SDLtd
General Contracor
Our company is a general contracting and framing company and we built a spec home and sold it a year ago. We installed a tankless John Wood (Noritz) JWC111-DV NG hot water heater in the home. It worked fine until 3 months ago and since then our plumber has gone back maybe 8 times to fix it and is now stumped. The water temperature fluctuates from hot to warm and goes especially crazy when the toilet is flushed. This happens in all 3 showers and even in the laundry sink where the hot and cold inlets are separate. The John Wood customer service tech support thinks it is nothing to do with the tankless because I used a laser hand held temperature reader and pointed it at the outlet pipes of the unit and observed only a 4 degree F variation. One thing our plumber did discover is that the pressure from the main line and after the pressure reducing valve was coming into the house at over 90 PSI. He reset it to 70 PSI. This Noritz unit is supposed to be able to handle 150 PSI but do you think that this high intake pressure could have damaged the plumbing fixtures and their mixing valves? The plumber has flushed the lines (water is hard) and we believe we have eliminated the possibility of cross flow by turning off cold water to tankless and opening a hot water tap. Water flow stopped so all seals must be fine? Originally one of the toilets had a hot water line plumbed to it rather than cold but that was fixed a year ago. Anyway, do you think my handheld temperature machine would be reliable in this application? We will check the pressure after the PRV again. Please ideas would be appreciated. The homeowners are frustrated and our plumbers are out of ideas.