5 KW Heat Strip With Circuit Breaker For 1.5 Ton - 5 Ton Universal Series Split System Air Handlers. Built-in circuit breaker ensures safety. Built-In Circuit Breaker: Yes. Universal air handler. MRCOOL heat kit is the compatible heat kit model for MRCOOL MDUI18024 and MDUI18036 capable of 15,001 BTU - 20,000 BTU of heating capacity to keep you comfortable through the winter months.