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John, restaurant equipment technician
Category: Appliance
Satisfied Customers: 2136
Experience:  25+ years experience. I'm now employed by a commercial cooking equipment service company
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I have a thermador professional rangetop that I just bought

Customer Question

I have a thermador professional rangetop that I just bought used. on installation, the two left burners have no gas and no spark, the other four burners and griddle all work, tho the flame is uniformly low on all of them. They will boil water or fry an egg, but it takes much too long to do each task due to the low flame
JA: How long has this been going on? And how severe is the problem?
Customer: I have only had it hooked up 2 days. No idea of prior history as i bought it six month ago when starting renovation. To boil 2 inches of water on any of the burners might take twice as long as expected
JA: Do you plan on doing the work yourself?
Customer: Probably. I've already disassembled the burner heads, cleaned the igniter connectors, examined the simmer controller etc.
JA: Anything else we should know to help you best?
Customer: not that I can think of, except the simmer controller has been superceded by a new model. If I have to swap that, I have to swap the potentiometers too. I believe but am not sure that my two non-functioning burners have XLO
Submitted: 12 months ago.
Category: Appliance
Expert:  Kelly replied 12 months ago.

Hi, welcome to Just Answer. Sorry to hear you are having appliance trouble, I know how frustrating that can be! My name is ***** ***** I look forward to helping you!

  • I suspect the unit may be set for LP and the regulator is adjusted incorrectly. Is it set for LP and what fuel are you using?
  • May I please have your model number so I am able to provide you with accurate, model specific information?


Customer: replied 11 months ago.
That might account for low flame/pressure but how about no gas or spark on burners 1 and 2? I don't know what prior owner used. I use natural gas. Model number not available
Customer: replied 11 months ago.
How would I check for propane? How much bigger is orifice?
Customer: replied 11 months ago.
Are you there? How can I check if it's set for propane? Unit is a Professional series about ten years old but don't have model number
Customer: replied 11 months ago.
Model psc486gl
Expert:  Kelly replied 11 months ago.

Are you hooked up to LP or NG fuel supply?

Customer: replied 11 months ago.
I use natural gas. Model is psc486GD. 4 burners on left, then griddle, then two burners. Two burners that don't work have XLO feature. I would be surprised if prior owner used propane. However, it was in a different house, not mine.
Customer: replied 11 months ago.
I will try to check the regulator for the setting. I understand the cap just needs to be looked at to see if it is set for NG or LP.
Expert:  Kelly replied 11 months ago.

I will place your question back to the list for others to see.

Expert:  John replied 11 months ago.

Hi, I'm John. If the previous owner was using propane the gas regulator needs to be set up for natural gas use. On dual fuel regulators, it's just a matter of changing the setting. If you have a single use propane regulator, you'll need to replace it with a natural gas regulator. The gas orifice holes for propane are half the size of those needed for natural gas use. This requires the installation of a conversion kit. I will see if I can locate a kit for you, and I'll get back to you. If, after installing the correct size orifices, you still have lighting problems, the ignitor wires will probably need to be adjusted for the strongest spark.

The burner orifices are available at You'll need to call them at(###) ###-####to get the part number for natural gas use. If I may be of further help, please let me know.

Customer: replied 11 months ago.
John - I already am switching to NG. The problem with two burners remain as described. I have ordered a new set of potentiometers and a simmer control unit
Expert:  John replied 11 months ago.

OK. Thank you.

Customer: replied 11 months ago.
John - I'm not sure if you can see prior answers on your end, but another expert responded earlier and told me about checking for propane. I did call but they have no info as thermador apparently doesn't give any info on replacement jets. I went back to Thermador and they are looking into what is needed to convert back. I don't know for certain about my problem with the two XLO burners that have no gas and no spark, but I suspect its the potentiometers and/or the simmer control module. There is no juice to the solenoid, hence my diagnosis. The potentiometers and control module are on order.
Customer: replied 11 months ago.
I changed the potentiometers, but no change. Waiting for backordered simmer module

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