Boiler won't start

I push the red button - nothing happens. I push it again, it seems to start and then shuts off. There's oil in the tank.

Model # & manufacturer? (Just a "red button" isn't much information to go on.)

It's an oil burner so the red button is the primary control re-set. Could be any one of many things. Plugged filter, oil line, pump strainer, nozzle
Bad electrodes, transformer
Bad oil pump, motor, pump coupling
Bad primary control, cad cell eye, electrical issue and the list goes on and on. Call an oil burner tech.

If it starts and there's no flame, best guess is bad nozzle. If it starts, has flame and then it shuts down best guess is dirty cad cell eye or bad primary control.

At any rate, anything that gets done will require a combustion test after the unit is repaired to verify the cleanliness of the flame. Sooty fires plug heat exchangers and make a mess of your basement.

Okay. Searching for the tech's phone number now. Thanks.

The problem was a worn out burner coupling end. It had been stripped and was completely round rather than socket shaped. Fortunately it was an inexpensive part. The tech cleaned the boiler and replaced the filter while he was here. Worth the call. I would never have found it.

Ahhh yes, number 10 on my list.

It's good to have it cleaned and set up for the season too.