# Flame sense without gas valve



## hvac5646 (May 1, 2011)

no burner, and erroneous fault codes are usually an indicator of a bad board...but sometimes could be multiple problems


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## how (Feb 26, 2011)

*low flame signal & flame sense w/o valve can also mean a bad valve.

*A poor ground can damage a board and sometimes it will just make it erratic. Check all your furnace ground wires to make sure they are all snug. 
Maybe you'll be lucky.


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## heatingman (Mar 17, 2012)

kingbuggy said:


> Hello,
> 
> I have a Janitrol natural gas furnace model number GMH80704BNAB. Up until last Thursday there was a red light on the board blinking 7 flashes which means LOW FLAME SIGNAL. The unit was still heating/cooling okay though.
> 
> ...


 first make sure that flame sensor is sending signal if it is its a bad board remember flame signal is measured in millavolts


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## how (Feb 26, 2011)

*Low flame signal* for a rectifying flame sensor requires a *dcma* check to check the flame rod. A visual check of the flame around the flame rod is needed to see if the low signal is caused by a poor flame envelopement of the sensor or not.

*Flame sense without gas valve* says that a flame sensor circuit signal was being received too long after the 24V to the gas valve power was shut off. A 24V check of the gas valve when the thermostat shuts it off will prove is the gas shut off is instant or delayed.

Either a faulty gas valve or a mother board could cause both of these fault codes.


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## ben's plumbing (Oct 6, 2011)

If you had a tech come out free...he seems like and honest guy..let him install board ..you will then know if it was the board...he was there we are not.....:yes:make sense to me...


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