What is a HIGH LIMIT SAFETY SWITCH?
A high limit is a thermostat with a bi-metal disc inside that opens a normally closed contact (NC) on temperature rise. They are called snap disc switch, high limit temperature sensor, thermo-disc, thermal limit and much more.
Limit switches can be a real nuisance when troubleshooting a stove. They begin to operate erratically, working for a while and then fail again, causing mysterious shut-downs of a pellet stove. A smart serviceman will always replace those "little trouble-makers" on a service call!
How a pellet stove limit switch works:
A high limit switch is a safety switch with normally closed contacts; the contacts open at the highest allowable temperature and interrupt the power to the auger motor or the pellet stove control.
Wiring diagrams for fan and high limit switches and FAQs:
Free wiring diagrams and troubleshooting information about the fan and high-limit thermostat snap discs are included with your order! We carry hundreds of pellet stove manuals with schematics and tips on how to solve problems in your store - courtesy of PelletStove-Parts.com - partner of applianceandair.com
How to BYPASS a limit switch?
Every limit switch is a significant SAFETY element in your pellet stove; they are located at different places inside your heater to KEEP YOU, your FAMILY and your HOME SAFE!
If you bypass a limit switch, there is nothing else that prevents an overheated pellet stove from causing a house fire.
Why do professionals bypass a limit switch?
Limit switches have to operate under harsh conditions, exposed to high heat and power surges. They may fail prematurely and stop the heater from running.
Bypass a limit switch is a standard procedure to find a problem with a pellet stove, but this is done just for "testing purposes" while working on a pellet stove. Technicians don't use a paper clip or the like. Instead they connect a flat auto fuse to the two wires to find a problem on the heater.
Why does my limit switch have a small red button on the back?
Pellet stoves incorporate MANUAL RESET limit switches, they have a small button on the back of them. After reaching the highest acceptable limit temperature, the switch trips and will stay in OFF position until a technician reset it.
They are the last safety element in a system; if they interrupt the power supply there is something wrong, fan motor problem, air flow restricted and so on - please read on how to solve an overheating problem on our instruction sheets (included with your purchase!)
An automatic limit switch will open the contacts and interrupt the power if the stove gets too hot,
they will resume power once the heater has cooled down again.
Information: Most pellet stoves have more than one high limit switch, sometimes an automatic reset and one manual reset switch.
