I’m experiencing a recurring “System Protect” message on my ADC-T3000 thermostat and I don’t know what it means.
The message is accompanied by a time interval (varies up to 5 mins in my case) and heating or cooling stops (or will not start) and the thermostat buttons are effectively locked out until that interval has expired. This error message is not mentioned in the user guide, nor can I find it mentioned anywhere on the web.
Does anyone know what System Protect means? I’m hoping for ADC-sourced info so I don’t have to make assumptions. This would allow me to effectively troubleshoot and/or accurately define the error for any HVAC provider whom I might contact for service.
System Protect is a 5-minute delay prior to calling for heating or cooling to protect the system from short cycling. It is only applied if the thermostat has detected an unexpected relay state internal to the thermostat during a call.
System Protect is intended to cover rare cases of power issues with the HVAC system. If System Protect is being seen frequently or appears on every call for heat or cool, it points to poor HVAC performance or pre-existing incompatibility. Frequent System Protect delays can be resolved by installing an isolation relay.
This info is direct from ADC documentation. An Isolation Relay can be installed by an HVAC professional to resolve the issue if you see this often!
Jason, this text appears to be different than the troubleshooting section in my T3000 User Guide (it only mentions a “Safety Delay”). Is there other documentation for the thermostat? I am having the same issue (and related reduced A/C performance). Trying to get more info before I call the A/C guy…
I have some additional info about my system. I have two different units in my house. Both Heat pumps w/ AUX electric heat stage (different size units, but same basic system). They are controlled by two different ADC-T3000 thermostats.
The downstairs T3000 shows a firmware version of 1.2 and it never shows the System Protect Message.
But, the upstairs unit is on firmware v1.3 and it displays the System Protect message very frequently (and during the hot weather, is not keeping up with the demand for A/C).
Could the firmware versions be part of the issues?
Just a follow up on my own issue. By the time I called the HVAC guy, I was getting a System Protect on every single cooling call about a minute in, and so no cooling was happening at all.
After he installed an isolation relay, although he was hesitant at first because he couldn’t understand what it had to do with anything, the problem literally hasn’t happened ever since. I’m about a month and a half now System Protect free.
Safety Delay and System Protect are different messages according to ADC dealer docs. I have never seen the Safety Delay message, but I have seen System Protect.
System Protect is relevant to the power being passed through the Tstat relays, which is why an Isolation relay helps.
From ADC:
" Thermostat displays “Safety Delay” on the screen
The thermostat will protect your compressor from short cycling and display “Safety Delay” with a timer on the screen. When the timer expires, the thermostat will automatically resume heating or cooling.
Thermostat displays “System Protect” on the screen
System Protect is a 5-minute delay prior to calling for heating or cooling to protect the system from short cycling. It is only applied if the thermostat has detected an unexpected relay state internal to the thermostat during a call.
System Protect is intended to cover rare cases of power issues with the HVAC system. If System Protect is being seen frequently or appears on every call for heat or cool, it points to poor HVAC performance or pre-existing incompatibility. Frequent or extreme System Protect delays can be resolved by installing an isolation relay."
There is not a specific schematic for an isolation relay on the T3000. An isolation relay is a general option when you are trying to isolate the power being used to control a device from the relay of the thermostat.
Typically an HVAC tech would wire an isolation relay where needed. In this case definitely on the Y wire, since you are having an issue with cooling, but I would do so on both W and Y.
My system has a single 24V power source. That means the same power source will be used to energize both sides of the isolation relay. That on the surface appears to defeat the purpose of separation.
Will sharing the single 24V power source be sufficient when installing the isolation relays to achieve the requirement from ADC?
IOW, must I install a separate 24V power supply as well? Like Kurt’s HVAC guy my two HVAC tech contacts were scratching their heads as to what the mechanical relays accomplish when using the single 24V source.
I have my theory that the mechanical relays are much slower and more forgiving than the one on silicon in the thermostat and simply having a slower switch in the path will make the one on the thermostat behave, but I would like to have some confirmation to that theory. I haven’t inspected the board for the actual system control, but I am guessing it is all silicon as well and no relays are to be found (It is a brand new system in 2019).
System Protect is commonly seen being caused by overcurrent across the tstat relays.
Current is drawn by a device, not forced by the source.
A relay uses a predictable and tiny current. You are isolating the power current draw so the Isolation relay handles the draw from the HVAC system components.
System Protect is commonly seen being caused by overcurrent across the tstat relays.
Current is drawn by a device, not forced by the source.
A relay uses a predictable and tiny current. You are isolating the power current draw so the Isolation relay handles the draw from the HVAC system components.
I encountered this message on 3 newly installed T3000 on 3 newly installed Carrier heat pump systems all while operating in the cooling mode. Simple remedy was moving the auxiliary heat wires on the thermostat from W1 to the W2. It has been over a week and no reoccurring problems.
I too have been plagued with the dreaded system protect. I had a old adc-t100 that died after 5 years. I got the 3000. I’m happy with it but it seems like the protect is going to be cool or heat. My issue however is this protect issue is affecting run time. My house is 65 degrees I turn the heat to 72 to it kicks on after the protect for 5 minutes and gets me to 69 then shuts down and shows system protect again. After the relay is engaged shouldn’t it stay on until the temperature is reached? Will an isolation relay fix this? I saw the W/Y wires should be isolated. Any others?
Will an isolation relay fix this? I saw the W/Y wires should be isolated. Any others?
Yes, an Isolation relay which isolates W and Y should resolve this for you. Since it is occurring on heat calls right now, at least W would need isolated, but I would do both.
Well I’m not calling emergency heat just the heat pump. I talked to my hvac guy he said if the issue is a power variance in the relay in the t3000 then he said by adding a bigger transformer should fix this. I can’t figure out what actually causes this. Is the t3000 sensing a voltage drop?
The T3000 uses digital relays which are sensitive to voltage and current draw variance.
If you see System Protect frequently, an isolation relay is required. The relay makes it so the system components do not draw power through the W/Y Thermostat relays, the thermostat relays are only connected to the Isolation relay trigger. The Isolation relay then switches the power draw.
That makes sense my hvac guy said aside from turning the circuit on it shouldn’t put a load on it. He said it could be the system as a whole is causing the fluctuations in the current being drawn which is why he said the new transformer should do it.
