Ventilation Louvres

Hi we have a tankless heater ( neckar JSD 20-Y/ASO ) powered by natural gas. When I switch it on the hot water?

runs normally but when I try to add some cold water the hot water stops running and I have to switch it off and then switch it on again. The heater is new, and we put it outside in the laundry laundry area so there's plenty ventilation. Thank you

Public Comments

1. To me, it sounds like you have a water pressure issue. The tank-less has a sensor in the water line that allows the tank to turn on when there is sufficient flow and pressure. It sounds like the pressure drops below the safety switches set point when you turn the cold water one. Some of these switches are adjustable. You may be able to readjust the switch down a little so that it stays on when you turn on the cold water tap. For safety, I would suggest that you have a professional adjust it. Real low water flow going through the tankless while it is on will create very hot water, so beware! If your house has a water regulator on the incoming water line, then you might consider turning up the pressure on that regulator.
2. tankless wate heaters are a bit more tricky, normally the temperature is preset by the installer or in some cases, the manufacturer, therefore adding cold water to the already preset temperature can cause an issue. on a tankless water heater, the temperature should remain constant when opening the hot water side on faucets, you shouldnt have to temper down the water. if its new, i suggest recalling the plumber who installed it and have them recheck the system , should be under warranty if anything is a matter with the unit itslef...........
3. It sounds like there is a plumbing issue that is allowing the hot and cold water to back-feed into the tankless unit. This will prevent the water from flowing. If the faucet is a single lever (does not have separate hot and cold handles) there could be some buildup that is causing the faucet to malfunction.