China Custom Limit Disc Thermostat Control Switches Therm o-Disc

Snap Disc, or 3/4″ Limit switch thermostats are bimetal mechanical thermostats that function via the thermal expansion and contraction of a bimetal disc that “snaps” from a convex to a concave shape at a set temperature. carrying up to AC 110V/400V, 10A-60A amps-240 Volts.

L150-20 Heater Limit Thermostat Thermodisc Open On Rise

KSD302 SHL120 Heating Limit Thermostat Thermodisc with Flange Plate Adapter

KSD302R-453 Normally Open/Manual Reset 3/4″ Snap Disc Limit Control Switches

Limit Disc Thermostat Control switches are the same for different stoves, Electric ovens, electric water heaters, electric heaters, household appliances, motors, refrigeration or heating equipment. so to replace it cheap you just have to understand their function.

Why are they called Snap Discs Limit Thermostat is because they are round like a disc and have a Bi-Metal Strip that Snaps when heated to a certain temperature!

Most Limit Disc switches are SPST Thermostat single pole single throw. This means one wire in and one wire out. So when the temp rises the wires are connected which means the switch is closed ( Equipment power outage ).

It will also keep the fans running after the Electric oven / electric heater has been manually or automatically turned off until the exhaust temperature cools down. Unless it is like the Disc Thermostat which has another identical switch just like it to keep the fans running. Sometimes they have a part number with a designation F for Fan or L for Low Limit but don’t be fooled they are the same type of switch! After all you can test it with a continuity checker or ohm meter. When the switch is cold the meter should read open or infinity on the ohms scale and when heated above 140 Degrees F the switch will close and read a short or no ohms Usually a bad low limit switch means the Electric oven, electric heater stops running after the 15-20 min Electric oven, electric heater start-up cycle.

Also the part numbers for each Electric oven, electric heater manufacturer may differ.
Since most open when the exhaust temp drops below 140 degrees f the part number may be called L140 Also they close when the exhaust temp rises above 140 degrees f or 150 degrees f so they may be called F130 or F160 Let’s get real here folks these Limit Disc switches are not fully digital with precise accuracy!! So 130 or 160 may be within the specs of the bi-metal strip inside meaning there are the same switch!!

So in the pic here below is one that I found cheap. Note the physical mounting is usually the same with the mounting holes 2 inches apart. Most Electric oven, electric heater have a male quick disconnect terminal but some Electric oven, electric heater like YAXUN who make their own switch have screw terminals. However the screws can be removed and a clip can go on it but they do charge more for the extra unnecessary hardware!!

Application: Applicable to electrical equipment and household appliances with large power loads such as welding machines, water heaters, heaters, electric vehicle batteries, washing machines, refrigerators, sanitary ware thermostats, etc.

1. Electrical parameters: 1) CQC, VDE, UL, CUL. AC250V 50~60Hz 5A / 10A / 15A~60A (resistive load).
2. UL AC 125V 50Hz 15A (resistive load).
2. Operating temperature range: 0~240℃ (optional).
3. Recovery and operating temperature difference: 8~100℃ (optional).
4. Wiring method: plug terminal 250# (bend 0~90° optional); plug terminal 187# (bend 0~90° optional, thickness 0.5, 0.8mm optional).
5. Electrical strength: AC 50Hz 1800V for 1min, no flicker, no breakdown.
6. Contact form: Normally closed type: temperature rises, contact disconnects, temperature drops, contact connects; Normally open type: temperature rises, contact connects, temperature drops, contact disconnects.
7. Shell protection level: IP00.
8. Grounding method: connected to the grounding metal parts of the device through the metal shell of the thermostat.
9. Installation method: KSD302 series with movable ring, fixed ring, mounting plate movable ring, ordinary stainless steel cover with mounting holes.
10. Temperature operating range: -32℃∽+320℃.