PH should represent the maximum heating output power and PL should represent the minimum heating output power. When this value is adjusted, the secondary pressure of the gas delivered to the machine will change accordingly. Simply put, the greater the numerical value, the greater the secondary pressure of the output gas and the hotter the combustion.

Do you have a pressure gauge? If so, just adjust the PH value and observe that the secondary pressure is between 1000- 1250 Pa, depending on your needs. PL value gas pressure value is between 100-250 Pa.

If there is no pressure gauge, it depends on the size of the flame. It is appropriate to see that the flame is close to one centimeter high at PL, and you feel that the flame is very high at PH, but the flame can no longer leave the flame and cannot reach the main heat exchanger above.

Good luck!