[Easley]

I am now at the design phase of heating and cooling my HT room. I don't want to spend $5000 on another HVAC unit just for one room. (OK, I agree it will be THE most important room, but..... ).


So here is my idea. I buy a 2 zone controller and some dampers from www.smarthome.com. I then make the HT room one zone, and the other zone will be the rest of the house.


This idea is nothing new, but the problem that arises is when the small zone (HT room) is calling for air, but the big zone is not. An example; that lets say it is winter time. When both zones are calling for heat there are no problems, but when the rest of the house has warmed, the HT may still be calling for heat. The main zone will shut off but the HT room will remain on. This is a MAJOR problem because the HVAC blower will become stressed because ALL of its air is trying to be crammed into the HT room. This will damage the HVAC. I read you need to allow at least around 85% of the air to flow.


So the solution is to somehow maintain the airflow going through the unit. One solution is to install a Barometric Pressure Relief Bypass Duct that would sense the extra pressure and route it back to the return system. But this can be bad for your unit because it is cycling air outside its normal temperature range.


So how about this solution; I would install 2 large (14" ?) supplies and 2 returns to the HT room. I would also NOT put all the non-living areas (bathrooms, hallways, laundry) on a zone at all (i.e. supplies would not have dampers). So in our example; When the main zone is off and the HT zone is on, we still have lots of air flowing through the system (HT room, bathrooms, hallways, and laundry). Problem solved. Right?


Here are the advantages and disadvantages:


Advantages

---------------

*Cheap (~$500)

*Low wind noise in HT because of large supplies

*Large supplies will heat and cool room quicker, minimizing the time the zone needs to be on.


Disadvantages

-------------------

*Will make non-living areas uncomfortable at times (but thats their problem right? )


Any thoughts on this idea?

 

[Jim Mc]

Steve,

Let me throw a fly in your mix.


It's winter the home needs heat or is comfortable and the theater needs cooling. Yes cooling. With many people and gear in a small room heat can really build up.


It's summer the home is comfortable and again the theater needs cooling. In cooling the HT the home gets to cold.


In both cases I think the solution is plentiful air circulation from the HT to the rest of the home.


I agree a seperate system is unrealistic. But if I had the money that would be the #1 choice.


Jim Mc

"The Stargate"

http://albums.photopoint.com/j/Album...&sp=1&vt=vpall

 

[jkv]

Quote:

Originally posted by Easley So here is my idea. I buy a 2 zone controller and some dampers from www.smarthome.com. I then make the HT room one zone, and the other zone will be the rest of the house.

This is a very good way to do it. I have 3 units for my home, each unit runs 3 zones for a total of 9 thermostats. The HT is on it's own zone.

Quote:

This idea is nothing new, but the problem that arises is when the small zone (HT room) is calling for air, but the big zone is not. An example; that lets say it is winter time. When both zones are calling for heat there are no problems, but when the rest of the house has warmed, the HT may still be calling for heat. The main zone will shut off but the HT room will remain on. This is a MAJOR problem because the HVAC blower will become stressed because ALL of its air is trying to be crammed into the HT room. This will damage the HVAC. I read you need to allow at least around 85% of the air to flow. So the solution is to somehow maintain the airflow going through the unit. One solution is to install a Barometric Pressure Relief Bypass Duct that would sense the extra pressure and route it back to the return system. But this can be bad for your unit because it is cycling air outside its normal temperature range.

I use barometric pressure relief values and have never had a problem after 4 years of use.

Quote:

So how about this solution; I would install 2 large (14" ?) supplies and 2 returns to the HT room. I would also NOT put all the non-living areas (bathrooms, hallways, laundry) on a zone at all (i.e. supplies would not have dampers). So in our example; When the main zone is off and the HT zone is on, we still have lots of air flowing through the system (HT room, bathrooms, hallways, and laundry). Problem solved. Right?

you should at least have a hvac contractor look at your setup even if you do the work yourself. Every zone has to have a return regardless of the size; large spaces should have 2. Place the outputs opposite of the thermostats and the returns should be placed somewhere close to a thermostat. This allows the thermostat to give you a more accurate reading due to the air circulation. Never put a return in a laundry room, kitchen or a bathroom.


What you have proposed is to always condition your living area when the HT room is calling; this may make the living area temp different to what you have the thermostat set for.

Quote:

Here are the advantages and disadvantages: Advantages --------------- *Cheap (~$500) *Low wind noise in HT because of large supplies *Large supplies will heat and cool room quicker, minimizing the time the zone needs to be on. Disadvantages ------------------- *Will make non-living areas uncomfortable at times (but thats their problem right? ) Any thoughts on this idea?

go with the zoning and put in the pressure relief values. Like I mentioned, I have 9 zones in a 6000 sq ft house. If nothing else, every area of the house has a very even, comfortable temperature. Plus, I don't have to condition rooms that are not being used, like the guest room or the play room.

 

[jkv]

Quote:

Originally posted by Jim Mc Steve, Let me throw a fly in your mix. It's winter the home needs heat or is comfortable and the theater needs cooling. Yes cooling. With many people and gear in a small room heat can really build up.

This is not a problem, at least for my setup. When you zone a hvac system, the tstats are connected to a zone controller and the zone controller is used to control the dampers and coordinate multiple tstats that may call. In the winter time, I always set the tstat in the HT to cool mode while the other tstats are set to heat. The zone controller arbitrates and will hold the calls from other tstats that want heat until the HT tstat has completed the cool cycle.

