For variable speed control, the ECM interface is proprietary in most cases (i.e., WaterFurnace Envision units use a PCM signal), which forces one to use the manufacturer's zone controller (i.e., WaterFurnace's Intellizone, Carrier's Infinity) to achieve variable speed control as a function of which / how many zones are calling for air (as opposed to simple on/off control which many after market zone controller do quite well - i.e., EWC).

Direct access to controlling the ECM's speed otherwise will require some serious engineering.  Probably within Ed's abilities noting his 10.5 ton 3 unit system is self-installed.

I'm not familiar with FHP Tranquility 27 units, which is what Ed installed.  Perhaps the variable speed control is not 'hidden' behind a proprietary interface, such that Ed can 'roll his own' zone controller.

And it sounds like Ed's "8 zones" are spread across 3 units, in total serving almost 10K SF.  That's on average 1250 sf per zone, which is a lot more than many zoned applications (including mine, which is less than 1000 sf per zone).  It's also an average of one zone per 3/4 ton, which is not impossible to accomplish with the right zoning control methodology and pipe sizing.

So, with an 'open' FHP interface to the ECM, with adequate duct sizing, and with some serious engineering, this is probably a doable project.  'Doable' as defined as not icing up the evaporator coil  (in my case my min. air volume through the evap coil is such that supply / leaving air temp (LAT) doesn't get much colder than 47° (F) - http://welserver.com/cgi-bin/plot/WEL0043/AirTemps-EvapCoil-3TonUnit.gif ), and having sufficient register air velocity to mix well with ambient room air.

Best regards,

Bill

Bill, What is causing the spikes over 90 deg on your return temps? Latent duct air heat from being exposed to high attic temps? Where are your sensors mounted? Directly to coil or in supply and return duct?

The 8 zones are only on the 4 Ton unit serving the upstairs, 5 Ton unit takes care of all the downstairs except the Master that will be taken care of by the 3rd unit.

I am able to easily lower or raise the fan speed by 15% via jumpers on the ECM board on the FHP unit I will replace the jumpers with relays controlled via the air flow sensor in the supply. ( And some other electronics )
I do have an extensive electronics background so I can handle this with no problem.

I also can modulate the Bypass damper electronically to maintain airflow, I can dump into the attic or will add another register in the open area if needed to maintain airflow. ( Rather than recirculate back to the return as that may lower air temps too much across the coil )

In my experimenting today with the fan speed control jumpers and opening only one zone at a time I am seeing good results.

I have a good differential temp gauge to monitor Supply and return temps, I don't have the Air Flow Monitor in the supply yet so I am only able to read the flow out of the registers via a hand held velocity meter not a real accurate way to do it.

This is not something I would necessarily do for someone else as it will certainly require some tweaking during the Heating and cooling seasons to get it right.

Thanks for the comments
Ed

It seems you understand the issues that are caused by excessive zoning .
maintaining proper cfm is key to effeciency .
maintaining proper static pressure is key to maintaining cfm, noise , and equal distribution .

the reason I avoid excessive zoning of air systems is , to many variables . the more zones you add the further away from a perfect design you must be willing to deal with , as different combos open and close it becomes impossible to design for all of them . I wish I could , I imagine in the future some type of expanding flex , but for now .

I am not criticizing and am very interested in how it works out for you

You may want to add some logic that requires 3 (for example) or more zones for the heat pump to come on.
Even if your air flows are ok, I would expect short cycling at times, which effects lifetime and dehumidification.

Maybe inverter based fully variable speed compressors will get more popular.

jonr - Zone controller has that option if I remember correctly to only come on if a certain percentage of zones are calling for air I will probably set it up that way, It can also turn on 1 heat strip and Y1 to temper the air dehumidify fast, The HAI Omni T-Stats I am using I believe have Humidity control.

geo fan - I didn't take it a criticism, I applicate your sharing your knowledge and experience

Ed

Ed, both of my (packaged) units are in my attic.  With daily highs here in Dallas now above 100 degrees ( http://welserver.com/cgi-bin/plot/WEL0043/SampledOutsideWeather.gif ), and with an attic that's now seeing highs of 133+ degrees ( http://welserver.com/cgi-bin/plot/WEL0043/SampledAtticTemps.gif ), whenever a unit goes idle, the air in the associated ducts heats up.

