Add tempering tank. Tempering tank made from old tank-type water heater, or small tank heater will passively heat incoming water. http://waterheatertimer.org/Tempering-tank.html
This works because tankless can only raise temperature so many degrees. If water is very cold, tankless cannot keep up, so the sensors shut down the unit. Passively preheating water... or using a small tank connected to power can preheat water enough so tankless works. Also delime tankless each year will help remove natural scale that builds up inside tankless heat exchanger. http://waterheatertimer.org/How-to-delime-tankless-water-heater.html
Gene
Water Heater Timers Save Money
If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7
Answers & Comments
Add tempering tank.
Tempering tank made from old tank-type water heater, or small tank heater will passively heat incoming water.
http://waterheatertimer.org/Tempering-tank.html
This works because tankless can only raise temperature so many degrees. If water is very cold, tankless cannot keep up, so the sensors shut down the unit.
Passively preheating water... or using a small tank connected to power can preheat water enough so tankless works.
Also delime tankless each year will help remove natural scale that builds up inside tankless heat exchanger.
http://waterheatertimer.org/How-to-delime-tankless-water-heater.html
Gene
Water Heater Timers Save Money
If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7