Why backflushing is important to the health of your espresso machine

#1: Post by **Compass Coffee** » Apr 06, 2008, 11:10 pm

Some people still seem opposed to backflushing. Seems some home machine manufacturers even recommend not backflushing even though the machine has a 3-way valve.

This was posted today on the SM List by a former nuclear reactor engineer now certified LM tech. It's information I've never heard explained quite this way before and I believe valuable.

Many folks have the wrong idea about what the backflush actually accomplishes.

Yes it does clean the shower screen, dispersion block and everything else that is inside of and above the portafilter sealing location against the group gasket.

And Yes this is important and if backflushing or a disassembly of screen etc. and cleaning is not accomplished fairly regularly the contamination of shots from the built up gunk and oils will provide a considerably less than pleasant addition of the shots taste.

The one thing that the backflush accomplishes, that has not been mentioned, is cleaning the passageways from the location at which the brew water is injected above the shower screen backward thru the three way valve and to the drain tray. This flow path can be from several inches to almost a foot depending upon what particular machine. If not backflushed this passageway will slowly fill with solidified oils and crud until flow is completely stopped. At this point things can become expensive.

Machines built prior to the advent of the three way valve had a disconcerting habit of spraying hot water/coffee all over the operator if the pressure was not allowed to relieve itself prior to portafilter removal after pulling a shot. Before the advent of the three way valve the norm for cleaning the group head was physical disassembly, brushes soap etc. and it worked perfectly well. IMHO - ALL machines with three way valves should be backflushed regularly.

An example: I recently did some work on a nice commercial single group Brazilia that has seen regular use in a local Bed & Breakfast for a number of years. No amount of 2000 psi air and / or acid flushes etc. would clean the drilled passageways in the group head. The passageways were drilled and welded closed at the casting boundary, so physically re-drilling the holes was not in the cards. The options included drilling the welds etc. etc. ----- the cheapest solution ended up being a three week wait for a new group casting. Reasonably regular detergent backflushing would have saved these folks about $450 all told (extra labor and price of parts), as well as not having to do without a machine for three weeks.

When pulling a shot from a group with a three way valve, you should hear a slight swoosh immediately after the pump stops. This is the three way valve venting the area above the coffee puck in the portafilter thru the valve and to the drain. If you don't hear it, it is time to get serious about doing some detergent backflushing until things are cleaned up.

Mike (just plain)

#2: Post by **Randy G.** » Apr 06, 2008, 11:37 pm

Compass Coffee wrote:Some people still seem opposed to backflushing. Seems some home machine manufacturers even recommend not backflushing even though the machine has a 3-way valve.

This was posted today on the SM List by a former nuclear reactor engineer now certified LM tech. It's information I've never heard expained quite this way before and I believe valuable.

The one thing that the backflush accomplishes, that has not been mentioned, is cleaning the passageways from the location at which the brew water is injected above the shower screen backward thru the three way valve and to the drain tray. This flow path can be from several inches to almost a foot depending upon what particular machine. If not backflushed this passageway will slowly fill with solidified oils and crud until flow is completely stopped. At this point things can become expensive.

Our nuclear engineer friend should read my article "3-Way Valve How and Why" {link location updated 2/2012} which thoroughly documents how a 3-way valve works and why it is important to backflush. The cleansing of the hidden passages is thoroughly documented and illustrated as is how a 3-way valve works and why backflushing is not only necessary, but should be required to maintain a warranty. The article has been reviewed by experts in the espresso machine repair business for accuracy.

Did he cover "water hammer"? I did...

#3: Post by HB » Apr 07, 2008, 12:27 am

Thanks for your comments Mike and Randy, I was surprised to find this topic wasn't among the site's FAQs and Favorites (it is now

).

I had the misfortune of seeing the results of an espresso machine that wasn't backflushed for three months (the new owner was not aware it was necessary). He kept the exterior of the machine shiny clean, but behind the dispersion screen lurked a layer of thick, black, sticky tar.

Portafilter "wiggle rinses" to wash off loose grinds and a quick water backflush if the machine will be idle for awhile are always a good idea. There isn't a clear consensus on how often you should use espresso cleaner in a home milieu; I do it once every week or two. The article Espresso Machine Cleaning - Why, How, and When and its feedback comments get into more details.

#4: Post by **FC+** » Apr 07, 2008, 10:28 am

Okay, newbie here, with a Gaggia Baby Class, what hardware do I need to backflush with?

#5: Post by **Mark08859** » Apr 07, 2008, 10:46 am

Compass Coffee wrote:Some people still seem opposed to backflushing. Seems some home machine manufacturers even recommend not backflushing even though the machine has a 3-way valve.

Granted, this is just from memory. The Silvia does have a 3-way valve that the manufacturer does not recommend backflushing. I know people backflush it all the time. From my reading, it seems that Rancilio maintains the pipes can't handle the pressure of a backflush and the owner risks voiding the warranty if they damage their machine.

Are there any other machines where backflushing is not recommended with a 3-way valve?

#6: Post by HB » Apr 07, 2008, 10:59 am

FC+ wrote:Okay, newbie here, with a Gaggia Baby Class, what hardware do I need to backflush with?

