In winter, when you leave the house and have boiler set on “wehchul” (외출) or on very cold days, you should set the boiler temperature a little higher to prevent the boiler pipe from bursting.
If you go out with the temperature turned off completely, there is a danger of the boiler bursting. (If you go out for a long time, inform the realtor or the landlord.)
Other ways to reduce the gas bill of the boiler for the winter is by attaching an air cap (purchased from a supermarket or Daiso) to the windows. By doing this you can minimize changes of the home temperature.

When there is a problem with the basic facilities for life in the leased house, the duty to repair lies with the lessor. However, if the problem is caused by the lessee’s negligence, the lessee has the duty to repair. When the lessor does not repair it, the lessee can ask the lessor for reimbursement for the repair. Repair fees of depends on the period of use of each boiler.