With almost 300 comments on our Repairing Commercial Fryers post, we figured it was time to get a video out there to better illustrate how easy it can be to fix a fryer yourself. In this video, Chris Tavano, walks you through calibrating the thermostat, bypassing the hi-limit, taking out the thermopile, taking out the combination safety gas valve, and other troubleshooting tips for commercial fryers. Please note, before fixing any kitchen equipment, you should ensure the power and/or gas is off first (in the example below, you’ll calibrate the thermostat before turning off power and gas).
Hello, welcome to Tundra Restaurant Supply. I’m Chris Tavano and I’m here to troubleshoot some fryer maintenance today. Common problems we tend to see are thermostat controls and calibration; in other words, your pilot light won’t stay lit, your burner won’t ignite, your oil is too hot or is too cold. A lot of common problems associated with that are the gas burner safety valve, as well as, the hi-limit control and thermopile [Chris said thermopiler, but it is indeed formally called a thermopile]. Today, we will be using our Frymaster MJ35 for our example maintenance.
Calibrating the Thermostat: Checking the Oil Temperature Against the Fryers Thermostat
Alright, so first thing we’re going to talk about is the thermostat and how to calibrate the thermostat to help calculate exactly what the problem is. So, a lot of times you’ll have your thermostat, and your hi-limit shutoff is around 450⁰.
So, what you want to do is set your thermostat to 350⁰, get a thermometer and put it in the oil basin itself, and you want to make sure that, that comes up to the temperature of 350⁰. At the same time, when that temperature has reached on the thermometer, you’re going to lower your thermostat down to about 250⁰ until it clicks off. And then you’re going to turn it slightly up, and let the oil cool down. And when that valve kicks back on for the fire, you’re going to make sure that, that temperature on your thermostat is also what’s reading in the thermometer that’s sitting in the oil.
Once you’ve identified the problem of your thermostat being off from the actual fryer oil temperature, the first place to look is your hi-limit switch. And what the hi-limit does is a safety precaution saying that it’s going to turn off your fryer at exactly 450⁰, and never go higher than that.
What we’re going to do in here is, you take your two-wires that go to your hi-limit switch, and we’re just going to unscrew them, and switch them in place to bypass that [we’re bypassing the hi-limit switch here]. We’re going to take the one that gives us the source to the thermopile. This one is our actual limit, and we’re just going to bypass it and go instead to the thermopile. Really, all you need to do is get the one that connects back to the thermopile so we have a constant source again of that flame.
Alright, if you found out that your hi-limit switch is not the problem, the next place to look is your thermopile. A thermopile converts your thermal energy into electrical energy. It is the source of your thermostat.
Back in this corner here we have our pilot light and our thermopile. The thermopile is the rod that is connected to this snaked wire. Takeout [usually unscrew] the probe itself and there’s your thermopile. [The thermopile needs to be checked for corrosion or broken wires and replaced if damaged.]
If you’ve found out that the hi-limit and thermopile are not the culprit of your thermostat controls, the next place to look is the combination safety gas valve. That is not an easy thing to replace, it is not a quick thing to replace, and it’s not necessarily cheap, but it is something that needs to be done, and it’s much better than buying a whole new fryer itself.
If you look at this particular model, the whole unit of the [combination] safety gas valve itself cannot be removed from right here, so what you’re going to do is find your closest joints. Unscrew those, and your other one right here. And your actually going to pull out the entire device with all of the component pipes associated with it. Once you pull that out, you can replace these pipes [take the pipes off of the combination safety gas valve] so that way you have the actual safety gas valve itself. And then you can get that replaced, you can hook it back up to your previous pipes, and then again, you can screw that back on to the actual gas lines themselves.
Alright, so your last troubleshooting tip would be the thermostat itself. If you find that you’ve gone through all of that stuff, and your pilot light is staying lit, but however, you aren’t holding temperature through what you had calibrated earlier, and it’s not being consistent, odds are the thermostat itself is bad and needs to be replaced.
Other Common Problems
Alright, so other common problems to try and troubleshoot with your fryer tend to be [small] explosions, it’s too hot or metal fatigue. A lot of times, you’ve got to check the basin of your fryer itself, and make sure that there are no thin spots, worn out spots or any holes within the basin. If that exists, you have to get a new fryer.
Other places you need to look are in your exhaust manifolds and in the flume burners themselves. A lot of times they get caked with grease and excess runoff, and over time, those just don’t get cleaned out the same way that the oil basin itself gets cleaned. So you’re going to want to check those on a monthly or quarterly basis, and try to clean out the soot. If it’s caked in there, odds are you might need a new fryer as well.
Another common mistake is liquid propane to natural gas conversions. Those are one-way valves, so to convert from natural gas to liquid propane, there’s one valve for that. To go from liquid propane to natural gas, there’s a different valve for that.