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  1. #1
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    Rational scc102e steam generator is losing water.

    In the middle of cooking the oven will stop and refill steam generator. This happens on a regular basis. Descaled and looks good. Greased pins to eprom. Reset drain valve and flapper. I don't see any evidence of external leaks. Oh and there r no codes. Every thing seems to be working fine. But it refills too often to not have a problem. Any help would greatly appreciated.

  2. #2
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    Thread Starter
    Let me clarify. The water faucet symbol with a question mark will flash. I think it comes on after so many seconds of trying to fill the steam generator. So maybe I have water pressure issue?

  3. #3
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    Several things to check.

    Solenoid inlet screens and the solenoids themselves.
    Inlet pipe into boiler
    Incoming water pressure (dynamic and static)
    Water level probe.

    If you are having water faucet show up then the boiler is taking too long to fill.

    By far the hardest to fix and find is the boiler inlet pipe being scaled. Since it is at the bottom the easiest solution if you have time is to remove boiler(make sure you have steam hoses) and. Clean through the SC pumo hole using a long screwdriver or length of pipe to break up the scale.

  4. #4
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    I'm going to throw this suggestion/question out there like I think I might have an idea. But, puh-LEASE...if I'm INCORRECT in my thinking, then correct me. I didn't go to skool on these.

    Now, I've done repairs and a thorough rejuvenation on our older Rationals (we got some 20+ year-old ones) when, while doing an op test in steam mode, I observed the steam generator heat the water to a point that it'd spew the water out of the generator and into the cooking compartment. Then the heat contactors opened (yes...OLD units) and the water control commenced to refilling the generator. As the water probe satisfied, it'd reheat the water again and, after a few minutes, it'd once again spew the water out into the cooking compartment. Over and OVER again.

    NOW...presently my feeble brain can't pin down anything in the manuals about the BOILER ('xcuse...uh...GENERATOR) thermocouple's PURPOSE...other than to find a fleeting explanation in an SCC manual that the GENERATOR thermocouple merely senses when an appropriate temperature is reached to start the cook timer. I can't seem to find anything saying it CONTROLS generator temperature.

    H-O-W-E-ver...when I was new on these and before I'd bothered to search out & read that, MY thinking was that the generator had BOILED OVER into the compartment due to a faulty generator temperature thermocouple.

    Each of those occasions that I'd observed that, I replaced the generator thermocouple and the problem went away.

    In a SCC102, with the potential to pound 37kW of heat energy at a mere 2 1/4 gallons of water in order to generate STEAM, I just thought it'd be plausible that, if the elements go unregulated by something monitoring the temperature and then turn off the HEAT, then the boi...uh...STEAM GENERATOR might just boil over into the cooking compartment.

    I just thought this was a possible cause of Ben's problem. OH...and Ben, those temperature probes in the oven are type K thermocouples, so no crossing anything to charts...which you really can't do ANYWAY with thermocouples. The actual temperature an oven probe is seeing should translate just fine in DEGREES on your Fluke or whatever digital multimeter you're using. Just be sure to isolate for good measure.

    I guess I should ask my question or those that might know better: Does generator thermocouple B5 have anything to do with regulating water temperature within the generator?
    Last edited by ECtofix; 03-21-2016 at 06:53 PM.
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  5. #5
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    Quote Originally Posted by benmechanic View Post
    Let me clarify. The water faucet symbol with a question mark will flash. I think it comes on after so many seconds of trying to fill the steam generator. So maybe I have water pressure issue?
    So I missed your later post.

    The book calls for 3/4" water inlet (I think). However, we have 3/8" John Guest tubing feeding several of ours. I don't recommend that and I'm intending to correct it where it appears to be a problem for us.

    In your case, I'd be looking into a water supply issue as Protocol suggested. A clogged Y-strainer or filter feeding the oven. As filter should be replaced at least every six months. ESPECIALLY id the quench water is also being fed through the filter.
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  6. #6
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    >Let me clarify. The water faucet symbol with a question mark will flash. I think it comes on after so many seconds
    >of trying to fill the steam generator. So maybe I have water pressure issue?

