| My first question is what is the quality of your water? Is it soft or hard and if hard just "how" hard? Second question is what brand and model of water heater is installed? There are quality differences among the various brands.
Tankless water heaters and hard water do not play well together. They WILL build up mineral deposits in the heating pipes and that will reduce the flow rate through the heater and also reduce the capacity of the heater to raise the temperature to the desired level. Tankless water heaters REQUIRE periodic descaling and the frequency is determinate on the water quality.
Did the plumber (or previous homeowner) leave the operation and instruction manual for the unit? If not, you may be able to access the manual via the manufacturer's website.
It is also possible that your unit has an inlet screen that is partially plugged. The instruction manual would describe how to clean this if it is fitted. |