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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
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Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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I'm replacing a Simple Comfort 2200 Thermostat with a

Customer Question

I'm replacing a Simple Comfort 2200 Thermostat with a Honeywell RTHL3550. I have a Heat Pump with backup heat strips. The Simple Comfort has the 24v wires installed.
The wires on the existing SC2200 are
C - Blue Wire
L - No wire
R - Red
B - No Wire
O - Orange
W2 - White
G - Green
E - Black Jumper wire to ?
Y1 - Yellow
Y2 - No Wire
I have wired the Honeywell according to the instructions. It says not to use wire C. If batteries run out will system still run? also the E wire was jumped to something. I did not see this before I unhooked it I thought it was coming from the wall but when I removed the old plate along came the e wire not connected to anything. Where should it go? I am getting heat but it does not seem to be as hot as before. The outside unit is coming on and the blower comes on at the same exact time. The entire system seems to run constantly like it cant keep up its 40 outside and I have thermostat set to 68 inside. It gets to 68 but stays right there and does not shut off.
Submitted: 11 months ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 11 months ago.

Hi I'm Brian and I'm here to help!

That model Honeywell will 'steal' some power from the terminals of components that are not being called to run but it is important to change the batteries once a year anyway.

Now for your wiring. Just to confirm, you had 6 wires connected to your old stat and now since you capped and taped the blue wire you only have 5 connected to the Honeywell, correct?

Expert:  Brian HVAC Guy replied 11 months ago.

5 wires from inside the cable coming out of the wall that is...?

Customer: replied 11 months ago.
that is correct 5 wires used
Customer: replied 11 months ago.
Sorry it took so long I never received an email or text or anything that you replied to me
Customer: replied 11 months ago.
Are you still there?
Expert:  Brian HVAC Guy replied 11 months ago.

No worries here.

As long as the wire that was on W2 is connected to Aux on the Honeywell and you have set the installer set up to Heat pump with auxiliary heat you should be getting all the heat you were with the old stat.

FYI: you should put in a little jumper from Aux to E if they are separate terminals on your new Honeywell (some of that model had separate Aux and E and some had a combined Aux/E terminal).

Is your outdoor unit pumping out freezing cold air? Is there an extra breaker in your main panel or air handler disconnect for an additional bank of electric heat that may be tripped? Perhaps you need to have it serviced and get the refrigerant level checked and auxiliary heat amperage checked.

Let me know if you have further questions on this subject. Otherwise, please remember to rate before leaving (3 stars or higher please!). Bonuses are always appreciated! Thanks for allowing me to help and thanks for using Just Answer!

Thank you,
Brian

Expert:  Brian HVAC Guy replied 11 months ago.

Yeah, still here. I had my own computer issues when you were having yours :P I typed all that once then lost it somehow! Sorry it took so long...

Customer: replied 11 months ago.
the new thermostat has aux and e combined, So no jumper anywhere?. Yes there is a separate breaker for heat strips. It is not tripped. Why does the outside unit and inside blower never shut off? I can manually turn the thermostat below the existing room temp and it will turn off but when it restarts it will not turn off the blower or outside unit. It acts like it turns off the heat strips but not the outside unit or the blower? The keep on running.
Expert:  Brian HVAC Guy replied 11 months ago.

The only jumper should be between R and Rc and it should have been a factory jumper.

The symptoms are behaving like your heat pump reached it's balance point which is where your home is losing slightly more heat than the heat pump alone can bring back into the home. At that point the heat pump will run all the time and the aux heat will cycle. If that is abnormal for your home compared to previous years for the temperature currently outside then it sounds like you heat pump has lost some capacity either through dirty coils, loss of refrigerant or your home has lost some sealing and/or insulating qualities and you're losing too much heat to the outdoors. Your thermostat is wired correctly so that's not the issue.

Expert:  Brian HVAC Guy replied 11 months ago.

I did have another thought... If you didn't plug the hole in the wall where your wires come through to the thermostat, it could be sensing some cold air in the wall behind and that will throw the temperature sensor off. It's also possible there is a difference in calibration between the two thermostats (very likely there is) and that could be causing this too. Honeywell thermostats are typically very accurate but you may want to check the temperature indoors and make sure the new stat isn't over-heating the space.

Customer: replied 11 months ago.
Hmmmm Interesting if I turn up the thermostat to 70 it gets there. But wont shut off the outside unit or the inside blower. If i manually turn it down to 66 it will shut off everything and eventually fall below that temperature in the house then it will turn on and keep it at 66 but again it wont turn off the outside unit or the inside blower and will hold it at 66 while everything is constantly running. yes the factory jumper on rc is in place. Where do you suppose they had that e wire jumped to on the old thermostat?
Expert:  Brian HVAC Guy replied 11 months ago.

I would guess that jumper may have been for a light for the emergency or auxiliary heat. That was pretty common in older heat pump thermostats.

Based on your findings, I would say your heat pump has lost some efficiency and is not running up to snuff. I would have the refrigerant checked at the very least.

Customer: replied 11 months ago.
ok I can do that but in the end the unit will keep the house at 75 if I set it to do that. It just wont shut off the blower or the outside unit once it reaches the thermostat setting it is like it will just turn off the heating unit and cycle that as needed to maintain the temperature setting but will not turn off the blower or the ouside unit.
Expert:  Brian HVAC Guy replied 11 months ago.

That means your heat pump is supplying either exactly at or slightly below the amount of heat your home is losing. That's why when the heat pump runs without the aid of any electric auxiliary heat, it never shuts off. The heat pump is doing it's best to maintain and that's all it can do. It doesn't have enough capacity at the moment to heat your home to the point where the thermostat will satisfy and turn everything off. That's the 'balance point' I referred to earlier.