Descaling plumbed in commercial espresso machine

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sultanoswing

#1: Post by sultanoswing »

Background:
Below is my commercial Wega one-group Airy (circa 1990's). She's a robust beast, but I haven't descaled her since installation a couple of years ago.



I recently pulled the group head and cleaned it up since there was some leaking from the electric solenoid. There was a mild amount of scale on the 'shroom only, and some scale in the copper lines - but nothing major. The commercial machine repairer I took the group to for parts check / purchase said NOT to descale with anything, and that they use and recommend bead blasting and hot tanking to properly descale and that anything else can cause more problems that it's worth. I guess they have a potential vested interest in us not descaling at home, perhaps.

Anyway, the machine is plumbed in and requires constant mains pressure to run properly (rotary pump) as evidenced by the fact that brew pressure was only 4-5 bar when I had an inline pressure regulator to aid proper water filter contact time installed recently. This has now been removed and brew pressure is back to 9.5 bar.

2 Questions:

1) Was the commercial repairer correct - ought I NOT descale using citric acid solution?

2) If I do descale, how do I best get the solution into the boiler without mains pressure supply?

Thanks in advance.

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djmonkeyhater
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#2: Post by djmonkeyhater »

You will find that this is a soft science so be ready for lots of diverse input. Anyway, I have a machine that is similar and made under the Astoria label.

As I got into this I had to learn to take the input from commercial repair places with a grain of salt. The shop down the hill from me doesn't advise against descaling or other forms of self-repair they'll just tell you that they don't see it work out well often. (Maybe think of two non-mechanically inclined people in a restaurant trying to do this with inadequate tools and not having allowed enough time for it.)

I descale mine with a chemical that I get from a espresso parts supplier. The brand is escaping me but it is for descaling commercial kitchen things like steamers, dishwashers and espresso machines. I do it every 6 months. It has some citric acid in it along with some other things. My machine has been installed for a couple years and I guess if I peel some of it apart in a couple years, I'll know if this was enough.

To get it in the machine, I have used two techniques:

1) Pull a fitting on the top of the machine and pour in the solution, usually to an overfill level so that the scale above the water gets exposed. Then put the fitting back in and fire it up.

2) I see that you have a filter to the left. I have also taken the filter body apart and put it back together full of pretty "thick" descaling solution. Then I operate the machine to get that solution into the boiler and brewing circuits. This technique gets descaling solution into the brew circuit and the above does not. You can pull up the autofill probe to get to the overfill state.

Now you can let the machine run for X hours (I do 4-6). Then start pushing fresh water through the machine until you can't taste the descaler. It usually takes a lot longer and a lot more water than I think to do it. I have an 8L boiler and I would guess that 10 gallons is a decent start.

For pushing the fresh in/out - I have a technique to save time that may or may not work for anyone else. On my machine, I can get a complete column of water through the water wand with some manipulation which allows me my to "siphon" water without steam pressure. It speeds up moving the water through quite a bit. I can explain a bit more if anyone wants to try it.

WES

sultanoswing (original poster)

#3: Post by sultanoswing (original poster) »

Thanks for the input. I had been sorely tempted to pour the descaling solution directly into the boiler when I had some of the fittings off recently (to cure a few minor steam leaks). I'd been about to do it (1 Tbsp citric acid / litre of water) before the commercial shop then advised against it.

Good thought about putting the descaler into the filter housing (sans carbon filter of course!). Subsequent to the photo above, I've installed a separate descaling filter before the carbon filter pictured.

Let's see what others have to add... :)

User avatar
HB
Admin

#4: Post by HB »

sultanoswing wrote:Anyway, the machine is plumbed in and requires constant mains pressure to run properly (rotary pump) as evidenced by the fact that brew pressure was only 4-5 bar when I had an inline pressure regulator to aid proper water filter contact time installed recently. This has now been removed and brew pressure is back to 9.5 bar.
I don't know the specific model your espresso machine has, but Procon pumps don't need positive pressure to operate correctly. Do most plumb-in machines require external pressure? and Rotary pump inlet pressure discuss the details.
sultanoswing wrote:If I do descale, how do I best get the solution into the boiler without mains pressure supply?
Also see How do you descale a non-reservoir machine? I added a tee and two stopcocks. The tee leads to a jug of descaler. To descale, I turn off the mains water stopcock and open the second stopcock leading to the jug. When the pump calls for water, it will draw from the jug.

Here it is in ASCII art:
--- main -->------S1-------+----------- espresso machine
                           |
                           |
                           S2
                           |
                           |
                          Jug
Dan Kehn

denniskeating

#5: Post by denniskeating »

Hello, I installed the setup as per Dan's advice, and it works great. You don't have to remove the mains water line to use the tee setup. I use a vinyl hose with a push-on fitting that threads onto the tee. No pressure needed.
My house has old pipes that deliver rust, and my filter setup has a prefilter and then the water filter. The water is so good coming out , I have thought of using the vinyl hose and tee to dispense drinking water for me and my dog. Water from the kit faucet can look rusty - yuk!
- Dennis

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JohnB.
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#6: Post by JohnB. »

If you own a blast cabinet & hot tank that would be the way to go but how many people do? I have a blast cabinet in my shop & that's how I descale the Vivaldi heating elements. A job that would normally take hours of soaking in a hot citric acid bath is finished in a couple minutes in a blast cabinet.
LMWDP 267

sultanoswing (original poster)

#7: Post by sultanoswing (original poster) »

HB wrote:Also see How do you descale a non-reservoir machine? I added a tee and two stopcocks. The tee leads to a jug of descaler. To descale, I turn off the mains water stopcock and open the second stopcock leading to the jug. When the pump calls for water, it will draw from the jug.
Yeah - that'd be very simple to add, since I've already (not shown in the above) got an inline tap and 1/4" line coming off as 'S2' just prior to the machine to supply descaled, carbon-filtered drinking water. Question remains though - will my rotary 'suck' from a non-pressurised jug or bucket? Hmmmm.....

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HB
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#8: Post by HB »

sultanoswing wrote:Question remains though - will my rotary 'suck' from a non-pressurised jug or bucket?
From the FAQs: Can a rotary pump suck up from a bucket?
HB wrote:Rotary pumps do not need positive pressure to work, so presumably a check valve would suffice (to prevent the water from draining out and introducing air bubbles). That said, I would double-check with the vendor beforehand because the manufacturer may call out positive pressure. For example, Eric reports that without positive pressure, the pump on the Quickmill Vetrano cavitates (link).

Image
Ball-type check valve assures water flows only one direction

Whether your espresso machine will extract correctly is another question. For example, some rely on the line pressure for preinfusion. I've read reports of some commercial espresso machines relying on line pressure to fill the boiler too. The owner's manual or your dealer should have instructions on proper installation.
Dan Kehn

djmonkeyhater
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#9: Post by djmonkeyhater »

Since life isn't always easy... Rotaries can pull from a bucket but be sure how "strong" your pump head is. I had a somewhat weak Procon rotary pump head on a machine and it would not do the bucket thing. It was generally fine as a pump with line pressure behind it - 8-8.5 bars but without line pressure it was useless. Months later I got a new head and now it will pull from a bucket.

WES

sultanoswing (original poster)

#10: Post by sultanoswing (original poster) »

[EDIT] OK - I tried the above schematic (plumbed in with a check valve to prevent flow back down to the taps) and the pump does indeed suck from a jug / bucket adequately!!

Now: to descale with citric acid or not...?