[jsb5717]

What exactly is it doing when you set the TStat for heat? Fan blow? Try to ignite but doesn’t? Ignites but turns right off? Ignites and runs for several minutes then shuts off?

If the fan is blowing and not igniting, or attempting to ignite then the first thing to check is the sail switch. It’s easily accessible on your rig (same as mine). It could just be dirty and need to be cleaned.