HVAC: zoned vs communicating thermostats

[AceCannon]

In my planning for my DIY home AV distribution and automation project, I had initally planned on Aprilaire 8870 thermostats controlled by CQC or Elk. Then I saw relatively inexpensive electric dampers and the gears started turning in my head. . . You know how it is, I'm sure. One controlled thermostat on each floor just doesn't sound as fun anymore.

Issues I have identified:

1. A zone controller can be used with cheapo, standard thermostats in each zone - but I don't think I could easily integrate this with my plan of a CQC diagram of the floor plan. Temps in each zone should be displayed and setpoints should be changeable on the interface viewer.

2. Temperature monitoring can be done in multiple zones with Elk keypads, Elk temp sensors. And I have read about folks using 1-wire setups for more economical monitoring. But then I am stuck programming my own logic for zone controlling, dampers, safety shut-off for extreme temps in bypassed air (when only one zone's duct is open). My understanding is CQC does not at present have a driver for a zone controller.

3. The Elk could easily control the dampers with relays. Manually shut off zones that won't need cooling. But that isn't nearly as elegant as being able to set a certain zone's target a few degrees different from other zones and have the dampers open and close appropriately. Someone has shared a set of Elk rules that attempt to mimick zone controllers, but it isn't clear to me how well this is working.


In summary, it seems to me that zoned HVAC solutions for the DIY'er wanting to have graphical representation in CQC may not exist.

What am I missing?

Addendum: I guess an Aprilaire zone controller linked to 8870's would fit my concept. Sounds expensive, though. An 8870 in each zone? Egad. But the setpoint of each zone could then be controlled by CQQ/Elk, and the zone control duties minded by the dedicated zone controller.

 

[gacevich]

i'm not sure if this answers your question, but i just got done zoning out my second floor...8870 in each zone. works fine, all t-stats viewable and controllable via cqc.

 

[AceCannon]

i'm not sure if this answers your question, but i just got done zoning out my second floor...8870 in each zone. works fine, all t-stats viewable and controllable via cqc.

What is doing the zone controlling? I.E., the dampers? Do you have a bypass damper and do you monitor the recirculating air temp?

 

[Herdfan]

2. Temperature monitoring can be done in multiple zones with Elk keypads, Elk temp sensors. And I have read about folks using 1-wire setups for more economical monitoring. But then I am stuck programming my own logic for zone controlling, dampers, safety shut-off for extreme temps in bypassed air (when only one zone's duct is open). My understanding is CQC does not at present have a driver for a zone controller.

I have one of these: http://www.arzelzoning.com/literature/Product_Catalog.pdf

It uses regular thermostats so as long as CQC can control the stats you are good. Presently I am using a barometric damper (ie. the pressure gets above a certain level, the bypass dumps the excess air into my garage). My eventual plan is use the logic in my Crestron processor to open the bypass damper based on which zones are calling. For example, if my Main Zone is calling and no other zones are calling, then I don't want the bypass opening no matter what. But if the MBR is the only zone calling, then I want the damper open so that it doesn't sound like a jet engine in the bedroom.

I would consider the Arzel controller a "dumb" controller as it has no logic. If stat A calls, it opens the damper. When it no longer calls, it closes the damper. The only logic it has is when one zone calls for heat and another calls for cool, it alternates them every 20 minutes.

So to use CQC this way, you would need to have a controller with at least one more zone than you need for the bypass stat. So if you had 3 zones, get the 4 zone controller and hook one to the bypass. The if only one zone is calling, CQC would see that Stat A is calling for heat/cool and send a message for Stat D to call for Heat/cool (what ever A is calling for) so then Stat D calls and the controller opens the damper. When A shuts off, then CQC would tell D to shut off.

You could really get complicated by adding temp sensors. So if the sensor indicated >5 degrees between call and temp, then the damper would not open.

 

[robolo]

Ace,
I have exactly the same setup and the same options.

[topic="4150"]Here[/topic] is a great discussion of the issues by Black Magic

and

[topic="7149"]Here[/topic] is Black Magic's Elk rules for creating a true zoned HVAC with ELK

Basically you use 1 communicating thermostat for each HVAC unit - this switches the HVAC on or off, heat or AC as directed by either CQC or ELK.

You use 1 damper and a stand alone temp probe for each zone. The CQC or ELK does the logic to determine the position of the damper for each zone and the need to turn the HVAC on/off/cool/heat via the communicating thermostat.

As I indicated this could all be directed by either ELK or CQC but with Black Magics ELK rules already written I plan to start there instead of trying to reinvent the wheel with CQC. Also I like the stability of ELK for HVAC.

As herdfan mentions one thing you do need is a bypass so that if only 1 zone damper is open the blower doesn't get screwed up from the overpressure. It is all in the above linked posts

robolo

 

[Black Magic]

The code that is in the above thread isn't the one I'm currently running on. The concepts are the same, I just had to adjust some of the logic to work with some underlying Elk bug fixes and existsing problems.

If the new code isn't up in a few days, please PM me.

 

[AceCannon]

The code that is in the above thread isn't the one I'm currently running on. The concepts are the same, I just had to adjust some of the logic to work with some underlying Elk bug fixes and existsing problems.

If the new code isn't up in a few days, please PM me.

We are pouring a foundation now, so I've got some time. . . When I get closer, I may hit you up again and see what code you are running!