Question about valves on 2 group Elektra HX

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DaveGrayson
Posts: 21
Joined: 12 years ago

#1: Post by DaveGrayson »

My two 3 way solenoid valve assemblies work, in that they route water to the bell when activated, and allow water from the bell to backflush from the portafilter/bell through the port on the bottom of the pilot assembly when the solenoid releases. However... when you pull a shot on one group, the high pressure water leaks out the bottom of the other group... ie: high pressure water (I am running 8 bar according to the gauge) must be overcoming the spring pressure in the other valve assembly and forcing its way through the valve and out the overflow port. Is this common/normal? If not, does it mean that I need new valves (as it looks like I can't get springs separately)?

JimH
Posts: 186
Joined: 13 years ago

#2: Post by JimH »

Just to clarify, is only one valve leaking or do both valves leak when the opposite group is activated?

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DaveGrayson (original poster)
Posts: 21
Joined: 12 years ago

#3: Post by DaveGrayson (original poster) »

happens on the opposite group regardless of which group you are using.

JimH
Posts: 186
Joined: 13 years ago

#4: Post by JimH »

OK, that helps. The springs in 3 way valves are about the strength of the spring in a clicky pen. They don't have to be very strong because the inlet orifice in the valve is very small. Consequently, they don't usually wear out very quickly. The odds of one failing are small, the odds of both failing is microscopic.

Instead of replacing the valves, have a go at opening them up. You'll probably need to replace the 2 tiny o-rings inside, they are usually pretty stiff after a long period of use and won't seal well when you reassemble. When you have the valve open, see how freely the solenoid moves. If it has scaled up or is covered in coffee oils, it will definitely need to be cleaned.

Make sure you examine the edge of the inlet orifice and the valve seat. Just a little bit of crud will prevent a good seal, which will leak under pressure. I had one group of a 2 group machine that was leaking after a full rebuild. I opened that valve up 3 times before I got it clean enough to stop leaking.

A different but unlikely possibility is that your brew pressure is actually much higher than you think. The pressure gauge might not be working well, so I would check the pressure coming out of the portafilter to see if it is accurate.

DaveGrayson (original poster)
Posts: 21
Joined: 12 years ago

#5: Post by DaveGrayson (original poster) »

Thanks a lot. Actually I had them apart several times for cleaning etc but I hadn't paid much attention to the valve seat. I will play further.

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erics
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#6: Post by erics »

You can replace the entire insert assembly BUT only after you take a real close magnifying glass view of the valve seat. The inserts are keyed to the exact valve make/model so have these handy when you inquire.

A very good source of parts (and knowledge) is Stefano @ http://espressocare.com/

Some Elektra parts stuff here - /downloads/
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

DaveGrayson (original poster)
Posts: 21
Joined: 12 years ago

#7: Post by DaveGrayson (original poster) »

On my Elektra 2 group there is a line from the right HX pipe to a safety valve that empties into the drain pan (not to be confused with the boiler safety valve atop the boiler). While I am pulling shots a significant amount of water passes through this valve to the drain pan. There seems to be more than enough water going through the group to pull the shots but as I am running on a 5 gallon water supply jug it does lower my supply pretty quickly. My machine's gauge reads 8 bar pressure during a shot, and I have tried knocking pump pressure back so that it reads 7 during the shot to see if it makes any difference but the valve still is active.

I am thinking about making a portafilter pressure gauge to verify actual pressures at the group and I am thinking about testing the safety valve itself to find out its actual trip point.

So my question is twofold... a) Is the valve supposed to activate at normal shot pulling pressures (in order to handle excess volume of water from the pump) and b) if that is the case, does anyone reroute that water back to the supply bottle rather than dumping it down the drain? I noticed that this is done by the manufacturer on my crappy little HB (Hamilton Beach).

Thanks, Dave

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erics
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#8: Post by erics »

You need to do some "search engine use". That valve is designed to relieve at ~11.5 to 12.0 bar and is a thermal expansion OPV.

The valve is, most definitely, NOT designed to leak/relieve during normal shot brewing. From what I have gleaned over the years, the Elektra pumps (and most rotary pump machines) are waaaaaay oversized and can easily accommodate leaks all over the place and still deliver enough water to gain the "typical" 9.0 bar.

There exists a wealth of info on this site re Elektra machines and I agree it is tough to navigate/search at first but then . . . the light bulbs shine.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com