Help me understand my heat pump thermostat

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  #1  
Old 10-25-13, 09:53 PM
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Help me understand my heat pump thermostat

Here is the system:

HP21-60-230-03 outdoor unit
CB31MV-51 Air Handler

T-stat is a Robertshaw 9620:
http://www.robertshawtstats.com/imag...s/110-732E.pdf


So W2 on the t-stat is jumpered to E, and those wires eventually energize the W1 terminal on my air handler, which kicks on electric heating:

When there is a call for heat, W1 of the thermostat energizes
the electric heat relay K32 (covered in the electric
heat section). After K32 closes, blower relay K20−1 is
energized.
There is a zone board, but lets ignore that for now and help me understand the t-stat.

My problem is that as I understand, the thermostat uses Y1 and Y2 as first and second stage cooling and heating (heat pump), depending on whether im in heat or cool mode. The differential for 2nd stage heat and cool is set to 3 degrees. IN heat mode, when you turn the thermostat hotter than 3 degrees past the current temperature, it energizes W2, which flips on the auxliary heat strips. Why does is skip second stage heat and go straight to auxliary heat??? Im so confused.

Am I all mixed up here? Please educate me.
 
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  #2  
Old 10-26-13, 12:15 AM
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Looks like the factory setting for stage two is 2 degrees on that budget thermostat. Did you change it to 3?

What are you using to determine the compressor speed?
 
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Old 10-26-13, 11:00 AM
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Yes, I changed it to three because at low speed, it takes a lot longer to get the house to temp, and it cannot maintain it on cold days, so it was an attempt to keep it at the first stage as long as possible. It works, but if its 50 or colder, it just kicks up and gets it done. But if I understand this t-stat correctly, its a 2H/2C thermostat. So, if it can't satisfy the demand at stage one heat, it just jumps to W2...fires up the strips and calls it good.

Im wanting to change it to a Focus Pro 6000 wifi:

https://customer.honeywell.com/resou...69-2738EFS.pdf

which is a proper 3H/2C stat. I THINK if I hook it up exactly the same way, it will actually utilize the Y2 in heat, using only the heat pump. Not sure when it will use auxiliary unless I make it via emergency function.

As for compressor speed, its controlled by Y1 and Y2. Im determining based on LED on my zone board. It tells me if Y1, Y2, or W1 is calling. On my board, that equates to first stage, 2nd stage, auxiliary with strips.

I think this new stat will satisfy my needs. Yes? Do you have any advice on some of the installer settings for my two stage heat pump with VS air handler?
 
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Old 10-26-13, 02:50 PM
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I would definitely replace the stat, but you can bypass the thermostat to test operation.

I'd turn off power to the indoor unit and zone control and remove the existing thermostat R, G, Y1 and Y2 wires then twist them together with a wire nut.
Restore power and verify that your LED's indicate the the outdoor unit SHOULD be in high speed heat mode.

The outdoor unit should also have a stage 2 LED.

1 = 10
2 = 0
3 = 1
5 = 3
6 = 3
7 = 3
9 = 3
10 = 3
12 = 1
13 = 0
14 = 0
15 = 5
16 = 0
26 = 0
27 = 82
28 = 65
32 = 0
36 = area the stat is in
38 = 1
39 = 1
42 = 1
 

Last edited by Houston204; 10-26-13 at 03:07 PM.
  #5  
Old 10-26-13, 09:37 PM
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OK, Thanks for the help! So...

Im nutting together Power, Fan, Compressor 1, and compressor 2? In 2nd stage (cool or heat) it sends both signals, not just Y2?

Also, do you know which parameters make this new Honeywell switch to stage 1 (assuming 1 degree), stage 2, and then auxiliary?
 
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Old 10-27-13, 09:45 AM
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I'm nutting together Power, Fan, Compressor 1, and compressor 2? In 2nd stage (cool or heat) it sends both signals, not just Y2?
Yep, thermostats do no open the circuit to Y1 when they energize Y2.

Also, do you know which parameters make this new Honeywell switch to stage 1 (assuming 1 degree), stage 2, and then auxiliary?
I've never seen it spelled out in manuals that I have read. The Honeywell Prestige gives you the control over stages 2 and 3 drop in temps.
 
