Posted Wed Mar 12, 2014, 2:33pm Subject: Re: Melitta BCM-4 - Disable Hot Plate?
I have yet to disassemble a BCM-4 however I believe the hotplate and the heat-exchanger which heats the water use the same heating element.
As you may know it is my belief that the BCM-4 will rival a TV in what it can brew but it has it's quirks. Hey, what do you expect for something you get free for trying some stale coffee.
My workaround for the issue you are bothered about is to fold up a paper towel and put it over the hotplate under the carafe. Listen for the end of the water in the heat exchanger (gurgling sound) then turn off the switch. It will still be about a minute until the brew is finished. Actually while there is water in the heat exchanger it can't get too hot so if you listen and get the switch in time you probably don't have to bother with the paper towel.
Does anyone know if the hot plate can be disabled in the Melitta BCM-4 or is it wired in series or someway that affects the brewing function?
Posted Thu Mar 13, 2014, 9:00am Subject: Re: Melitta BCM-4 - Disable Hot Plate?
Since the BCM-4 is my favorite little coffee dripper I figured I should know what is inside one. I took the bottom cover off of one.
As I suspected there is an aluminum plate onto which are mounted a Cal-rod type heating element and the tube through which the brew water passes. There is a click type thermostat and what appears to be a safety thermal fuse also attached to the plate. The top of the plate (apparently anodized) is what you see and place the carafe upon.
You might be able to change the thermostat to a lower temperature part but disabling the hot plate while heating the brew water is not possible. I would hesitate messing with the thermostat as the brewing temp is just about right on.
If the paper towel "insulator" seems too "kludgey" to you, you might cut a disc of ~ 3/32" wood vernier to place under the carafe.
OK thanks Pill. I have an extra one, I will try to open it up to see how it's wired.
Posted Thu Mar 13, 2014, 12:20pm Subject: Re: Melitta BCM-4 - Disable Hot Plate?
Yes I have the bottom off one too.
When I run it without water, the thermo switch opens the circuit completely in less than a minute (no current draw).
I need to run it with water to see what happens when the thermo switch operates. If it's like with no water then the hot plate doesn't heat until everything cools down which would allow plenty of time to switch the pot off before heating starts again.
Posted Thu Mar 13, 2014, 2:01pm Subject: Re: Melitta BCM-4 - Disable Hot Plate?
After the The BCM-4 brewing cycle completes, full power is cycled ON for approximately 12 secs and OFF for just under 2 minutes. This kept the water in the carafe at 182-184F for a few cycles. Here's a typical cycle.
ON 7m 42s 13s 12s 11s 13s 12s 12s ------------------------------______-- ---_________-----___________________-- ---___________________-----___________ _________-----__________________----- OFF 71s 86s 111s 115s 117s 118s
I'm going to take Phil's advice (thanks Phil) and experiment with insulation between the carafe and the hot plate.
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