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Old 04-16-2009, 08:05 AM   #61
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Return Air Vents


Jim-

It's been a while. Thanks for all the help. It's been a long winter and I've had too much time to think. I am getting ready to start some major projects on the house over the next little bit, adding a new laundry room on the main floor of the house, repiping the place with pex and the big one, a small, albeit three story addition on the back of the house to add a full bath, powder room, mudroom and some storage. It should be fun, the architect is working up the plans now. But somewhere in there, I am going to get to this return air problem. Figure if I am opening up one can of worms, why not open them all.

Anyway, I feel great about the plan we setup to improve the return air but I am wondering, while I am at it, how hard would it be to convert the system over to a multizone? I think ultimately I'd like to have 3 zones, one for each floor of the home, does that make sense? I've done a bit of research and overall it doesn't seem too complicated, but was hoping you could talk me through it a bit. Anything to watch out for? Any special considerations? Any suggested materials?

Thanks!

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Old 04-16-2009, 10:02 AM   #62
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A multi zone system is going to need to have some room to split everything up. You need to seperate things a bit more then what you have. Your returns should also be seperated to each area that you have a zone. So each zone Idealy would have a seperate trunk line off the end of the coil. Also idealy the returns would be the same. A seperate return for each zone. So any air that gets pumped into a room (or zone) doesnt have to leave that room (zone) to return to a return grill, if that makes sense. Zoneing I found for me wasnt to expensive. The dampners are 100-150 each per zone. The key pads are 100-150 per zone. The panel was few hundered. You will need a bypass dampner from the plentum to the return. Youll need a few other sensors too (outdoor & discharge). You will find if you take this project on (which is nothing compaired to what you have planned already) you will probley remove and replace both plentums you already have on the unit in order to make more room and seperate the zones. You will most likley end up haveing to reduct the majority (probley all) of the house. So if you prepaired to spend 1500-2k worth of equipment and Reduct the house I say go for it. I have done it and love it. I have a much smaller house then you (1500 sf) and have & zoned 3 bedrooms and the rest of the house seperatly (much diff. then yours). At night I run only the bedroom heat or a/c and have the rest of the house on a 7 day timer to turn on in the Am. Guest bedroom/office I turn on when Im going to use those rooms. And If I have them all on. Its evens out all the temps threwout. The side of the house that the sun hits and those rooms always seem hotter now dont.

Heres the equipment I have. Honeywell Networked Zoning.
http://customer.honeywell.com/Honeywell/UI/Pages/Catalog/SystemCategory.aspx?Catalog=Homes&Category=Network ed+Zoning_131&ChannelID={2EB2F178-20ED-44E0-97FB-CCFB4218DD64}

Panel:W8835A1004
Outdoor Temp sensor: 50022037-001
Discharge Air temp sensor: C7835A1009
Thermostats: TH9421C1004 (4 of them)
Dampners: ARD12's (2) and ARD8's (2) ARD9 (1)
Bypass Dampner: SPRD12
120 to 12volt transformer: AT140D

Dont go by the list prices on the Honeywell sight. I payed around half those price for everything. Search google you will find atleast 3 good, big websites that have everything. Heres one.
http://www.iaqsource.com/category.ph.../?category=656
They have part number for complete kits.

Heres a PDf that might help your too.
http://customer.honeywell.com/techli...0s/50-9420.pdf

There is also a telephone access modual I have that's very nice: W8735D1009
You could look into that too. Everything uses 3 wire IAQ wireing to each componet back to the main zoning panel.

Feel free to ask any questions if you start this project. Thanks JIM
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Old 04-16-2009, 10:12 AM   #63
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Thats a good zoning system.
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Old 04-16-2009, 02:08 PM   #64
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Makes perfect sense. I think I am actually in better shape for this than it appears.

First, I need to improve the return air regardless and it will effectively be divided up by the 3 zones, 2nd floor, main floor and basement.

As for the supply, currently there are two branches from the air handler, one that supplies the 2nd floor and one that supplies the main floor and the basement. My thinking is that I will simply close off all the current supplies to the basement and run a third branch for all new ductwork in the basement, while leaving the 2nd floor and main floor ductwork the way it currently is. Will this not work? The way I see it, there will be a separate return air and supply air branch for each zone.

