I have a Heil gas furnace SP80 with electronic hot surface ignition.
The burners are not working, but the blower is running constantly, even if the thermostat is on the off position. I have tried to reset the unit, but it doesn't work. I had a technician come out and he got it to work for 20 minutes, and said it was loose connections. But now he things I need to change the control board. From other postings, but not for a Heil, the recommendations were to change the relay, pressure switch or low limit switch. Do I really have to change the whole control board? Please help!:confused:

It might have tripped on the safety high temp control. On many units it will trigger the blower to run as if the unit has over heated. Look on the wiring diagram on blower door to see if you can find it on your unit.

Thank you so much for replying hvac1000! The tech said that he checked the temp. limit sensor and it was fine and that is why he now thinks it is the control board. Does that sound right to you?

Yes if the limit sensor is OK then the board is the next logical item. They are expensive. If he relpaces it and it does not do the trick it is his responsibility to remove it and not charge you for the board. I say that because I have seen many invoices where the service tech said it was the board and was not then they want to leave the board in the unit and charge the customer for something they did not need.

Thanks again hvac1000! I didn't know that I could make him remove it and put the old one back! Also, any idea as to how much it costs?

I didn't know that I could make him remove it and put the old one back

If a service tech tells you that a part is going to repair your unit and it does not because the part they replaced is not defective demand they your GOOD part be put back in the unit. Many times a service tech will say that 2 or more parts are defective causing the problem but that is a real LONG shot since over the vears usually only one part is causing the problem.

I really hate to guess at cost since it is variable in different parts of the country but I would get a price from him with a separate price for the labor to replace it and post the prices here. I am sure there are many service techs here who will tell you if you are getting ripped off or not.