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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My Aprilaire 8436 thermostat screen is blank. I assume the

Customer Question

My Aprilaire 8436 thermostat screen is blank. I assume the batteries are dead but with new ones the screen is still blank. Suggestions??
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.
Hi, I'm Tim and I'm an HVAC expert here to assist you with your questions. Please provide all information I request as it makes it more difficult to troubleshoot something when I'm not there onsite. Essentially, you become my eyes and ears. Thanks for the opportunity to help. At the end of our dialog, you will have a chance to rate my service, but please wait until we are finished and you're satisfied you have all the information you need.
Is this controlling a gas furnace?
Customer: replied 1 year ago.
Hello. How do we get the thermostat powered up? Yes gas. A Buderus Logamax plus GB142
Expert:  Tim H. replied 1 year ago.
Check your Buderus. Is the switch on? Circuit breaker blown? If these check out, see if a low voltage fuse is blown on the Buderus board.
Customer: replied 1 year ago.
Buderus is heating other zones active thermostats
Expert:  Tim H. replied 1 year ago.
Do you have a zone panel? Multiple zones?
Customer: replied 1 year ago.
Yes. 6 zones
Expert:  Tim H. replied 1 year ago.
But is this just 6 zones going to zone motors? Do you have access to a voltmeter?
Customer: replied 1 year ago.
Yes
Expert:  Tim H. replied 1 year ago.
Tom take the thermostat off the wall and measure from the red wire on R to any other wire. Let me know if you have 24 volts AC?
Customer: replied 1 year ago.
Ok. Will try it
Customer: replied 1 year ago.
Sorry volt meter batteries are dead. Wont respond to new ones. 10:30 PM my time. Gotta sign off as have early meeting tomorrow.
Can I reconnect tomorrow?
Expert:  Tim H. replied 1 year ago.
Yes, of course, Tom
Customer: replied 1 year ago.
I noticed yesterday that magically they both were lit. This morning after a temperature drop I went to turn the heat on. One was working and responded immediately. The living room one is dark again. Comments?
Expert:  Tim H. replied 1 year ago.
Check with your voltmeter from the red wire on R terminal to any other wire. You should have 24 volts AC.