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Old 10-28-13, 08:01 AM
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While I don't have any humidity issues, is it possible for this Air Handler to utilize a thermostat such as the Pro 8000 Redlink for humidity? The only catch is that I have a zone board that cannot 'pass' a signal, but if it could....would it work?
 
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Old 10-28-13, 06:11 PM
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http://www.innovation-group.com.ua/d...m/ah/9618h.pdf

Yes, this air handler has a D/S terminal.
As you have posted it wouldn't work with a zone control system.

 
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Old 11-03-13, 12:00 PM
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I have my t-stats installed. It doesnt take them long to go from Y2 heat pump to auxliary. But, they determine that the capacity of the heat pump won't get the job done I guess, which is better than the old one.

When using the 'fan only', these t-stats, like my old ones, run the fan at 'low speed'. Thats useless when two zones are calling. Is it possible to make the fan run at high speed when it is getting a call for fan only but no compressor?
 
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Old 11-03-13, 12:54 PM
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http://www.innovation-group.com.ua/d...m/ah/9618h.pdf

I see no adjustment for Fan Only operation.
 
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Old 11-07-13, 10:09 AM
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They all seem to be functioning as expected. In fact, they are doing exactly what I want which is running HIGH heat pump instead of heat strips. I had to change the setting to 'economy' instead of 'comfort' to make it do that, otherwise, it pretty much just skipped the second heat stage.

One thing that is odd is that either in heat OR cool mode, if you change the set point by ONE degree, it pretty much kicks on the secondary heating or cooling, and then when it reaches the set point, it ramps down to the primary stage. I have no idea why It does this, but I have checked the wiring and it is correct. I do not think it does this when it comes on by itself...only when I make it come on by changing the set point. I don't understand why.
 
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Old 11-07-13, 11:23 PM
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The stat is measuring to a tenth of a degree and only displays whole numbers.
It will have a demand greater that 1 degree when you adjust the stat.
 
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Old 11-08-13, 08:20 AM
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for what it might be worth ...

robertshaw offers 3h/2c thermostats:

I have the RS4320 non-programmable (which I prefer) which I used to replace a failed 9620.
the RS4320 has nicer control and setup options.
and there's a RS6320 programmable version .

I bought mine online for about $60 two years ago...
 
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Old 11-08-13, 10:09 AM
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Good to know!

I thought it kicked on by itself when it was a full degree off, is that not true? Because when its on by itself, its usually first stage.
 
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Old 11-14-13, 07:04 PM
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Got a problem.

Teh heat pump tripped out the compressor. It does this frequently during the winter. Anyway, when I switched the t-stat over to 'emergency', I get no emergency. The W1 is hooked to the emergency/aux terminal. On my Zone board I see the "W1" is lit up and the G is lit up. This indicates that the fan and the emergency heat should be on. However, no fans seems to be coming on. Is this a zone board deal? Or do I need to change my fan control on the t-stat?


When I do the system test for the thermostat, I get stage 3 heat, which obviously turns on the strips since the compressor is tripped out.

But the emergecncy heating system test does not yield any hot air...or any air at all.


What gives?

EDIT: Just checked the trip switch on the compressor. It does NOT seemed to be tripped. So why isnt the compressor running? Is this a thing with cycles per hour setting on the t-stat?
 

Last edited by agdodge4x4; 11-14-13 at 07:29 PM.
  #16  
Old 11-15-13, 10:36 AM
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Looks like my board will not respond to a W1 and G call alone. I need a relay installed for it to know what to do with it. What is the "L" terminal on my t-stat for?
 
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Old 11-16-13, 11:58 AM
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The heat pump tripped out the compressor. It does this frequently during the winter.
As your zone dampers cycle off the head pressure in your heat pump will increase, possibly causing high head pressure lockouts. I recommend setting all zones at near the same setpoint in heat mode.

Looks like my board will not respond to a W1 and G call alone.
What board are you referring to? The furnace should heat with 24VAC to W1.

L is the light on the stat. The stat lights it up when Aux heat is energized when configured for heat pump operation. L can be wired to a float switch other safety switch to alert your when a problem has occurred.

It seem like you have alot of stats and systems. Are you the only person logging in under your name? Are we referring to a FocusPro TH6220?
 
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