You see more return air spikes on the 3 ton unit ( http://welserver.com/cgi-bin/plot/WEL0043/AirTemps-EvapCoil-3TonUnit.gif ) than the 5 ton unit ( http://welserver.com/cgi-bin/plot/WEL0043/SampledAirTemps-EvapCoils.gif ) because the sample frequency for the 3 ton unit is 2 minutes as opposed to 30 min. for the 5 ton unit.  Since I have zoning on the 3 ton unit, it doesn't make any sense to do any time averaging, while the 5 ton unit, with no zoning, runs in much more of a steady state environment.

My return air sensors are located just before the 4" pleated air filter ( http://www.pbase.com/neukranz/image/84285553 ), which is a little 'up stream' of the coil.

My guess is you need a minimum of about 800 cfm flowing through the coil, and a compressor running in 1st stage,  to keep the coils from icing up.  So, as long as your ducts are sized to handle 800 cfm on an individual zone basis, and you've got some fancy kind of control scheme to keep the ECM somewhere between 800 and what I estimate to be 1550 cfm, including shifting back and forth from 1st and 2nd stage cooling, then you're in good shape.  You'll definitely need to 'roll your own' zone controller.

I would suggest some caution if you have a duct with an attached pressure controlled damper, set up either as a bypass from supply to return, or supply to 'dump,' you're going to need some serious control logic to prevent the ECM from oscillating back and forth as it 'sees' a varying ESP.  It definitely will result in air velocities that sound like the wave action of the ocean.

Good luck!

Best regards,

Bill

If I understood Bill correctly in another topic, he uses some minimum amount of opening in all dampers to add additional flow.  This makes sense - if one zone is calling for cooling, it is likely that other zones can use some amount of cooling also.       Ends up being a mix of a zoned and non-zoned system.

This is correct.  I first used a borrowed flow hood to affirm Manual D concepts. 

I then used the flow hood to measure all registers in each of the single zone situations.  Learned a lot more, and found the Manual D analysis to be pretty good after adjusting the analysis to 'as built.'

I lastly used the flow hood to set air velocities appropriately at each register.  This required adjusting the minimum 'stops' at each damper motor.  This primarily allowed me to slow down the air velocity in the smallest zone to a quiet level.  I found the additional and small amount of air going to the zones not calling for air was beneficial in simply causing them to not cycle as much.

I believe what I did was not rocket science.  In fact, I believe there's a whole HVAC industry of professionals who do this kind of work as a business.  My guess is they do it in one one hundreth of the time it took me, because they have years of learning and experience.

I also learned that having the right instrument makes all the difference.  I was fortunate to have access to a multiple thousand dollar instrument that thus had accuracy ability to indeed affirm Manual D design principles.  It's easy to see why the professional companies that do air balancing as a business invest into similar instruments - it's a requirement to get the data fast and accurately.  I learned there's plenty of subtleties to accurately and consistently measuring air flow.

Best regards,

Bill

I realy like that idea. keeping it simple

I think the summary of "many zones" is something like:

Advantages:

Fine tuned temp/comfort
Reacts well to variable loads (example: solar gain in one area)
Ability to turn off areas not in use

Possible disadvantages:

complexity
poor dehumidification
low efficiency
short run times
heat exchanger icing


Options for making many zones work:

oversized ducts/pipes
variable speed fan (constant flow)
require percentage of zones
minimum 'stops' on each damper/valve
storage/buffer (only practical with water)
variable or multistage HPs
bypass dampers

I percieve electronic zone dampers as a substitute for good design (in most cases).
Geos are refrigeration systems where airflow is the key to efficiency.
Choking a refrigeration system does not improve efficiency.
Frankly I fear that you have a system that is not being designed by an air flow pro.
'course as you point out the cost is on you.....I won't feel a thing.
Sorry if that sounds harsh but you started this thread by telling us your system is performing poorly and you've evolved into telling us it's designed badly.
I wish you luck. Really.
Joe

That's an interesting observation that dovetails with some of my earlier research.

I read that Carrier's Infinity / Bryant's Evolution zone system gets the zoning job done without a bypass. It supposedly 'learns' the characteristics of each zone and slightly opens non-calling zones to absorb extra CFM on a predictive basis above that able to be sent to smaller calling zones.

I was totally sold on the Infinity system until I learned that it could not be applied to geo systems. ClimateMaster marketing folks wrote me that they hadn't yet been allocated the 'lab time' (R&D resources) by Carrier (the Mother Ship) to properly integrate Infinity smarts into the CM product line.

