MemberFebruary 20, 2020 at 4:44 pm
I wrote this up as a reply to the article “Rational SCC Service Codes.” I guess what I wrote was too long because it wouldn’t let me post it there.
WELL, it took me awhile to write this…and I’m gonna put it somewhere! So, HERE looked like the next best place…
* * * * * *
From my own experiences working on Rational ovens, I’ve found that the most common service code to show up is service 10 on SCC (Self-Cooking Center) ovens and E13 on CM (CombiMaster) ovens. Those codes mean the SC pump (self-cleaning pump) is not functioning. As an explanation on why that is, let me answer a few questions along the way:
What does the SC pump do?
It serves to drain the steam generator.
When does it operate?
After every TWO cumulative hours of steam generator operation, the oven’s control is programmed to drain the steam generator to rid the steam generator tank of mineral-enriched water so it can refill the tank with fresh water.
What do you mean “mineral-enriched”?
As water boils to make steam, the water level obviously drops. Repeated water fill cycles will “top off” the existing water level.
ALSO, as water boils to produce steam, solid impurities in the water (mainly lime scale) DO NOT ride along with the steam into the cooking chamber. The scale remains inside of the steam generator.
Subsequently, every water level “top off” brings in still MORE lime scale with it. Over time, this results in an even richer concentration of limescale in the water. If left in there, that scale begins to stick to the tank walls.
So, the self-cleaning pump empties out the mineral-enriched water every two hours to reduce the lime scale’s chances of lingering around and sticking to stuff in there. Ultimately, this reduces the frequency of maintenance needed. HOWEVER, it does NOT eliminate the need for that maintenance altogether. Eventually, a descaling WILL be required.
What does all THAT have to do with the SC pump not functioning?
Firstly, be aware that if that pump is NOT functioning, this will greatly accelerate the need for descaling the tank by a technician. Ignoring the service code for any length of time could quickly lead to far more expensive repairs down the road.In one case, I had to replace an entire steam generator – simply due to massive amounts of lime scale buildup. The cost ended up being thousands of dollars in parts ALONE!
Secondly, the CAUSE of an SC pump not working is almost ALWAYS attributed to it getting jammed up by a loose shard or chunk of scale. As a quick solution, that simply requires a tech to manually drain the steam generator, remove the pump, dislodge the debris from the pump, then re-install it. At that juncture, I’d normally attempt to rake out any other loose scale before re-installing the pump. However, that should be followed up by a proper descaling performed sometime in the near future.
How do I prevent the SC pump from getting jammed again?
If you have a Rational SCC oven manufactured 2008 or later (ones with the CareControl drawer next to the hand shower):PERFORM THE CARECONTROL CYCLES REGULARLY. That means at least once or twice WEEKLY. Along with the detergent tablets (red wrappers) used for making the cooking compartment spic-n-span, the Care tabs (blue wrappers) that go into the drawer…IS A DESCALER. The Care tabs are a mild citric acid concentrate which dissolves lime scale. If you do what I say here, you will never need to hire a technician to descale your oven. Here’s a video on that: How To Clean a Rational SCC Combi Oven
If you have a CombiMaster or a pre-2008 SCC oven, those ovens don’t have the CareControl feature. So…at LEAST once every six months, call your service company to have them do preventative maintenance on your oven. Among the other things that technician might address during a PM, an inspection of the steam generator will be done. Based on that inspection, a chemical descaling will probably be necessary.
If the oven has been PMed at proper intervals, then scale buildup will be light. Descaling of the steam generator can easily be performed within a hour to an hour and a half.
If the oven’s regular maintenance needs have been neglected, scale buildup might be heavy. A chemical descaling will hardly put a dent in a heavily “rocked up” steam generator (see pictures below). Therefore, physically removing the scale will be necessary before chemically descaling it. Having to do so will add many labor hours and some parts to fulfill a descaling. Physically extracting scale will often require removal of the steam generator, some hammer-n-chiselling to break the scale up into smaller pieces….and maybe a shopvac. After all that, THEN a chemical descaling to finish it up.
MemberFebruary 22, 2020 at 7:27 am
Very good read
MemberFebruary 23, 2020 at 9:46 am
Agreed. I learned something.
MemberApril 30, 2020 at 2:02 am
I havent seen a rational that bad (Convotherms yes) but your spot on with your descriptions and analogies Ectofix, love your work!
MemberApril 30, 2020 at 8:35 am
We have twenty-seven Rationals, with half of them being old CPC and C-line ovens (think 1995).
Pictured was the steam generator out of our only CM unit (SCC-line). The three shifts of our in-room dining’s culinary staff let it chug away while empty. So, it ran 24/7 for over a year to achieve that condition.
I’ve since grilled them (REPEATEDLY) to quit doing that. I told them to simply leave the door open when no food is in it, thereby allowing the oven to do its automatic blow-down once it cools off.
MemberJuly 16, 2020 at 2:24 pm
Awesome explanation ectofix!
We also see Service 10 as one of the most common displayed errors of our customers.
Every customer uses the unit differently. Those who use the unit in continuous mode steam all day will see scale build-up because the sc-automotic ectofix described (every 2 hours on units after 2008-09, every hour units prior), will never be allowed to energize. This is because Rational does not want to disturb customers cooking. Unit door must be left open for a whole minute in this case before unit will attempt sc-automatic.
The Care tabs have a dual purpose of descaling steam generator and rinse cycle for interior cabinet.
Cleaning is critical also to prevent corrosion of the cabinet due to salts from foods and pitting by steam/chlorides in water. The stainless steel of the cabinet needs to be cleaned and dried to allow the chromium (passive) to reform.
<font face=”inherit”>Because of all these benefits, Rational recommends cleaning daily even if used in steam all day and the unit looks clean. My recommendation to our customers is clean daily after cooking in the smallest of clean cycles to save on chemicals (light or save program). This is especially for customers that do nothing but steam all day and skip cleaning because it still looks clean. For those customers doing high temp grilling/roasting will clean any way and use a higher level of </font>cleaning<font face=”inherit”> (medium or strong) because of grease and smoke. Those that don’t? Well, I’ve seen fires starting when they open the door and the fan wheel stops spinning. In this case, the door must be closed immediately, unit switched off and allow fire to die down.</font>
MemberMay 25, 2021 at 9:14 pm
Are you able to describe to me how to use/set up the rational descaling foot pump?
Log in to reply.