Is my mini split malfunctioning

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  #1  
Old 04-21-19, 06:28 AM
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Is my mini split malfunctioning

I had a Carrier

18,000 Btu 20 Seer Carrier Single Zone Ductless Cassette Mini Split Heat Pump System

Model: 38MAQB18R-3 - 40MBCQ18-3 - 40MBQB01C installed September 2018. I have been disappointed with the way it maintains a temperature since. When it was hot I had to set the temp to 86 or thereabouts to keep the room around 76. In the winter it as even more difficult to keep the room a constant temp of about 71. Sometimes I had to set it at 76 or so to get it to 71. The other times I would lower it to 70 and it still heated even though the temp was actually 74. At night if I left it set at 72 the actual temp in the morning was often 65 or below. If I set it to 76 then the actual morning temp might be 76 or it might be 66. This morning it was set to 86 in A/C mode with the room temp of 71. The unit started putting out heat even though it was in A/C mode, not Auto. I never use Auto as it does even more oddness. It is always set in Heat when it is cold and A/C when it is hot.

I have had the installers come twice. They check it and say it is properly charged and is working fine. They say the unit acts that way because it is mounted in the ceiling and the temp sensor is there as well. It has a wireless remote which also has a temp monitor. It accurately reads the actual room temp.

I assume a $5000 unit should be better than this. What do I do now? I contacted Carrier directly. They would not comment other than to say i needed to work through the dealer.


 
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Old 04-21-19, 01:23 PM
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It sounds like it's working correctly. The temperature at the ceiling will always be above what is set on the thermostat. So based on this..... to be comfortable in the room.... the thermostat must be set higher than what is desired when heating.
 
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Old 04-21-19, 01:45 PM
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I thought that as well. I understand the temp at the ceiling is several degrees higher. But then why does the remote have a “follow me” position where it is supposed to regulate the unit's temp based on the temp at the remote? And, why was the unit heating when it was is the A/C position?
 
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Old 04-22-19, 03:53 AM
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The first thing you need to consider is that having a mini-split is not like having a full blown HVAC systen throughout the entire space.
It can ony circulate air within the space it is in and the throw of the fan.
When a mini-split cycles you immediately have unconditioned air outside of the reach of the cooling unit rushing in to affect cycling.

It is possible there is a problem with the system but I would suggest that you use the temperature in the area directly controlled by the unit and understand it's limitations.
 
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Old 04-25-19, 09:22 AM
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Perhaps a ceiling fan to keep the air in the room lightly circulated would be the answer if indeed the temp difference is that large.
 
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Old 04-25-19, 10:36 AM
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I understand the idea of the unit in the ceiling and the temperature sensor in the ceiling. However, the unit has a remote that has a “Follow me” function where it senses the temperature at the remote rather than the ceiling. I keep it pointed at the unit but next to my primary seating position. I would assume the temperature is supposed to regulate based on the temperature at the remote.

Again, during cold weather with the unit in the heat mode it allows the room temperature to drop to six or more degrees below the set temperature overnight. In the morning I have to turn the temp up to 78 or so to get the unit to raise the temperature above the 65 or thereabouts it is at the time. Once I get it up to 70 or so then it will hold the temperature.

Just seems like Temperature regulation should be better than this.
 
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Old 04-25-19, 10:59 AM
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https://www.kickstarter.com/projects...-air-recircula

The unit has a circulation fan with moving louvres. I also have a hot tube installed.

 
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