At that point WF (whose zoning and dehu controls are a bit primitive compared with Climadry and a similar Lennox option) became attractive to me simply by being an independant company totally committed to geo.

This makes sense.  When I custom set all of my damper minimum 'stops' by figuring out all of the possible air flow scenarios on my 3 zone system, using a flow meter, I had to compromise on a single setting for each damper even though it wasn't necessarily ideal, in order to accommodate worst case single zone calling  situations.  End result is that some amount of air is bypass through all zones, but, it's not variably adjusted depending on which zone is calling (like it's done with the Infinity controls).

Best regards,

Bill

Curiously, when my new construction customers ask for zones, I encourage manual main line dampers that send the desired amount of flow into each zone simultaneously. The added bonus is nothing extra to break down. Doesn't sound too far removed from a zone system that lets air bleed air to other areas.
Curt, I think if it were left up to Climatemaster, they wouldn't have zones.
j

I'm surprised this isn't something you would always do (manual balancing dampers on each supply run, each near the supply plenum) on a new construction bid/project that is non-zoned.  I would think it would make balancing the air much easier, and done more effectively, versus doing it at each register.

Best regards,

Bill

Code calls for some method of regulating flow. Code minimum mechanics use registers with dampers. Average guys use volume dampers on branches as well.
What I was describing was seperate upstairs/downstairs trunks with manual main dampers. This is not common, but works well and costs less than electronic dampers. You will have to seek out mechanics to do this (as we do) and pay extra.
Most of the jobs I do currently are retrofit where I have to work with what's already there. Curiously, the ECM blowers get very good feed back on balancing even poor duct systems....kinda makes you wonder why anyone needs zones....
Honestly, zones are a product of a lack of confidence by consumers that duct work is capable of balance without assisstance. Caused by code minimum ductwork, inspired by "lowest bid" shopping. I find it ironic that folks now purchase the $2,000ish zone upgrade, but pass on the duct pro that may have been $1,000 higher on the initial bid.
Put another way, in my mind, most zone systems solve symptoms, not actual problems and are therefore flawed from the get go. 
(I speak of course about resi air zones, not commercial or hydronic) 
J

Thanks Joe.  I know you're not one of the "average" contractors, so the additional detail was good to see.

Here in Texas, where many/most air handler units are up in attics, with flex duct runs attached to a large supply plenum, for new construction, the good and better HVAC contractors put in manual dampers a few feet 'down line' for each supply run - in every single connection to the plenum.  Post installation, air flow balancing from room to room is done at the manual dampers, not at the registers.

I'm not aligned with your frequent comments that zoning is simply a 'bandaid' for poor installations to start with.  If the zoning is designed properly, conforming to Manual D principles, then, in my opinion, it will reduce capacity needs overall in certain living situations, will substantially increase comfort when there's diversity of exposure for the structure, and will reduce operating costs.

I believe the (really) hard part is finding the HVAC professional who is skilled to design the duct system properly, particularly here in the Texas market where competition is so 'cut throat.'  It's hard for an HVAC firm, here in Texas, to pass on the cost of a well designed duct system, let alone a zoned system, when there's five other HVAC firms ready to compete to the same customer with a lower bid with no investment in duct design.

It's actually pretty sad.  As a result, there's many HVAC professionals, here in Texas, when they get requested to come fix a problem or do a retrofit job, who just shake their heads in amazement when they see the poor duct design/installation, and mentally note that it's no wonder the customer has whatever failure needs to be fixed, or has whatever the retrofit request is.

Right now, here in Texas, with highs each day over 100+ degress, it's Christmas time for the HVAC guys.  As a result, there's lots of HVAC guys, all competing against each other, constantly putting lots of pressure on margins.  Even for a potential customer willing to pay a premium to get a duct system properly designed, it's tough to get.  And getting a zoned duct system done correctly requires paying near commercial pricing.

Best regards,

Bill

 

Christmas time is not a great time to shop overtaxed pros.
That it is difficult for duct pros to get a higher price for good work is a result of a poorly educated populus.
Time and again, people research duct systems only after there is trouble heating/cooling their new castle.
Most systems are purchased by the "lowest bid" method or the "throw out the high, throw out the low method", neither of these consider the important things.
Code is no help either, requiring only that some method of balance (no matter how poor) is available, and a certain temp achievable.
All I can say is buyer beware; unfortunately you'll get what you pay for.
j