How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rick Mather Your Own Question
Rick Mather
Rick Mather, HVAC Technician
Category: HVAC
Satisfied Customers: 3634
Experience:  35 years experience, HVAC
12095340
Type Your HVAC Question Here...
Rick Mather is online now
A new question is answered every 9 seconds

I have a trane XL80 2 stage gas furnace, and when I turn the

This answer was rated:

I have a trane XL80 2 stage gas furnace, and when I turn the head on everything cycles, the ignitor comes on and then the gas valve opens and the burners ignite for a few seconds then shut off. The Flame sensor is new and local HVAC guys have tried 2 differnt control boards on it. They also replaced a limit switch. Any other ideas as to what might be causing this problem?

Rick Mather :

There is something going on with the flame detection. was leads changed from flame rod and was flame rod flame signal checked with millivolt meter

JACUSTOMER-k754ctdh- :

yes they changed the flame rod and put a new wire on it as well and check the microamps

Rick Mather :

THe reading came back normal?

JACUSTOMER-k754ctdh- :

no it was low

Rick Mather :

Are control board grounded properly

Rick Mather :

Then flame has to adjusted to make it read with stronger signal, check gas pressure

JACUSTOMER-k754ctdh- :

yes, they tried the one that was on the furnace after replacing the limit switch, and two others after that and they all did the same thing.

JACUSTOMER-k754ctdh- :

and they were all grounded properly

Rick Mather :

flame has to be adjusted with meter on to find proper reading

Rick Mather :

weak signal will not work

JACUSTOMER-k754ctdh- :

Flames all look good gas pressure is good, pilot on water heater right next to furnace is fine.

Rick Mather :

Flame rod may have to be bent into flame better

JACUSTOMER-k754ctdh- :

That was also tried

Rick Mather :

well I have no magic

Rick Mather :

request question closed and pleae don't accept

Rick Mather :

please

JACUSTOMER-k754ctdh- :

yeah the guys here were stumpped too, I just don't want to have to buy a new control board if its not the problem

JACUSTOMER-k754ctdh- :

just wanted a second opinion, I will accept you asked everything they did and that was without even seeing the unit. thats good enough for me

Rick Mather :

thank you

Rick Mather and other HVAC Specialists are ready to help you