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ckHave a Bunn Airpot brewer that will not heat water fast enough to recover from brewing a pot of coffee. Will get to temperature, just takes a long time.
I have a Bunn CWTF-APS coffee brewer that does not seem to ‘recover’ quickly. It will heat to temperature, brew one pot and before the second pot is completed the water is no longer hot. Hoping to learn what part(s) would be most common to cause such a problem.
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10 Replies
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I would check the incoming power and ensure the unit is de-scaled. The fact that it is still making temp after a longer period of time tells me it something with the heater. With enough scaled build-up the unit’s heaters are insulated taking longer to heat up. The heater might have to be replaced if it is severe enough. I hope this helps!
-Joe
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This unit has two heaters in the tank. A lower wattage and a high wattage that does quick recovery. We need to know what options you have as far as voltage, single or dual, Facet, etc. to tell you more. More than likely the temp control for the quick recovery is the culprit, as the quick recovery element would make it not heat at all.
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fixbear is correct.
There are two types of heaters for the water tank:
The high-wattage main element(s) are the primary heat source and are immersed in the water. They’re controlled by a thermostat. Units set up for 120v power use just one of those elements. Units set up for 208v use both elements (connected in series). This element is the one that provides rapid temperature recovery during and in-between brew batches. The tank also has a “keep warm” element. Basically it’s just a low wattage heater wire that’s layed out in loops within an adhesive foil-like mat. That mat wraps around (and sticks to) the outside of the tank and serves as a heat blanket. This element is constantly on…as long as the “heater switch” (on the back of the unit) is turned on.Sounds like the main element(s) aren’t working. Consequently, the “keep warm” element is probably all you got heating the water.
Some things that will prevent the main element(s) from working:
A bad element A faulty thermostat An open thermal safety fuse An open limit thermostat Faulty wiring or connectionHere’s the schematic:
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I got this off of a water heater info page. Here are some characteristics of limescale on heater elements:
Water Heater Problem Symptoms due to SedimentsNot enough hot water – deposits in the tank form the insulating blanket between heating elements and water, decreasing the contact surface and heat transfer.
Noisy operation – sizzle, hiss are characteristic in electric water heater, while gas and oil fired units may rumble and pound.
Longer heating time
Shortened heater life
High operating costs are results of the increased energy consumption
The last one may be minimal because it is a smaller heater but it is a characteristic.
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Joe, with the Bunn pots they have a circular heater (s) that tends to flake off scale due to the expansion and contraction. The scale then drops to the bottom. It then winds up in the brew tube as a blockage and creates a slow brew condition. That’s why they come with the wire snake to break it free. It would take a super deep buildup to slow heating noticeably. Much after having to disassemble and clean. This one accually has 3 heater elements, a keep warm outside and a low and high inside.
On the other hand, wonder if someone moved the selector switch to 120 volt?
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Scale can certainly be an unrealized issue in coffee brewers. It typically builds up without anyone seeing it.
If you’ve ever taken the top off a Bunn tank, you’d say “Eewww!” for what you’d find in there. Kinda like (but not the same as) what you’d find in a several-year-old ice machine that were never serviced.
However, I’ve never seen a coffee brewer’s failure or poor performance attributed strictly due to scale buildup.
A contributing factor to its failure? Maybe. However, few coffee brewer owners wouldn’t be willing to pay for the labor to delime it though. I did it once. It’s a PITA.
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We obviously haven’t heard from our guest, But I forgot to mention that maybe someone slid the voltage switch from 220 to 120?
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That would definitely cause the problem, but someone would’ve needed to remove the front panel for access to that switch.
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Users do to adjust brew amount due to pressure variations to get a full pot. Sometimes they forget about closed shop (holidays) evaporation only to have it go over the top.
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Every fall when we reopen we get the short brew complaint for pour over units in the seasonal offices…. yep, evaporation.
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