What's wrong with my idea to replace the pump in a Keurig?

OK, I’m lazy. I use a Keurig coffee maker. My wife does not drink coffee and I like the convenience of the one-cup-at-a-time system.

Over the years, Keurig has made changes in their design that only aggravate the user. Their original B60 was a nice machine. It was not overly noisy and mostly reliable.

In the second generation, Keurig introduced “quiet brew” technology to be used in the B65 and higher models. They still made the B60, but used a overly noisy pump (louder than my alarm clock). Now, perhaps this was done in the spirit of reliability; perhaps the noisier pump is more reliable, I don’t know. But I do know that the noisy pump annoys me to no end.

Now, I want to replace the water pump with a ice maker solenoid. I would plum the ice maker solenoid to my reverse osmosis water (I only use RO water in my Keurig to prevent hard water problems).

From what I can determine, the Keurig uses a 12V DC pump for the water (all the components on the Keurig are 12V DC it would seem). The ice maker solenoid is 120V AC-25 watt. So I would need a 12V relay to take the 12V signal for the water pump and use it to open the ice maker solenoid. Then, plum the RO water supply (which is under somewhere between 8 and 60 PSI–it’s a captive air tank that is at 8 PSI empty and the full pressure is dependent on water line pressure, but it cannot exceed the water line pressure which is 60 PSI per my water supplier).

So, what have I not considered? I can get a 12V relay that is rated to switch 125V AC at 20 amps. My ice maker solenoid is rated at 25 watts or 0.2 amps. I am guessing the 12V draw by the solenoid would be less than that of the water pump, so that should be OK. There is a check valve between the water pump and the water tank, but I cannot believe it would take more than 8 PSI to open (the minimum pressure from the RO system), so even with a near-empty tank, it should still fill the hot water tank of the Keurig.

Has anyone else tried to do this? Can anyone find an issue I haven’t considered?

Assuming this is the owner’s manual for your model, I don’t see anything in it that talks about connecting to a water line. How will you regulate the pressure, and for that matter, the amount, of water going into the unit?

What could possibly go wrong?

No, the manufacturer does not say anything about connecting the maker to a water line. It is not in their interest. They had a model that would connect to a water line, but it was a commercial model and sold for many times the residential models.

This explains how the model works. Keurig does not recommend any repair on their units (other than replacement, and you can only buy Keruig 2.0 models now, as far as I can tell). The last thing the manufacturer wants is a way to improve the lifespan of existing units.

What I am trying to do is reverse engineer an out of production model to eliminate the noisy pump and provide a more reliable product at the same time. I doubt the manufacturer would approve of this modification, particularly in light of the DRM they introduced with the new models (at the same time they stopped selling the older models).

Yeah, I know I am trying to stop “progress”, but IMHO, their progress is not in the best interest of the consumer.

That is exactly what I am asking.

I’ve fixed a cappuccino maker or two (ok, two), and I wonder what the PSI for a coffee maker would be. In one cappuccino maker, the manual warned of taking the scoop out early, lest high-pressure grounds be launched everywhere. The components certainly seemed designed for high PSI.

I imagine a coffee maker is probably lower pressure, but possibly still higher than your water line, in which case the coffee would just get wet and no coffee come out.

Point well taken. I also have worked with a cappuccino maker and am aware of your concerns. It seems those machines use steam (water above 212F) to create the pressure.

The Keurig operates a bit differently. According to the pdf in Post #4, there is a separate air pump to provide the pressure for forcing the water thorough the grounds, which I would not be modifying. All I am intending to do is replace the water pump with a solenoid connected to a pressurized water line.

Like I said, I think it will work OK, but sometimes I overlook the obvious. I appreciate any negative comments since I doubt I’ll get anyone to say “looks good to me”.

Bless you, I feel your pain concerning appliance design/operation.

Your concept sounds feasible. If understood correctly, you intend to replace the original Kerig pump discharge with line pressure delivered from your RO system.

My only comment is : Does the substitute pressure/flow of your RO match the Kerig design criteria for their original pump discharge?

Here’s something you’ll *definitely *need to change about your original plans:

Everywhere you intend to “plum” something you need to actually “plumb” it. If you go ahead as written and “plum” things together you’ll find rotten fruit in your coffee and water leaking on your floors. That way lies sadness. :smiley:
Seriously …

ETA: slight ninja here by gogogophers

I read the PDF and it seems to me the big issue is you need the flow rate from your RO reservoir and through your 120VAC solenoid to be close to the flow rate of the factory pump. You could probably get by with +/-50% difference. But not 2x and certainly not 10x difference.

My bet is a refrigerator icemaker solenoid under 60psi head of pressure will flow water vastly faster than Keurig’s pitiful 12v noisemaker. The result will be an overfilled or overflowing heater tank and inconsistent coffee.

You might visit an aquarium shop and talk to the them about low noise water pumps. The pressure / volume requirements for aquaria aren’t too far off what you’re looking for.

RE: “Now, perhaps this was done in the spirit of reliability; perhaps the noisier pump is more reliable, I don’t know.”

I know a guy at a consulting company that tests the ‘sound quality’ of products. Sometimes products are made with specific sounds to make them appear attractive to the buyer and user.

For example; vacuum cleaners. They could make a vacuum cleaner that is near-silent, but it wouldn’t sound like it was doing much. A lot of work goes into making vacuum cleaners that sound like they’re doing a good job.

That’s likely not the case here, but it is a possibility.

BTW I’ve been to Keurig’s engineering facility. I got the impression the brewers are a relatively low-priority part of the company - its selling the k-cups that counts

Great feedback. I had considered the flow rate issue and considered it irrelevant since it is not run on a timer, but gets feedback from level sensors in the hot water tank. If it shuts off at the correct level, what difference does it make how fast it gets there?

But both gogogophers and LSLGuy got me thinking that maybe I should look into this a bit more.

I looked up the motor PN from the pdf and found it is rated for 700mA at 12V, or 840mW. This is fine, since my 12V relay has a coil that is rated for 360mW. I could not find a flow rate for the pump, but I know the volume it pumps so I can time it to determine what the flow rate is. With that bit of information, I can put a flow restriction in the water line, if needed, to take care of that.

The only other issue I have to wrestle with is that there is a water level sensor in the reservoir that prevents the unit from operating if the water level is too low. I need to defeat that sensor to make the machine think it is always full (ideally, I would replace it with a pressure switch so if the water pressure was low, it would act as if it was out of water, but I think if I just pay attention when I use it, I should be OK.

My original idea was to eliminate the reservoir, but it looks as if it is necessary. The heating chamber is closed (so it can pump the hot water through the k-cup), but has solenoids that vent it to the reservoir, depending on where it is in the brewing process. Since this vent can contain water, the reservoir needs to be there to catch any overflow.

I am pretty sure I have it figured out, now. I have also found a message board that specializes in the repair of Keurig units, so further questions will go there.

Thanks!

Just switch to cold brew.


https://www.oxo.com/cold-brew-coffee-maker

Convenience of a single cup at a time (but you can also use it to make a whole pot if you want), tastes better than hot-brewed, and you can easily adjust the strength cup-by-cup.