I didn't get any responses in the thread I posted in so I'm starting this new one.

Anyone's help would be greatly appreciated.


I'm fairly new to this site. I currently have a 90%high efficiency furnace and a 5 ton A/C unit to heat and cool a 3100s.f. home. I have a full basement and will be putting in a dedicated H/T space approx 15 Ft. wide by 22ft. long. Will branching off my existing ductwork to heat and cool the theater with returns effect the efficiency or function of the furnace or A/C unit? I belive the A/C unit is a 12 or 14 seer unit. Thanks.

Usually the efficiencies of HVAC equipment are based off of ideal conditions as instituted by the ARI. So...in the real world you are not receiving the stamped efficiencies and there are so many variables that affect efficiency.

Is the question you are asking really....will this unit heat and cool my home including my new home theater?

Of course each home is a little different but I would imagine it would be sufficient. Is your basement a walkout lower level? As far as the DX cooling, it will be more beneficial for your compressor(s) to increase the cooling load so they don't cycle as much...plus your basement will always be cooler in the summer.

Did that help any? Or raise more questions?

Good answer Greg^.

Seems like you are wondering if your equipment can handle the new load of the basement.

I'd ask if the area is already conditioned? Are there hvac outlet that already service the area? Perhaps the original installer sized the system to handle the basement as a whole?

Cooling load on the summer should be low, and as Greg suggests might actually be benificial to the load on the AC system. As for heat, you might be OK, and if not it is easy to add a supplemental eletric heat or vent free gas heater.

I'd ask a qualified installer to come out and give you an estimate and pick his brain a little. It would be nice to have a supply and a return for the room so at the bery least the air will change out and be filtered.

If the room is just too big and the loads to high, perhaps a dual zone system would work to allow you to keep your existing HVAC equip?

Tboy

Just a FYI, you say that you are fairly new to the site so...

You need to be aware that there are some fairly simple things that you can do to limit the transfer of the sound from the HT to the rest of the house via HVAC duct work.

The choice of material (metal versus acoustic duct board or flexible acoustical ducts) the design of the route (Include some S curves) will make a big difference in how much sound get's broadcast through out the house via the duct network.

Lastly you should also be aware of two things:

The heat load in the HT when it's filled with family and friends and all the equipment running is pretty high so don't underestimate the cooling capacity required.

The average residential HVAC technician will be pretty clueless about the techniques you can use to manage the sound control aspect. You will need to do your research and ask specifically for certain products.

He is more then likely to say "well I've been doing this for 20 years and I've never heard of Acoustical flex duct"

Also looking into zoning your system as an option. That will allow you to have multiple controllers off the same unit. This can be done even with units that are too small for the total area. The main benefit of zoning is that the unit will only heat/cool the areas that require it. So you may be cooling the theater while the rest of the house is already cool enough. You can also shut off unused areas of the house. There are good sides and bad sides of zoning of course. One of the bad sides is that the unit doesn't run long enough to dehumidify some areas. Like if you cool just the theater with a 5 ton unit, it will cool rapidly and not run long enough to get all the moisture out of the air.

Have an HVAC guy, not a sales rep, look at the system and size it up. For my basement, we installed a heat pump and put the thermostat inside the theater. We could've zoned the unit, but, decided against it; We always watch movies together and door to the theater will only be closed when in use.

Thanks,

Yes there are two vents for heating and cooling. They are on opposite ends of the basement. Depending on the final plan, one could possibly end up being inside a storage closet with the theater on the other side of the wall. That setup may require running and extension from where the vent is cut to the theater. There are no cold air return however.

I guess my main concern is if I start cutting into the existing duct work to provide heat, A/C and returns for the entire basement in addition to the theater, will it overtax my my furnace and A/C unit as well as effect the climate in the rest of the house.


If it helps I have 8 foot ceilings in the basement

call a few HVAC companies in your area to come out and size up your situation. Ask for a load calculation. Tell them you intend to use the space for a HT and that there will be a significant amount of heat generated in that room.

There is a science to HVAC, but its not overly complicated.

There is a science to HVAC, but its not overly complicated.


Hey!!! I resent that! ;)

Hey!!! I resent that! ;)

let me guess......HVAC guy?

I have found that HVAC is one of the LAST bastions of construction that hasn't been fully infiltrated by the DIY'er......I mean you can go to Home Depot and buy just about anything for a plumbing project, or an electrical project......Actually you could get everything you need to plumb or wire an entire house at Home Depot......Try doing that with HVAC and you will be sorely disappointed.

Occasionally you can find a supply house that will sell you everything but the equipment, but don't expect any advice from them.....they want nothing to do with you.

But you can buy the text books on Amazon and you can buy the load calc software on the net, and you can accomplish a great amount of the work. Heck you can even buy bottom tier equipment over the net......you just have to find someone to come out and charge it for you.

Needless to say if you put forth a significant amount of effort you can do most of the HVAC work........its that pesky problem of finding someone to come out and check your work and charge the system.

