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Goodman Heat Pump and Nest

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whyme1465

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Discussion starter · #1 ·
My prior Nest Thermostat died and I received a replacement. The original was installed my HVAC guy who is now out of business. I have a Goodman 5 ton heat pump (DSZC18). It is two-stage. When looking at my HVAC's wiring, I don't see the two stage wires as they should be from what I've read in the Nest Pro Installation manual. There's also a wire he labeled as * that has no function on the Nest per his programming.

What do you suggest for confirming correct wiring of a Goodman 2-stage heat pump? Prior to needing to replace my nest cold and hot air was working fine. I'm worried the system wasn't being used efficiently by the Nest or using the 2-stage setup.

I included pictures of the wiring I have, the Nest programmer, the Nest Pro manual, and the DSZC18 wiring diagram.

Thanks!


 
#3 ·
That thermostat is not wired for a 2 stage outdoor unit. It is wired for 2 stages of heat.
Nest is a terrible choice for a thermostat. You were tricked by a large advertising budget for an at best mediocre product
 
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#5 ·
I suggest having a professional come out and verify which wires go where because if that's how it was originally wired, there's no way you were utilizing your two-stage heat pump. And electricity doesn't care about wire colors, so it's anyone's guess what that wire under * goes to.
 
#7 ·
Ran out of wires, possibly there is another wire behind the Sheetrock.

Can't say I seen another green wire on the RV....sounds like they ran two separate wire bundles.

This is confusing.....two greens and two whites....

Looks like at least one transformer...
 
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Discussion starter · #8 ·
Thanks for the feedback. At least you confirmed he was an idiot which I suspected.

Is the Nest that bad? For a Goodman 5 ton heat pump, does it make much of a difference what thermostat I use?

I based my decision on wirecutter's review comparison between Ecobee and Nest. The Honeywell thermostat was initially recommended, but I didn't like the interface and smart features.
 
#10 ·
Possible they tied the 2 stages into one stage as your Y2 is not hooked up, guessing you have auxiliary heat?

Paying for two stage and getting one stage?

Quality question to ask the Installing Contractor
 
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#13 ·
whyme1465 said:
For the past year it seemed to work. Got cold air and hot air. By not using two stages, how efficiency am I losing?
Click to expand...
Well, no way to put a true percentage on it. And you are also loosing a good bit of its comfort ability.

whyme1465 said:
I don’t have an auxiliary heat that I’m aware of. Just the Goodman Dcsz18.
Click to expand...
Aux heat would be in the air handler, and not something you readily see.

Call a qualified service tech out to fix all of the low voltage wiring issues.
 
Discussion starter · #14 ·
I took pictures from the blower unit. There are 5 wires coming from the compressor unit. There are 7 going to Nest (duplicate green and white). I'm worried he didn't pull enough wires from the compressor unit to the blower. W1 and C seem to be duplicate. I imagine this is consistent with not utilizing the two-stage system. Does it look like I need more wires pulled from the heat pump to the blower? That's going to be a lot of work. Pretty pissed this guy didn't know what he's doing.
 
#15 ·
I'm wondering if you have a heater kit, unless it's a 5 kW. Those wires spliced to the line voltage wires (big black and red wires) are kind of small. Also looks like you have a blank plate in the first picture. Can you take a picture of the whole control box?
 
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