MicroAir 356 H1 Thermostat

cef2lion · 10-14-2022, 07:20 AM

I bought an installed the MicroAir 356 H1 this past Spring. I have the 6535 basement heat pump.

The 356 works just fine except for one issue. When off shore or generator power and the 356 shut off I have a open freeze sensor message on the display. Once I connect to shore power or start the generator the message goes away. Again this is with the 356 turned off.

I connected MicroAir tech support and they said to check the gray freeze sensor wiring. My install was plug and play using there molex pigtail. No wiring splicing. I'm not sure why it would be a wiring issue anyway.

It appears the 356 is reading the freeze sensor wiring when turned off and no shore or generator power. It would only have 12V chassis battery power when this message is displayed.

I wonder if any others have seen this. It doesn't cause issues I would just like to resolve it and not have the message displayed. When I have the 6535 running on heat or AC mode I get no such message. It works fine. I have the latest firmware. I just sent another email to MicroAir support as they have not gotten back to me in awhile.

cef2lion · 10-14-2022, 08:20 AM

Tech Support got back to me and said to make sure I don't have auto gen enabled. I verified that. I set Gen auto start to available but disabled and the freeze sensor message goes away. Contrary to how the manual says to configure it. I passed this back to tech support and will see what they say.

cef2lion · 10-14-2022, 02:22 PM

After reviewing the service manual it appears the freeze sensor thermisters do not close the freeze sensor circuit unless there is AC power present. The MicroAir 356 thermostat doesn't monitor if AC power is present. It appears they only monitor the grey freeze sensor wires. Pins 1 and 3 on the molex plug. As long as the MicroAir 356 has 12V power it monitors the gray freeze sensor wires.

Once you go on shore power or generator power the thermisters close the heat pump freeze sensor circuit. I think anyway. Then the open freeze sensor message goes away on the MicroAir 356.

I passed my thoughts and findings on to MicroAir tech support. I would like to hear from anyone else that has installed the MicroAir 356 without AutoGen start to see if they see the same open freeze sensor message off shore or gen power. If so maybe MicroAir can look into this deeper. It doesn't effect the thermostat operation but displays an message that is confusing.

If so I think the MicroAir logic that displays the message is in error. They would only monitor the freeze sensor gray wires if the thermostat is turned on and heat or cool is selected for the heat pump. They would have to monitor the gray wires as well if heat and backup gas mode is selected. On just gas heat they wouldn't want to monitor the gray freeze sensor wires as the heat pump would be active.

When I enabled AutoGen operation but have it disabled the message goes away. That's because the MicroAir 356 only supports a monitoring the freeze sensor or AutoGen start. It can't support both at the same time. Its in the owners manual.

jerichorick · 10-27-2022, 07:59 AM

Quote:

Originally Posted by cef2lion

After reviewing the service manual it appears the freeze sensor thermisters do not close the freeze sensor circuit unless there is AC power present. The MicroAir 356 thermostat doesn't monitor if AC power is present. It appears they only monitor the grey freeze sensor wires. Pins 1 and 3 on the molex plug. As long as the MicroAir 356 has 12V power it monitors the gray freeze sensor wires.

Once you go on shore power or generator power the thermisters close the heat pump freeze sensor circuit. I think anyway. Then the open freeze sensor message goes away on the MicroAir 356.

I passed my thoughts and findings on to MicroAir tech support. I would like to hear from anyone else that has installed the MicroAir 356 without AutoGen start to see if they see the same open freeze sensor message off shore or gen power. If so maybe MicroAir can look into this deeper. It doesn't effect the thermostat operation but displays an message that is confusing.

If so I think the MicroAir logic that displays the message is in error. They would only monitor the freeze sensor gray wires if the thermostat is turned on and heat or cool is selected for the heat pump. They would have to monitor the gray wires as well if heat and backup gas mode is selected. On just gas heat they wouldn't want to monitor the gray freeze sensor wires as the heat pump would be active.

When I enabled AutoGen operation but have it disabled the message goes away. That's because the MicroAir 356 only supports a monitoring the freeze sensor or AutoGen start. It can't support both at the same time. Its in the owners manual.

I'm wondering if this is really an error or simply a discovery on your part? If I understand you correctly, once 120V power is restored this message goes away.

Question: Does the generator start when in Auto Start and the system calls for service with the 'error' message present? If this is the case, when the generator starts the message goes away I would guess. (Because your system is different than mine I don't see this error. I have 3 roof heat pumps and 2 gas furnaces.)

I'm a beta tester for Micro-Air. I have the 354. A new design layout is in the works. There are some really nice features being prepared for implementation. I hope the new release will happen next week.

cef2lion · 10-27-2022, 09:23 AM

I’m pretty sure it was a discovery. But I have not heard from anyone else using the 356 with the basement air an no auto gen start. I never heard back from MicroAir. They did suggest it was a discovery. I had hopes they would pass it along to their development team. I can live with the message but it would be nice if they could correct it.

I just got an app update on my IPhone for MicroAir. The release notes said it was to support 1.0.6.0 firmware. I’m at 1.0.5.0 now. The newer version isn’t showing up as yet. Look forward to it.

Lv2Roam2 · 10-28-2022, 05:07 AM

"I'm a beta tester for Micro-Air. I have the 354. A new design layout is in the works. There are some really nice features being prepared for implementation. I hope the new release will happen next week."

Rick Per your comments above - will this new layout include all the models? Thanks ...

jerichorick · 10-28-2022, 06:08 AM

Quote:

Originally Posted by cef2lion

I’m pretty sure it was a discovery. But I have not heard from anyone else using the 356 with the basement air an no auto gen start. I never heard back from MicroAir. They did suggest it was a discovery. I had hopes they would pass it along to their development team. I can live with the message but it would be nice if they could correct it.

I just got an app update on my IPhone for MicroAir. The release notes said it was to support 1.0.6.0 firmware. I’m at 1.0.5.0 now. The newer version isn’t showing up as yet. Look forward to it.

The engineer is off till next week. I think that may be why you haven't heard back.

jerichorick · 10-28-2022, 06:14 AM

Quote:

Originally Posted by Lv2Roam2

"I'm a beta tester for Micro-Air. I have the 354. A new design layout is in the works. There are some really nice features being prepared for implementation. I hope the new release will happen next week."

Rick Per your comments above - will this new layout include all the models? Thanks ...

I asked Roger that very question and he said YES,

Because this new design is so robust I suggested his company consider making a version for the stick and brick market. He liked the idea. His only hesitation is from the fact that there are so many thermostats on the market today. I still think it has a chance to have a place of value to the homeowner wanting a diverse thermostat. The call is far above his pay grade.