After the descaling, I was going to try pressure testing. I was planning to cap off all the boiler fittings except the ones for the heating element, heat exchanger nuts (the big ones that take a 12 mm allen wrench), pressure safety valve, water level probe, vacuum break, the line that goes to the pressure gauge, and the line that goes to the hot water valve. Then I'd half fill the boiler with water, install the above-listed nuts and components except the hot water valve (which is missing anyway), attach my air compressor to the fitting for the hot water valve (need adapter), and pressurize the boiler. I'd install new gaskets. I hope to check the boiler for leaks, test the function and setting of the safety value, and check the accuracy of the boiler pressure gauge. The main aim is to verify the boiler is sound, before I proceed further.

My air compressor goes to 100 psi. The data plate says the operating boiler pressure is 1.5 bar, which is about 22 psi. I am thinking I should be able to safely take pressure up to 2.0 or 2.5 bar, without damaging the boiler, assuming it is sound in the first place. I am also assuming that if the safety valve doesn't start releasing around 2.0 or 2.5 bar, it should be replaced.

Does this sound like a correct procedure?

Or do you think it is not necessary? When professional espresso repair shops refurbish these machines, do they pressure test the boilers? I don't want to make unnecessary work for myself, not to mention buying 9 or 10 brass caps that I won't have any further use for.

Do not pressurize a tank under test unless it's full of water. If something breaks, a gallon of 100 PSI air has a lot of energy, a gallon of 100 PSI water has essentially none. I'd also use a bicycle pump, full of water, it's probably only one pump to 100 PSI.

Ira

Thank you! Boiler almost full of water, bike pump. Got it!

The lines are all cleaned up after 48 hrs in a citric acid bath. 1 lb powdered citric acid in a 50 quart cooler filled with 150 F water. The water turned green and the brass nuts now have a copper color which I will polish off.

I think I made a mistake by putting the heating element in the bath. The elements themselves are now clean, but the steel terminals and nuts turned black. A few minutes with a wirewheel cleaned them up. Hopefully no damage done.

The boiler still has a bunch of crust around the heating element, even after the citric acid bath. I'm going to try something else soon - either vinegar or, as a last resort, CLR.

Incidentally, for maintaining copper cooking pots - I have a lot of these - I use a paste product called "Twinkle" which is sold in hardware stores. Just rinse pot with hot water, rub on Twinkle with a sponge, rinse off with hot water, turns tarnished copper back to shiny in a twinkle.

A little progress every day. This took a couple hours with the buffing wheel.

The boiler is now in 50% vinegar 50% water. The citric acid wasn't making much difference to the worst crust at the heater fitting, which appears to have been leaking for a long time. If that doesn't work, I'll try CLR.

In my experience, citric acid needs to be hot to do much of anything.

Ira

Possibly I didn't use enough citric acid; 1 lb in the cooler was only about 1 TBS per quart of water. But the water was very green and all the brass had a coating of pink-salmon color, so the acid was active.

Not having a big enough bucket I descaled my boiler by filling it with citric acid and powering up one or two of the elements with 117V, Two got it boiling and one kept it quite warm. Went through 1 1/2 bottles of Dezcal, about 3 pounds worth I think. I did the tubing in a stainless pot on the stove carefully arranging the tubing so the bubbles would rise up the tubing and pull in more fresh solution. The outsides get beautiful in a few minutes, the insides took a day or two.

Ira

Oh, that is clever! Wish I'd thought of doing that.

I've switched to vinegar. The inside of the boiler is starting to respond. The crust on the outside, around the heater gasket, is also starting to soften. We're getting somewhere!

While waiting for the boiler to descale, I've worked on the frame. The "floor" of the frame is rusty under and around the heater element gasket, which must have leaked for a long time. I am using a wire wheel, scraper, paint stripper and EvapoRust to remove the rust and old paint, and then I'll repaint with a Hammerite type paint.

I stripped the paint off the boiler. Underneath was chrome but copper was showing through the chrome in conspicuous areas.

I stripped the chrome off with abrasives, wire wheel, hand sanding to 1000 grit.

The next step is polishing and buffing.

But I need a break from working on the boiler, so it is back in the vinegar bath until I'm ready to deal with it again.

I'm pretty much done with rehabbing the boiler. Not going to obsess over the polishing and buffing. After all it is an internal part and will soon get tarnished. Unless - I could shoot it with clear lacquer. Hmm.