LOCKOUT CIRCUIT WITH MANUAL RESET FOR RECREATIONAL VEHICLE HEATER
A lock-out circuit for preventing over-heating of a recreational vehicle heating system includes a temperature limit switch and a lock-out relay. The temperature limit switch is electrically coupled with the heating system and is operable to open when its temperature exceeds a threshold temperature and to reset and close when its temperature drops below the threshold temperature range. The lock-out relay has a contact electrically coupled with the temperature limit switch and a high impedance relay coil electrically coupled with the heating system in parallel with the temperature limit switch. The temperature limit switch and the lock-out relay remove substantially all power to the heating system when the temperature limit switch opens and re-establish power to the heating system only after the temperature limit switch has reset and voltage is at least temporarily removed from the lock-out relay.
1 . A heating system for a recreational vehicle, the heating system comprising:
an electrical heating element;
a fan for passing air over the electrical heating element and into the recreational vehicle;
a relay system for switching power to the heating element and the fan;
a controller including switches and a thermostat for triggering the relay system; and
a lock-out circuit for preventing over-heating of the heating system, the lock-out circuit comprising—
a temperature limit switch electrically coupled with the electrical heating element and operable to open when its temperature exceeds a threshold temperature range and to reset and close when its temperature drops below the threshold temperature range; and
a lock-out relay having a contact electrically coupled with the temperature limit switch and a high impedance relay coil electrically coupled with the heating element in parallel with the temperature limit switch;
the temperature limit switch and the lock-out relay operable to remove substantially all power to the electrical heating element when the temperature limit switch opens and to re-establish power to the electrical heating element only after the temperature limit switch has reset and voltage is at least temporarily removed from the lock-out relay.
2 . The heating system of claim 1 , wherein an impedance of the relay coil of the lock-out relay is at least one hundred times a resistance of the electrical heating element.
3 . The heating system of claim 1 , wherein the contact of the lock-out relay is a normally closed contact.
4 . The heating system of claim 1 , wherein the electrical heating element is an electric resistance heating element.
5 . The heating system of claim 1 , wherein the electrical heating element is part of an air conditioner.
6 . The heating element of claim 5 , wherein the electrical heating element is an electric resistance heating element.
7 . The heating system of claim 1 , further including an evaporator coil, a condenser coil, and a compressor pump for pumping refrigerant gas between the evaporator coil and the condenser coil.
8 . The heating system of claim 7 , wherein the relay system includes a heating element relay, a fan switch relay, a fan speed relay, and a compressor pump relay.
9 . A lock-out circuit for preventing over-heating of a recreational vehicle heating system, the lock-out circuit comprising:
a temperature limit switch configured to be electrically coupled with the heating system and operable to open when its temperature exceeds a threshold temperature and to reset and close when its temperature drops below the threshold temperature range; and
a lock-out relay having a contact electrically coupled with the temperature limit switch and a high impedance relay coil configured to be electrically coupled with the heating system in parallel with the temperature limit switch;
the temperature limit switch and the lock-out relay operable to remove substantially all operating power to the heating system when the temperature limit switch opens and to re-establish power to the heating system only after the temperature limit switch has reset and voltage is at least temporarily removed from the lock-out relay.
10 . The lock-out circuit of claim 9 , wherein an impedance of the relay coil of the lock-out relay is at least one hundred times a resistance of an electrical heating element of the heating system.
11 . The lock-out circuit of claim 10 , wherein the contact of the lock-out relay is a normally closed contact.
12 . The lock-out circuit of claim 11 , wherein the heating element is an electrical resistance heating element.
13 . The lock-out circuit of claim 10 , wherein the heating element is an electrical resistance heating element.
14 . The lock-out circuit of claim 9 , wherein the heating system is part of an air conditioner.
15 . A heating system for a recreational vehicle, the heating system comprising:
a electrical heating element;
a fan for passing air over the electrical heating element and into the recreational vehicle;
a relay system for switching power to the electrical heating element and the fan;
a controller including switches and a thermostat for triggering the relay system;
a roof-top enclosure for housing the electrical heating element and the fan; and
a lock-out circuit positioned in the enclosure for preventing over-heating of the heating system, the lock-out circuit comprising—
a temperature limit switch electrically coupled with the electrical heating element and operable to open when its temperature exceeds a threshold temperature range and to reset and close when its temperature system drops below the threshold temperature range; and
a lock-out relay having a contact electrically coupled with the temperature limit switch and a high impedance relay coil electrically coupled with the electrical heating element in parallel with the temperature limit switch;
the temperature limit switch and the lock-out relay operable to remove substantially all power to the electrical heating element when the temperature limit switch opens and to re-establish power to the electrical heating element only after the temperature limit switch has reset and the controller has been operated to at least temporarily remove voltage from the lock-out relay.
16 . The heating system of claim 15 , wherein an impedance of the relay coil of the lock-out relay is at least one hundred times a resistance of the electrical heating element.
17 . The heating system of claim 15 , wherein the contact of the lock-out relay is a normally closed contact.
18 . The heating system of claim 15 , wherein the electrical heating element is in an electrical resistance heating element.
19 . The heating system of claim 15 , further including an evaporator coil, a condenser coil, and a compressor pump for pumping refrigerant gas between the evaporator coil and the condenser coil.
20 . The heating system of claim 19 , wherein the relay system includes a heating element relay, a fan switch relay, a fan speed relay, and a compressor pump relay.