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AnthonyIOSOS · Dec 6, 2009, 01:07 PM

I recently turned on my heater for the first time. The fan is blowing, but there is not hot air. I went into the attic and reset the ignitor switch and still no luck. The green light in front of the furnace is blinking ten times, indicating the line voltage polarity is reversed. What should my next step be in making this furnace work.

The furnace was recently put in before buying my home.

hvac1000 · Dec 6, 2009, 05:28 PM

The furnace was recently put in before buying my home

If the furnace is new or close to new call the contractor that installed it since it will be under warranty.

If not use a meter and start checking for reverse polarity OR if that is not the case reverse the 24 volt low vlotage leeds going to the board.

AnthonyIOSOS · Dec 6, 2009, 06:26 PM

Originally Posted by hvac1000

The furnace was recently put in before buying my home

If the furnace is new or close to new call the contractor that installed it since it will be under warrenty.

If not use a meter and start checking for reverse polarity OR if that is not the case reverse the 24 volt low vlotage leeds going to the board.

Is reversing the 24 low voltage leads safe to do? I will unplug the unit, reverse the leads and turn the unit back on. I just want to make sure if leads were reversed incorrectly that it would not cause any electrical explosions or fires.

AnthonyIOSOS · Dec 6, 2009, 06:27 PM

Also if I got a meter and tested for reverse polarity what would be my next step?

hvac1000 · Dec 6, 2009, 06:48 PM

First you need to reverse the leeds and try the unit. Yes it is safe to reverse the 24 volt leeds.

KISS · Dec 6, 2009, 07:01 PM

A meter would be tough. They say revered polarity, but it's really phase reversal.

The 24 VAC peak must coincide with the 120 VAC peak which would be difficult to detect.

Polarity reversal interferes with the flame detection circuitry.

AnthonyIOSOS · Dec 9, 2009, 09:58 AM

Originally Posted by hvac1000

First you need to reverse the leeds and try the unit. Yes it is safe to reverse the 24 volt leeds.

Thanks for all the help. I contacted the people who sold the home and those people contacted the company that installed the heater. The heating company came out and reversed the leads for me. Heater is up and running!

Next project fix the broken sprinkler head...