Some questions about zoned system

[matt_i]

I am considering a 2 zone system for my ducted shop heating, basically have two thermostats and some relay logic where one side calling for heat blocks the other zone until the first call is done plus a timer-off delay so air can continue to flow after the tstat goes back open. Selector switch for using both zones if I would like to heat the entire thing up that would have to have 1 of the 2 tstats be the "master" in that scenario.

It of course requires motorized dampers, they apparently come in normally open (mechanically) or normally closed varieties. No big deal, if zone 1 is calling then I close zone 2 dampers...or open zone 1 dampers depending.

I don't have a regular black-box controller, so I have a couple of questions.

First, the picture looks generic and not that exact model. It looks to me like that slides completely into the open end of a rectangular duct without having to "splice" it in between two sections (?) Then drill hole for motor shaft, the motor & housing sits on the outside.

Second, I am guessing here that there's some kind of internal control so the motor doesn't burn up trying to close/open the entire time its actuated with a maintained voltage. The link only describes 2 wires so it seems like there's no "confirmation" that the thing closed, it just "holds" position like a relay coil eventually without being worried about motor windings (?)

Third question is I feel certain I would have to upsize the control transformer. I don't see a spec on the device for the amp draw which I could work back to the "power" output of the transformer. Are there a couple standard sizes for this or (?)

Thanks for any input on this or cautions on this type of system that maybe I'm missing. My wiring diagram/ladder logic is not with me right now and I will post it up when I get back to it.

 

[matt_i]

Edit: already see a problem, it appears the motor is mounted on the 2nd dimension, so I would need a 22x8 rather than an 8x22. Searched again and came up with this model, which has power-open and power-close, which I can integrate into my logic.

http://www.supplyhouse.com/EWC-22X8ND-22-x-8-ND-Motorized-Damper

Spec sheet for above.
http://s3.supplyhouse.com/manuals/1296597322000/46325_PROD_FILE.pdf

Is there any reliability gain to be had by brand or with the power-open-power close over the top-style spring-return model (?)

 

[Ohmthis]

They make dedicated zone panels that will have the controls you may want already installed. The damper does slide into the duct and the motor is already installed on the damper. Yes you need to upsize the control transformer for the dampers, I used a 40va (I'll have to go back and verify) transformer on the last one I did. There are different brands and styles of systems. For instance, when zone 1 calls for air, zone 2 closes, but the extra air (air cfm the blower makes) needs to go somewhere. You can either dump it back into the return with a bypass damper, or bleed the pressure off to the other zone. Honeywell controls is what I've used, but please research the other manufacturers and find what works best for you.

 

[justinjoyal]

Instead of relays and stuff, why not use a simple 2-zone controller ? Cheap and easy!

 

[1953mercury]

I set a system up like that to heat my home (above) and shop (below) 30 some yrs ago on my forced air furnace. Been working flawlessly ever since. Would post some pics and wiring diagram, but I'm gone for the winter. Mike

 

[Stuff]

Also need to check that your furnace won't overheat when servicing a single zone because of the reduced airflow.

 

[brewchief01]

Normally the zone panel will get powered from its own transformer, Honeywell 2 zone panel and 2 dampers is about as simple as you can get, if each zone can't handle most of the airflow then a barometric bypass damper may be needed.

The Honeywell panel can have a sensor hooked up that will shut off the heat or AC if the temp in the ductwork is too high or low.

Sent from my XT1254 using Tapatalk

 

[matt_i]

Also need to check that your furnace won't overheat when servicing a single zone because of the reduced airflow.

Good point but the system already feeds what I call "zone 1". I built a new shop attached to the existing of roughly equal size and I am building the "zone 2" ductwork currently.

The two halves are separated by an internal garage door so I can separate the two halves, doesn't make sense to me to heat all the thing when I am just working on one side. It seems like I use 2 therms to heat the one side on an 8hr day in winter, generalized 25-30F outdoor, so that's around $1.60. The investment of about $300 in motorized dampers and maybe $100 in controls would seem to be somethign I will eventually recoup. Not to mention the furnace will heat half of the shop up more rapidly than trying to ramp up *all* the area at once.

But i would like to have the option to heat it all, if I am needing both sides.

 

[justinjoyal]

Normally the zone panel will get powered from its own transformer, Honeywell 2 zone panel and 2 dampers is about as simple as you can get, if each zone can't handle most of the airflow then a barometric bypass damper may be needed.

The Honeywell panel can have a sensor hooked up that will shut off the heat or AC if the temp in the ductwork is too high or low.

Sent from my XT1254 using Tapatalk

Exactly what he ^^ said.

Should get you troublefree functionning for many years.

 

[matt_i]

Curious about the static pressure damper. How do you know when one is needed? Is the symptom that the furnace is tripping high-limit because it cannot transfer heat fast enough thru the secondary side of the heat exchanger? (because of limited airflow)

 

[Ohmthis]

There will always be a need to bleed extra air. If not you will get whistling from excessive pressure. I think you are over thinking this. You can get a 2 zone panel, 2 zone dampers for the supply, a way to bleed excess air (a few different ways, you must find which one would be best for you), and two thermostats. That's pretty much it.

 

[Want2race]

Good info in this thread.

Honeywell make some good zone control boards. I've had a few issues so next I'll probably try another brand

As for overpressure just look for a static dampener. Really easy to install and adjustable to keep it quiet

I've bought normally open and normally closed dampers. Normally open appear to last longer but my sample size is really small