bcarrigg90 Senior Member Joined: 13 Feb 2012 Posts: 43 Location: cincinnati Expertise: I live coffee
Espresso: Delonghi EC 702 Grinder: Capresso Infinity - Modified Drip: French press is as close as...
Posted Fri Dec 7, 2012, 12:27pm Subject: DeLonghi OPV leaks at steam temp.
I've just started realizing that the hiss i hear whenever my ec702 reaches full steam temperature is from the over pressure valve releasing some of my steam pressure. I can see a small stream of air bubbles shooting down the tube back into the resevoir. There certainly isn't enough pressure for this valve to be opening. The steam temp is only 120º C, so i really don't want any of that pressure wasted. Should i try taking apart the valve to see if theres a badly seated seal or something? I would like to eventually upgrade it to a metal valve, rather than the plastic one it has, but i need to figure out which fittings i need to be able to connect all the hoses to a different valve first.
Oh, and i already tried a good thorough descaling to no avail. Its done this since i received the machine off Amazon. It was an open box item.
bcarrigg90 Senior Member Joined: 13 Feb 2012 Posts: 43 Location: cincinnati Expertise: I live coffee
Espresso: Delonghi EC 702 Grinder: Capresso Infinity - Modified Drip: French press is as close as...
Posted Fri Mar 29, 2013, 2:48pm Subject: Re: DeLonghi OPV leaks at steam temp.
Three months later, I still haven't figured out what's going on with this thing. I ordered two new OPVs since then, and both h had the same issue. Am I completely wrong in thinking that the opv should never open unless you choke the pump? I don't see any reason why this valve would be designed to intentionally open while just heating up. There is water that comes out while the pump is running also, so I feel I am losing pressure and flow that should be running to my shot. Any suggestions? I'm almost to the point of gluing a plug into the valve so it essentially takes it out of the system. Then it's just up to me to not break the pump, but I might be willing to take that risk.
As you can see, and know from experience, that 120C temperature does not generate a lot of pressure, a little over 1 bar. It would seem if the valve is leaking at that low pressure you would be unable to brew. It should also leak at the equivalent brew pressure, though flow also enters in.
You could make a PF pressure gauge and test machine brew pressure. You can use a blind basket and occlude outflow and then measure the backflow and approximate the pressure. If you remove the tank and put a glass full of water in its place you can run the pump with a blind basket and catch and measure the return flow.
bcarrigg90 Senior Member Joined: 13 Feb 2012 Posts: 43 Location: cincinnati Expertise: I live coffee
Espresso: Delonghi EC 702 Grinder: Capresso Infinity - Modified Drip: French press is as close as...
Posted Sat Mar 30, 2013, 4:18am Subject: Re: DeLonghi OPV leaks at steam temp.
I should have some time on monday to go through some of those steps and take some measurements. The weird thing is that I can still brew. It's like the valve does not open completely, but just enough to lower my pressure and let steam leak out the back.
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