Quick question for anyone to answer. My HVAC system in my basement is currently sized to accommodate the basement and 1st floor. I was thinking about zoning it to give me more control in the basement versus using it all as one zone controlled by a thermostat on the 1st floor. Zoning is preferable and should be able to be done my me fairly easily. I would end up with 4 total zones: 1st floor, HT, main basement area, and future basement bedroom. I would install zone dampers on each branch duct in the basement (6 total duct runs using 8" flex). I would NOT install a damper for the 1st floor since all of my runs for the basement would have to come off the main trunk line.

My questions is will this work OK? What I see happening is if any zone in the basement calls for heat/air that zone + 1st floor get it since the other basement zone dampers close. If 1st floor calls for heat/air ONLY that zone gets it since all the other dampers close. Maybe I am wrong. I just thought I would ask the question and hope someone here might have an idea about this.

Any help is appreciated.

John

It might work but I'm no pro. I don't see why you would want air going to the first floor all the time. What if it's winter and the theater calls for AC? That means the first floor cools off when it doesn't need it. Why not just go ahead and put in a fourth damper?

Also, be sure you know what you are doing. Closing off 3 zones creates a lot of pressure in your ducts. That pressure will cause a lot of air noise out the ducts, burn out the fan in the unit and could freeze up the unit from the lack of air moving through.

What if it's winter and the theater calls for AC?

Yes with enough people a well insulated and sound proofed space may need AC in the winter. A separately zoned system would be ideal.

Now there are just a couple of problems with this. Not all AC compressors are designed to work when the outside temp is below freezing so you need to check your system.

An alternative is if the first floor get's mixed with the HT air then you can run "fan only mode" and mix the cooler upstairs air with the HT air to cool it down. You could also open a window on the first floor and add that to the mix. Certainly not an elegant solution but it's the only one I've got.

It would be a lot of work for very little impact. It will work they way you suggest, but as was pointed out, you'll be using A/C in the winter so the vast majority of supply air will be routed to the 1st floor where it isn't needed. That will result in then needing to heat the first floor back down to setpoint. You'll also lose the ability to focus a large volume of air to a small area when needed because the 1st floor will always be a gaping hole in the system whenever it has reached setpoint and doesnt require any additional supply air.

If you are going to zone, you really need to plan on isolating the 1st floor ductwork so you can put a damper on it. Then add a bypass damper for those times where only 1 or 2 smaller zones are calling.

Don't look at all the 1st floor duct runs coming out along the length of your trunk line as a severe problem. It's much more likely that the most convenient way to rework your supply lines will be to disconnect your basement supplies, tie them into three smaller trunk lines and run them back to tie into your system between your system and the main trunk line.

Chances are all your runs are flex-duct, so if you can master the use of zip ties and duct tape, you could do the vast majority of work yourself.

but as was pointed out, you'll be using A/C in the winter

You think so? I am locating my equipment out of the room other than the PJ and am venting it outside the HT area. I did not think there would be enough heat buildup in the room to warrant AC in the winter. Maybe though.

CPanther95, I may have to get you to come by one evening soon (since you are only a couple miles from me) and take a look at my HVAC setup now and have a beer while you are there if you do not mind. I can PM you my address if you'd like. Right now it is a single metal supply line coming off my unit (roughly 12" x 24") with flex in all the runs coming out of the top of the supply duct. I may be able to splice a tee or 45 into the main supply line and run a second supply line alongside the main one. From there I could run flex to all my register locations. I would hate to have to rip the whole supply duct out if I can help it. I should have done this before I framed out the basement ceiling but I was not thinking about it as I thought I would be able to zone the basement much easier. Right now I have NO supplies in my basement at all so any runs for the basement are going to be new as there were never any registers put into the basement during construction of the home. Oh the hazards of a spec home.

Right now my return air is flex from the kitchen area above right into the top of the return air plenum on the unit.

Or I can go the cheap a$$ way, run all my new ducts for the basement and just let the 1st floor control both the basement and the 1st floor. Or NOT!!!

John

I sent you a PM with my phone number - call me any time.

If they sized the equipment for both floors, but didn't run any of the basement supplies - then there wouldn't be much additional work (since you have to run the basement supplies anyway). Typically, you'd just insert a new supply plenum box with 4 dampers - 3 to the basement zones, and 1 to your existing supply box feeding your 1st floor supplies.

