Hypothetical: All radiator vents and main vent are stuck closed. What happens?

CoachBoilermaker

Radiators would not get hot.

Thermostat stays on.

Boiler keeps making steam?

Where does the steam go?

mattmia2

Shuts off on pressuretrol or vaporstat. depending on the pressure and size of the piping it might compress the air enough that some steam makes it in to some emitters and condenses and pulls more steam in to the emitters so it heats some but poorly and uses a lot of fuel doing it.

Jamie Hall

And you might be quite surprised at how fast it will build pressure once it starts to steam…