Do I need to install motorized dampers on the return air as well, or just the supply?

I understand the need for the bypass damper, but what do the two sensors do?

So, any thoughts?
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Old 04-16-2009, 02:59 PM   #65
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Outdoor sensor, is for freeze protection when using a humidifier.
Also displays outdoor temp on thermostats.
Discharge sensor, protects the furnace from over heating, and the A/C from freezing the coil.
When only one zone is calling.
No need for dampers on the return.
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Old 04-16-2009, 03:02 PM   #66
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OK, great. So, assuming I have 3 distinct branches for the supply, this should be a pretty straightforward process? That is to say, no need to worry about reducting the whole house? Or do I?
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Old 04-16-2009, 03:15 PM   #67
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Don't need to reduct the whole house for 99% time.
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Old 04-16-2009, 03:18 PM   #68
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So, effectively I need to...
1) Add dampers to all three of the supply branches
2) Place a thermostat in each zone
3) Add a multizone panel to manage everything
4) Install the bypass damper between the return and the supply
5) Install a discharge sensor

Is that the project in a nutshell?
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Old 04-16-2009, 03:30 PM   #69
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Pretty much.

Of course, you need to size the damper to move enough air for the smallest zone to call by itself.

If you use the panel suggested earlier. Seldom will the basement zone have to call.
It uses auto master technology.
Helps prevent needless short cycling.
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Old 04-16-2009, 03:35 PM   #70
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Hmm. So, they damper isn't just the same size as the duct? Can you explain this a bit more? I am confused. Or are you just talking about the bypass damper?

As for the basement, that's actually why we are doing this. My mother-in-law lives with us in an apartment in the basement. Ultimately we'd like a way to heat/cool the basement without necessarily heating and cooling the rest of the house. We'd like her to be comfortable without having insanely high energy bills. So, am I going about this the wrong way?

Last edited by stubits; 04-16-2009 at 03:41 PM.
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Old 04-16-2009, 04:38 PM   #71
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I was talking about the bypass damper.

Zoning is a good way.

The 8835 panel will auto master.
Means the zone that calls the most will be the master zone.
So if the basement were to call for heat more then the other zones. The basement will become the master, and the other zones become slave zones.
So that when teh basement calls for heat. The zone panel looks at teh temp of the other zones, and will give them some heat also. Depending how far away from set point temp they are.

This prevents short cycling because it eliminates those zones from calling for heat 5 minutes after teh basement zone is done calling.

Same in summer. The zone that calls for cooling the most, will become the master zone.

It saves a lot of wear and tear on your equipment, and can save money on heating and cooling.
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Old 04-16-2009, 08:00 PM   #72
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Ok, starting to make sense.

So, how do I go about properly sizing the bypass damper? All of the zones are actually the same size, each is one floor of the home, approximately 650 sq. ft. per zone. Any suggestions?

The auto master system is interesting to know. Are there other sorts of systems? Is the auto master system the best? Are there systems that are more programable? For example, we'd like the basement zone to be the master during the day, but one of the other zones to be the master during the evening. Is that too complicated? Are are the options?

Thanks!
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Old 04-17-2009, 06:18 AM   #73
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The system will determine which to use as the master, by determining the zone of greatest demand.

You can't change it yourself.
Its a comfort feature.
Having the basement as the master zone, when one of the other zones calls twice as much. Would mean the other zone wouldn't be able to maintain temp.

Their are other zone systems out there.

But, not as well set up. They won't have auto zone mastering. So they will allow your system to satisfy one zone. And 3 to 5 minutes later start up for another zone. That could have used some heating or cooling while the first zone was running.
But because its not a communicating system. It can't know if another zone will need conditioning if a few minutes.

Your basement zone won't need as much A/C as the first floor zone, which may not need as much A/C as the second floor zone.

Suppies are suppose to be sized to deliver X amount of CFM.

So you need to find out which zone has the least amount of CFM delivered to it.
Then subtract that from how many CFM your equipment must move.
That tells you how many CFM your bypass must handle.
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Old 04-20-2009, 09:06 AM   #74
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This is great information! Thanks!

