Tankless Water Heater DIY Warranty
 

Which manufacturers have the best support for those who DIY install thier tankless water heaters? Some brands void the warranty for DIY, others offer limited support. Would like real world experiences if possible.

That's an interesting question. I have only had to deal with Navien as a company. The other makes offered parts through the wholesaler and didn't get involved in the warranty much (maybe the issues I had were not warranty issues)

Navien forces you to phone them, try to resolve the issue over the phone or they send you the part. It has always been free even after the warranty period was over. Problem is that you have to be an installing contractor (or fake it).