Furnace Problem

[harry_and_thea]

Suburban NT-30SP. Still trying to diagnose my intermittent furnace problem. Want to make sure my thermostat is ok. I get instant fan when I turn the thermostat up. Is this normal? This model furnace does not have a time delay relay on it. Should there be one in the thermostat?

[Joe_Way]

2oldman wrote:

Pauljdav wrote:
I have had to replace the main board with a fans 50 plus on every furnace I have had.

Don't understand.

THIS

[2oldman]

Pauljdav wrote:
I have had to replace the main board with a fans 50 plus on every furnace I have had.

Don't understand.

[darsben1]

My first check would be the sail switch

[Pauljdav]

All the thermostat does is provide instant power to the furnace main board. The main board desides what to do next.

I have had to replace the main board with a fans 50 plus on every furnace I have had. I recommend it as it is much better quality than the original.

[2oldman]

I get instant fan no matter where the temp setting is.

[harry_and_thea]

Thanks. So problem is not thermostat.

[darsben1]

You should get instant fan. Then the furnace does all its prechecks. Instant fan gives time for the fan to purge the firebox of any gas should you have a leaky valve etc. Also the sail switch has time to close the connection to allow the gas valve to open.