Thermostat blowing fuses ??


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Old 12-27-12, 10:01 AM
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Thermostat blowing fuses ??

My husband installed a Rite Temp 6020 thermostat. Since then, the fuses in our trane air handler continue to blow after about a week, causing our aux. heat not to kick on during colder temps when our heat pump can't keep up. He has replaced the fan in the air handler, along with capacitor, and we have checked to ensure we have proper air flow. We also change our filter about every 30 days. We never had this problem before when we still had the old manual thermostat, which leads us to believe it is the thermostat. Ritetemp customer service is certain we have it wired properly, but I'm not convinced. Another thing to note is that the backup heat does not kick on until the room temp is 4 degrees below what we have the therm stat set on. If I am recalling correctly, the old thermostat would engage the backup heat when was 2 degrees below the set temp. Here are some pics, any help or advice is appreciated. (We have had 2 different hvac techs out here who were not familiar with this brand of thermostat, and were of no help at all, short of trying to sell us a new one for $200)

The manual to the thermostat The RiteTemp Support Site - 6020 Technical Support Page

picture of the thermostat 100_07931_zps8bb447f4.jpg photo by mommyathome1 | Photobucket

picture of the "fuses" that continue to blow 100_07921_zps92a69735.jpg photo by mommyathome1 | Photobucket

finally the model plate from our trane air handler 100_07901_zpsa0bc83f6.jpg photo by mommyathome1 | Photobucket

We are close to just purchasing a trane brand thermostat, but would like to see if we can't fix this problem without spending more money. I did try to get up in the attic to find the other end of the wiring from the thermostat, but I failed at that and will have to wait until hubby gets home so that he can get up there and check. Thanks in advance!!
 
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Old 12-27-12, 06:49 PM
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I am going to try to help you here since I am not really up on the Air handler.. I have not seen this style before, so I am guessing this is for the heat strip itself. (Hopefully HVACtech will stop by soon)

What is the model/part # of this "Fuse" you've been replacing?
 
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Old 12-30-12, 06:06 AM
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microtemp g4am0600 110C. We've had 2 techs from separate companies out that can't explain the problem. At this point, we're all scratching our heads
 
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Old 12-30-12, 08:13 AM
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Your heat strips are running hot due to low airflow.

The most probable cause is a sticking heat sequencer.
It could also be a dirty evaporator coil or a faulty thermostat.

A heat rise measurement in emergency heat mode will tell you if you have sufficient airflow. CFM = (volts x amps x 3.41) / (1.08 x DT)

Measuring the base of the sequencer for 24VAC when it sticks will tell you if the stat (or stat wire) or the sequencer is at fault.
 
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Old 12-30-12, 08:19 AM
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I guess I should read the whole thread instead of skimming. The fuse that keeps blowing is a thermal fuse and is caused by low air flow.
 
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Old 12-30-12, 08:21 AM
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If this was a Honeywell I'd feel more confident that it must be the sequencer.
 
 

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