Ok, so from what I understand about the auto master system, it won’t really affect how we as users experience the system, right? What I mean is, does it give preference to the master zone? Let’s say during the summer I want my bedroom (zone 3) cooler than the basement (zone1 – master). Does the basement win out, or, within reason, can the two zones have different temperatures? Does this make sense? Is the auto master mostly to make sure that the HVAC system is running most efficiently?

Ok, now some questions about sizing. As you know from all my previous posts, I don’t think this system was designed with a whole lot of thought and care (not enough return air, oversized air handler, etc). I’d rather not rip out all the ductwork and the whole system, but I want to make sure I’m not making any big mistakes here.

So, each floor is approximately 650 sq. ft. of living space and I think I’d like to make each floor its own zone. Can you give me a VERY rough estimate of how many CFM I should have per floor?

Currently the supply air plenum is 22 ľ x 20 x 20 and there are three branches coming off of it, there are two 10x8 rectangular ducts that service both the basement and first floor. There is also a supply stack that runs from the plenum up to the attic where it branches off to service the 2nd level. I haven’t been able to figure out what size it is yet, I need to get up into the attic to figure it out.

In order to make this all work, I will seal off the existing supply to the basement so that both of the 10x8 supply ducts will only service the main floor of the home. I will add new ductwork just for the basement. I will keep everything the same with 2nd level.

Ok, so here are my questions…

1)Can one zone have more than one damper? That is to say can I put a damper on both of the 10x8s and have them operate together? I assume the answer is yes, but just checking.
2)What size ductwork would you recommend to service the basement? It is 650 sq. ft and three rooms (bathroom, bedroom and living room/kitchenette).
3)I think it would make sense just to replace the supply plenum, no? If so, is this one sized correctly? Should I get one that is bigger? Smaller?
4)In order to make this work I think I need to move the whole HVAC setup forward a few inches. Will that be hard to do? I will already by disconnecting the return and the supply. I know I’ll have to rework the gas line a little bit, as well as the vent, but otherwise, should it be manageable?
5)As for the bypass damper, thanks for the explanation on sizing it. That makes sense. Where would it be located? Can I connect it from the supply plenum to the return plenum/drop?

Thanks!!
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Old 04-20-2009, 11:17 AM   #75
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Quote:
1)Can one zone have more than one damper? That is to say can I put a damper on both of the 10x8s and have them operate together? I assume the answer is yes, but just checking.
2)What size ductwork would you recommend to service the basement? It is 650 sq. ft and three rooms (bathroom, bedroom and living room/kitchenette).
3)I think it would make sense just to replace the supply plenum, no? If so, is this one sized correctly? Should I get one that is bigger? Smaller?
4)In order to make this work I think I need to move the whole HVAC setup forward a few inches. Will that be hard to do? I will already by disconnecting the return and the supply. I know Iíll have to rework the gas line a little bit, as well as the vent, but otherwise, should it be manageable?
5)As for the bypass damper, thanks for the explanation on sizing it. That makes sense. Where would it be located? Can I connect it from the supply plenum to the return plenum/drop?

Thanks!!
1. Yes. You just daisy chain the wiring from one damper to the next.
2. Do a load calc, and you will know how many CFM needed for each floor.
Also makes it easier to size the bypass damper.
HVAC CALC that advertises here, is a good program to use.
3. Depends. If you have room to install the additional supply trunk. And to install the bypass damper. No need to replace the plenum. If you don't have enough room on the plenum. Then making it longer will help.
4. Might have trouble with the A/C lines.
5. If you have a central return. Connecting it to the return box and supply works good(This contradicts Arzel instructions, but we ain't talking about an Arzel system).
If you don't have a single central return. Then connectin the bypass to the return that can handle both the bypass volume, and the retrn air for the area it serves works.

Last place, is direcly to the return plenum.

1-Honeywell Y8835A1028 System saver kit.

Comes with:

1) W8835A1004 Envirazone Zone Panel (3H/2C)
(3)TH9421C1004 VisionPro IAQ Thermostats
(1) AT140A Transformer
(1) C7835A1009 Communicating Discharge Air Sensor
You may want to get the optional outdoor temp sensor. Comes in handy if you have a humidifier.
Bypass damper is not included, since no way for them to know what size you need.
You can set the thermostat for any zone at any temp you want.
You can even use auto change over.
Which would make it that one zone can call for cooling. And later, that zone could call for heating if it were to get to warm.

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