Quote:

It's summer the home is comfortable and again the theater needs cooling. In cooling the HT the home gets to cold.

not if it is on its own zone

Quote:

In both cases I think the solution is plentiful air circulation from the HT to the rest of the home. I agree a seperate system is unrealistic. But if I had the money that would be the #1 choice.

zone the system the right way and you will not have these problems. I am running 9 zones and every area that is controlled by a zone is comfortable and maintains the proper temperature.


One of my zones is a sun room, which in Atlanta during the summer could be a problem with comfort, but the zoning allows it to be cooled separate from the rest of the house. The example you gave with trying to cool a HT in the winter while the rest of the house wants to be heated is another good example.

 

[Shag]

Can someone explain how "zones" work in a HVAC context? I am about to run ducting for my entire basement (in which one room is my media room), and would be interested in being able to control the temperature in my basement independently (gets mighty cold during out Minnesota winters). How difficult/expensive would zoning off my basement be vs just running standard ducting work off the trunk lines?

 

[jhill32]

Shag,

Have a read at the link posted by Easley here . It does a nice job explaining the concept.


Basically, it allows for different rooms (zones) to ask for the heat/cool individually. The same equipment actually supplies the heat/cool air, but through the use of dampers (essentially duct on/off valves) only the room that needs the air gets it.


Depending on where you attach your new ductwork, you may have limited success in retrofitting in a zoned system. Obviously, you need to attach your new ductwork before any other runs are made to the rest of the house in order to fully utilize a seperate zone for the basement.


If your house was constructed like most others in this area, you will probably find that you have two main runs of ductwork in your basement, running the length of the house. One of them is the pressure side, with various runs of 6" round pipe feeding air to floor registers above, the other is the return. That means, in order to have the basement as a separate zone, you will need to add a third main duct to feed just the basement registers. The returns for the basement can be added to the existing return duct.


I have a full 2-story house, and I was hoping that I could at least make separate zones for the first and second floors. But, since the feeds that branch off of the main pressure duct are spread throughout the length of the house, there is no way to reasonably split them up and create separate zones.


Depending on how much of your basement is undergound, it should actually be easier to control the temperature. Generally, the biggest problem with cold basements, is that people don't plan for enough registers and returns. I have 4 registers (pressure side) and two returns added right on to the existing ductwork, and it works fine.


You only live a few miles from me, come on over and see for yourself

 

[JAB]

I've been having a similar debate recently. My HVAC contractor is against using a zone controller, because althouth the zone controller will easily handle the HT calling for cooling while the rest of the house is calling for heat, the heat pump is not designed to deliver cooling when the outside temperature is low. He says that doing a low ambient temperature retrofit on the heat pump would be expensive.


Unless Dennis disagrees, I'm going to dump all the hot air from my equipment closet and projector into (a) my HVAC closet, where it can be processed through a central air return, or (b) into an open room outside the HT, where I can install a ductless air conditioner if I need to remove the heat from the house.


As far as I can tell, the ductless air conditioner designed for low ambient temperature operation should not cost more than about $1,000 installed. The equipment itself is readily available for around $600.


/jab

 

[steve]

Use a zone controller and over-sized supply ducts. Just keep in mind that some zone controllers give priority to the heat mode, while others allow you select which mode (heating or cooling) is to have priority.

If you have over-sized ducts, you should not have a problem with too much backpressure, wich can harm the compressor or fan. Alternatively, install a pressure bypass line that will re-direct the air flow if the back pressure becomes excessive.

In my situation, the theater is located in the lower level, along with a party room, a spare bedroom, an exercise room and two bathrooms. The rooms (other than the theater) are not used often, and were placed on one zone. The theater is on the second zone. The theater always needs cooling; it never needs heating, even in the winter. By using a zone controller that allows the cooling mode to have priority (such as a Robertshaw controller, available at Smarthome), the theater is always at the desired temperature.

If the other rooms require cooling while the theater is being cooled, the damper for those rooms opens. However, if the other rooms require heating and the theater is being cooled, the other rooms must wait until the cooling requirements for the thetare are met and the switchover is made.

My supply ducts are 16 by 20 inches in size (I have a geothermal HVAC system). The oversized ducts permit zoning without the need for a bypass line, and also results in a slow airflow, which translates to a very quiet system - so quiet that I can not hear the airflow, even when the sound system is off.

BTW, if you don't use the theater as much as you use the other rooms, install an X10 thermostat in the theater (or simply turn off the thermostat when the theater is not in use). In this way, you can ensure that the thermostat that controls the other rooms will maintain those rooms at the desired temperature until such time as you wish to use the theater.

Steve

 

[Cain]

Yo Stevie!! Welcome to AVS!!!


I struggled with this HVAC business also, until I finally buckled under and am going with a separate Unit for the HT.


It has a number of advantages, one of the key ones is the ability for me to continually add fresh air to the room, to avoid it getting stuffy. I'm looking at around 3K total.


Geddy helped me pick out my carper Friday, with my Aunt the Interior Decorator (8Something's Mother). I now have carpet, chairs, wall fabric and all equipment picked out.


You really need to stop by here and learn from my process while/before you start your HT.


Also, you are foolish if you do not hire Dennis Erskine to design your HT. His service is far more valuable than the amount of money he charges.


Best wishes, take care,


-- Cain