According to WholeLatteLove, it has a three-way valve:

No one likes trying to get rid of soupy espresso grounds after they've brewed their morning shot. That's why the Gaggia Baby Class features a three-way solenoid valve that relieves pressure from the portafilter once your shot has been brewed. This results in a drier espresso puck and easier disposal.

So all you need is a blind (no holes) basket and espresso cleaner (Cafiza, Puly Caffe, JoeGlo, etc.).

Mark08859 wrote:Are there any other machines where backflushing is not recommended with a 3-way valve?

None that I'm aware of.

According to one vendor who wishes to remain anonymous, Rancilio makes this recommendation purely to reduce warranty claims. Too many new owners used excessive amounts of espresso cleaner (or used dishwasher machine powder) and would clog the grouphead, resulting in a warranty claim ("Uh, no water comes out. I keep it very clean."

). Of course this recommendation ignores the fact the consumer will brew tainted coffee and have potential problems with blockage in the second year -- when it will no longer be under warranty.

#7: Post by **Compass Coffee** » Apr 07, 2008, 12:25 pm

Mark08859 wrote:Are there any other machines where backflushing is not recommended with a 3-way valve?

The original SM List post was in response to a La Spaz' Vivaldi owner mentioning hadn't backflushed in IIRC a year ownership because either vendor or manual said backflushing not recommended...

#8: Post by HB » Apr 07, 2008, 12:51 pm

Compass Coffee wrote:The original SM List post was in response to a La Spaz' Vivaldi owner mentioning hadn't backflushed in IIRC a year ownership because either vendor or manual said backflushing not recommended...

I can only assume the owner misunderstood or the vendor was poorly informed. The La Spaziale comes with a backflush disk from the factory. In addition to regular backflushing, the La Spaziale dispersion screens must be removed regularly for cleaning to remove trapped coffee.

Buyer's Guide to the La Spaziale S1 wrote:In the center of the S1 grouphead is a small 8mm bolt that holds the brass water diffuser and dispersion screens on. Notice that read dispersion screens, not screen. The manufacturer explains that there are two dispersion screens, a smaller one beneath a larger one, to reduce grinds passing back up through the grouphead and to prevent channeling.

#9: Post by **cafeIKE** » Apr 07, 2008, 1:02 pm

HB wrote:There isn't a clear consensus on how often you should use espresso cleaner in a home milieu; I do it once every week or two.

- On a machine used, and plain water backflushed, daily, a taste change is detectable after a chemical cleaning and seasoning shot after as little as one week.
- As "every week or so" is elastic, in keeping with H-B OCD guidelines, a ritual weekly chemical backflush keeps everything ship shape. Personally, since most dinner parties are Saturday night, I opt for Saturday morning cleanings.

#10: Post by **Randy G.** » Apr 07, 2008, 1:17 pm

Mark08859 wrote:The Silvia does have a 3-way valve that the manufacturer does not recommend backflushing. I know people backflush it all the time. From my reading, it seems that Rancilio maintains the pipes can't handle the pressure of a backflush and the owner risks voiding the warranty if they damage their machine.

My article touches on what you can do if a manufacturer or reseller states that you should not backflush a machine with a 3-way. In my articles FAQ at the end, it states:

My manufacturer or reseller says I will void the machines warranty if I backflush. Now what?
Ask them what happens if the machine starts making bad-flavored coffee, or if the 3-way valve fails because of a buildup of coffee crud. Ask them if returning the machine for cleaning is covered by the warranty. Ask them how the brewing path is supposed to be cleaned. See if they will cover shipping costs both ways for cleaning or repair costs under warranty. Get it in writing and please send me a copy. I would be interested in reading their opinion.
Keep in mind that every commercial machine comes with blind filters for backflushing, and their design in this case is really no different from a home machine with a 3-way valve when it comes to backflushing.

As far as the pipes not handling the load, it would be interesting if you could quote the source. As I mention in my article, there is virtually no difference at all between a choked shot and backflushing. The major difference is that a user will tend to run a choked shot for fifteen seconds waiting for something to dribble out while a backflush only runs the pump for two three seconds once pressure is built. How many manufacturers void the warranty if a shot chokes the machine?

Here's another angle. Rancilio now equips their machines with an adjustable OPV, and yet there is no pressure gage for the user to judge whether they have set it correctly. Does the OPV have stops to prevent it from causing an over-pressure incident if it is incorrectly set? If you adjust it incorrectly, is the warranty void? it would seem that this adjustable OPV is a far greater warranty or liability problem then any damage backflushing could cause.

IMO, the "no backflush" policy from Rancilio is just a matter of them applying a corporate CYA. When a vendor says not to backflush, I have to wonder why would a company who makes money repairing machines tell you not to perform a widely-accepted maintenance procedure that would help prevent breakdowns and thus the need for repair.

For any owner of a machine with an electrical 3-way valve - if you have not backflushing with a cleaning agent in the last two or more months- disassemble the 3-way and examine how much crud is in there, then realize that the same is also in the brewhead's passages where your brew water passes through en route to your coffee each morning.