Post By GranDad
EM7000 water flow meter
Can anyone tell me how accurate the amount of water delivered to the cup in between shots should be.
I push the program button then either the 1 or 2 cup button (as per instructions) to save the amount of the shot
using my scales under the cup I aim for 30ml which usually happens plus or minus a mil or so.
After making a few more shots and testing the quantity it seems to vary anywhere between
28 - 40 mil, is this normal or should I be looking at a new water flow meter?
Can anyone help.
Is the 7000 able to do flow? I thought it was time based programming?
Edit: after reading the user manual it definitely says "volume".
Things to try.
1. Use a stopwatch to time the shots, see if they are running for the same amount of time or not, while getting different volumes.
2. Without the portafilter in the group, run a number of shots and weigh the results. If these are consistent in volume it may point to the problem. The user manual says that the single and double shots are preprogrammed for 30ml and 60ml but there is no possible way for the machine to measure what's in the cup. It must have a predetermined amount of water that usually produces 30/60ml in the cup, but there will always be water left in the puck.
3. How consistent is your puck prep? What grinder are you using? Are you weighing the dose prior to each shot while getting different yields? My Brevvile DB has volumetric shots, but because it's measuring the water before it gets to the puck it's only as consistent as my puck prep. If I have a lower dose in the basket I get a higher yield because there is less water being held back in the puck. The machine has still given me the same volume of water but I've used it differently.
Last edited by level3ninja; 2nd December 2018 at 04:44 PM.
I wouldn't be surprised if that was within the accuracy of the flowmeter.
Originally Posted by GranDad
I use a 7000 for my daily cuppa (my fave machines are banned on noise issues). Grinder (far more important than the machine): I use Mahlkoenig Vario gen2 and gen3's. The timers are dead accurate on weight (within 0.1g - the limit of my scales) and the shot length is also stable, accurate and consistent. Using a friends (famous commercial grinder) and the shots are everywhere - to the extent that I took my setup over to his place to sort it out. Then I found out his doser was way off weight.
FWIW, I reckon you are seeing timing issues due to dosing and tamping variations. A rough rule of thumb - 10% more coffee grind weight is about 25% more shot volume.
Thank you all for you replies.
I have a VST basket, 15 grams, and a Sunbeam EM700 DC belt driven grinder that doesn't require shims for a fine grind
and I measure the weight precisely and find 15 grams is the sweet spot for my shots. I know Tampit recommends 15.5.
I grind and tamp so that the pressure shows right in the centre of the orange of the meter and that takes about 30 secs for the delivery
of approx 30 mil (text book settings, and they work)
The taste is noticeable when the water content has risen by 5mil
Tampit is saying that his 7000 gives consistent results, so for the $24 for the flow meter, and the clean out my machine will get
it is probably worth a try.
SUNBEAM COFFEE MACHINE EM7000 flow meter em7000 | BigWarehouse Spares
Originally Posted by GranDad
I am glad you posted that gauge reading!
Cleaning out (actually descaling - I use white vinegar at the concentration shown in the manual) is always a good idea. If you use good quality water the 7000 does not need a descale very often, however there is a really simple test. Run about 30ml through the group into a clean glass, cover it and allow it to cool to room temp. Does it taste different from the water in the tank? If so, descale it.
Unlike the 6910, the gauge on the 7000 is also a lot more consistent across different machines.
VSTs flow a lot faster (about 50% more) than standard baskets and the shot should always about 1/2 a "colour range" difference (higher) in the gauge reading on a 7000 to balance the shot*. Not just mine, the other half a dozen 7000s various friends own. Also, VSTs often run longer before blonding in a 7000 (more so than most other machines I play with). A lot of my 7000 shots go for around 35 - 40 seconds (not counting preinfusion - timing from the start of the flow into the cup) - although that really depends a lot upon the particular grinder. The start of blonding is the key to when to stop the shot - and VSTs are persnickety when it comes to stopping at blonding. Too long by a second or two and you have a cup of quinine.
Another minor point - VSTs really love naked p/fs - more so than most baskets. They also love flat based tampers and are quite allergic to curved bases - instant inconsistency plus poorer tasting shots using even a subtly curved base. I suspect that is also related to the higher flow rate. BTW, those things applies to every machine I have ever used with a VST.
Before you do the flow meter, try to get the gauge at the top of the orange / beginning of red. If anything, a little higher again works better on light / medium roasts. Also try to tinker with the shot timing and see what happens.
Hope this helps.
Enjoy your cuppa.
balance the shot*: I think what happens deep in the bowels of the 7000s electronics is that you need to crank the pressure up (i.e. grind finer or it runs into overdosing) to compensate for the higher flow rate of the basket. That also slows the shot down, so sometimes it also needs to run a little longer (slayer shot? - I think it is loosely related). Like all such things, balancing a whole range of factors to match the capability of the gear in front of you is the secret to getting truly great shots. Also as I have stated a few (hundred?) times, the grinder is way more important than the machine.
Thank you Tampit for your reply.
However the plot has now thickened.
This morning when making my shot there was no pressure gauge reading and the shot continued to run.
I factory reset the machine as per page 9 of instructions.
Retry-ed and still no pressure gauge and no water cut off, just continually runs.
Strange that two things failed at once, could be the CPU, but everything else is OK.
Perhaps an input signal? Looked at the circuit but it does not show the pressure sensor as such. there are a couple of A to D inputs that are un-named perhaps these are temperature and pressure sensor inputs.
Does anybody know where the pressure sensor is located? meter is a stepper motor so it must have a physical sensor.
Thinking logically if the water flow meter failed completely the CPU would probably think it didn't have to output a reading to the pressure stepper motor (gauge) so maybe I am back to my original problem?
Last edited by GranDad; 5th December 2018 at 04:16 PM.
Reason: Latter Thought
The water flow meter finally arrived.
It was a simple job to replace it, all functions have returned to normal.
So it looks like the flow meter is a requirement of the pressure gauge.
At some stage i will disassemble the old part to see why it failed, for some reason they have glued it all together.
The new one had to be disassembled to re-orientate the pipes, but that was simple.
Thank you all for your help.
Here is a picture of the disassembled flow meter.
I was quite suppressed to find it spotless inside.
The encoding impeller span perfectly on its bearing.
you can see the two little magnets at the top of the impeller
these encode the count with the aid of a Hall effect device.
so it looks like the electronics failed. Not the mechanics.
Its been a week and all my shots have been plus or minus 1 ml
in quantity. The new water flow meter was a good investment.