Cross-post from CoffeeGeek Machines & Grinders forum since no one has responded with input to my request below:

Help requested: On my Quickmill Anita, when I start pulling a shot when the boiler pressure is at max, it barely has time to complete pulling the shot (25-30 sec) before the boiler pressure hits the min level and kicks on the boiler refill.

Here are the details:

- Deadband seems to be working fine, cycling between ~.95-1bar to 1.2bar. Elapsed time from when boiler kicks on at min level to when it kicks off at max level is 10 seconds, time from when at max level to when it kicks on again at min level is 1 min, 12 sec, and total cycle time from boiler start at min level to the next cycle start at min level is 1 min, 22 sec.

- Steam pressure is good, but occasionally instead of the boiler pressure staying at ~.9bar when steam wand is open, it sometimes dips to ~.75bar. I'm not seeing excess water coming out of steam wand when opening to start (something ChrisCoffee suggested to check).

- ChrisCoffee suggested to listen for a steam leak with the machine cover off, and while I heard a slight one, it's intermittent. The 2 things I did that seem to have eliminated it are to tighten the nuts on the steam wand internals and to bleed off a good amount of steam by pressing the pressure release pin on the top of the boiler. After doing both and letting the boiler build back to full pressure, I hear no more steam leak. However, I'm still just barely able to finish a 25-30sec shot before the boiler kicks on again.

- Latest suggestion from ChrisCoffee tech is to replace the vacuum breaker valve (which I just ordered), but I'm not confident that's the problem.

I seem to remember when first using this machine that I didn't even have to time the start of the shot to when the boiler pressure was at max (i.e., I could start it in the middle of the boiler pressure cycle and still finish the shot before the boiler kicked on again, pulling the same 25-30sec shot). The only thing I might have changed over time is that I now brew ristrettos instead of normal doubles. Don't know if the machine is working harder for this.

So, any ideas on what's going on? Is it normal, and I'm just letting my caffeine buzz find non-issues? Or does it seem that my intra-shot boiler pressure is falling faster than normal?

SWR wrote:Help requested: On my Quickmill Anita, when I start pulling a shot when the boiler pressure is at max, it barely has time to complete pulling the shot (25-30 sec) before the boiler pressure hits the min level and kicks on the boiler refill.

Boiler refill? As in the boiler drawing in water? I can't see any malfunction that will connect boiler refills with running the pump. In fact, the "ordinary" malfunction is a bad solenoid valve, where running the pump overfills the boiler.

If the boiler refill comes on regularly at any time at all except after steaming or drawing water, you have a leak. Open up the machine, find it, seal it. Rare random refills can happen because of vibration or other tiny deviations with the boiler level probe.

The boiler pressure will drop faster when you are pulling a shot than when you are idling. How much faster depends on the machine. On the Tea, the heat cycled once a minute on idle, and once every twenty seconds when making espresso. On the Elektra Semi, the boiler runs pretty much all the time during a shot. This is simply the response of the machine to the cold water going through the HX.

The way the boiler responds to steaming will depend on the size of the steam tip and how much milk you are steaming. The Tea, with its low volume tip, still cycled on and off during steaming, and never went below the normal minimum point. The Elektra, with a bigger boiler, larger volume tip, and smaller heater, holds pressure fairly well for about 25 seconds (good for about 6 ounces), then drops like a rock. If you recently started steaming larger portions of milk on the Anita's high volume tip you can expect similar behavior. Otherwise, there could be a steam leak downstream of the steam valve, or a continuous steam leak so large it is affecting performance. (you'll be getting the boiler refill kicking in every half hour or worse in that case).

A simple D'oh that can cause all this is a dripping hot water tap. If the area under it is wet, tighten it.

SWR wrote:So, any ideas on what's going on? Is it normal, and I'm just letting my caffeine buzz find non-issues? Or does it seem that my intra-shot boiler pressure is falling faster than normal?

The boiler pressure drops during an extraction, as Jim said. Whether it's enough to force the heater on depends on factors like the heat exchanger size, boiler size, flow rate, and deadband of the pressurestat. The prosumer E61s that I've used, including the Anita, will call for heat before the end of the extraction, I believe around the 20 second mark. You can see this occur in John's video of the Vetrano, which shares the same group as the Anita:

From Banish Uneven Extractions with the Weiss Distribution Technique:

You may have read some home baristas expressing concern that the vibe pump's pressure drops when the heating element kicks in. It's true that some machines' brew pressure will drop as much as 0.5 bar. If I'm feeling especially persnickety, I'll time the cooling flush so the drop will be as late in the extraction as possible, e.g., by waiting until the top of the boiler cycle, or starting at the bottom of the cycle so the heating element runs during most of the extraction. However I've not endeavored to demonstrate it makes any difference in shot quality if it occurs at the 10 second versus 20 second mark. It's one of those "matter of principle" issues.

Speaking of, does this boiler pressure activity have a negative effect on your espresso, or are you just curious / concerned?

Thanks so much, guys. This is the input I was looking for.

Sorry if my descriptions aren't/weren't accurate, but to clarify, the "boiler kicking on" that I'm seeing is just the cycling of red/green lights which seems to indicate calling for more heat. I am not getting the loud noise when it's filling the actual boiler.

Thus, I was just concerned that I couldn't finish a shot before my green light went off and called for more heat. I thought it was supposed to stay green during the entire shot, and Dan was right in that I read that it could negatively impact the shot.

The shots seem to be fine, but wanted to make sure I didn't have a leak or something else to cause the boiler pressure gauge to drop quickly during a shot. Sounds like it's running normally.

Thanks again!