water temperature adjustment

Sometimes the shower works fine, and temperature control for the water is perfect. Other times, there IS no temperature control. The water comes out either all hot - or close enough that it doesn't make any difference - or super cold, and twisting the temperature control dial has no effect. Over...

Hi, I have NAVIEN NCB 240E combi in my house. Paragraph 3.2 says: The default space heating supply water temperature range is 104°F (40°C, Absolute MIN) to 180°F (82°C, Absolute MAX). ● The default space heating return water temperature range is 86°F (30°C, Absolute MIN) to 149°F (65°C...