Some boiler questions

[Mike Lamb]

Most of the household boilers I see have no backflow prevention valve. Does the pressure reduction valve also serve as a backflow valve?

Is there a simple way to tell if the circulation pump is working. Most have no visible moving parts. I can usually feel them vibrate but I don't know if that is an indication of whether it is actually working. Sometimes cast iron radiators heat up pretty quickly and sometimes not.

[kurt]

Yes, same thing.

Put a screwdriver tip on the circulator, put your ear on the screwdriver handle. You can hear it if it's running.

If it's super hot and you can't hear anything, it's broken or air locked.