My Bunn coffee maker boiles over the top vent

Bunn machine smells hot
* Check for unusual sounds from brewer (other than sizzling from warmer plates). There should be a gradual boiling sound accompanied by some steaming at the top of brewer. This will turn off and ready light indicating the brewer is ready to brew.
* You may sometimes hear a slight boiling sound from time to time (about 15-30 mins apart). Notify your vendor as the warmer blanket may be out. (your brewer will still work but call them anyway.)
* Check your manual for setting up procedures and checks. It's available on line: http://www.bunn.com/product-manuals
* Constant boiling (more than 15 mins) with lots of steaming is a sign of an electrical problem. Unplug machine and call vendor for service.
* Final; Unplug unit and check for 'stuff' in pour over tray. I've found Chocolate, Cream, Milk, powder, sugar, honey, and a dead rat in the tray. Crew will repour old coffee or beverages into brewer to 're-heat' them. Notify vendor for cleaning or replacement (it happens all the time.)
Aloha, ukeboy57

There is usually a warmer blanket or heat control that will keep the brewer at a ready temperature.
* If your noticing a lot of boiling that continuously runs for more than 30 mins then the brewer needs to be serviced. The thermostat is probably shorted.
* Reheating is normal for table units, especially in a cold office. If it comes on more than normal (say within 5 mins) then have the brewer checked. The thermal blanket is bad and or the thermostat is set too high. (or out of calibration) Needs to be replaced.
* Call vendor for service to be safe
Aloha, ukboy57

There is usually a warmer blanket or heat control that will keep the brewer at a ready temperature.
* If your noticing a lot of boiling that continuously runs for more than 30 mins then the brewer needs to be serviced. The thermostat is probably shorted.
* Reheating is normal for table units, especially in a cold office. If it comes on more than normal (say within 5 mins) then have the brewer checked. The thermal blanket is bad and or the thermostat is set too high. (or out of calibration) Needs to be replaced.
* Call vendor for service to be safe
Aloha, ukboy57

if it's actually boiling, replace the high temp limit fuse on the top of the tank on the inside rear of the brewer. may be stuck shut. if it's just overflowing the container, recallibrate by using a 64 ounce measuring cup and the instruction on the inside of the front panel

This is usually caused by the thermostat allowed the machine to boil the water. We offer an out-of-warranty exchange to get a new machine. If you will call customer service at 800-352-2866, we will be happy to assist you in getting a new machine.

Sounds like you need a new thermostat.

The pressure stat is defective and needs to be replaced.

THis sound is usually caused by the water being low in the tank. This can be because the machine is left on for long periods without being used. If this is not the case, then it would probably be your heating element getting small holes in it.

Unplug the machine and remove the top. You will find a little box with a knob or a "T" on it, this is the thermostat. Just turn it down a little, put the top back on and plug it back it.

I would suggest descaling the unit, or replacing your thermostat.
A defective thermostat would not cut out the heater after the water is boiled, excessive scale would render the thermostat ineffective, but not to the extent you describe.

Hope this helps.