Can two stats control one AHU???...............(Starch)

Unknown

use a fast stat commericial with wireless remote, sensor has a 2 hour over ride. Have solved many issues with this one.


Peace Be With You


David C. Broome

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John Starcher_4

I have a client.....

....in an office building that has been converted to an office and a condo. (don's ask) The condo portion used to be part of the original office setup, and the whole thing is heated and cooled by an American Standard heat pump/ahu system.

Now that the units are two, they have (surprise!!!) a comfort issue in the condo, since the thermostat is located in the office section.

What's that you say? Install a zone control system?? Great idea!!!!! I proposed doing just that, and it would be fairly simple to do. That is, if it were like a hundred bucks or so total cost. Ok, I'm exaggerating a little, but the price of adding the zone system was not, how should we say, palatable.

Their response? "Can't you install another thermostat in the condo, with some type of switch? That way, the condo owner could flip the switch and control the temperature when he is there, and flip the switch back to the office stat when he leaves."

While I see this as a completely idiotic solution, I am willing to consider their wishes (I get a lot of business from these people!) Has anyone ever tried this? I'm wondering if i just interrupt the "R" wire through a switch if it would do what they want. I'm concerned, though, about any electrical feedback through the "unused" stat interfering with system operation.

TIA for any thoughts and replies.

Starch

carol_3

It seems to me that this might work, though I've never done it. Would need to be sure that the two stats are wired in parallel, though, not in series with each other.

(A 2-zone system doesn't cost that much!)

John Starcher_4

You are right, Carol.....

...it doesn't cost that much.

I agree with you about the parallel issue. My concern is if any voltage could feed back through one of the other terminals (O,Y,G, or whatever) in the unused stat. It's hard to say without knowing about the internal electronics on them, right?

Larry C_13

Use a 4 pole switch or relay

If you are worried about the other thermostat lines affecting the active 'stat, use a four pole switch or relay to switch all of the wires at the same time.

Larry C

John Starcher_4

David....

...can you give me a little more information on this?

Who makes it??

Jim Pompetti

Years ago

I had something similar . 2 offices 1 stat . I connected a SPDT relay to the lights in the office , when the lights came on they had control . Lights out the other office had control . Work great , one office was open all day the other at night.

John Starcher_4

Great idea, Big Jim!

Do you remember how you interupted the control wiring through the relay? Was it just the R wire??

Jim Pompetti

easy

Since I was only using A/C I did the red wire .but it (RED WIRE)would work for heat to