Homeowner experiencing spurts of cold water when hot water is on. The homeowner previously had another plumbing company out who initially installed their tankless. Upon initial inspection, I found there were no check valves installed on the dedicated recirc line as well as the incoming cold line. I shutoff the dedicated recirc and turned the recirculation mode off at the unit. Then I tested for spurts of cold water and found no cold, but some spurts of less than constant hot water. I also found that the condensate line was done in pex and leaking at a fitting. I recommended installation of their 2 check valves as well as replacement of the condensate line with cpvc. The homeowner opted to call the company who installed the tankless for the recommended solution.