RS6220 TStat, Confirm w/2stage Wiring Pls

ceburyJune 22, 2012

Can someone verify for me this RobertShaw 6220 Thermostat is wired correctly (for Coleman 2Stage 16/14 DBYX-F036D110). Specifically, that Y2 post is unnecessary for Stage2 cooling to actually work?

The image at the bottom is the wiring, as-installed, by my installers.

Below is the link to the wiring diagram, from the Installation Guide, for the Non-Heat Pump configuration for 2stage heat/cool.

When Stage-2 cool is needed (temp differential is beyond the thresh, in my case 3 degrees) , the cool DOES come on.

and tstat will SHOW Stage-2 symbol appropriately, but it doesn't "sound" or seem any different as far as noticeable air-flow or compressor noises - but that's good news, not a bad symptom, if the unit IS really operating correctly.

It doesn't seem right though, especially since the Stage-2 heating post is wired.

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You need a wire for the Y2 connection in order for the AC to work as a 2-stage system. I think the AC is currently either wired as a 1-stage set up, or it is using a timer on the furnace control board to go from the first to second stage. The thermostat is displaying the stage-2 symbol, but I don't think it means anything because there is nothing connected to Y2.

Are there any more available wires? Usually Y2 is the blue wire and the fan (G terminmial is a green wire). I speculate the installer did not want to run an additional wire and rigged it so it only works with the second stage.

    Bookmark   June 22, 2012 at 5:23PM
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That's all the wire there is, so everything you said is what I suspected, too. I paid an extra $1000 for the two stage AC, not getting much for that.

I need new wire pulled anyway, as I want a powered thermostat with battery backup, not just battery operated.

Thanks for the response.

    Bookmark   June 23, 2012 at 3:03PM
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I would like to think that you are already getting power through the Red wire.

You've only got 5 wires here. I would go for 7.

    Bookmark   June 25, 2012 at 4:14PM
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>>> I would like to think that you are already getting power through the Red wire.

I'm no expert, just only know what I've read in the various manuals, but yeah the Red is source/Hot from the transformer on the unit itself and it's purpose is to energize the other terminals/relays (like the blower, compressors-Y1/W1,etc ). This tstat unit (and others models I read through) require a C "common" hot terminal to be a secondary source wired (along with R) to actually power the tstat for things like backlight, humidifier, remote sensors, etc. Which is why I was bummed when I saw there was no C connected or another wire available, as I wanted the nightlight option.

Correct me if I'm wrong.

    Bookmark   June 26, 2012 at 4:03AM
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I stated it poorly. You get one side (+) of the transformer but not the other (-). 7 would be your minimum. But if you ever went to a multistage heatpump, you'ld need at least 1 more (for the reversing valve).

    Bookmark   June 26, 2012 at 2:14PM
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