I picked up a used, but working older Oscar yesterday. I did a quick test by running some water through the grouphead and releasing steam. The pump worked, the heater cycled and it made lots of steamy steam.

It appears to be in great shape aside from a, um, dent in the boiler, a slightly bent frame and a crispy hole in the site of the wall plug from what must have been a rather exciting electrical arc event...

As best as I can tell the boiler deformation is either from an over exuberant effort to remove a fitting or, given the bent frame, dropping the machine while the plastic bits were off.

Pics:


It does not show very well in the first picture, but you can see from the second one how the area next to and below the boiler inlet fitting is pushed in. The fitting itself had quite a bit of scale/corrosion around it that I brushed off.

The machine was up to pressure and running for about 1/2 hour before I tested. There was no wetness around the fitting or that end of the boiler, so I do not think there are any integrity issues.

Now for a few questions.

What is the best way to loosen that fitting so I can remove and clean it? Will a good soak in citric acid solution do the trick?

What is the purpose of the capped off T fitting (blue arrow)? Hmm, could I put a boiler drain there?

What is the best way to test the 3-way solenoid at the grouphead? Just pull a few shots?

I'll be replacing the power cable as soon as I finish this post. I can't believe he actually plugged this thing in anywhere near his house and let it warm up for me to test.

Thanks.

With the power cable replaced I did some more testing. It appears that though the pump works, water flow is intermittent. I get steam to start as expected, then two to three ounces of water, then steam again. The cycle is pretty consistent.

When it is cold, I get a constant flow of water, though it does not seem very strong. This in itself is not a big deal as it could just be an old pump giving up the ghost or that the machine needs a good clean. With that in mind, I decided to remove the neplax vale on the side of the group head.

Someone has removed it in the past. Their attempt to put it back on was, well, not good. most of the threaded stem has been stripped.

When I opened the valve there was a very fine coat of scale, consistent with my impression that the machine is little used. The plastic valve part is also in good shape. I don't think the thread on the grouphead was stripped, but my eyes are not as good as they used to be.

It looks like I have what should be a good machine damaged by someone who had no clue what they were doing. I'll have to strip this thing down to see what other damage has been done. Given what I paid, I have a fair bit of room before this becomes a bad buy, but given what I've seen so far, who knows.

It keeps getting worse. The threads on the grouphead are damaged. They look salvageable if I can find out the correct tap and thread size.

How could somebody so completely mangle such a coarse threaded part?

Too bad I can't change the thread title. It should be: Oscar, then unintended rebuild.

Here is a picture of the stripped neplax:


You can see how badly threaded it is. It was being held by the lasat two intact threads closest to the neplax body. I don't think I want to rely on that to hold something that could get to 9 or 10 bar of preasure.

Small victories today: I got the frame straitened so everything fits back together nicely, the boiler is mostly disassembled.

Tomorrow's quest is to figure out if the brew head is salvageable.

fredk01 wrote: I get steam to start as expected, then two to three ounces of water, then steam again. The cycle is pretty consistent.

Good luck with the 'rebuild'! All I can say is lots of patience and be more careful than careful when undoing those fittings (all it takes is just a broken fragile part to ruin the whole project). Sometimes less is more. ie, in the case of that blind-plugged elbow fitting - I might just leave it as is and not attempt to disassemble it, considering the state of the boiler and that it doesn't do anything important and might have been modified(?). Also, use a counter torque whenever possible (ie two wrenches in opposite direction when trying disassemble the fittings so that the stress is not passed on to the boiler)

The quoted above does concern me however. Did it still release steam after you've exhausted the hx(ie. After a long long flush)?

samuellaw178 wrote:...

The quoted above does concern me however. Did it still release steam after you've exhausted the hx(ie. After a long long flush)?

Yup. It is not just an extra long cooling flush. It keeps cycling between steam and water.

There has been examples of ruptured HX (especially after stored frozen) - which could contribute to the steam+water you see. But it's too early to tell with the limited info and hopefully that's not it.

One sure way to test is if you do a blind flush, the boiler will keep filling until it triggers the overpressure valve...As I understand you've started the rebuild - might worth a check before plunging further.

Dumb, dumb, dumb...

I was impatient trying to remove the heater coil. The picture above is the result. After my comments about the threaded neplax valve, karma baby...

I got a PM from plindy, thanks Pete, and all my questions are resolved. Apparently the first boiler bend was fixable. I'm not sure about the one above.

I'll get the guys at work to clean the threads on the grouphead and I should be able to put a new neplax in. The other solution I though of was to put in an OPV as the cold water supply. From what I can tell, the neplax is there as a safety valve for the HX water loop. That would eliminate the need for a neplax. The threaded hole could then be tapped out larger and plugged. That's much cheaper than replacing the head and adds brew pressure control.

I've taken apart the one way valve for the cold water supply and the 3 way solenoid on the grouphead and both appear to be intact. At Pete's suggestion I looked for corrosion or a failed part in the brain. All looks good there. I'm thinking that the issue is with the pump (an inexpensive replacement).

I still need to work out a way to get the heater coil out of the boiler without further damage.

Random thoughts on boiler pressure while I contemplate how to proceed:

Normal operating pressure of a boiler is 1 to 1.3 bar, 14 to 18 psi. Not much pressure there at all, however...

Saftey relief valve pressure is 16 bar, 232 psi. That is enough to make for an exiting boom if a boiler fails.

I expect that the boiler is designed with a margin of safety in the 15 to 20% range, so thats 268 to 278 psi.

A boiler failure under normal operating pressure doesn't sound like that big a deal. Kinda like having a flat tire with hot water.

At the other end of the range, it could get exciting. At the very least I expect a catastrophic failure would ruin all the electronics and do fun things to the plastic case.

The new boiler is going to add $200 to $250 depending on shipping and exchange. Replacing the whole machine would be 3 to 4 times that, IF I can find a decent used machine. They do not come up that often in Canada.

I should probably verify function on everything else possible first though.

So, if I reassemble the machine and disconnect the heater coil, I should be able to test the function of the various solinoids and other parts as per the tips page on the electro.it website. If there are no other failed parts, even with the cost of replacing the boiler this will be a reasonable cost used machine.

fredk01 wrote: Saftey relief valve pressure is 16 bar, 232 psi. That is enough to make for an exiting boom if a boiler fails.

How did you get the number? It was my understanding boiler safety valve is generally around 1.8-2.5 bar.

There's another safety valve which is the OPV (overpressure valve) that oversees the brew circuit (~9 bar operation and max 15-16 bar as you cited).

The $200-250 boiler sounds like a reasonable price actually. I've always thought it would cost an arm and a leg.