good filter on the unit. (the once a year jobs that take out everything)

But, keep this stuff in mind, and esp the previous post about radon etc, and talk to no less than 3 hvac guys or one you already trust.

I know a little about it, but would not takle it myself as in addition to what I know, I also know what I don't know.

Good luck.

 

just put a couple of supply vents in and try to get a return in somewhere and you will be fine!you can do it yourself!

 

A couple questions
Is it a large open area?
I would recommend 6" or 7" supply take offs sticky backed with dampers, flex duct and matching defuser.
If you install a return duct in that area I recommend a filtered one.
nylon hanger strap
large zipties 14"
sheet metal strews 1/2 or 3/4 long
existing main trunk duct work metal?
tools required:
sheet meal shears. I prefer 90º cutters to the standard cutters. Keeps your fingers away from the metal.
perminate marker
cordless drill
staple gun
pair of scissors
dikes

if you set the take offs at the main trunk to 50º open it should not rob heat or a/c from above area. * the closer to the supply the more noise you will get from the duct work*
Another option would be installing a duct damper system for the basement area. A thermostat will regulate the heat and or a/c in that area. This would take the guess work out of the balancing

 

You put the vents in where you want them/need them, include a cold air return for the basement area. Then you do a balance on the system. thermometers in the various rooms/floors and adjust the vent openings. When you close down on a cold room that will increase air flow in the others. May take a week or so, balancing is not a fast thing if done correctly. Also consider that btu loading in a room may change with the time of day. The fancy systems use room thermostats and automatic vents, cold deck & hot deck with mixing boxes. Or you could go with a chilled water system and each room has it's own thermostat and fan.

 

good grief people, why don't we will have him put vav boxes,chiller, boiler and control it with johnson controls or some other ddc control type.

 

pff250hd I see where your headed. Systems can get over welming to unexperianced. I wouldn't reccommednd a Vacuum Steam Heating and Cooling System. lol

 

Wow,

First off, thank you to all who responded. Let me see if I can recap--I could need as much as a commercial boiler system, or as little as a couple vents, of which I should never attempt to install, and should have at least 3 qualified pros bid on the job, but then again, I should just do it myself. I'm totally confused. Maybe this will help.

The overall basemetn is about 1600sf. Of that, there will be 1 bedroom about 165sq, a workshop about 165sq, the mechanical/storage area about 160sf, and the remaining 1100 or so will be in open family areas and the bathroom. I don't know if that helps any or not.

The more I re-read the posts, I'm leaning towards finding someone who is qualified. After reading the posts, I'm beginning to doubt whether I am.

I do appreciate the help though

Oh, I forgot to mention, I live in MN, not TX anymore. The basement is a poured wall walkout that is already insulated with r-13 rigid foam. The A/C heating unit is a 3.5 ton and the overall living space with basement will be around 4400sq. Coming from TX, I thought this was very small, but the house is insulated to R-30 in the walls and R-44 in the attic areas.

Thanks