    Water flow problem.

    >By far the hardest to fix and find is the boiler inlet pipe being scaled.

    Protocol is correct. Guaranteed.

    What we do is remove the boiler, pull the elements, run various flexible utensils down that absolutely stupid fill elbow on the boiler, and physical descale all over, followed by an overnight soak in descale solution, flooding the lower boiler and that elbow.

  7. #7
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    First check the water level probe for scale.

    Water inlet solenoid might not be opening, or screen is plugged.

    The water inlet pipe might be scaled up at the outlet inside the generator. What I have done a couple of times is empty the generator, remove the SC pump, and if you look inside the generator through that hole you can see if the water inlet pipe is scaled. I have used a long I believe its a 3/8" drill bit and drilled out that scale by going through the generator drain outlet.

  8. #8
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    Thread Starter
    Thanks for all the reply's. I'm glad to be know I'm going in the right direction. Long story short( new filter, clean screens, clean and checked water probe) I cleaned and check the outlet tube on the bottom of the steam gen. This is an intermittent problem. I have some concerns about what the filter "holder". Seems like it takes too long for the pressure to build back up. Probably order a y1 fill solenoid too. as for ECtofix I don't see any evidence of over heating the steam, but I sure will look into that further. Will post back in acouple days THANKS

  9. #9
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    Have never had the boiler over boil water and have had to replace an ntc maybe once.

    I would suspect a self test to reset boiling point would fix the issue as that determines boiling point of where the unit is located.

    Based on serial and whether your unit has care control you will either want a dual or triple solenoid. At this point I will also usually rip off the quench box cover. It's about an extra minute to check if the orifice is washed out and it'll save me a future service call down the road.

    It's good that you've already cleaned out the elbow leading into the boiler. I usually find the worst spot is right after the curve where rigid tools won't go. Hopefully you've used something to chase the line or have cleared it from inside the boiler as well.

  10. #10
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    Quote Originally Posted by Protocol. View Post
    Have never had the boiler over boil water and have had to replace an ntc maybe once.

    I would suspect a self test to reset boiling point would fix the issue as that determines boiling point of where the unit is located.
    That's why I sorta questioned it as I suggested it. It happened mostly on our old Rational C-Line ovens. As old as they are, I don't think they'll do a self-test.

    Quote Originally Posted by Protocol. View Post
    I usually find the worst spot is right after the curve where rigid tools won't go. Hopefully you've used something to chase the line or have cleared it from inside the boiler as well.
    I didn't even think about that confounded fill port, although I've had to clear them several times on units that resembled a rock quarry inside.

    I'm not saying this is the perfect tool, but I've ALWAYS kept a few of these handy to clear out passages. It goes to town on grease or scale when driven by the power of an electric drill:
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  11. #11
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    I'm lucky to have seen a c-line only a few times.

    I also carry a bunn deliming spring. Those damn things are dead useful. I have also taken a cheap plumbing snake and cut off the large diameter end if I need something with a bit more power. Those seem to be more useful for Altoshaam combi ovens.

  12. #12
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    Quote Originally Posted by Protocol. View Post
    I'm lucky to have seen a c-line only a few times.

    I also carry a bunn deliming spring. Those damn things are dead useful. I have also taken a cheap plumbing snake and cut off the large diameter end if I need something with a bit more power. Those seem to be more useful for Altoshaam combi ovens.
    Have you checked the venting valve( like a check valve) on the steam generator fill hose up behind the steam generator? |If it is stuck open water will bypass as it is trying to fill and will take a lot longer causing the water light to come on. check for water going down the drain as the fill solenoid is activated, this is the clue. ( something to consider if you know you have good pressure coming out of your fill valve)

  13. #13
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    Is the supply water softened? The water probe/ level control system on that unit is way advanced, like NASA smart lol. Rational recommends the SCC to NOT have softened water. The probe has a hard time reading softened water. So if it's having a hard time reading it then it may fill more than necessary.

    If it is softened you can change the parameters to "softened water" in the service menu.

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