Chinadog's Tennessee Theater! - Page 18

I wouldn't be surprised if he doesn't offer a little "side work" for half the cost. You know, "I got a guy......."

Business must be REALLY good in your neck of the woods!

Bud sounds like you are finally gettin somewhere. So I assume (hope) the part I have quote above is not to be considered conversion to a 2nd dedicated zone..

Great news, that! I mean, as good as writing someone a $3k+ check can get, anyway

Bud,
Sounds like you finally have a plan that you can trust; and is justifiable.
Your perseverance is paying off.

Hey Chinadog. I've got a very basic HVAC question i hope you don't mind i ask here. Does adding another Zone allow you to have AC to cool your theater in the winter while the rest of your house gets heat at the same time? I haven't been able to figure that part out. I would think you would need a whole separate AC system to do that. If so, what's the benefit of just adding another zone?

Hopefully Chinadog won't mind me answering this, but the short answer is yes. The unit will run on heat until the demand there is met and then the unit will switch to cool and run on cool until the demand is met there. It doesn't do both simultaneously.

However, the longer answer is your unit has to be specifically outfitted to provide cooling when temps drop below 40 IIRC.

EDIT: That's all from memory, so the finer details might be a little off, but you get the idea.

Thanks for the explanation guys. I guess I always had it in my mind that you'd ideally have to have both AC and Heat at the same time in different parts of the house, but maybe not... That simplifies things.

I want to tackle some of these zoned HVAC questions/misconceptions. I have owned and lived in homes with zone control. The net out is my energy costs were reduced (significantly) and comfort in the home improved. For example, when the upper floor needed cooling (nearest the roof), why am I also sending cool air to the main floor which is perfectly comfortable? With guest bedrooms, when not being used I could allow temperature swings from 60 to 80 degrees ... when occupied, I could make the room comfortable for the guest (or uncomfortable when I wanted them to leave ). With South facing rooms and North facing rooms, I was not heating or cooling rooms which would be made uncomfortable to satisfy the comfort of the opposite side of the house. The baby's room (that was a long time ago) could be set to temperatures better for the child without needing to heat/cool the entire house.

Zone control boards can handle Heat/Cool "calls" in two ways. One is round robin. The first room calling for service gets serviced and once satisfied the next area is serviced, etc. The other is "priority". You can assign the master bedroom as Priority 1, the family room as Priority 2, etc. The area with the highest priority is serviced first. Most zone controllers are priority based. If you have two areas assigned the same priority, then all of those areas are serviced "round robin" before moving on to the next priority.

Let's deal with this heat and cool at the same time issue. Let's acknowledge you cannot send both heated and cooled air down the same duct at the same time and get the results you want. In any given zone (even it is only one for the entire house), your system has been designed to raise, or lower, the temperature in the house by x number of degrees over y number of minutes. At the same time, your thermostat has been set up such that it will not call for heating/cooling unless the temperature is more than +/- n number of degrees off the set point (this can vary from 3 to 5 degrees and with electronic T-stats, you can control this (within reasonable limits).

So, let's back up into this matter of the theater wanting cooling while your living room wants heat. Here's the reality (with entirely made up numbers). Temperature swings with any given room don't occur rapidly (in the absence of a mass ejection event). You could reasonably expect to see a 3 degree swing over, say 15 minutes (bad day). On the other hand, your HVAC system will make up that swing in, say 5 minutes. So, let's say your living room is demanding heat, your theater cooling. Your living room is cooling at the nasty rate of 1 degree every five minutes. Your theater is heating up at a rate of 1 degree every five minutes. What that means, in the end, is your theater will heat up by one additional degree in the time it takes to make the living room toasty. You really won't notice this. (Understand this example is "made up" ... the rate of temperature change will vary by climate and how well your home is insulated. None-the-less, your HVAC system design is such that it will heat/cool far faster than what is lost/gained.)

While one zone could want heating, and other cooling, your system will not do both at the same time. By the same token, you're not going to notice this (one exception). What you will notice is the reduction in your heating/cooling costs. (The one exception could be where you have a room you've allowed to swing from 60 to 80 degrees and now you want it up to 70 for your guest ... the time it takes to service this could result in more than a 1 or 2 degree difference elsewhere).

On final thought .... you really, really need to know what your system is doing with respect to the number of minutes it will take to raise/lower the temperature. Many people will change the temperature setting in their office or home during the time it is not occupied ... I cannot tell you the number of times this was taken to such an extreme that it actually took more energy to recover than it would take to have just left the T-stat alone.

Oh. And I have now reached the age where I can be a grumpy ol' man. When I see a rabid environmentalist zealously conserving non-renewable resources, I get to thank him/her for their efforts and then call them a hypocrite if their HVAC system is not zone controlled.
Edited by Dennis Erskine - 2/13/13 at 6:25am

That doesn't sound like something I want happening in my house, let alone my theater.

Nice :0

Will it do Dolby TrueHD?

Actually, it is a vector T-stat ... no pixels.

There is one other very important aspect to HVAC zoning that was not covered in this whole discussion, and that is regarding what must be done to adjust the total amount of a HVAC system's output. This is the same exact situation I was confronting with my system, so I thought I would share with everyone the available options using Bud's system as an example.

Let's assume the current HVAC system can supply 800 CFM. A zone control is added to the system, along with two supply lines and a single return air line for the theater. If the theater calls for cooling, for example, it is not correct to assume that all 800 CFM of supply will go to the theater. The HVAC can only supply the air amount of air that is returned and the supply / return lines to the theater cannot handle that amount of capacity. Hypothetically speaking, even if the supply and return lines could handle all 800 CFM that would lead to another problem - short run times since 800 CFM to a single room would cool the room extremely quickly. On the other side of the coin, if the HVAC supplied / returned the 200 CFM (approximately) designed for the room, there will not be enough air moving across the A-frame cooling coils, leading to the formation of ice on the coils and reducing operating efficiency or worse - burning the unit out.

So what can be done to zone just the one room while still allowing for sufficient run times and enough air moving across the coils? One way is to have a HVAC system with a variable speed blower motor that can be programmed to work in perfect coordination with the zoning system. These systems are also designed to adjust the coolant circulation to be matched with CFM output level of the fan. Another approach is to use a pressure-balanced bypass diverter, which is essentially a short run of a large rigid pipe (10" or 12") that runs between the main supply trunk just beyond the coils directly to the main return air line. In the absence of a variable speed blower, all returns tied to the system will be open, the single room will receive the expected amount of supply and the pressure balancing diverter simply diverts the remaining over-supply back into the return air duct. The last option is that the excess capacity is essentially bled out to a single larger duct in the zone that is NOT calling for supply in the most inconspicious spot or even a storage area. So intead of the excess capacity being recirculated through the unit, it is dumped into the larger zone so the HVAC system can maintain its CFM past the coils.

It looks like Bud's guys are going with the bypass diverter, which is an excellent choice to retrofit his single-zone system in the most efficient way possible.

That would be awesome if you could hook it up to the air hockey table or pop a shot.

Strange indeed.. Maybe you should have your water tested. It's uncommon to have copper tube fail on city water. Even in the case of galvanic corrosion it's usually not the copper that fails. I wonder if you have some stray current going through the piping.

It's also weird that you have two failures so close together. The question is: What's changed?

Tim