Setting up a zoned hot air system

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Old 02-21-15, 06:20 PM
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Setting up a zoned hot air system

I want to install a retrofit zoning system in our house. We have a two story house out in the sun with a very pitched roof and temperature differences vary dramatically throughout our house.

I have been reading/researching the various retrofit zone systems. Let me say what I would like to do and then maybe someone can tell me if there is a system for it.

Note sure how many zones I am going to do but want something expandable. At least 4 zones, maybe 6.

I realize each zone needs a thermostat, but is there a system that just has remote thermostats that aren't actually controls, but controlled from a main area (whether a cell phone app of centrally located thermostat). I don't need each individual zone to have it's own thermostat controls, but need to be able to control all the zones and ideally I could do it all in one area.

For instance I just installed a Nest thermostat in our house. It's a nice product, but if I wanted to use nest, I'd have to put a nest up in each room... right? Ecobee has a system where you can add remote sensors, but I don't think you can set it up for zone controlling.

Someone point me in the right direction! Thanks
 
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Old 02-21-15, 07:36 PM
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You didn't say if it's a hot water, steam or forced air system. Creating zones requires a lot more than adding thermostats.
 
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Old 02-21-15, 10:02 PM
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It's a forced air system. I'm aware its more than the thermostats. I'm willing to make the investment in all the parts - dampers, control panel, etc. But my main question is about controlling the system.

The bottom line for me is I don't want to have controllable/programmable thermostats in every zone. Obviously I need temperature sensors in each zone, either wired or wireless. But the system I am hoping to set up involves a central thermostat where I can set the temperature for any zone.

The more reading I do, I don't think there are many systems like this. The honeywell HZ432 system looks like the most flexible... but are there other systems similar to this?
 
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Old 02-22-15, 12:45 AM
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Zoning of forced air systems is usually a bad idea, sometimes a very bad idea. The furnace requires a certain airflow to maintain the proper temperature differential across the heat exchanger, too much airflow and it will run cold and be susceptible to corrosion and too little airflow and it will be too hot and be susceptible to cracking. When you close off different zones you will change the airflow and depending on the number and sizes of the zones it could a significant difference in the airflow.

Some variable speed furnaces can compensate to a degree but a standard furnace will definitely be be compromised. More zones also brings up the problem of micro-zoning where the furnace may be asked to heat an area so much smaller than it was designed for that overheating of the heat exchanger to the point of failure is almost inevitable.

IF you have to zone, then the zones should be as few as possible and as close to the same size as possible. It will still be hard on the furnace.
 
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Old 02-22-15, 03:06 AM
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But the system I am hoping to set up involves a central thermostat where I can set the temperature for any zone.
That's how commercial and store systems work. I don't believe a system is available for home where only one thermostat is used.
 
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Old 02-22-15, 06:26 AM
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I would think you would also run into return air problems, in commercial spaces there is a common return air plenum.
Just MO
Geo
 
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Old 02-22-15, 08:11 AM
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http://dms.hvacpartners.com/docs/100...onekit-2xa.pdf

A Carrier zonecc4kit uses a single thermostat with multiple sensors to control temperature and motorized dampers.

The sensors can be upgraded at a later date to smart sensors that can give you the ability to change the setting and push Hold if 4 conductor wire is available at the sensor. No internet control is available for the zone control.



The Honeywell zone kit accepts a Redlink module that would will allow you to use wireless Redlink thermostats and gives you the option to add an internet gateway.

Whichever option you choose, remember to allow at least 30% of capacity for each zone and the need for a barometric bypass.
 
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Old 02-22-15, 10:07 AM
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I would agree with Houston204, motorized dampers would be the best way to go although I don't know anything about Carrier Zonecc4kit.
 
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Old 02-25-15, 07:15 AM
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I, too, have a forced air system - one zone covering two floors. We live mostly on the first floor and have closed all second floor vents, including addition of vent covers. Two questions: 1) can this create the reduced airflow issue mentioned by Furd and 2) is this economical or am I just heating the second floor from first floor vents?
 
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Old 02-25-15, 02:52 PM
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Hi, Tony.

Yes, closing the dampers on the second floor most definitely can reduce the airflow through the furnace. IF you have a relatively new furnace with a variable speed fan (blower) it may compensate by running the blower faster to move more air through the remaining ducts and registers. This will increase the pressure in the ducts and make any leaks in the ductwork worse. If you do not have the variable speed blower then it will still cause a pressure increase although not as much and the flow will definitely be less. At the very least you should check the discharge temperature from a register close to the furnace and see what temperature the air is after the furnace has run for a while. That temperature should not exceed 120 degrees at the highest and I would prefer around 105 degrees at most.

If you want to be even more cautions you could check the temperature rise across the heat exchanger by measuring the temperature in the return plenum and the discharge plenum and taking the difference. The furnace label will show a minimum and maximum differential temperature and you should be in the middle of the range.

As for the second question, of course you are heating the upstairs with heat from the downstairs registers. I somewhat doubt that you are saving all that much in fuel but it might be some savings. The real question is are you comfortable with this arrangement? Most likely your furnace is way oversize for the house as this was (and unfortunately, still is) common practice.
 
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Old 02-26-15, 05:20 AM
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Furd, thanks for the prompt reply. At the very least you should check the discharge temperature from a register close to the furnace and see what temperature the air is after the furnace has run for a while. That temperature should not exceed 120 degrees at the highest and I would prefer around 105 degrees at most.

Read more: http://www.doityourself.com/forum/th...#ixzz3Sqw8fbhJ

I checked the temp and got a reading of 130; in fact, each register on the first floor was at least 105. I'm going to open the second floor registers a bit and see what happens.
 
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