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ECM Technika IV drip

Postby keno on Sun Jan 13, 2013 2:41 pm

Just upgraded to a new ECM Technika IV after using a Valentina for 6 years. So far, very satisfied with this machine!

But I had a quick question for other Technika owners. After pulling a shot or backflushing there is a small drip from a button like protrusion just below and behind the grouphead water exit. It starts out at about one drop every 10 seconds and gradually slows over a few minutes to only an occasional drop.

Image

Is this normal? Have other Technika owners noticed this? I'm assuming that it's normal since there is a hole in the bottom of it and another hole in the drip tray below it. Also, just curious as to what this is for since I've never seen this on other machines.

Thanks,
Ken

PS Have to give a shout out to Jim P at 1st-Line. The machine arrived on Friday, but unfortunately the rear and left-side panels were damaged in shipping. I emailed 1st-Line around 7 pm not expecting to hear anything until Monday, but within 10 minutes I had heard back from Jim saying that they will send out replacement panels. Great customer service!!
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Postby Louis on Sun Jan 13, 2013 2:58 pm

Expansion valve? As the cold water is heated in the boiler, its volume expands. An expansion valve is used to allow excessive pressure to bleed out (normally set at around 12bar so it doesn't open during a 9bar shot).
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Postby HB on Sun Jan 13, 2013 4:29 pm

I agree with Louis; it's an expansion valve drain. The Expobar and other espresso machines have a similar drain into the driptray. Some vibratory pump espresso machines use a tee into the return leg of the OPV (see How can I adjust the brew pressure of a vibe pump espresso machine? for more details).
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Postby keno on Sun Jan 13, 2013 5:00 pm

Thanks Louis and Dan. So the OPV is just set to drain into the drip tray instead of back into the reservoir like it did in my Valentina? Makes sense because I didn't see any return hose into the reservoir.
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Postby Louis on Sun Jan 13, 2013 5:24 pm

I don't know your machine but I understand it uses a rotary vane pump. If so, there is no Over-Pressure Valve (OPV). Rotary vane pump rather use a bypass valve to return from the pump outlet excessive pressure to the pump inlet. The spring in the bypass valve can usually be adjusted to set the pressure. In the end, it achieves the same result, but without the need to return water somewhere.

This is different from the expansion valve, that prevent the boiler/pipe to fail under a too high pressure.

A vibe pump OPV (and even more a rotary vane pump bypass valve if you could see it) would not be dripping. You would see a continuous flow of water when pulling a shot.
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Postby allon on Sun Jan 13, 2013 7:26 pm

When I saw the subject line I thought it would be about an intravenous drip....
LMWDP #331
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Postby erics on Sun Jan 13, 2013 7:46 pm

You would see a continuous flow of water when pulling a shot.

That's very correct assuming your OPV is set correctly in a machine with a vibration pump.

For all practical purposes, the only time you should see some flow from that spigot is during initial machine warmup when the pressures within the heat exchanger can bump into the 11-12 bar range (expansion valve setpoint) as the water expands due to the thermal excursion. During the course of pulling a shot or simply flushing, the brew gage should rest steadily at 9.0 bar (or wherever you reasonably want).
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Postby keno on Sun Jan 13, 2013 8:16 pm

Yes Louis, it has a rotary vane pump. But now I'm confused again. I understand your point that this is not an OPV because a rotary vane pump will just return the overflow back to the pump.

But if it is an expansion valve to prevent boiler pipe failure as you say and as Eric says
For all practical purposes, the only time you should see some flow from that spigot is during initial machine warmup when the pressures within the heat exchanger can bump into the 11-12 bar range (expansion valve setpoint) as the water expands due to the thermal excursion. During the course of pulling a shot or simply flushing, the brew gage should rest steadily at 9.0 bar (or wherever you reasonably want).

then I'm wondering if I might have a problem.

The only time I never see any flow from it is during initial warmup of the boiler. I only see any flow after pulling a shot or backflushing. I do think the pump pressure is set high on this machine as it shows 10.5 bar when pulling a shot or backflushing.

So, any more thoughts guys?
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Postby Louis on Sun Jan 13, 2013 8:28 pm

Your machine has more valves than you might suspect:
1. A bypass valve, part of the pump body, to keep brew pressure at a preset amount (9 bar), used when the pump runs
2. An expansion valve, that allow excessive pressure to bleed out when there is no other way out (set at ~12 bar), used when cold water is heated up
3. A vacuum breaker valve, to allow steam boiler air to get out when the boiler first come to pressure
4. You might also have a safety valve that will open up if something bad happens and boiler (steam) pressure raises to excessive level.

I assume on a HX machine, 1 and 2 are on the HX water path, while 3 and 4 would be on the boiler itself. Others can confirm?

So what you see appears to be normal.
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Postby erics on Sun Jan 13, 2013 8:30 pm

then I'm wondering if I might have a problem.

Maybe, but only a tiny problem. Loosen the locknut on the pump pressure adjustment screw and rotate it 1/6 turn counterclockwise. That should be reasonably close to 9.0 bar when simply flushing through an empty portafilter.
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