The Bunn CW Series overflows the pot. How canwe

Over Boiling or constant heating of tank water is an indication of a shorted thermostat (or out of calibration). Call your vendor for service. (especially if this equipment is on loan.)
*** the following is for information only. Repairs should be performed by a qualified Bunn Tech. ***
* VPR's and similar machines REQUIRE a pre-fill and heating period prior to brewing. This means it's sitting on a level table and filled with water until water sprays from the brew head. At this point the unit is plugged in and the heater is turned on (there may be some water discharge from brew head as the water expands). Ready light will come on in about 15 mins.
* To Brew; Place coffee grounds in filter, place in funnel and brew head, clean empty decanter under funnel, slowly pour one full decanter of water (cold or hot) into brew tray. Do not overflow tray. Allow water level to sink before adding more water. Only fill with one pot as an equal amount will come out the brew head and funnel.
* Make sure the decanters are all the same size. do not mix a 12 cup pot with a 10 cup pot. One will over fill and the other will under fill. Make sure they match (in cup volume) FYI; Thermo Air pump pots are usually bigger than one pot. Typical filling only to 3/4th of the container. (I think most are in 2.5 to 3 liter sizes)
* If your not getting a full pot then the brewer was partially empty. The second brew (if done within the next hour) should come out full.
* If your still not getting a full pot then the water is leaking or is boiling off. Does it always steam from the top? Thermostat is shorted. Unplug the brewer and call vendor for service.
* Final; Follow the Bunn set up and care instructions (manuals from Bunn.com for down loading. *FREE*)
Aloha, ukeboy57

PS; There is a slight chance that your thermostat is set too high. There is a dial on the thermostat that can be turned counter clockwise to lower the temperature of the brewing water. Water should be about 190-205 F for coffee. Tea drinkers want 210 F which is too close to boiling point of water. If your in the mountains (+2000 feet) then the boiling temp will lower. Was it possible the brewer came from a low (sea level) location and moved to higher altitude? Then the setting is off and must be set lower (a fine adjustment). But note that if your on the top of a high mountain (like Haleakala, Hawaii) then it has to be set a lot lower and you will only get luke warm brews at 9,000 feet!. Adjust the knob clockwise to get it to boil. Then back it off counter-clockwise a bit till it stops boiling. Make another brew to check if the reheat comes to a boil but stops after a minute or so. It should not boil on longer than 2-3 mins. Back it off a bit more if it does. Brew again to check. If none of this works then you will need to replace the thermostat. If your at a really HIGH altitude location, then you will need a specially adapted high altitude brewer. Call your coffee vendor for advice.

Sorry this brewer is usually set up for a full pot brew. I have reset this for a small (but not half) pot brew as the customer wanted to use a metal carafe (with their own logo). I also tried once to get it to half pot brew but it can get tricky if you actually brew twice to get a full pot (in the same pot).
* there is a siphon action that starts once the boiler tank gets filled to a certain point. From that point it will continue to flow until the boiler is emptied to the level that stops the siphon action and leaves enough water in boiler to reheat for the next brew. Achieving the siphon point may be a larger volume of water for 1/2 a pot but may work for 3/4ths a pot. The 1/2 way mark may be affected by the brewers "level" while placed on a table or sagging in the middle of a weak table.
* Usually if you want a smaller brew then go with a smaller brewer. Though there is a hot water tap that will give you 2-4 cups of hot water (it gets tepid after that) which you can use for the "Mug" style brew. But it does get messy.ukeboy57
* Final, If you don't mind a little more than 1/2 pot brews then ask your vendor to adjust the machine for you. Though a reminder NOT the double brew in the same pot as it will overflow.
Aloha, ukeboy57

