Only Hot Water In House . This is one of lemon's few intelligible postings. If you adjust the thermostat and the water temperature remains the same, the problem may be a broken or faulty thermostat. Central heating boiler installation in Chester NGas Heating Solutions from www.n-gas.co.uk Your next move is too see if your burner ignites. To do this, you’ll want to start by turning the burner off and set your home’s thermostat to 120 degrees. If the dip tube mechanism is broken, you may have cool.