If it wasn't for the EPA and the laws on freon.....the HVAC guys would have a little more trouble holding onto their turf. ;) :D

Guess I lucked out. I had my furnace and AC replaced and just told the sales guy I wanted it big enough to handle the basement once it was finished. There were two existing vents in the basement (one along the inside wall of what will be in the finished section). From what I picked up reading here, I added two vents (using 8" insualted flex duct) off the main trunk to the outside wall and closed off the one on the inisde wall. Then I added a return using a stud wall cavity. When the guys that installed it came out to do the routine maintenace, there wasn't really anything to do since it so new, so the guy ran all of the calcualtions for me and it turns out that everything is within the specs. Cost 39.95 to find that out. He also gave me some good advice on how and where to create the opening for fresh air into the furnace room. All in all, money well-spent.

And the one thing he noticed that no one else told me is that it looks like there is a problem with the install. The ductwork from the top of the furnace that connects to the actual main trunk appear to have been sized down to fit the exisitng opening, instead of creating a larger opening to the correct size for the new furnace, so now it is short cycling. I need to see if I can get that fixed.

I agree with the advice to get someone to run the calcs for you and see what your actual situation is.

AN oh yeah, just my .02....
I mean you can go to Home Depot and buy just about anything for a plumbing project, or an electrical project..

NOT me...I have to go to HD and Lowes then back to HD to get everything I need for a plumbing project!.

Tom

let me guess......HVAC guy?

I have found that HVAC is one of the LAST bastions of construction that hasn't been fully infiltrated by the DIY'er......I mean you can go to Home Depot and buy just about anything for a plumbing project, or an electrical project......Actually you could get everything you need to plumb or wire an entire house at Home Depot......Try doing that with HVAC and you will be sorely disappointed.

Occasionally you can find a supply house that will sell you everything but the equipment, but don't expect any advice from them.....they want nothing to do with you.

But you can buy the text books on Amazon and you can buy the load calc software on the net, and you can accomplish a great amount of the work. Heck you can even buy bottom tier equipment over the net......you just have to find someone to come out and charge it for you.

Needless to say if you put forth a significant amount of effort you can do most of the HVAC work........its that pesky problem of finding someone to come out and check your work and charge the system.

If it wasn't for the EPA and the laws on freon.....the HVAC guys would have a little more trouble holding onto their turf. ;) :D

I don't feel that I need to defend the industry but while it may look easy...there are plenty of pitfalls that are apparent all over the forum.

BTW I am not an installer/contractor, but I do think it is a good idea to put restrictions on refrigerant so not any regular joe can be dumping it down the drains. :eek:

Granted...I deal with commercial systems which are infinitely more complex so I have little room to talk about residential systems.

I have found that HVAC is one of the LAST bastions of construction that hasn't been fully infiltrated by the DIY'er......I mean you can go to Home Depot and buy just about anything for a plumbing project, or an electrical project......Actually you could get everything you need to plumb or wire an entire house at Home Depot......Try doing that with HVAC and you will be sorely disappointed.

I am in the HVAC trade, and the only reason heating parts and equipment are not sold to the end user is strictly for safety. The last thing the public needs is DIYers trying to fix natural gas and propane furnaces. Honestly how many people would feel comfortable knowing that there next door neighbour the Walmart greeter was dabling in furnace repair.

Bill

I am in the HVAC trade, and the only reason heating parts and equipment are not sold to the end user is strictly for safety. The last thing the public needs is DIYers trying to fix natural gas and propane furnaces. Honestly how many people would feel comfortable knowing that there next door neighbour the Walmart greeter was dabling in furnace repair.

Bill

This might be true, but I don't see a furnace to be much more dangerous than a gas stove, or better yet, a gas log.

I am in the process of rethinking my ductwork and Hvac to be able to better utilise my unfinished basement. So far, I've had contractors come out who either seem incapable of putting some good thought into the design, or unwilling.

As an engineer, I rarely find somebody willing to put some thought into a project and charge a fair price.

I mean to design a product or something for somebody sure that deserves a great deal of pay, but to relocate ductwork in a manner other than the easist route???

Thats why I DIY!

Tboy

Usually the contractor will only revert back to "what has worked in the past". This is called covering their a$$! Why would they take the liability to start re-routing stuff when the way they did it initially works. They could care less about home theaters!

Also, just because you are an engineer doesn't mean your expectations can be applied to Joe contractor from your local HVAC installer. :cool:

If you want to DIY that is great. Please be very thoughtful though and don't just go re-routing stuff and running nothing but flex in your basement and then come back complaining when you aren't getting enough air into your basement.

HVAC designers get the most of their work by repeat business because they helped a customer fix an HVAC issue that a lot of times ends up being operator error.

At least that is my opinion....

Also, just because you are an engineer doesn't mean your expectations can be applied to Joe contractor from your local HVAC installer. :cool:

I only meant to say that as an engineer, It's easy to look at something and think that not much thought went into this or that.