You must have a heck of a lot of air pressure coming to the first floor if it was sized for both floors but there are no supplies for the basement. Then again, most contractors really undersize units. They do it for better humidity control, but most take it too far.

I've got 2 zones on my first floor and 5 zones (just reduced from 6) on my upstairs system. If you want to get a better visual of the zoning system, you can check out the unit in my attic.

No, the pressure is not that bad for the 1st floor. I'm going to give you a buzz shortly. I really need to look at a system to get it in my head what I can do. Thanks for the help and all others that have replied.

John

How effective making zones for your HVAC system on cost of electric or gas? Is the cost of zoning worth what you save on your bill? Or is it just a matter of convience?

It can save money, but the big factor is much more comfort. If you use it to cut off rarely used zones, that's where you'll save your money - focusing all your conditioned air only to the areas that need it and giving you shorter run times. It can also save quite a bit shutting off bedrooms during the day.

If it is just to have better regulated temperatures, it won't necessarily save you much. If your wife is like mine and likes to sleep at 60 degrees, but wants the master bath at 73 - it can cost more. ;)

Bottom line is most people are controlling the temperature of a hallway, not the areas of their home that they actually spend their time.

I just zoned our house. No idea if it will save money on the utils. It was done because our unit was sized for the main floors only, so zoning was a way to handle the additional load the basement represents.

I can say the comfort of our house is much improved. The rooms are generally the temps we want them to be, instead of the freeze in the den, boil in the bedroom scenario we often faced.

CP95 - nice to see you back in this forum. I remember your build thread. I have found your advice helpful in the past.

The BD/HD-DVD forums have kept us all pretty busy the last few months. :(

You think so? I am locating my equipment out of the room other than the PJ and am venting it outside the HT area. I did not think there would be enough heat buildup in the room to warrant AC in the winter.
Yup...you will. Even in Adak or White Horse you'll use A/C in the winter. (Yes, I've been there)

How effective making zones for your HVAC system on cost of electric or gas? Is the cost of zoning worth what you save on your bill? Or is it just a matter of convience?

yeah, it's worth it....

I have 3 units in my house (basement, first floor and second floor), with each unit broken up into 3 zones for a total of 9 zones (with 9 thermostats of course....). I had the HVAC contractor zone the system while the house was being built (6000 sf); I think the upcharge for this work was around $5000 back in 1998 and my heating/cooling bills are much less than my neighbors for the same (or larger) size house.

The greatest thing about this is the comfort, no more cool/hot rooms at the far end of the house; the house is an even temperature.

I also keep the thermostats turned way back for unused rooms; the guest rooms are set for 55 in the winter when they are not occupied, why heat a room if no one is using it?

I also run my A/C in the theater even in the winter. You will be surprised how hot a room will get when 6 people are sitting there for 3+ hours, not to mention the comfort of getting some cooling air. A zone controller will negoiate when multiple zones call for heat vs cool at the same time so while the theater will call for A/C, the remainder of the zones that call for heat will be satisfied.

HTH

Well thanks to a local AVS fellow, namely Matt (CPanther95), I am definitely going to zone. He and his wife were kind enough to allow me to come over and take a look at the zoning on his upstairs unit last night and after looking at it I can say without a doubt I can do it, so I will do it. I really needed the visual of a setup and his was exactly what I needed.

I will be zoning both my upstairs and downstairs units. My master BR is always colder than the rest of the upstairs since the thermostat is in the hall by the other 3 bedrooms and my master is above the garage. It will be on a separate zone.

The basement unit will be 3 separate zones, one for the main basement, one for the HT, and one for the 1st floor.

On a side note, his Matt's HT looks and sounds wonderful. I must commend Dennis Erskine on a nice design and Matt on a wonderful room. Being able to feel the bass hit even without butt kickers was too cool.

Tonight I am going to go down and take some photos of my current progress and post them. My boys are down in Columbia tonight for our local HS state championship basketball game (watching not playing). That leaves me and the wife and my 4yo alone so I may be able to go and get some things done down there. This weekend is going to be a big weekend and I hope to get a LOT done. I will post everything to my HT construction thread.

Thanks again to everyone, especially Matt. You guys are welcome to come and check out the HT anytime.

John