VPS/VPR are pour over brewers. Like the 12 cup brewers you find at home, they need to be filled with 12 cups of water (a full pot), heated and then peculated over the coffee grounds and collected in a decanter.
BUT there is one main difference! The VPR and similar COMMERCIAL coffee machines are quick brewers. They usually have a pre-heated pot of water stored inside the machine.
* VPR's and similar machines REQUIRE a pre-fill and heating period prior to brewing. This means it's sitting on a level table and filled with water until water sprays from the brew head. At this point the unit is plugged in and the heater is turned on (there may be some water discharge from brew head as the water expands). Ready light will come on in about 15 mins.
* To Brew; Place coffee grounds in filter, place in funnel and brew head, clean empty decanter under funnel, slowly pour one full decanter of water (cold or hot) into brew tray. Do not overflow tray. Allow water level to sink before adding more water. Only fill with one pot as an equal amount will come out the brew head and funnel.
* Make sure the decanters are all the same size. do not mix a 12 cup pot with a 10 cup pot. One will over fill and the other will under fill. Make sure they match (in cup volume) FYI; Thermo Air pump pots are usually bigger than one pot. Typical filling only to 3/4th of the container. (I think most are in 2.5 to 3 liter sizes)
* If your not getting a full pot then the brewer was partially empty. The second brew (if done within the next hour) should come out full.
* If your still not getting a full pot then the water is leaking or is boiling off. Does it always steam from the top? Thermostat is shorted. Unplug the brewer and call vendor for service.
* Final; If your unplugging when not in use. Then follow the Pre-heat instructions mentioned above prior to plugging the brewer back in. If the tank has been emptied at night or dried up after an idle week. Then there is a chance you may over heat and blow the thermal fuse. Or at best have a half pot short brew as the water dried up.
* Note leaving the brewer plugged in without brewing daily is not a good idea. The water evaporates and eventually drys out the pot. Takes about 1-2 weeks but it does blow the fuse(s) and the unit will need service.
* Final; Follow the Bunn set up and care instructions (manuals from Bunn.com for down loading. *FREE*)
Aloha, ukeboy57

* call vendor for service. Brew timer or water level float needs adjustment.
* Make sure your using the correct brew pot for this machine. It's 64 oz decanter if I remember right. Some of the older glass pots are smaller. Especially if it's the roundy one that looks more like a ball. It should hold at least 1 quart of water easily. Ask your vendor for the correct pots (they don''t like you using 'other' brands of coffee if it's printed on the pot.
* Long shot but possible the valve was put in backwards. Either way the vendor should replace it.
Aloha! ukeboy57

Have you cleaned lately, put in an empty filter and fill with cold water with a tablespoon of white/clear vinegar. Run the brew cycle, empty pot and while still worm fill with cold water again with out vinegar. Than check filter to see how much hard water chunks are in the filter. Repeat with and without vinegar tell filter is clean. One question though is there a lot of steam coming out of the top during the brewing cycle if so inside there is a tube that may be cracked, broken or came loose, have to look inside. requires opening or disassembling unit to check. REMEMBER when taking apart UNPLUG unit first.

Sounds like the switch is stuck in the operate position. Therefor once the machine hits temperature it just brews. Your local Bunn distributor should be able to recommend an engineer to replace the switch or supply the correct t,hope of switch if your confident enought Tom replace it yourself.

The brewer is on a gravity feed system, after the initial fill, whatever you put in is what comes out. as for the start button check the water connection on the back, there might be a problem with the solenoid.

These tanks can't actually be overfilled since all water poured in displaces the exact same amount of water coming out the spout. So, whatever amount of water you pour in, will be the same amount of water that flows to your pot minus the amount absorbed by the coffee grounds and filter.

Your problems sounds like an undersized (Non Bunn) filter, or clogged brew basket. To verify this, try pouring in only half the water for your brew cycle and wait for it to finish dripping, then pour in the rest. If no overflow has occurred, you simply have the wrong type of filter. If overflow begins again, you have a clogged brew basket, since no Bunn can flow too fast for the brew basket to keep up with it.

This is because Bunn filters are manufactured differently than generic store bought paper filters. They will flow faster, brew cleaner and stand up better than normal generic filters.
Remember, Bunn makes their OWN filters for good reason.
They made the first, best paper filters for drip coffee pots, and all others are just generic dioxin gas producing paper.

The procedure for setup of this coffee maker can be found here -

http://www.bunn.com/pdfs/commercial/manuals/10613.0000.pdf

Please email if you have additional questions.

There is a brew timer on the left side of your machine near the heater switch. you need to remove an access panel to access it. turn this down a little, let the water heat up, then try another brew. Adjust as needed, brewing another pot between each setting.