For example, I have a kitchen timer magnet that sticks on your fridge. The magnet is on the top back side, and nothing on the bottom. When you hit the stop start button since there was nothing on the back behind the button the whole thing pops off as it rocks. First thing I thought man NOBODY must have tried this out on a fridge (and it came from the sharper image). My wife didn't even notice, she just uses two hands (which is what you have to do if you want to keep it on the fridge).

I am trying to put alot of thought into this, but not being a real DIY topic as mentioned makes it a little harder.

Certainly the original installer won't be asked back since he obviously put zero thought into the original layout (one branch has no less than 9 90 deg bends in the basement alone!!)

Tboy

I only meant to say that as an engineer, It's easy to look at something and think that not much thought went into this or that.

For example, I have a kitchen timer magnet that sticks on your fridge. The magnet is on the top back side, and nothing on the bottom. When you hit the stop start button since there was nothing on the back behind the button the whole thing pops off as it rocks. First thing I thought man NOBODY must have tried this out on a fridge (and it came from the sharper image). My wife didn't even notice, she just uses two hands (which is what you have to do if you want to keep it on the fridge).

I am trying to put alot of thought into this, but not being a real DIY topic as mentioned makes it a little harder.

Certainly the original installer won't be asked back since he obviously put zero thought into the original layout (one branch has no less than 9 90 deg bends in the basement alone!!)

Tboy


http://ec1.images-amazon.com/images/P/0071361294.01._AA240_SCLZZZZZZZ_V44301082_.jpg

$42 from amazon. Most of the design elements are common sense....no 90* bends in your flex is a good example. ;)

There shouldn't be 90 degree bends in flex???

My hvac guy put a 14" flex instead of running metal in my crawl space, and the first thing it does off the unit is take a 90 degree bend...

???

There shouldn't be 90 degree bends in flex???

My hvac guy put a 14" flex instead of running metal in my crawl space, and the first thing it does off the unit is take a 90 degree bend...

???

No 90 degree bends as in sharp 90's that reduce the cross sectional area down to nothing...I would hope you used a radiused elbow type 90...although it is all flex so just make it radiused if it isn't! :D

Thanks to everyone for all the help.

tlogan6797,

How exactly did you create a cold air return using a stud wall cavity? Did you run flex tubing between the studs?

My original HVAC contractor (not the builder, waaaay overpriced) but the company who did my A /C at he previous house did mention putting in dual zones but it was too expensive for me at the time. Maybe I'll give him a call and ask for a load calculation.

Means you literally use the wall as your duct...just cut in a return grill and you are good to go....

What greg_mitch said, excpet that I used a metal liner inside the stud wall cavity (mostly so that an inspector can see what I'm doing with the return). You can find the correct size parts at HD (at least I did), then I attached a round take-off to the top of the metal liner, cut a hole in the drwall to fit around the take-off, then attached the flex duct from there to a take-off on the return plenum. Just cut a 12" square hole near the floor. Pretty straight-forward.

Tom

http://ec1.images-amazon.com/images/P/0071361294.01._AA240_SCLZZZZZZZ_V44301082_.jpg

$42 from amazon. Most of the design elements are common sense....no 90* bends in your flex is a good example. ;)

Does anyone have any other recommendations to books or software? I plan on getting the above book to continue my education on HVAC. I also found HVAC-Calc online, is this software any good or are the calculations specified in the above book?

I am not looking to get into the field, just want to finish my basement and maintain my system. And I dislike paying people to do a job that I can learn to do.

For example, I was quoted $900 to install a Aprilaire 700 humidifier in my central air furnace. I did the job myself for $350 and 2 months sooner than the HVAC guy would do it. Also I didn't use a crappy saddle tap to supply water, I sweated a tee and a proper shutoff valve.

Skipp

Does anyone have any other recommendations to books or software? I plan on getting the above book to continue my education on HVAC. I also found HVAC-Calc online, is this software any good or are the calculations specified in the above book?

I am not looking to get into the field, just want to finish my basement and maintain my system. And I dislike paying people to do a job that I can learn to do.

For example, I was quoted $900 to install a Aprilaire 700 humidifier in my central air furnace. I did the job myself for $350 and 2 months sooner than the HVAC guy would do it. Also I didn't use a crappy saddle tap to supply water, I sweated a tee and a proper shutoff valve.

Skipp

wow $900 for a humidifier??? I should start installing them on the side so I can finance my HT project. I could make an easy thousand a month just sacrificing two saturdays a month.....

A tragic accident happened in Toronto this week on Valentines day, a natural gas explosion that leveled a three story house. The gas fitter (a professional) was miraculously pulled out alive and is in hospital with 2nd degree burns. The home owners body (wife/mother) was recovered 3 days later. DIYers please have your work inspected. Changes that you make may affect the safe operation of your equipment. Sorry if you feel this is preachy but the safe handling of gas, propane, and oil fuels and the appliances that use them needs to be respected.

house explosion (http://toronto.ctv.ca/servlet/an/local/CTVNews/20070217/house_explosion_070217/20070217/?hub=TorontoHome)


Checkout some of the related stories and videos from earlier in the week.


Bill